DEPARTMENT OF THE INTERIOR 

UNITED STATES GEOLOGICAL SURVEY

GEORGE OTIS SMITH, DIRECTOR

BULLETIN 426

GRANITES OF THE SOUTHEASTERN 

ATLANTIC STATES

- BY

THOMAS LEONARD WATSON

WASHINGTON

GOVERNMENT PRINTING OFFICE

1910
b';)

Jl
CONTENTS.

Page.

Introduction............................................................. 13

CHAPTER I. GRANITE IN GENERAL .......................................... 16

Scientific discussion.................................................. 16

Definition ....................................................... 16

Mineral composition.............................................. 16

Chemical composition............................................ 18

Texture ......................................................... 19

Physical properties................................................ 20

Color........................................................ 20

Weight...................................................... 20

Strength...............................^..-.-..-...------.-- 21

Hardness.................................................... 21

Porosity.......................................... 1.......... 21

Varieties of granite............................................... 22

Structure........................................................ 22

Rift and grain................................................ 22

Joints ..................................... f ................. 23

Occurrence .............................................. 23

Vertical joints ........................................... 24

Horizontal joints......................................... 24

Slickensides ............................................. 25

Rock variations.................................................. 25

Dikes ....................................................... 25

Acidic dikes.......................s......... ............ 25

Basic dikes............................................... 28

Quartz veins................................................. 29

Basic segregations (knota).................................... 30

Inclusions .................................................... 30

Minerals on joint faces........................................ 31

Weathering ...............................................'....... 32

Distribution of the granitic rocks ....................... 1.............. 34

Coastal Plain..................................................... 34

Piedmont Plateau................................................ 35

Appalachian Mountains............................................ 37

CHAPTER II. GRANITES OP MARYLAND ...................................... 39

The Maryland Piedmont region....................................... 39

Distribution of the granites............................................ 40

Scientific discussion .................................................. 41

Varieties of the granite ........................................... 41

Mineral composition.............................................. 41

Chemical composition ............................................ 42

Structural features................................................ 43

Joints..............:..-..................................... 43

Schistosity................................................... 44

Dikes........................................................ 44

Granite.................................................. 44

Pegmatite ............................................... 45

3

102395
4 CONTENTS.

CHAPTER II. GRANITES OF MARYLAND Continued. PageScientific discussion Continued. 

Structural features Continued.

Quartz veins................................................. 46

Inclusions................................................... 46

Basic segregations (knots)..................................... 47

Physical tests .................................................... 48

Absorption tests.............................................. 48

Miscellaneous tests ........................................... 49

Individual quarry areas................................................ 50

General statement................................................. 50

Granites......................................................... 51

Ellicott City area............................................. 51

General statement........................................ 51

Descriptions of quarries................................... 51

Baltimore County .................................... 51

Howard County........................:............. 53

Guilford area................................................. 54

General statement........................................ 54

Descriptions of quarries................................... 54

Woodstock area.............................................. 56

General statement .......... ............................ 56

Descriptions of quarries .................................. 57

Port Deposit area ............................................ 59

Frenchtown area............................................. 61

Minor granite areas .......'.............-.......-............. 62

Dorseys Run area ........................................ 62

Sykesville area........................................... 63

Garrett Park-Brookville area.............................. 64

Franklinville area........................................ 65

Benson and Baldwin station .............................. 65

Texas area............................................... 66

Relay area............................................... 66

Gneisses................ ....................................... 66

Introductory statement....................................... 66

Jones Falls quarries .......................................... 67

Gwynns Falls quarries........................................ 68

Other gneiss quarries......................................... 69

CHAPTER III. GRANITES OF VIRGINIA ...................................... 70

The Virginia Piedmont region ......................................... 70

Distribution of the granites ........................................... 70

Scientific discussion ................................................... 71

Mineral composition......r .................... ............... 71

Chemical composition............................................ 72

Kinds of granite .................................................. 72

Nature of the granite outcrops .'..................-....-.....-..... 73

Even-granular granites ........................................... 73

- Medium gray biotite granite of the Richmond-Petersburg area.. 74 

Dark blue-gray biotite granite of the Richmond-Fredericksburg

area....................................................... 76

Light-gray muscovite granite of the Fredericksburg area........ 76

Dark gray hornblende-biotite granite of the Falls Church area.. 77

Yellow-green and pink epidote granite Unakite............... 77
CONTENTS. 5

CHAPTER III. GRANITES OP VIRGINIA Continued. PageScientific discussion Continued.

Porphyritic granite.............................................. 78

Gneisses......................................................... 79

Introductory statement....................................... 79

Gneiss of the Richmond-Fredericksburg area.................. 80

Gneiss of Lynchburg, Va...................................... 81

Gneisses of Fairfax and Alexandria counties ..................." 81

Other gneiss areas............................................ 82

Structural relations in the Richmond-Fredericksburg area .......... '82

General statement............................................ 82

Contacts..................................................... 82

Apophyses................................................... 83

Inclusions ................................................... 84

Basic segregations (knots)...................................... 84

Joints....................................................... 84

Dikes ....................................................... 85

Aplites.................... .............................. 85

Pegmatites............................................... 86

Individual quarry areas. ............................................... 88

Petersburg area.................................................. 88

General statement............................................ 88

Descriptions of quarries ...................................... 89

Richmond area .................................................. 92

General statement............................................ 92

Kinds of granite ............................................. 93

Structural features ...... ..................................... 93

Mineral composition.......................................... 94

Descriptions of quarries....................................... 95

Chesterfield County (south of James River)................ 95

Henrico County (north of James River)................... 103

Fredericksburg area............................................... 106

Introductory statement....................................... 106

Descriptions of quarries....................................... 106

Fairfax County area ............................................... 108

Introductory statement.....:.................................. 108

Descriptions of quarries....................................... 108

Falls Church and vicinity................................. 108

Annandale and vicinity................................... 109

Blue Ridge region................................................. 110

General discussion of the granites ............................. 110

Unakite ..................................................... Ill

Area in Nottoway and Prince Edward counties..................... 1.12

Charlotte County................................................. 112

Fluvanna and Goochland counties................................. 112

Lunenburg County ............................................... 113

Prince William. County............................................ 113

Other granite areas............................................... 114

CHAPTER IV. GRANITES OF NORTH CAROLINA .............................. 115

Distribution of the granite............................................ 115

Scientific discussion .................................................." 115

Kinds of granite ...................................... ........... 115

Mineral composition...................'.............. ............ 11(3
6 CONTENTS.

CHAPTER IV. GRANITES OF NORTH CAROLINA Continued. PageScientific discussion Continued.

Chemical composition ............................................ 116

Structural features ................................................ 117

Joints....................................................... 117

Basic segregations (knots) .................................... 117

Dikes...-................-...-.....-.---....---.--..--...--.. 118

Basic igneous dikes....................................... 118

Granite dikes ............................................. 118

Pegmatites............................................... 119

Aplites.................................................. 120

Quartz veins................................................. 120

Relationship between the jointing and the basic dikes .......... 120

Individual quarry areas .............................................. 121

Even-granular granites ........................................... 121

Distribution ................................................. 121

Coastal Plain granites ........................................ 121

General statement........................................ 121

Descriptions of quarry areas............................... 122

The Contentnea Creek area ........................... 122

The Elm City (Toisnot) area........................... 123

The EockyMount and Spring!)ope area................ 123

Piedmont Plateau granites .................................... 124

General statement........................................ 124

Northeastern Carolina granite belt ........................ 124

Introductory statement............................... 124

Franklin County ..................................... 125

Granville County .................................... 125

Vance County......................................... 125

Greystone area................................... 126

Middleburg area ................................. 128

Wake County........................................ 129

Raleigh area..................................... 129

Wyatt-Rolesville area ............................ 131

Warren County ...................................... 131

Summary of granites'of Northeastern Carolina belt..... 132

Metamorphic slate and volcanic belt....................... 132

Carolina igneous or main granite belt...................... 133

Introductory statement................................. 133

Gaston County....................................... 134

Mecklenburg County................................. 134

Charlotte area.................................... 135

Morning Glade Church area....................... 136

Davidson area.................................... 136

Cabarrus County..................................... 137

Rowan County....................................... 137

Dunns Mountain area............................. 137

Woodleaf area.................................... 143

Iredell County....................................... -143

Davidson County..................................... 144'

Davie County........................................ 145

Forsyth County..............i...................... 145

Guilford County ..................................... 145

Brown Summit area ....._........................ 146
CONTENTS.

CHAPTER IV. GRANITES OF NORTH CAROLINA Continued. 

Individual quarry areas Continued. 

Even-granular granites Continued.

Piedmont Plateau granites Continued.

Carolina igneous or main granite belt Continued. 

Guilford County Continued.

Summerfield area................................. 146

Friendship area .................................. 146

Jamestown area .................................. 146

Greensboro area.................................. 147

Alarnance County .................................... 147

Western Piedmont gneiss and granite belt.................. 148

Introductory statement............................... 148

Granite.............................................. 148

Surry County .................................... 148

Wilkes and Alleghany counties.................... 152

Gneiss............................................... 152

Appalachian Mountain granites....................... : .-. - .. 153

General description ...................................... 153

Carolina gneiss........................................... 154

Roan gneiss.............................................. 155

Cranberry granite ........................................ 155

Blowing Rock gneiss...................................... 156

Beech granite ............................................ 156

Max Patch granite........................................ 156

Unakite ................................................. 157

Henderson granite........................................ 159

Whiteside granite ........................................ 160

Summary of the granites of the mountain region........... . 160

Porphyriticgranites...............................:.............. 161

General statement............................................ 161

Microscopic characters........................................ 161

Coastal Plain porphyritic granites ............................. 162

Anson and Richmond counties ........................ 162

Franklin County..................................... 164

Piedmont Plateau porphyritic granites......................... 164

General description ...................................... 164

Description of individual areas............................ 165

Gaston County....................................... 165

Iredell County....................................... 166

Cabarrus County..................................... 167

Rowan County....................................... 168

Davidson and Davie counties.......................... 168

Forsy th County...................................... 169

Guilford County ..................................... 169

CHAPTER V. GRANITES OF TENNESSEE. ...................................... 171

CHAPTER VI. GRANITES OF SOUTH CAROLINA ................................ 172

The South Carolina crystalline region.................................. 172

Distribution of the granites............................................. 173

Scientific discussion .................................................. 173

Mineral composition.............................................. 173

Chemical composition............................................ 174

Types of granite.................................................. 175

.General statement............................................ 175
8 CONTENTS.

CHAPTER VI. GRANITES OF SOUTH CAROLINA Continued. Page. 

Scientific discussion Continued. 

Types of granite Continued.

Even-granular granite ........................................ 176

Porphyritic granite............................................ 177

Granite gneiss................................................ 177

Structural features of the granites.................................. 178

Dikes ....................................................... 178

Aplite................................................... 178

Pegmatite ...............................:............... 179

Quartz veins ..........:...................................... 180

Joints....................................................... 180

Vertical joints............................................ 180

Horizontal joints......................................... 181

Slickensides ..........._:................................ 181

Basic segregations (knots) .................................... 181

Inclusions................................................... 181

Physical tests ................................................... 182

Specific gravity and absorption ................................. 182

Compressive strength......................................... 182,

Individual quarry areas............................................... 183

Distribution ..................................................... 183

Descriptions of quarries........................................... 184

Abbeville County............................................. 184

Anderson County............................................. 184

Chesterfield County.......................................... 185

Edgefield County............................................. 185

Fairfield County....................................I......... 185

Greenville County............................................ 189

Greenwood County............................................ 190

Kershaw County............................................. 190

Lancaster County............................................. 191

Laurens County.............................................. 193

Lexington County............................................. 194

Newberry County............................................ 195

Oconee County............................................... 196

Pickens County .............................................. 197

Richland County............................................. 198

Salnda County............................................... 200

Spartanburg County.......................................... 201

Union County................................................ 202

York County.................................................. 203

Clover area.............................................. 203

Filbert area.............................................. 205

CHAPTER VII. GRANITES OF GEORGIA. ...................................... 206

The Georgia Piedmont region ......................................... 206

Topography....................................................... 206

Geology......................................................... 207

Rocks of the plateau ...........f .............................. 207

Age relations of the rocks..................................... 207

The granites......................................................... 208

Field relations. .................................................... 208

Distribution ......................... r ............-..-.---...-.-. 209

General character of outcrops'.................1.-................. 210
CONTENTS. 9

CHAPTER VII. GRANITES OF GEORGIA Continued. 

The granites Continued.

Chemical composition ............................................ 211

Mineral composition .............................................. 212

Physical tests................................................. ... 212

Structural features of the granites. ................................. 213

Joints....................................................... 213

Slickensides ................................................. 214

Dikes and veins. . ............................................ 214

Granite dikes ............................................ 214

Aplite dikes.. ............................................ 215

Pegmatite dikes and veins. ............................... 216

Origin of phenocrysts in the porphy ritic granites ................... 216

Relations of the granites and the granite gneisses ................... 217

Varieties of granite. .............................................. 217

Even-granular massive granites . ................................... 217

General statement. ........................................... . 217

Blue-gray granite of the Oglesby-Lexington arsa ............... 218

General description. ...................................... 218

Microscopic characters. .................................... 219

Chemical composition.................................... 220

Physical tests............................................ 220

Descriptions of quarries.........................'.......... 221

Introductory statement............................... 221

ElbertCounty ....................................... 221

Madison County ..................................... 223

Oglethorpe County................................... 223

Light-gray granite of the Elberton-Echols Mill area ............ 224

General description ...................................... 224

Chemical composition ................ .........i.. ........ 225

Absorption tests. ......................................... 225

Descriptions of quarries. .................................. 226

Introductory statement. .............................. 226

ElbertCounty ....................................... 226

Oglethorpe County ................. .................. 227

Medium-gray granite of the Fairburn-Newnan-Greenville area . . 228

General description. ...................................... 228

Microscopic characters .................................... 228

Chemical composition. .................................... 229

Absorption test. .......................................... 229

Descriptions of quarries. .................................. 230

Introductory statement. ..... __ .................... 230

Campbell County..................................... 230

Coweta County..... ............ ...................... 231

Meriwether County. .................................. 232

Light-gray granite of Stone Mountain. . ........................ 233

General description. ...................................... 233

Chemical composition ..................................... 234

Physical tests .......:.................................... 235

Description of quarries .................................... 235

Isolated areas of even-grained granite .......................... 237

POJ. phyritic granites .............................................. 238

General statement ............................................ 238

Microscopic characters ........................................ 239
10 CONTENTS.

CHAPTER VII. GRANITES OF GEORGIA Continued. PageThe granites Continued.

Porphyritic granites Continued.

Chemical composition......................................... 240

Physical tests ................................................ 241

Description of individual areas ................................ 241

Campbell, Coweta, and Fayette counties................... 241

PikeCounty.............................................. 242

Fulton County ........................................... 243

WarrenCounty........................................... 243

Hancock County.......................................... 244

Baldwin County.......................................... 247

Greene County- - .......................................... 248

Columbia County ........................................ 249

Granite gneisses.................................................. 250

Introductory statement....................................... 250

Chemical composition ........................................ 251

Physical tests..................'.............................. 252

Lithonia-Conyers-Lawrenceville area .......................... 253

General description ...................................... 253

Lithologic characters ..................................... 253

Descriptions of quarries...................;............... 254

General statement. .......................... 1........ 254

Dekalb County....................................... 255

Gwinnett County .................................... 259

Jackson County...................................... 260

Eockdale County...................................... 261

Walton County ...................................... 262

Odessa-Mountville area....................................... 262

Introductory statement................................... 262

Lithologic characters ..................................... 262

Descriptions of quarries.......................-..:........ 263

Meriwether County .......................................... 264

Coweta County .............................................. 264

Heard County ................................................ 265

Newton County ............................................... 266

Clarke County ............................................... 266

CHAPTER VIII. GRANITES OF ALABAMA ..................................... 268

The crystalline area ..................................................... 268

The granites ......................................................... 268

APPENDIX ................................................................ 270

Statistics of production ................................................. 270

Bibliography ........................................................ 272

INDEX ....................................."............................... 275
ILLUSTRATIONS.

Page. 

PLATE I. Map of Maryland showing distribution of granite quarries and of

granite and gneiss areas........................................ 40

II. Quarries near Glen Echo: A, Joints and faults; B, Intersecting joints. 42

III. Pegmatite dikes: A, Ilchester station, Md.; B, Orange Grove, Md.. 44

IV. A, Gaither's granite quarry, Ellicott City, Md.; B, Guilford &

Waltersville Granite Company's quarry near Woodstock, Md...... 52

V. Weathering of granite: A, Weller quarry, near Woodstock, Md., ' 

showing elongated concentric shells of granite; B, Long Granite 

Company's quarry, near Oglesby, Ga........................... 58

VI. A, McClenahan Granite Company's quarry, Port Deposit, Md.; j5,

Guilford .& Waltersville Granite Company's quarry, Guilford, Md.. 60

VII. Map of Virginia showing distribution of granite quarries ............. 70

VIII. A, Gneiss quarry near Lynchburg, Va., showing regular banding of

the gneiss; B, Cook quarry, near Petersburg, Va ................ 80

I.. A, Monumental granite, Donald quarry, near Richmond, Va., B, 

Pegmatite dikes cutting granite, Donald quarry, near Richmond, 

Va .......................................................... 86

X. Jointing in Netherwood quarry, near Richmond, Va.: A, In gray

granite; B, In blue-gray granite, which intrudes the gray........ 94

XI. A, Wray quarry, west of Richmond, Va., showing joint systems; B,

McGowan quarry, south of Manchester, Va., showing sheeting... 96

XII. A, McGowan quarry, south of Manchester, Va.; B, Gneiss inclusion

in granite, McGowan quarry, near Manchester, Va .............. 98

XIII. Geologic map of North Carolina showing distribution of granite quarries........................................... ................ 116

XIV. A, Pegmatite vein with quartz center, Harris clay mine, northeast 

pit, 2|- miles north of Bryson, N. C.; J5, Whiteside Mountain, a 

granite dome, Jackson County, N. C.............................. 118

XV. Leopardite (quartz porphyry) near Charlotte, N. C.: A, Section

across black streaks; B, Section along black streaks.............. 136

XVI. A, Rowan Granite Company's quarry No. 2, near Salisbury, N. C.;

B, Bowlder outcrop of syenite southwest of Concord, N. C ....... 140

XVII. A, Bowlder quarry, Phillips Mountain, near Faith, N. C.; B, Stone

Mountain, a granite dome, Wilkes County, N. C ................ 142

XVIII. Surface of orbicular gabbro-diorite, Davie County, N. C............ 144

XIX. A, B, Mount Airy Granite Corporation's quarries, Surry County, N.C. 148

XX. Monolith of granite from Mount Airy, Surry County, N. C..... 150

XXI. Map of South Carolina, showing location of granite quarries........ 172

XXII. A, Rion quarry, of Winnsboro Granite Corporation, near Winnsboro,

S. C.; B, Near view of part of quarry face in Rion quarry........ 186

XXIII. A, Bowlder outcrop of gray granite, Rion quarry, Fairfield County, 

S. C.; B, Bowlder outcrop of coarse-grained granite, 3 miles southwest of Heath Springs, S. C.; C, Bared slope of granite gneiss, 

Beverly quarry, Beverly station, Pickens County, S. C........... 192

11
12 ILLUSTRATIONS.

Page.

PLATE XXIV. Map of Georgia showing distribution of granite areas and location of granite quarries ................................... 210

XXV. A, Stone Mountain, a granite dome, Dekalb County, Ga.; B, 

Stone Mountain quarries, Stone Mountain, Dekalb County, 

Ga...................................................... 236

XXVI. Surface of granite gneiss, Lithonia, Dekalb County, Ga....... 252

XXVII. A, East slope of Pine Mountain, a granite gneiss dome, Litho- 

.nia, Ga.; B, Quarry face of granite gneiss, Arabia Mountain 

quarries, near Lithonia, Ga............................... 256

FIGURE 1. Map showing distribution of granite in crystalline region of South

Atlantic States .......................................... J-c'-A. 14

2. Generalized section showing relations of the Coastal Plain formations

to the Piedmont Plateau crystalline rocks...,................... 35 .\

3. Contact of hornblende-biotite gneiss with granite at McG6wan »| 

quarry, south of Manchester, Va .............................. 80 *

4. Contact between blue and gray granites at Netherwood quarry, near

Richmond, Va., showing inclusions of the gray in the blue...... 83

5. Relations of blue to gray granite as shown at Netherwood quarry,

near Richmond, Va........................................... 83

6. Banded aplite-pegmatite dike in blue granite at McGowan quarry,

south of Richmond, Va....................................... 84

7. Contact between blue and gray granites, showing pegmatite cutting

both, at Netherwood quarry, west of Richmond, Va............. . 85

8. Faulted pegmatite intersecting blue granite at Donald quarry, near

Richmond, Va............................................... 86

9. Pegmatite cutting across schistosity of granite gneiss at Middendorf

quarry, west of Manchester, Va................................ 86

10. Pegmatites showing irregularities of outline and width at Richmond 

Granite Quarrying Company's quarry, 4$ miles north of Richmond, Va...................................................... 87

11. Section at Petersburg Granite Company's quarry No. 2, 2 miles west

of Petersburg, Va............................................. 91

12. Section from Richmond west to Midlothian, Va., and beyond...... 92

13. Section at Philadelphia quarries, near Richmond, Va., showing

relations between the blue and gray granites................... 104

14. Sketch in Cartwright & Davis quarry, near Fredericksburg, Va.,

showing relation of granite to gneiss............................ 107

15. Quartz vein in Cowherd quarries, Columbia, Va., showing jointing coincident with schistosity of inclosing gneiss.............. 113

16. Banded aplite-pegmatite at Anderson quarry, near Rion, S. C..... 188

17. Banded aplite-pegmatite at Anderson quarry, near Rion, S. C ..... 188

18. Map of Oglesby-Lexington and Elberton-Echols Mill granite areas,

Georgia....................................................... 219

19. Map of Stone Mountain and Lithonia-Conyers-Lawrenceville

granite and granite gneiss area, Georgia........................ 233

20. Map of Piedmont, Georgia, showing areas of porphyritic granite... 238
GRANITES OF THE SOUTHEASTERN ATLANTIC STATES.

By THOMAS LEONARD WATSON.

INTRODUCTION.

Economically, granite is the most important rock in the crystalline 

region of the Atlantic States south of Susquehanna River. Areally, 

it is one of the dominant rock types the distribution of which is shown 

on the map (fig. 1). Commercially, it is produced in this region in Georgia, Maryland, North Carolina, Virginia, and South Carolina, the five 

States being named in the order of their production. No production 

is reported from Alabama and Tennessee. The statistics on pages 

270, 271 of this report indicate the annual value of the granite industry in these States to be about $3,500,000, or about 20 per cent of the 

granite output of the entire country.

In Bulletins 313 and 354, published in 1907 and 1908 by the United 

States Geological Survey, the granites of Maine and of Massachusetts, 

New Hampshire, and Rhode Island were described by T. Nelson Dale 

from both the scientific and the economic standpoint. The present 

work similarly describes the granites in the Atlantic States south of 

Pennsylvania, including Maryland, Virginia, North Carolina, Tennessee, South Carolina, Georgia, and Alabama. Chapter I contains a 

scientific discussion of granite adapted to the general reader, with 

special reference to the granites of the region described; in later chapters the occurrences are considered by States, the matter relating to 

each State being subdivided into a scientific part treating of the granite in that particular State and an economic part describing individual 

granite areas and quarries.

The field work on which this report is based was done in 1898, 

1899, and 1903 for the state geological surveys of Georgia and North 

Carolina and in parts of the years 1905 to 1908, inclusive, for the 

United States Geological Survey. During this time the writer visited 

the granite quarries in each State described. The petrographic work 

included the study of more than 600 thin sections of typical rocks.

13.
14 GKANITES OF SOUTHEASTERN ATLANTIC STATES.

100 zoo Miles

FIGURE ] . Map showing distribution of granite in crystalline region of South Atlantic States.
INTRODUCTION. 15

The writer is indebted to the published reports on granite by the 

state geological surveys of Georgia, North Carolina, Maryland, and 

South Carolina, which he has used freely in the preparation of those 

parts of the report treating of the granite of these States. Much helpful information has been derived from Bulletins 313 and 354 of the 

United States Geological Survey on the granites of Maine, Massachusetts, New Hampshire, and Rhode Island, by T. Nelson Dale, and 

from the works of Merrill, Geikie, and Buckley.

To Professors Clark and Mathews, of the Maryland Geological Survey, the writer is indebted for the loan of thin sections of the Maryland granites in the geologic collections of Johns Hopkins University, 

and of Plate IV, A; to Dr. Joseph Hyde Pratt, state geologist of North 

Carolina, for the loan of Plate !&X; to Dr. George P. Merrill, of the 

United States National Museum, for the loan of Plates XV and 

XVIII; to the Mount Airy Granite Corporation for the loan of Plate 

XIX; and to Mr. R. E. McClenahan, of Port Deposit, Md., for Plate 

VI, A. Miss A. T. Coons, of the United States Geological Survey, 

has contributed the statistical tables of granite production.

The word "granites" in this report is restricted to the quartz-bearing plutonic rocks, and includes both the massive and the schistose 

forms of even-granular and porphyritic textures. The only exceptions are in North Carolina, the augite syenite, leopardite (quartz 

porphyry), and orbicular gabbro-diorite occurring in that State being 

briefly described. The so-called "black granites" are not discussed. 

38971° Bull. 426 10 2
CHAPTER I.

GRANITE IN GENERAL.

SCIENTIFIC DISCUSSION.

DEFINITION.

Granite is the family name applied to a large and common group 

of entirely crystalline igneous rocks-, consisting essentially of quartz 

and potash feldspar (orthoclase or microcline, or both); more or less 

plagioclase feldspar albite (soda feldspar) or oligoclase (sodalime feldspar), usually the latter, or both is generally present. 

Besides these minerals, which make up the mass of the rock, there 

is as a rule a small amount of either white mica (muscovite) or black 

mica (biotite), or both, locally hornblende, and here and there 

pyroxene. Each of these is evident to the eye without the aid of a 

lens.

Normally, granite is a massive rock without foliation or banding. 

When it takes on a foliated or banded structure, subsequent to its 

crystallization, it is no longer a true granite, but a granite gneiss.

MINERAL COMPOSITION.

The light-colored minerals, feldspar and quartz, are the essential 

minerals in granite and make up the mass of the rock. Of these, 

feldspar is the more conspicuous and generally the more abundant. 

It is readily distinguished by having two cleavages inclined at an

angle of 90° or nearly 90°, the cleaved surfaces being smooth and 

brilliantly reflecting. The mineral is usually white, gray, or pinkish, 

but is sometimes green. Two kinds of feldspar are generally present, the more abundant of which is usually potash feldspar, a silicate of alumina and potash. This may be either orthoclase or microdine, or both, distinguished only by means of the microscope. The 

other feldspar (plagioclase) albite (soda feldspar) or oligoclase 

(soda-lime feldspar), or both, but usually oligoclase can generally 

be distinguished from the potash feldspar by the fine parallel lines 

on its basal surface. The potash and soda-lime feldspars are readily 

distinguishable from each other under the microscope. The granites 

which form the subject of this bulletin are generally characterized 

by nearly equal proportions of potash and soda-lime feldspars and 

are, technically, quartz monzonites.

16
GEANITES IN GENERAL. 17

Quartz is the next most abundant mineral and is readily distinguished by its glassy luster, uneven fracture, and brittleness. It is 

colorless, gray, or dark smoky, less commonly bluish or opalescent.

Mica, the third most abundant mineral in granites, may be present in two forms white (muscovite or potash mica) and black (biotite or iron-magnesia mica). One or both of these minerals may be 

present in granite, and they are alike in cleaving along one direction 

into thin elastic folia, a property by which they are easily distinguished from the other constituents. They are distinguished from 

each other by their color. With only a few exceptions the granites 

described in this bulletin are mica granites. Biotite is much the 

commoner of the two micas, and granite containing biotite but no 

muscovite is sometimes called granitite.

Hornblende, a constituent of many granites, is much less common 

than mica in the granites here described. It may be as dark in 

color as the black mica (biotite), but it is readily distinguishable 

from biotite by the fact that it does not cleave into thin elastic 

scales, but possesses two cleavages inclined at an angle of approximately 124°. Augite and hornblende, when present in a granite, 

resemble each other so closely that they can at times be distinguished 

only by means of the microscope.

Besides these more important minerals which usually determine 

the character of the granite, others are present in microscopic proportions and are usually called minor accessory minerals. Of these, 

minerals like zircon, apatite, magnetite, ilmenite, titanite, pyrite, 

garnet, allanite, rutile, tourmaline, and fluorite are regarded as original. Others, such as chlorite, epidote, kaolin, sericite, and calcite, 

are the result of chemical changes in the feldspars or the dark ferromagnesian minerals, or both, and are therefore secondary. In a 

few instances calcite has been regarded as an original mineral in 

granite.a With the exception of fluorite, all the accessory minerals 

enumerated have been found in the granites described in this bulletin.

Of the minor accessory minerals named, pyrite (iron disulphide) and 

calcite (calcium carbonate), when present in an exposed surface of 

granite, are harmful, the pyrite producing discoloration on oxidation 

and the calcite when dissolved causing weakness in the stone.

The relative proportions of the minerals in granite differ within 

rather wide limits for granites from different localities. The percentages of feldspar and quartz are large, while that of the bisilicate minerals (micas, hornblende, and augite) is small. This variation in the 

percentages of the minerals is shown in the table below, which gives 

the mineral percentages of well-known granites.

a Bull. U. S. 'Geol. Survey No. 313,1907, p. 17, references cited.
18 GRANITES OF SOUTHEASTERN ATLANTIC STATES. 

Percentages of minerals in various granites.

Constituents.

Mica........................................

1.

43

«4

2.

?S

<n

59fi

3.

28.85

22.45

44.65

4.05

4.

28.2

32.5

35.5

/3.3

5.

o55.4

15.1

26.0

3.3

6.

058.9

1.3

28.5

10.3

7.

12.26

29.95

33.82

17.83

8.

8.91

34.86

42.28

10. 41

9.

6 53. 33

2.55

33.41

10.71

a Reported as microcline chiefly, subordinate orthoclase. 

6 Reported entirely as microcline. 

c Albite.

d Plagioclase.

« Biotite.

/Biotite, 1.3; hornblende, 2.0.

1. Red granite from Egypt.

2. Porphyritic granite from the Vosges. Prestwich, Jos., Geology: Chemical, physical, and stratigraphical, vol. 1,1886, p. 42.

3. Biotite granite from Hardwood Island quarry, Maine. Dale, T. N., Bull. U. S. Geol. Survey No. 313, 

1907, p. 173.

4. Hornblende granite from Rockport, Cape Ann, Massachusetts. Washington, H. S., Jour. Geology, 

vol. 6, 1898, p. 794.

5. Acidic granite from south end of Millstone Hill, Barre, Vt. Rept. State Geologist for 1901-2,1902, p. 56.

6. Granite (medium stock) from eastern slope of Millstone Hill, Barre, Vt. Rept. State Geologist, 1901-2, 

1902,p. 56.

7. Hornblende-biotite granite (quartz monzonite) from Cecil County, Md. Maryland Geol. Survey, 

1902, p. 120.

8. Biotite granite (quartz monzonite) from Port Deposit, Cecil County, Md. Maryland Geol. Survey, 

1902,p. 119.

9. Biotite granite from Platte Canyon, Jefferson County, Colo., Bull. U. S. Geol. Survey No. 150, 1898, 

p. 173.

The figures above indicate, as is usual, much variation in the relative proportions of the feldspar and the quartz, and to a greater extent 

in the potash feldspars (orthoclase and microcline) and the soda-lime 

feldspars (plagioclase): A careful examination, however, of the chemical analyses of the granites described in this bulletin discloses a smaller 

range in the relative amounts of the potash and soda-lime feldspars 

than is usual for normal granites from widely separated areas.

CHEMICAL COMPOSITION.

The chemical composition of-granite, though conditioned by mineral composition, is now regarded to be of less economic importance 

than the latter. The chemical analysis corroborates the microscopic 

analysis. The analyses of granite here given will suffice to show the 

general range in composition.

Four analyses of granites from Scotland, Ireland, Italy, and Sweden 

give the following:

Analyses of European granites.®

Silica (Si02 )............................................. 70. 60-74. 82

Alumina (A1203 )........................................ 14. 86-16. 40

Ferric oxide (Fe203 )...................................... .10- 1. 63

Ferrous oxide (FeO)..................:..,.......'......... .36- 1. 64

Manganese oxide (MnO).................................. .00- .48

Magnesia (MgO)........................................... .23- 1. 00

Lime (CaO).............................................. . 89- 2. 47

Soda (NaaO)............................................. 3.51- 6.12

Potash (K20)........................................... .3. 55- 5.10

« Geikie, Archibald, Textbook of Geology, 4th ed., 1903, vol. 1, p. 207.
GBANITES IN GENERAL. 19

Ten analyses made in the laboratory of the United States Geological Survey of granites from Arizona (1), California (4), Colorado (4), 

and Michigan (1), show the following ranges:

Analyses often United States granites.0-

Silica (Si02 )............................................. 66.28-77.68

Alumina (A12 03 )........................................ 11. 63-16. 38

Ferric oxide (Pe2 03 )------------------------ - --- - --- - .00- 2.73

Ferrous oxide (FeO)...................................... . 09- 1.88

Magnesia (MgO).......................................... . 04- 1. 63

Lime(CaO).............................................. .12- 3.75

Soda (Na2 0)............................................. 2.85- 5.16

Potash (K2 0)........................................... 1. 87- 6. 50

Titanium dioxide (Ti02 ).................................. Trace- .54

Phosphoric oxide (P205)................................. Trace- . 30

Analyses of granites from Maryland, South Carolina, and Georgia 

show the following ranges for the individual States:

Analyses of Maryland, South Carolina, and Georgia granites.

Constituents.

Silica (SiOs).................. ................................

Lime (CaO) . ................................................

Soda (U&iO)... .......... ....................................

Potash (KsO).... ............................................

Maryland."

62.91-74.87

12.89-19.13

Trace- 2.07

.51-3.23

. 16- 2. 19

. 48- 4. 89

1.95- 3.94

1.48- 5.36

South Carolina. 6

62.34-73.26

13. 72-17. 22

.70- 1.85

1.24- 2.49

.22- 1.30

1.28-3.28

.55- 5.39

2. 85- 6. 89

Georgia.*

63. 27-72. 56

14.81-19.93

} .94-2.85

.20- 1.30

1.19- 3.27

4. 14- 5. 88

3.29- 5.85

o Eight analyses. W. F. Hillebrand, analyst.

6 Thirteen analyses. Earle Sloan, analyst. Bull. South Carolina Geol. Survey, ser. 4, No. 2, 1908, pp. 

177-223. 

c Twenty-one analyses. Bull. Geol. Survey Georgia No. 9-A, 1902, pp. 241-242.

TEXTURE.

Texturally, granites are holocrystalline granular rocks. The 

crystalline granules (minerals) are in close contact and usually interknit. Granites, therefore, possess a minimum of pore space and a 

maximum degree of strength. Some granites are even grained; 

others contain prominently developed feldspars, with or without 

crystal outlines, embedded in a finer even-grained groundmass that 

is, they are porphyritic in texture. The prominent or distinct crystals 

of feldspar are known as phenocrysts.

Difference in the magnitude of the minerals (granularity) 6 of 

even granites gives rise to a variety of texture. Three grades of 

texture may thus be distinguished (1) coarse, in which the feldspars 

generally measure over 1 cm., or two-fifths inch* (2) medium, in

" Bull U. S. Geol. Survey No. 228, 1904, p. 197, analysis D; p. 231, analysis A; p. 232, analysis A; p. 240, 

analysis E; p. 241, analysis F; p. 185, analysis B; p. 161, analyses A, C, F; p. 78, analysis A.

& Cross, Iddings, Pirsson, and Washington, The texture of igneous rocks; Jour. Geology, vol. 14,1906, 

pp. 694 et seq.
20 GEANITES OP SOUTHEASTERN ATLANTIC STATES.

which they measure under 1 cm. (two-fifths inch) and over 0.5 cm. 

(one-fifth inch); and (3) fine, in which they measure under 0.5 cm. 

(one-fifth inch).a In some coarse-grained granites the feldspars 

measure one or more inches and in some fine-grained ones as low as 

one-fiftieth inch.

Under the microscope the arrangement of the minerals in granite 

shows that these have observed the following order in crystallizing 

out: (1) Minor accessory minerals (magnetite, apatite, zircon, 

titanite, pyrite, and ilmenite); (2) characterizing accessory minerals 

(hornblende, biotite, and muscovite); and (3) the essential minerals 

(feldspars and quartz). Examination of any medium or coarsegrained granite will show the quartz filling the spaces between the 

feldspars. Some of the earlier-formed minerals are, as a rule, partly 

or entirely inclosed by the later-formed ones (feldspars and quartz). 

In many granites the feldspars and quartz are intergrown, indicating 

overlapping in part of the periods of crystallization of these minerals.

PHYSICAL PROPERTIES.

Among the more important physical properties of granite are 

color, weight, strength, hardness, and porosity. These are briefly 

discussed in the order here named.

COLOR.

The usual color of granites is some shade of gray, though pink or 

red varieties are not uncommon. Color depends chiefly on the 

relative abundance of the dark ferromagnesian mineral or minerals 

(biotite or hornblende, or both) and the character of the feldspars. 

Those granites containing a large proportion of biotite or hornblende 

are of darker gray color than those containing but little. The pink 

and red colors are due to the presence of pink and red feldspars.

The Appalachian granites described in this bulletin are, with few 

exceptions, of some shade of gray varying from nearly white (Stone 

Mountain, Ga., granite), through medium gray (Richmond, Va., 

granites in part, and the Guilford, Woodstock, and Port Deposit, 

Md., granites), to dark blue-gray (Richmond and Fredericksburg, 

Va., granites in part; Winnsboro and Heath Springs, S. C., granites 

in part; and Oglesby, Ga., granite). A part of the granite of Dunns 

Mountain, near Salisbury, N. C., is of a pronounced beautiful pink

color.

WEIGHT.

The specific gravity of a rock is the ratio of its density to that of an 

equal volume of distilled water at 4° C. (39.2° F.). The specific 

gravity of granite ranges from 2.593 to 2.731, with an average of

a Dale, T. N., Thegranitesof Maine: Bull. U. S. Geol. Survey No. 313,1907, p. 20.
GRANITES IN GENERAL. 21

2.663. The weight of granite, expressed in pounds per cubic foot, is 

obtained by multiplying the specific gravity by 62.5, the weight in 

pounds of a cubic foot of distilled water at 4° C. (39.2° F.).

STRENGTH.

Hundreds of tests to determine the compressive strength of granite 

have been made. It will suffice here to direct attention only to the 

usual range in the ultimate compressive strength of granite, which 

is from 18,000 to 34,000 pounds per square inch. The range in 

ultimate compressive strength of the Wisconsin granites is, according 

to Buckley,'* from about 15,000 to 43,973 pounds per square inch. 

For the compressive strength of the granites described in this bulletin, 

see pages 49-50,149,183, 213, 221, 252, 253.

HARDNESS.

By the hardness of a building stone is meant its resistance to wear. 

The principal factors which determine hardness are (1) aggregation 

of the constituent grains or the firmness with which they adhere, 

thereby diminishing proportionately the pore space; (2) actual 

hardness of the individual mineral grains; (3) size and relative 

abundance of the component minerals; and (4) mineral composition. 

Tests for hardness show that granites differ greatly. As stated by 

Dale,6 "this difference is due not merely to differences in the percentage of quartz, but also to variations in the character of the 

feldspars."

POROSITY.

Fresh granite contains less than 1 per cent of water and is capable 

of absorbing a small fraction of a per cent more. According to 

Ansted 0 granite' usually contains about 0.8 per cent of water and is 

capable of absorbing about 0.2 per cent more; a cubic yard of granite 

usually contains, therefore, 3.5 gallons of water. The pore space 

in 14 Wisconsin granites, as determined by Buckley/* ranges 

from 0.019 to 0.62 per cent, and the ratio of absorption of the same 

granites ranges from 0.04 to 0.50 per cent. According to Merrill 6 

certain Maryland granites absorb from 0.196 to 0.258 per cent of 

water after drying twenty-four hours at 212° F. and then being 

immersed, for twenty-four hours. The writer-^ found that the ratio of 

absorption of 12 Georgia granites ranged from 0.037 to 0.093 per cent.

oBuckley, 11. B., On the building and ornamental stones of Wisconsin: Bull. Wisconsin Geol. and Nat. 

Hist. Survey No. 4, 1898, pp. 361, 390.

6 Dale, T. N., The granites of Maine: Bull. U. S. Geol. Survey No. 313,1907, p. 22.

e Quoted by Hull, Edward, A treatise on building and ornamental stones of Great Britain and foreign 

countries, 1872, p. 30.

dOp. cit.,p. 400.

«Merrill, G.. P., Stones for building and decoration,.3d ed., p. 435.

/Watson, T. L., Granites and gneisses of Georgia; Bull. Geol. Survey Georgia No. 9-A, 1902, p. 351.
22 GRANITES OF SOUTHEASTERN ATLANTIC STATES. 

VARIETIES OF GRANITE.

Granites are usually classified, mineralogically, on the basis of the 

prevailing accessory mineral or minerals mica (biotite or muscovite), 

hornblende, and augite. Thus a granite containing muscovite (white 

mica) is termed a muscovite granite; one containing biotite (black 

mica) a biotite granite (granitite).; one containing both a muscovitebiotite granite; one containing hornblende a hornblende granite; one 

containing hornblende and biotite a hornblende-biotite granite, etc. 

The name unakite is given to a granite with pink feldspars and rich in 

epidote that occurs in the Unaka Mountains of eastern Tennessee and 

western North Carolina and is known in two localities in the Blue 

Ridge of Virginia.

The varieties of granite occurring in the region covered by this 

bulletin are chiefly biotite, muscovite, and muscovite-biotite granites, 

and hence are referred to as mica granites. The biotite granites 

greatly predominate.

A general classificatory scheme of the granites occurring within 

this region is not given here; those of each State, however, are classified in the respective chapters.

STRUCTURE.

Under the term structure are included all divisional planes that 

traverse granite, whether of microscopic or macroscopic proportions, 

such as rift and grain, joints, faults, etc.

RIFT AND GRAIN.

The rift and grain in granite are structures of considerable economic 

importance, for they lessen the cost of quarrying, when well developed, 

by facilitating the operations of the workmen. They are obscure 

microscopic foliations, inclined at an angle of about 90° to each other, 

along which the rock splits more easily than in other directions. The 

rock splits easier in the direction of rift than of grain. These structures may not be visible to the ordinary observer, but are easily 

detected by an experienced stonecutter.

In the study of the hornblende-biotite granite of Cape Ann, Mass., 

Tarr a found that rift consisted of minute fractures and faults crossing 

the feldspar and quartz alike, although some go around the quartz 

grains rather than through them. Whittle 6 details similar observations for the granite quarried at Redstone, N. H., and remarks that 

notwithstanding the pronounced rift and grain of this granite it stood 

a compression test of 22,370 pounds to the square inch and was not 

appreciably weakened by the microscopic fractures. Dale c later corroborated Whittle's observation on this granite.

a Tarr, R. S., The phenomena of rifting in granite: Am. Jour. Sci., 3d ser., vol. 41,1891, pp. 267-272. 

6 Whittle, C. L., Rifting and grain in granite: Eng. and Min. Jour., vol. 70,1900, p. 161. 

c Dale, T. N., The granites of Maine: Bull U. S. Geol. Survey No. 313,1907, p. 27.
GRANITES IN GENERAL. 23

Rift and grain data were collected by Dale 0 at 53 quarries of 

Maine granites; at 29 of these the rift was vertical, and at 24 it was 

horizontal and the grain .was vertical. According to Dale the 

courses of the rift and grain are distributed as follows:

Courses of'rift in Maine granites.

Number of 

quarries.

N. 10° W.-N. 10° E............................................ 6

N. 22°-50° W................................................. 5

N.30°-77°E................................................... 3

. N. 60°-70° W................................................. 9

East-west to N. 85° E. and N. 80° W.....,...................... 6

Courses of grain in Maine granites.

N. 20°-25° W.........................

N. 45°-72° W.. .......................

Number of 

quarries.

........................ 2

........................ 2

........................ 4

........................ 6

East-west to N. 80° E........................................... 10

From these observations Dale says: "It appears, therefore, that 

when rift or grain is vertical the east-west and west-northwest to 

northwest courses are the most common, and next the north and 

east-northeast to northeast courses." b

The rift and grain are not always pronounced in the granites of the 

southeastern Atlantic States, but, as a rule, they are sufficiently 

developed to facilitate quarrying operations. In some places they 

are but poorly defined, but nowhere, so far as the writer is aware, are 

they entirely absent.

From the numerous tests it seems that rift, in some cases at least, 

influences the crushing strength of the granite. That is to say, the 

ultimate strength of granite is greater when pressure is applied at 

right angles to the rift than when applied parallel to it. c

JOINTS.

OCCURRENCE.

Joints in rocks of commercial grade are of considerable economic 

importance, for their character and abundance largely determine the 

size of blocks that may be quarried. Where not too closely spaced 

and not discolored by sap they greatly benefit the quarries; but where 

too abundant and closely spaced and where they intersect at sharp and 

obtuse angles, they are decidedly harmful, as the extraction of dimension stone is rendered impossible.

a Dale, T. N., The granites of Maine: Bull. U. S. Geol. Survey No. 313, 1907, pp. 28, 29. 

b Idem, p. 29.

c See results of tests of materials by J. W. Keilly, as quoted by Dale, T. N., The granites of Maine: Bull. 

U. S. Geol. Survey No. 313,1907, p. 29.
24 " GRANITES OF SOUTHEASTERN ATLANTIC STATES.

Two systems of joints, a vertical set and a horizontal set, and, in 

many places, a third, diagonal system intersect the granites treated in 

this bulletin. These may be widely spaced or closely spaced. Usually the spacing is sufficiently wide to admit of dimension stone being 

quarried. Motion in the granite masses since the formation of the 

joints is evident from the polished and striated surfaces of the joints.

VERTICAL JOINTS.

Considerable variation is shown in the development of the vertical 

joints. In most places they are conspicuously developed; in others, 

especially in the granite domes of Georgia (Stone Mountain and similar domes in the Lithonia area) and North Carolina, they are much 

less abundant. Visible jointing is not apparent in the Mount Airy, 

N. C., quarries.

Observations in the quarries of the southeastern Atlantic States 

show two principal sets of vertical joints, lying in the northeast and 

the northwest quadrants; in many quarries tnere is also minor 

jointing in two other directions, east-west and north-south. In 

some localities the joints are irregular with respect to continuity, 

strike, and dip. Joints indicating a considerable degree of curvature 

are noted in a few localities and are described in some detail in the 

chapters on the individual States.

HORIZONTAL JOINTS.

Joints dividing the granite into "sheets" are usually strongly 

developed in the granites of the Southern States. Such joints are 

usually parallel to the granite surface. In flat-surface exposures 

they approach a horizontal position; in gently arched exposures 

they have approximately the same degree of curvature as that of 

the granite surface; and in the steep domes they are correspondingly 

steep, observing parallelism with the doming surface.

Horizontal joints are usually more conspicuous at and near the 

surface, and become less prominent below. They apparently disappear in most quarries that are opened to any considerable depth. 

Ordinarily the joint planes separate the rock into thinner sheets at 

or near the surface and into thicker sheets at greater depth. The 

thickness of the sheets shows considerable variation, ranging from 

several inches to 6 feet or more.

There is a great diversity of opinion among geologists as to the 

cause of these joints, some regarding them as one of the effects of 

external temperature changes (solar heat), and some believing them 

to be due chiefly to compressive or torsional strain.0

a See a recent review of the literature on "sheeting" by Dale in Bull. U. S. Geol. Survey No. 313, 1907, 

pp. 30-38.
GRANITES IN GENERAL. 25

Joint structure, vertical and horizontal, in the granites of the 

Southern States is shown in Plates II, X, and XI.

SLICKENSIDES.

In most of the granite quarries where the joint structure is at all 

well developed the joints show smooth, more or less polished and 

striated surfaces, indicating considerable movement in the granite 

masses since the formation of the joints. A very thin coating or 

veneer of a reddish and yellow to greenish-yellow mineral substance 

is developed on many of the joint surfaces. This is an alteration 

product, derived from certain original minerals of the fresh granite 

and resulting from the rubbing together of the two sides along the 

plane.

ROCK VARIATIONS.

Under the term "rock variations" are grouped those variations 

from typical granite that are due to injection, infiltration, inclusion,

segregation, etc.a

DIKES.

The dikes in the southern granites are divisible on a chemical 

basis into two groups (1) dikes of acidic composition, including 

very fine grained, nearly mica-free granite (aplite), and very coarse 

grained granite (pegmatite); and (2) dikes of basic composition, 

including diabase and amphibolite.

ACIDIC DIKES.

Granite-aplite. Granite-aplite differs from normal granite in its 

greater fineness of grain, in containing very little or no mica, and in 

its very light, nearly white color. Dikes of it are only occasionally 

seen in the granites .of the Southern States. They have been noted 

by the writer in the Richmond, Va., granite area; 6 the Raleigh, 

N. C., granite area; c the Columbia and Lexington granite areas 

and the Anderson quarry in Fairfield County, S. C., and the Stone 

Mountain, Ga., granite area/ and are plainly of an intrusive nature. 

They occur both as separate dikes in the granite and associated with 

the pegmatite dikes as banded aplite-pegmatite dikes. They are 

usually less than 6 inches thick, and in color they are very light, 

except those of the Columbia, S. C., area which are decidedly reddish 

brown. They are very fine grained in texture, the mineral particles 

not being distinguishable, as a r-ule, with the unaided eye. For a 

detailed description of the individual occurrences see pages 85, 120, 

178-179.

oDale, T. N., op. cit, p. 42.

6 Bull. Geol. Soc. America, vol. 17, 1900,'p. 530.

cfiull. North Carolina Geol. Survey No. 2,190G, pp. 33,180. Jour. Geology, vol. 12,1904, pp. 403-404.

rfJour. Geology, vol. 10, 1902, pp. 180-190. Bull. Georgia Geol. Survey No. 9-A, 1904, pp. 275-276.
26 GEANITES OF SOUTHEASTERN ATLANTIC STATES.

Pegmatite. Pegmatites are present, usually, in great numbers in 

the granites of the Southern States, and some of them attain considerable size. (See PL III.) They are abundant in some quarries 

and entirely absent in others. Only here and there are they so 

numerous as to interfere seriously with quarrying operations, the 

most noteworthy example being at the city quarries of biotite granite 

at Raleigh, N. C., where hardly a block of any size can be quarried that 

is entirely free from pegmatite dikes; this is illustrated in the state 

building in Raleigh, which is constructed of this stone.

The pegmatites are granitic in their mineralogy, consisting of 

very coarse crystallizations of feldspar and quartz with less mica 

(muscovite or biotite, rarely both). As a rule, these minerals are 

not uniformly distributed through all parts of the dikes, but are 

scattered very irregularly, first one and then the other predominating. 

The pegmatites associated directly with the granites in the quarries 

are as a rule remarkably free from unusual or rare minerals. Garnet 

is commonly present, and in the dark-blue granite quarries of Fredericksburg, Va., massive granular magnetite is associated with the 

garnet. In the pegmatites of the granite quarries at Stone Mountain, Ga., both tourmaline and garnet occur. Black tourmaline is 

observed in some of the pegmatites of the Johnson quarry near 

Pacolet, S. C.

Many of the larger pegmatite dikes penetrating the crystalline rocks 

of the southern region contain unusual minerals. This is especially 

true of parts of the crystalline area in Virginia and the Carolinas.0

The potash feldspars, orthoclase and microcline, are the dominant 

feldspar species in the pegmatites, though an acidic plagioclase is 

usually present. The commonest colors are white and reddish pink, 

with pronounced green in some of the Virginia dikes. Twinning on 

the Carlsbad law is common and good cleavage development is a 

marked characteristic. The quartz is usually of the light and the 

dark smoky varieties, which contrast sharply with the feldspar. Of 

the micas, both muscovite and biotite occur in places associated in the 

same dike, but usually separated, with biotite probably more common than muscovite. The biotite is usually present in large, stout, 

platy forms, at some places irregularly distributed between the feldspar and quartz, at others distributed along a central axis in the 

dike. The micas are of the usual kinds and are in no way noteworthy.

As a rule, the pegmatites are more irregular in width than the 

aplites, though here and there they extend for considerable distances

a Watson, T. L., Mineral resources of Virginia, 1907, pp. 270-285, references cited. Kunz, G. F., Bull. 

North Carolina Geol. Survey No. 12,1907, pp. 25-28. Graton, L. C., and Lindgren, AValdemar, Bull. U. S. 

Geol. Survey No. 293, 1906, pp. 20-22, 35-40, 42-43, 53-54, 57. Keith, A., Cranberry folio (No. 90), 1903; 

Mount Mitchell folio (No. 124), 1905; Pisgah folio (No. 147), 1907, Geol. Atlas U. S., U. S. Geol. Survey.
GEANITES IN GENERAL. 27

with remarkable regularity. Some dikes are very extensive, are 

apparently deep seated, and are of aqueo- igneous origin. Others are 

small, are surrounded entirely by the granite, and probably denote 

true veins of segregation. Locally they conform to the joint courses, 

and in some of the gneisses they are insinuated in the planes of the 

schistosity, but at many places they apparently do not conform to 

any definite or fixed direction but cut the granite at random and at 

all angles.

The pegmatites in some localities are of different periods of formation. In the Richmond (Va.) granite area a there are three granites 

(including the granite gneiss), representing as many periods of intrusion, each of which was accompanied by the formation of pegmatites. 

The structural relations of the pegmatites to the granites in the 

Richmond area are shown in figures 4, 5, and 7.

Faulting has been observed in the pegmatites at the Donald 

quarry (fig. 8) in the Richmond area; in the large granite exposures 

on the Adams place near Clover, in York County, S. C., and at the following quarries in North Carolina: The Raleigh City quarry; the 

Carrigan quarry, 3 miles northeast of Mooresville, Iredell County; 

and the Walker quarry, 1£ miles southeast of Ridge Summit station, 

Guilford County. The displacement amounts to only a few inches, 

and in each locality the faulting occurs at the point of intersection 

of one pegmatite by another.

Granite. The granite dikes differ from those of aplite and pegmatite in being formed of fine or medium grained granite, and they 

correspond in composition and otherwise to the normal granite. 

They vary in width from a few inches to 40 feet as an extreme, near 

Camak, Ga.; usually they vary from 4 to 12 inches. They are dark 

gray in color and fine to medium grained in texture, and are composed 

of potash (orthoclase and microcline) and soda-lime (oligoclase) feldspars, quartz, and biotite as the essential minerals, together with the 

usual microscopic accessory minerals.

Granite dikes are typically developed in some of the granite 

quarries of Maryland, Virginia, North Carolina, and Georgia. The 

more important localities are the following: Maryland, Weber's 

quarry at Ellicott City, and the railroad cut at Dorsey Run; Virginia, 

Davis and Cartright quarries, near Fredericksburg; North Carolina, 

Greystone quarries in Vance County, and Mount Mourne in Iredell 

County; Georgia, Sparta quarries in Hancock County, near Camak, 

and at Holders Mill in Warren County, and the Odessa quarry in 

Meriwether County.

a Watson, T. L., Lithological characters of the Virginia granites: Bull. Geol. Soc. America, vol. 17,1906, 

pp. 530-539.
28 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

A chemical analysis of specimens collected from a 40-foot dike of 

fine-grained dark-gray granite cutting porphyritic granite gneiss near 

Camak, Warren County, Ga., yielded the following results:

Analysis of granite dike near Camak, Ga.

[T. L. Watson, analyst.]

Silica (Si02 ).................................................. 68. 76

Alumina (A12 03 ).............................................. 16.80

Iron oxide (Fe203 )............................................. .99

Lime (CaO).................................................. 2.72

Magnesia (MgO).............................................. 1. 00

Soda (Na2 0)................................................. 4. 82

Potash (K?0)................................................. 3. 70

Ignition..................................................... .29

A chemical analysis of selected specimens from different parts of 

light-colored granite dikes penetrating massive granite and gneiss in 

the railroad cut at Dorsey Run station, Howard County, Md. ; gave 

the following results.*

Analysis of granite dikes at Dorsey Run, Md. 

[W. F. Hillebrand, analyst.]

Silica (Si02 )..............:.......................-........... 70.45

Alumina (A12 03 ).............................................. 15.98

Ferric oxide (Fe2 03 )........................................... .75

Ferrous oxide (FeO)........................................... 1. 84

Magnesia (MgO)............................................. .77

Lime (CaO)................................................. 2.60

Soda (Na2 0)................................................. 3. 83

Potash (K20)................................................ 3: 59

Water(H2 0).................................................. .43

Lithia (Li20).. .............................................. Trace.

100.26 

BASIC DIKES.

Dikes of basic igneous rocks, principally diabase or its altered form, 

penetrate the granite in many localities, especially in North Carolina 

and to a smaller extent in South Carolina and Georgia. In several 

of the North Carolina granite quarries as many as half a dozen dikes 

were observed in a single quarry. The dikes are rarely 50 feet across 

and usually are less than 4 feet.

. Lithologically two types are indicated. The principal type is 

usually an unaltered massive rock, thin sections of which display the 

mineralogy and texture of diabase. The pyroxene in this type may 

be considerably altered in some of the dikes, and in hand specimens 

the rock has a pronounced greenish color, from the amount of chlorite 

present. The other and less abundant type is more or less completely thinly schistose, is largely composed of hornblende with some

o Keyes, C. R., Fifteenth Ann. Kept. U. S. Geol. Survey, 1895, pp. 722, 723.
GRANITES IN GENERAL. 29

feldspar and quartz, and may contain much pyrite; it is, therefore, 

a typical amphibolite.

The structural relations of the dikes to each other and to the 

inclosing granites clearly indicate at least two different periods of 

formation. In some places both the inclosing granite and the dike 

are schistose in structure, indicating intrusion of the dike material 

into the granite prior to the period of dynamic disturbance that 

induced schistosity in the two rocks. These dikes are regarded as 

pre-Newark in age. In many localities, however, the dike rock is 

entirely massive and the granite schistose in structure, indicating 

that the dike material was intruded into the granite after the period 

of dynamic disturbance. A few of these dikes have been traced from 

the granites into the Triassic sandstones along the eastern border of 

the Piedmont region, and are therefore of Mesozoic age.

In the North Carolina quarries conditions are more favorable for 

studying the relations of the basic dikes to joint structure than in 

the granite areas of the other Southern States. Of 71 dikes measured 

in the North Carolina quarries, 37 lie in the northwest quadrant and 

22 in the northeast, 13 have a north-south course, and 2 an east-west 

one. Likewise, measurements of 136 joints show that 44 lie in 

the northwest quadrant and 57 in the northeast, and that the remainder have north-south and east-west courses. Furthermore, in nearly 

every quarry exposing basic dikes the strike of the dikes and that of 

one set of joints were coincident, probably indicating that for the 

North Carolina areas the jointing has exercised some influence on 

the direction .of the dikes."

QUARTZ VEINS.

Quartz veins of large dimensions are numerous over the crystalline 

region of the Southern States, but they are rather exceptional in the 

granite quarries of that region. In a number of the North Carolina 

quarries and in the Port Deposit quarries, Maryland, quartz veins of 

small dimensions have been observed. These commonly occur in 

those quarries in North Carolina where pegmatite dikes are abundant. 

The quartz veins are more or less closely associated with the pegmatites, and do not exceed a few inches in width. The quartz composing 

the veins is of the usual clear vitreous variety.

In the Columbia quarries of Fluvanna and Goochland counties, Va., 

quartz veins up to 2 feet wide are abundant. They are very irregular 

in thickness and inclose thin seams of chlorite (from biotite) along 

central and contact positions.

a Watson, T. L., and Laney, F. B., with the collaboration of Merrill, G. P., The building and ornamental 

Stones of North Carolina; Bull, North Carolina Geol, Survey No. 2,1906, pp. 184-187.
30 GEANITES OF SOUTHEASTERN ATLANTIC STATES.

BASIC SEGEEGATIONS (KNOTS).

In many of the quarries the granite contains dark-gray or black 

basic segregations (knots) of fine-grained texture, formed from the 

cooling magma. The segregations are finer grained and of darker 

color than the granite in which they occur. Thin sections show the 

same essential minerals as in the granite but in different proportions, 

the dark ferromagnesian minerals, biotite and hornblende, or both, in 

large excess, with less quartz and feldspar. Some segregations are so 

fine grained and so very dark in color that it requires very close nakedeye examination to detect other minerals than the ferromagnesian silicates. In outline the knots are. usually circular or elliptical, muchelongated masses, ranging in diameter from less than an inch to 

several feet.

The distribution of the segregations in the granite is subject to considerable variation, but is always irregular and without definite order 

or orientation. From some quarries they are entirely absent, in 

others they are developed only locally, and in others still they are so 

abundant as to disfigure the rock and exclude it from use for the 

higher grades of work. The segregations appear to be most abundantly developed in the hornblende-biotite granites, especially those 

of the Falls Church area in Virginia and the Mecklenburg Countv 

areas in North Carolina, where many of them are large.

The following table shows the percentage of silica in and the 

specific gravity of basic segregations in granite.0

Silica percentage and specific gravity of knots.

Locality.

Port Deposit, Maryland. ...................................

Silica.

Granite.

73.70 

73.70 

69.78 

69.64 

68.97

Segregation.

62.20 

64.39 

56.95 

65.01 

57.89

Specific gravity.

Granite.

2.69 

2.69 

2.69 

2.72 

2.68

Segregation.

2.83 

2.73 

2.77 

2.73 

2.78

« Bascom, F., Maryland Geol. Survey, Cecil County, Md., 1902, p. 112. 

INCLUSIONS.

Inclusions are irregular fragments of country rock of all sizes and 

shapes that have been torn off and incorporated in the granite during 

its intrusion. They not uncommonly closely resemble the basic segregations (knots) described above, but can usually be distinguished 

from them by their different microscopic structure. Inclusions of 

this kind occur here and there in the granites of the Southern States, 

but are especially well marked in the granites of the Woodstock and 

Sykesville districts, Maryland.a At Woodstock the inclusions are 

chiefly irregular blocks of gneiss, 6 to 8 or even 10 feet in size. Their

a Keyes, C. R., Origin and relations of central Maryland granites: Fifteenth Ann. Kept. U.. S. Geol. Survey, 1895, pp. 723-724, 726-729.
GRANITES IN GENERAL. ^ 61

outlines are sharply defined against the granite which contains them. 

In the Sykesville district the inclusions comprise fragments of all 

sizes and shapes, of limestone, soapstone, pyroxenite, vein quartz, 

and hornblende and biotite gneisses.0

In the Richmond-Fredericksburg area, Virginia, the .dark-blue 

gray granite in some of the quarries contains inclusions of the massive 

light-gray granite and of the gneiss. The foliation of the gneiss 

inclusions incorporated in the granite at the McGowan quarry is 

entirely preserved (PI. XII, B).

In the Carolinas and Georgia granite areas inclusions have been 

noted but are less numerous and, with several exceptions, are not so 

pronounced in character as in the Maryland and Virginia areas.

MINERALS ON JOINT FACES.

The surfaces of the joint planes in the granites of the region discussed in this bulletin are at many places coated with minerals which 

occur but sparsely or not at all in the granite. Generally the coat 

consists of the barest film or veneer of a yellow, yellowish-green, or 

reddish mineral substance, which, as a rule, is probably damourite, 

in some places epidote, or a mixture of the two, being a dynamic 

alteration product resulting from movement in the granite mass. 

M the old state (Middendorf) quarries, near Granite station, Virginia, the joint faces are coated here and there with radiating tufts 

or clusters of stilbite, a hydrous silicate of alumina, lime, and soda. 

Joints in some of the North Carolina quarries are coated with pyrite, 

which has probably resulted from infiltrations along the joint courses.

At Stone Mountain, Ga., the minerals uranophane 6 (CaO, 2U03 , 

2Si02 + 6H20) and hyalite (Si02 . nH30, opal) occur as incrustations, 

coating the faces of many of the joints that cut the light-gray biotitebearing muscovite granite. The uranophane is of yellow color and 

the coating of it does not exceed one-eighth to one-sixteenth inch in 

thickness, and is usually less. It is tipped or coated with clear, 

colorless, and transparent droplike globules of hyalite. The two 

minerals are so intimately associated that it is almost impossible to 

effect a complete separation of them.

A chemical analysis of the uranophane by Packard gave :

Analysis of uranophane from Stone Mountam, Ga. 

SiO,,... ....................................................... 18.55

UWQ^.. ..................................................... 47.18

(U0o) 2 , Fe203 , PA- - .................................... -o. ... 4. 95

Al,0~8 . ........................................................ 6. 33

Cab.......................................................... 6.64 

MgO...................... '.-................................... 1.98

H20 (ignition). . .............................................. 13. 28

98.91

"Keyes, C. K.,, Origin and relations of central Maryland granites: .Fifteenth Ann. llept. U, S. Geol, 

Survey, 1895, pp. 720-729.

6 Watson, T. L., On the occurrence of urauophane in Georgia: Am. Jour. Sci., 4th ser., vol. 13, 1902, pp. 

464-460.

38971° Bull. 426 10 3
32 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

In Maryland G. H. Williams" reported the following minerals on 

the surfaces of the joints that intersect the gneiss in the large quarries 

on Jones Falls and Gwynns Falls, at the northern and western 

limits of the city of Baltimore: Haydenite (chabazite), laumontite, 

harmotome (or phillipsite?), stilbite, beaumontite (heulandite), 

siderite, pyrite, barite, halloysite, epidote, garnet, and tourmaline.

WEATHERING.

When exposed for a sufficient length of time to the atmosphere 

all rocks undergo decay, the siliceous crystalline rocks like granite 

being converted superficially into a loose, incoherent mixture of 

ferruginous sand and clay. As a result of this process of degeneration, 

or weathering as it is commonly called, the rocks of the Southern 

States are very generally covered with a mantle of variable thickness 

of residual materials. Frequently the loose, decayed rock mantle 

must be removed before quarrying can be commenced. (See PI. V, B. )

Notwithstanding this widespread decay of the rocks over the southern region, exposures of the granite are numerous, presenting a 

variety of form. They appear chiefly as flat-surfaced masses of 

variable extent, as large and small bowlders either lying on the surface or partly buried in the residual material (Pis. XVI, B; XVII, A; 

XXIII, A, B}, as dome-shaped masses of large and small dimensions 

having steep or gentle slopes (Pis. XIV, B; XVII, B; XXV, A, B; 

XXVII, A), and as low or high ledges alongstream courses (Pls.X,XI).

Much has been written recently on the decay (weathering) of 

granite, but it will suffice here to give only some of the more important 

references to the literature:

JULIEN, ALEXIS A. The durability of building stones in New York City: Tenth 

Census, vol. 10,1884, pp. 370, 371; A study of the New York obelisk as a decayed 

.bowlder, Annals New York Acad. Sci., vol. 8,1893, pp. 93-166. .

KEYES, C. E,. The origin and relations of central Maryland granites: Fifteenth 

Ann. Rept. U. S. Geol. Survey, 1895, p. 725; Surface disintegration of granitic 

masses: Proc. Iowa Acad. Sci., vol. 1, pt. 3, 1893, pp. 22-24; Secular decay of 

granitic rocks, Proc. Iowa Acad. Sci., vol. 2, 1895, pp. 27-31.

MERRILL, GEORGE P. Stones for building and decoration, 3d ed., New York, 1903, 

pp. 418-446; The physical, chemical, and economic properties of building stone: 

Maryland Geol. Survey, vol. 2, 1898, pp. 92-94; A treatise on rocks, rock weathering, and soils, 2d ed., New York, 1906, pp. 185-195, 231-232; Disintegration of 

the granitic jocks of the District of Columbia: Bull. Geol. Soc. America, vol. 6, 

1895, pp. 321-332.

WATSON, THOMAS L. A preliminary report on a part of the granites and gneisses of 

Georgia: Bull. Georgia Geol. Survey No. 9-A, 1902, pp. 298-348; Weathering of 

the granitic rocks of Georgia: Bull. Geol. Soc. America, vol. 12, 1901, pp. 93-108.

The views shown in Plates V, A, B, and XVII, A, indicate the mode 

of weathering usually characteristic of granites, particularly where

a Notes on the minerals occurring in the neighborhood of Baltimore, 1887,17 pages. (Quoted by Mathewa, 

E. B.,op. cit.,p. 164.)
GBANITES IN GENEBAL. 33

traversed by joints. Joints are easy lines for the percolation of surface 

waters, which move downward along the vertical joints and laterally 

along the horizontal joints, producing disintegration and decomposition of the granite, extending inward from the joint surfaces. The 

incipient stage of granite weathering may be observed in any exposed 

granite ledge by the whiteness and opacity of the feldspars, the rock 

having undergone kaolinization from hydration. The amount of 

water increases rapidly as decomposition advances.

In the more advanced stages of weathering, solution and oxidation, 

promoted through atmospheric waters, become dominant factors in 

the process. As a result of these changes, disintegration and decomposition, the granite is finally reduced to sand and clay, more or less 

discolored by iron oxides set free through decomposition of ironbearing minerals, such as biotite, hornblende, etc.

The weathering of siliceous crystalline rocks like granite involves

the following chemical changes: A loss in silica, a greater proportional 

loss in lime, magnesia, and the alkalies (soda and potash), and a proportional increase in the amounts of alumina and sometimes of iron 

oxide.a In extreme cases the total loss may be nearly 75 per cent of 

the entire rock mass,6 though it rarely amounts to more than 60 per 

cent. Careful study of District of Columbia granites by Merrill and 

of Georgia granites by the writer shows the total losses produced by 

chemical decay (decomposition), calculated from chemical analyses of 

the fresh and corresponding decayed rock, to be as follows:

Total percentage losses accompanying the decay of granites.

DISTRICT OF COLUMBIAN

Foliated gray micaceous granite................................ 13. 79

GEORGIA.**

Light-gray biotite granite, Swift & Wilson quarry, Elberton...... 7. 92

Blue-gray biotite granite, Lexington Blue Granite quarry, Lexington...................................................... 14. 56

Porphyritic biotite granite, Heggie Rock, Columbia County...... 15. 84

Biotite granite gneiss, Crossley quarry, Lithonia.................. 26. 69

Porphyritic biotite granite gneiss, Brinkley Place, Camak........ 34. 04

Porphyritic biotite granite, McCollum quarry, Coweta County.... 35.07

Biotite granite, Cole quarry, Newnan............................ 38. 45

Biotite granite, Coggins quarry, Oglesby......................... 44. 72

Biotite granite, Greenville Granite Company's quarry, Greenville. 71. 84

o Merrill, G. P., A treatise on rocks, rock weathering, and soils, 2d ed., New York, 1900, p. 220. 

6 Watson, T. L., A preliminary report on a part of the granites and gneisses of Georgia: Bull. Geol. Survey 

Georgia No. 9-A, 1902, pp. 312-317.

cMerrill, G. P., Bull. Geol. Soc. America, vol. C, 1895, pp. 321-332. 

d Watson, T. L., Bull. Geol. Survey Georgia No. 9-A, 1902, p. 333.
34 GKANITES OF SOUTHEASTERN ATLANTIC STATES.

It should be remarked that decay was not equally advanced, chemically, in these granites. However, in each one the decayed product 

represented loose material. Those granites showing the smallest percentage loss listed in the table crumbled largely through physical 

changes (disintegration). The most advanced stage in chemical decay 

(decomposition) is represented in the granite from the Greenville 

Granite Company's quarry, Greenville, Ga.

An interesting form of weathering very frequently observed in the 

southern granites is illustrated in Plate V, A, B, which shows granite 

bowlders consisting peripherally of concentric shells, which break off 

one after another in passing from the surface toward the center. This 

form of weathering has resulted from the more rapid decay on the 

edges and corners than on the flat sides of the jointed granite blocks, 

the blocks being gradually rounded and formed into bowlder-like 

masses of varying size.

DISTRIBUTION OF THE GRANITIC ROCKS.

Reference to the map (fig. 1) will show that the region discussed 

includes the southern half of the northern Appalachians and all of 

the southern Appalachians. The boundary between the northern and 

southern Appalachians a is a line drawn from the most easterly point 

of Kentucky southeastward across Virginia and North Carolina to 

Cape Fear, on the Atlantic. The two divisions show decided differences in the forms of relief and in the drainage. .

The region is divided into three well-defined physiographic provinces, which are intimately related to its geologic structure. These 

are, named in order from southeast to northwest, (a) the Coastal 

Plain; (ft) the Piedmont Plateau; and (c) the Appalachian Mountains. 

The three provinces observe a general parallelism with each other 

and with the present coast line, trending northeast and southwest.

COASTAL PLAIN.

The easternmost of the provinces, known as the Coastal Plain, comprises the area between the Atlantic Ocean and a line passing in a 

general southwesterly direction from a point near New York City to 

Columbus, Ga., through or near Trenton, Philadelphia, Baltimore, 

Washington, Richmond, Petersburg, Raleigh, Columbia, Augusta, 

Macon, and Columbus. There is a general widening of the Coastal 

Plain region to the southwest from about 100 miles in northern Maryland to 200 miles or more in Georgia. It is characterized as a low, 

flat-lying area, whose elevation gradually increases from sea level at 

the coastal border to 400 or 500 feet at its western edge. It is coma Hayes, C. W., Physiography of the United States; The southern Appalachians: Nat. Geog. Mon., No. 

10, New York, 1896, p. 305.
GEANITES IN GENERAL. 35

posed of loose and partly consolidated sediments, chiefly sands, 

clays, and marls, which preserve a gentle seaward dip.

No granites are found within the Coastal Plain except in small areas 

of a few inliers of the Piedmont crystalline rocks, which are exposed 

mainly along the stream courses near its western margin by stripping 

off the veneer of loose sediments. The inliers are composed, either 

partly or wholly, of granite, and quarries are opened in a few of these 

areas in Maryland, Virginia, the Carolinas, and Georgia.

PIEDMONT PLATEAU.

The middle province, known as the Piedmont Plateau, is named 

from its position along the eastern foot of the Appalachian ranges. 

It is bordered by the Coastal Plain on the east and extends to and 

along the southeastern base of the Appalachian Mountains. It 

averages about 50 miles in width in Maryland but broadens toward 

the southwest until it reaches a maximum of approximately 125 

miles in North Carolina; it narrows through South Carolina and 

Georgia, and finally .passes beneath the Paleozoic and Coastal Plain 

sediments in central Alabama. (See fig. 2.)

Piedmont Plateau Contact

(Fall line) Coastal Plain

FIGUKE 2. Generalized section showing relations of the Coastal Plain formations to the Piedmont Plateau

crystalline rocks.

The surface of the Piedmont Plateau shows a gentle eastward slope 

from an altitude of 1,000 to 1,200 feet at the western edge to one of 400 

to 500 feet along the eastern margin. Geologically the region is formed 

of a complex of highly metamorphosed sedimentary and igneous 

rocks of Paleozoic and pre-Paleozoic age, largely concealed beneath 

a cover of residual material due to decay. Because of the, thick 

mantle of loose residual material exposures of the fresh rock are less 

numerous than they are farther north.

The Piedmont Plateau differs markedly from the Coastal Plain in 

the nature and origin of its surface features and in the age, kinds, 

and structure of its rocks. Its surface is not a smooth plain but is 

broadly undulating or rolling, and the streams cross it in rather deep 

and narrow channels. Less reduced areas of the harder rocks, rising 

several hundred feet above the upland surface of the plateau, are 

not uncommon over the region. Toward the eastern margin the 

hills rise but little above the plateau surface but as the western margin is approached they rise higher and higher above the general surface until, in North Carolina, a few of them reach elevations of several thousand feet. Through the Carolinas and a part of Georgia
36 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

the western limit of the plateau is irregular and is marked by the 

change from the general sloping surface to the steep slopes of the 

Blue Ridge and its outliers. Farther south in Georgia and Alabama 

its western limit is less well defined, owing to the fact that the surface of the mountain belt has been worn down nearly to that of the 

plateau. The transition from the rocks of the plateau along its 

northwest margin to the metamorphosed strata of the mountain 

province is less distinctly marked and not so abrupt as the change 

from the Coastal Plain sediments.

The rocks of the Piedmont Plateau are wholly crystalline and are 

derived in part from original sediments and in part from original 

igneous masses. They include chiefly crystalline gneisses and schists 

associated with crystalline limestones, quartzites, and phyllites, 

intrude.d by granitic and gabbroitic rocks and more basic rocks 

(peridotites-.and pyroxenites). The gabbroitic rocks include a wide 

range of ftype.Sj,. many of which are admirably suited for structural 

purposes and have.been or are being quarried in places for building 

and-ornamental ; .s.to.ne. The abundance, variety, and general excellence of the granites make them the most important for use in commercial work. The entire production of granite from the southeastern Atlantic States is from tjie Piedmont province.

Over parts of the Piedmont region in Maryland, Virginia, and 

North Carolina"'Ne.wark:: ." (Triassic)'. sediments, including sandstones, 

conglomerates, and shalesV'h^ave been deposited.- These sediments 

are broken by faults and are penetrated by large and small dikes 

of diabase, which'are "quarried in places, the product being known 

to the trade as "black granite."

As a rule, the original'features of the rocks composing the Piedmont Plateau have been'largely changed by profourid'inetamorphism 

since the formation of the rocks. The principal changes' h'ave been

recrystallization and textural modification. The most marked 

textural change has been the development of pronounced foliation 

or schistosity in most of the rock types. The foliation or schistosity 

of the rocks is in general coincident with the trend of the province, 

northeast and southwest, but varies in dip. It is present in both 

the sedimentary and the igneous rocks. In the former the foliation 

is so strongly developed that it largely obscures the original bedding 

planes, and frequently renders their determination impossible. In 

the igneous rocks foliation is in places so pronounced as entirely to 

obscure the original appearance of the rock; in other places all 

gradations between the unaltered massive rock and the foliated 

types may be traced.

The streams crossing the Piedmont Plateau have rapid currents 

as far as its eastern border, but even the largest rivers are not navigable. Several of the easternmost areas, however, in Maryland
GRANITES IN GENERAL. 37

and Virginia more especially, lie adjacent to tide water, where shipment by water is possible over the larger navigable streams which 

cross the Coastal Plain region. But, notwithstanding the favorable 

location of these areas, practically all the quarried material in the 

Piedmont region is shipped by rail, largely because of the excellent 

transportation facilities afforded by the numerous lines of railway 

which traverse nearly all parts of the region.

Granites are extensively worked at the following localities in the 

Piedmont Plateau south of Pennsylvania: At Port Deposit, Guilford, and Woodstock, in Maryland; near Fredericksburg, Richmond, 

and Petersburg, in Virginia; near Mount Airy, Salisbury, and Ore}- 

stone, in North Carolina; near Beverly, Columbia, Heath Springs, 

Lexington, and Winnsboro, in South Carolina; at Stone Mountain, 

Lithonia, Oglesby, and Sparta, in Georgia; and in numerous minor 

areas. Plates I, VII, XIII, XXI, and XXIV show the location, by 

States, of the granite quarries from Pennsylvania to Alabama.

APPALACHIAN MOUNTAINS.

The Appalachian Mountains" region is bordered by the Piedmont 

Plateau on the southeast, and'extends northwestward to the eastern 

limits of the greater Appalachian Valley, comprising a mountainous 

belt of variable width. It extends southwestward from the high land 

of South Mountain in Pennsylvania, through Maryland, Virginia, 

and western North Carolina, and terminates in northern Georgia 

and eastern Alabama. Throughout their extent the eastern members of this belt are generally known as the Blue Ridge. Maximum 

heights of 6,600 and 6,700 feet arc reached in western North Carolina, 

and there is a gradual lowering toward Alabama and Virginia. The 

mountain belt widens to its greatest, width-of about 70 miles in 

western North Carolina. Its southeastern edge is marked by the 

southeastern front of the Blue Ridge, and the northwestern edge 

by the' somewhat higher Unaka Range. It merges into the Blue 

Ridge toward the Virginia line, and terminates southwestward in 

northern Georgia. Between the two ranges the area is occupied 

by numerous groups of irregular mountain masses which rise to 

elevations of 4,000 to 6,700 feet. The mountains are rugged and 

deeply dissected.

Roanoke River and the major streams north of it, like the James, 

Potomac, and. Susquehanna, rise west of the Blue Ridge and flow 

southeastward across it into the Atlantic Ocean. New River, which 

gathers its waters in the Blue Ridge region of northwestern North

aHayes, C. W., Physiography of the United States: The southern Appalachians, 1890, pp. 305-33fi. 

Willis, Bailey, Physiography of the United States: The northern Appalachians, 1890, pp. 109-202. 

Powell, J. W., Physiography of the United States: Physiographic regions of the United States, 189fi, 

pp. 05-100. 

Keith, Arthur, The Appalachian mountains and valleys: Science, n. scr., vol. 25,1907, pp. 805-807.
38 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

Carolina, follows a northwestward course across the greater valley 

and the plateau into the Ohio. From Roanoke River southwestward 

the crest of the Blue Ridge marks the divide between the Atlantic 

and the Gulf drainage. The southeastern slopes of the Blue Ridge 

are usually steep, in contrast with the more gentle northwestern 

slopes.

Igneous rocks, comprising acidic and basic volcanic rocks and 

granites of pre-Cambrian (Algonkian) age, make up a considerable 

part'of the mountain belt (Blue Ridge) in Maryland and Virginia.0 

The granites are closely associated with arid cut the volcanic rocks, 

forming long, aarrow belts, which vary in width up to 6 miles. The 

granites vary in texture and composition and, as a rule, are greatly 

changed by metamorphism, many of them resembling schists.

Keith's studies b of the region farther southwest, in the western 

Carolina portion o'f the belt, disclose the fact that the main mass 

of the mountains is composed of gneisses, through which have been 

injected igneous rocks of various descriptions, mainly granites. 

According to Keith, these rocks are, for the most part, Archean, 

but include'some also of Algonkian age. The granites, which are 

very abundant over the Carolina portion of the mountain belt, 

vary in texture and color and show marked evidences of metamorphic 

changes. They are described in some detail on pages 153-161.

Over many parts of the mountain belt, but more especially over 

the western Carolina portion, granites of excellent quality are to 

be found. These, however, have nowhere been developed, except 

that here and there a quarry has been opened to supply a very local 

trade. The remoteness of many of them from lines of transportation, tke ruggedness of the region in general, and the practical lack 

of demand for stone of this kind within the belt have been the principal factors against development.

a. Keith, Arthur, Geology of the Catoctin belt: Fourteenth Ann. Kept. U. S. .Geol. Survey, 1894, pp. 

285-395.

f> Keith, Arthur, Cranberry folio (No. 90), 1903; Asheville folio (No. llfl), 1904; Mount Mitchell folio 

(No. 124), 1905; Nantahala folio (No. 143), 1907; Pisgah folio (N«. 147), 1907: Geol. Atlas U. S., TJ. S. Geol. 

Survey.
CHAPTER II. 

THE GKANITES OF MARYLAND.

THE MARYLAND PIEDMONT REGION.

The Maryland portion of the Piedmont province embraces a small 

trapezoidal area which is bounded by the fall line on the east, Catoctin 

Mountain on the west, Potomac River on the south, and the southern 

boundary of Pennsylvania on the north. 0 According to Abbe, its 

topography embraces features of three different classes the broad, 

rolling upland surface, the valleys carved in the upland, and the 

residual masses which rise above the upland. It is divided near its

central portion by an area of high land known as Parrs Ridge into an 

eastern and western district, each of which has its own peculiar 

characters. It has an approximate total area of 2,500 square miles, 

including Cecil, Harford, Baltimore, Howard, and Montgomery, and 

parts of Frederick and Carroll counties. Parrs Ridge forms the 

divide between the streams flowing eastward across the Piedmont 

into Chesapeake Bay direct, and those which flow westward to the 

Monocacy and thence to the bay.

It is in the eastern division of the Piedmont that the granites are 

found. The drainage of this district flows to the east and southeast. 

Susquehanna and Potomac rivers, which drain directly into Chesapeake Bay, traverse it on its northern and southern boundaries. 

Among the larger intermediate streams which head on Parrs Ridge 

are Patuxent, Patapsco, and Gunpowder rivers. These streams are 

not navigable beyond the western limits of the fall line, and material 

quarried in that region must be shipped either by rail, canal, or 

wagon routes.

To the east of Parrs Ridge the rocks consist of highly metamorphosed sediments and a complex of intruded igneous masses which 

have been more or less metamorphosed, rendered schistose, or 

laminated. The highly metamorphosed sedimSnts b comprise the 

following formations, which, according to the Maryland Geological 

Survey, range in age from Archean to Ordovician: The Baltimore 

gneiss, the Cockeysville marble, the Wissahickon mica gneiss, the 

Octoraro schist, the Cardiff quartzite, and the Peachbottom slate. 

The igneous rocks comprise extensive areas of gabbros, granites, and 

other plutonic types.' The gabbros were intruded earlier than the

a Abbe, Cleveland, jr., A general report on the physiography of Maryland, Maryland Weather Service, 

1899, p. 117. 

6 Maryland Geol. Survey, vol. 6,1900, pp. 105-113.

39
40 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

granites, but the .exact period of intrusion of the igneous masses is 

still somewhat uncertain. In addition to these, small dikes of acidic 

volcanic rocks (metarhyolite) occur along the lower Susquehanna 

in the vicinity of Frenchtown and Havre de Grace, and a series of 

Mesozoic diabase dikes can be traced with interruptions across the 

entire eastern part of the Piedmont district. 0

The western division of the Maryland Piedmont extends from Parrs 

Ridge to Catoctin Mountain. On its east side the rocks are scarcely 

distinguishable from those of the eastern division, but in the western 

part the rocks are much less metamorphosed. Semicrystalline sediments, chiefly limestone and sandstone of Cambro-Ordovician and 

Mesozoic age, and igneous rocks, chiefly Archean basic and acidic 

volcanic rocks and Mesozoic diabase, compose the rocks of this 

division.6

The rocks east of Parrs Ridge are more crystalline and the folding 

is a little more pronounced than in the western division of the Piedmont. The older rocks have suffered extreme metamorphism which 

has produced in them a marked lamination or schistosity, accompanied by recrystallization. Schistose structures, having a general 

northeast-southwest trend and variable dip, are developed in both the 

sedimentary and the igneous rocks.

DISTRIBUTION OF THE GRANITES.

The granites and gneisses of Maryland are limited to the Piedmont 

Plateau province (see PL I); and within this region the quarrying 

industry is confined to a triangular area between the Coastal Plain on 

the east and Parrs Ridge on the west, including the whole or parts 

of Cecil, Harford, Baltimore, Howard, and Montgomery counties. 

The granites occupy several distinct areas in the eastern division of 

the Piedmont Plateau. The largest of these areas extends from

Sykesville southward to Washington and across the Potomac into 

Virginia. The most important, economically, is the lenticular are^a 

that extends southward from Rising Sun through Port D.eposit and 

along the .southwest side of Susquehanna River. Of the fifteen areas 

where granite is ^prominently developed, there are at least five which 

include quarries of'considerable.''.economic importance. 0 These are, 

named from north to south, (1) Port Deposit, (2) Frenchtown, 

(3) Ellicott City, (4) Woodstock, and (5) Guilford. Besides these 

there are several minor, areas in which quarries have been worked 

from time to time >to supply the local demand for stone. The most 

important of the smaller areas is that of Dorseys Run, on the Baltimore and Ohio Railroad between Ellicott City and Woodstock.

a Maryland Geol. Survey, vol. 6, 1906, pp. 113-118. 

6 Idem, pp. 118-123.

c Mathews, E. B., An account of the character and distribution of Maryland building stones, together with 

a history of the quarrying industry: Maryland Geol. Survey, vol. 2, 1898, p. 138.
BULLETIN 426 PLATE I

Granite quarries 

Inumben m*r to lift*)

granite 

Dioritc andgabbro

Fall line

QUARRIES

1 Baldwin

2 Frenchtown (Perryville Granite Co., Luken & 

Yerkes)

3 Port Deposit (McClenahan Granite Co.)

4 Amoss

5 Franklinville ^Cotton Duck Factory Co.)

6 Phcenjx (J. Baker)

7 Rapsb'urg

8 Jones Falls (Gatch, Atkinson, Schwind, Peddicord)

9 Gwynns Falls (Schwind, Peddicord, Leonard)

10 Stevenson (Shoemaker)

11 Fox Rock

12 Guilford and WaltersvilleGraniteCo.(Woodstock)

13 Fearing & Atherton

14 Dorsey Run

15 Werner Bros.

16 Gaither

17 Patap.tco Quarry Co.

18 Maryland Granite Co.

19 Guilford and Waltersville Granite Co. (Guilford)

20 Guilford Granite and Stone Co.

21 Garrett Park (Riggs)

22 Rockville

23-25 Potomac River Quarries

26 Cabin John (Gilbert)

27 Dickerson (Standard Lime and Stone Co.)

28 Savage, B. F. Pope Stone Co., W. T. Manning

29 Franklin Road (Langley Quarry Co., Maryland 

Quarry Co., T. R. Martin & Sons)

30 Windsor Hills (Campbell), Dickoyvillo (Hook& 

Ford Contracting Co.)

31 Woodberry (Hook fk Ford Contracting Co.)

32 Govanstown

33 Lockraven (Conway Co.)

34 Standard Lime and Stone Co.

35 Baltimore and Ohio Railroad

36 Rowlandsville (Thomas S. Gsiry, Armstrong & 

McDowoll)

MAP OF MARYLAND, SHOWING DISTRIBUTION OF GRANITE QUARRIES AND OF GRANITE AND GNEISS AREAS.

Based on maps of Maryland Geological Survey, vol 2, 1898; vol. 6, 1906.
GRANITES OF MARYLAND. 41-

The others are Sykesville, Garrett Park and Brookville, Franklin ville, 

Benson, Baldwin station in Cecil County, Texas, and Relay.

Quarries of gneisses of granitic composition have been operated 

for many years near and in the city of Baltimore, grouped about two 

centers Jones Falls and Gwynns Falls, on the north and west sides 

of the city, respectively.

SCIENTIFIC DISCUSSION.

VARIETIES OF THE GRANITE/'

On the basis of mineral composition the Maryland granites are 

divisible into the following leading types: (1) Biotite granite or 

granitite, under which most of the granites of the State may be 

grouped, including Port Deposit, Frenchtown, Woodstock, Dorseys 

Run, Texas, Ellicott City, and Ilchester among the most important 

areas. In addition to biotite, the granites of some of the Port Deposit

localities, of Woodstock, Dorseys Run, Ellicott City, and Ilchester contains considerable epidote and allanite, and may be designated as 

allanite-epidote granitite; (2) muscovite-biotite granite, of which the 

Guilford area is the only typical representative; and (3) hornblendebiotite granite, represented by the granites occurring northeast of 

Washington, near Garrett Park, and near Rowlandsville, in Cecil 

County.

Structurally there are three rather well-marked types of the Maryland granites (1) even-granular (massive) granites; (2) porphyritic granites; and (3) banded or schistose granites (granite-gneisses). 

To these should be added the two subvarieties graphic granite and 

pegmatite. Quarries are worked in some of the larger pegmatites for

feldspar.

MINERAL COMPOSITION.

- Conforming with other w^ell-known granites, the Maryland rocks 

are made up of a mixture of quartz and feldspar with biotite usually 

as the third essential mineral. Orthoclase, abundant plagioclase 

(oligoclase), and microcline in variable amount compose the feldspathic constituent. Biotite is an important constituent in all the 

granites of the State. In some of the areas it is associated with 

hornblende; in others with muscovite, epidote, and allanite. In 

the granites near Garrett Park and Rowlandsville hornblende forms 

an important constituent and is about equal in amount to biotite. 

At Guilford muscovite occurs with biotite as an important mineral. 

Besides these there occur magnetite, apatite, zircon, titanite, and 

locally some other minerals.

a Williams, G. H., Petrography and structure of the Piedmont in Maryland: Bull. Geol. Soc. America, 

vol. 2,1891, p. 321; T-he general relations of the granitic rocks in the middle Atlantic Piedmont Plateau: Fifteenth Ann. Kept. U. S. Geol. Survey, 1895, pp. 057-084.

Keyes, C. R., The origin and relations of the central Maryland granites: Fifteenth Ann. Kept. U. S. Geol. 

Survey, 1895, pp. 714-718.
42 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

Examination of the table of analyses of the Maryland granites 

given below discloses the fact that in about half of them soda is 

equal to or greater than potash, indicating the prevailingly large 

quantity of plagioclase (soda-lime feldspar) present in these rocks. 

Again, one of the most striking features of the Maryland granites is 

the prevalence of microcline, which has developed in part from 

orthoclase by pressure metamorphism.

The granites of some of the Port Deposit localities, of Woodstock, 

Dorseys Run, Ellicott City, and Ilchester,0 contain a considerable 

quantity of epidote and allanite as important characteristic constituents, and for this reason they were grouped by Keyes b as allaniteepidote granites.

CHEMICAL COMPOSITION.

Variation in the chemical composition of. the granites and gneisses 

of Maryland and the District of Columbia is indicated in the analyses 

of these rocks, which follow:

Analyses of Maryland and District of Columbia granites and gneisses. 

[Analysis 1, by William Bromwell; analyses 2-12, by W. F. Hillebrand; analysis 13, by G. P. Merrill.]

SiOt........ .........

AI2O3 . ...............

FesOi.. .............. 

FeO.................

MgO.. ..............

CaO .................

Na20.. ..............

K2 0......... ........ 

H2O-atllO°0...... 

HaO+at 110° C...... 

TiOs.. ...............

PsOs.. ...............

MnO. ........ .......

BaO... ..............

SrO. ....... .........

LijO... ........ ......

1. 

73.69 

12.89 

 1.02 

2.58 

.50 

3.74 

2.81 

1.48

| 1.00

99.77

2

74.87 

14.27 

Tr. 

.51 

.1C 

.48 

3.0C 

5.30 

/ .66 

\ .20 

n^

.21

Tr

Tr.

99.89

3.

72.57 

15.11 

1.02 

.59 

.30 

1.65 

3.92 

4.33 } .«

Tr.

99. 9(i

4.

71.79 

15.00 

.77 

1.12 

.51 

2.50 

3.09 

4.75

.04

Tr.

100. 17

71.45 

14.36 

'2.07 

2.78 

1.17 

1.58 

1.95 

3.28

1.30

Tr.

99.94

0.

70.45 

15.98 

.75 

1.84 

.77 

2.00 

3.83 

3.59

.45

Tr.

100.20

7.

09. 33 

14.33

"3." 60 

2.44 

3.21 

2.70

2.67

1.22

.10

Tr.

99. 2ti

8.6

66.08 

14.93 

1.58 

3.23 

2.19 

4.89 

2.65 

2.05 

f 1.09 

i .16 

.50

.10

.10

.08

Tr.

Tr.

100.23

9.c

62.91 

19.13 

.98 

3.20 

1.69 

4.28 

3.94 

3.38

| . 63

Tr.

100.14

10. c

67. 22 

15.34 

2.78 

3.41 

1.65 

1.30 

2.00 

3.26 

f .29 

\ 1.08 

.84

.14

.13

.04

Tr. 

Tr.

100. 14

11. c

63.43 

10.09 

3.36 

3.87 

2.33 

.80 

2.38 

3.22 

.23 

2.67 

.91

.11

.09

03

Tr.

Tr.

100.12

12. c

78.28 

9.96 

1.85 

1.78 

.95 

1.08 

2.73 

1.35 

.12 

.83 

.70

.11

.08

.02

Tr. 

Tr.

100.44

13.d

09. 33 

14.33

"3." 60 

2.44 

3.21 

2.70 

2.07

| 1.22

Not 

(let.

Tr. 

Tr.

99.00

. Biotite granite (quartz monzonite), Port Deposit, Cecil County, Md. 

:. White granite, Brookville, Montgomery County, Md.

aMathews, E. B., Maryland Geol. Survey, vol. 2, 1898, p. 142. (See Grimsley, G. P., Jour. Cincinnati 

Soc. Nat. Hist., vol. 17, 1894.)

b Bascom, F., Geology of the crystalline rocks of Cecil County: Cecil County Kept.. Maryland Geol. Survey, 1902, p. 120.

c Williams, G. H., The general relations of the granitic rocks in the middle Atlantic Piedmont Plateau: 

Fifteenth Ann. Kept. U. S. Geol. Survey (1895), pp. 070, 672.

d Merrill, G. P., A treatise on rocks, rock weathering,'and soils, New York, 1906, p. 186.

1. 

2

3. Muscovite-biotite granite, Guilfofd, Howard County, Md.

4. Biotite granite, Woodstock, Baltimore County, Md.

5. Biotite granite, Sykesville, Carroll County, Md.

6. Biotite granite dike, Dorseys Run cut, Howard County, Md.

7. Biotite granite gneiss, Broad Branch quarry, District of Columbia.

8. Hornblende-biotite granite, Rowlandsville, Cecil County, Md.

9. Biotite granite, Dorseys Run cut, Howard County, Md.

10. Gneiss from Potomac Stone Company's quarry, 1 mile below the Chain Bridge, District of Columbia.

11. Chloritic gneiss from Emery's store, northwest of Cabin John Bridge, Montgomery County, Md.

12. Gneiss from second lock at Great Falls, Montgomery County, Md.

13. Foliated biotite granite from the District of Columbia.

oHobbs, W. H., Johns Hopkins Univ. Circ., vol. 7, No. 05, 1888, p. 70; Am. Jour. Sci., 3d ser., vol. 

38,1889, p. 223; Tschermaks Min. pet. Mitt., vol. 11,1890, p. 1.

6 Keyes, C. R., The origin and relations of central Maryland granites: Fifteenth Ann. Rept. U. S. 

Geol. Survey, 18 5, p. 717.
U. S. GEOLOGICAL SURVEY BULLETIN 426 PLATE II

QUARRIES NEAR GLEN ECHO, MD. 

A. Joints and faults. B. Intersecting joints.
GRANITES OF MARYLAND. 43

The high soda content in the Maryland granites in general has been 

commented on above. In many of the analyses soda equals or 

exceeds .potash, indicating in these the predominance of plagioclase 

(soda-lime feldspar) over orthoclase (potassic feldspar), which 

places the granites with the quartz-monzonite type.

Analysis 12 in the table does not correspond to any known igneous 

type, but is in close agreement with certain siliceous sediments; as 

Williams a remarks, '' so far as the chemical evidence can be relied 

upon, we may safely regard the rock as of sedimentary origin." 

The other gneisses represented by analyses in the table are of igneous 

origin.

STRUCTURAL FEATURES.

JOINTS.

Jointing, both vertical and horizontal, is prominently developed 

in the Maryland granites (see PL II, A, B), and a third set of diagonal 

joints is distinct in many of the quarries. The courses of many of 

the principal vertical joints are N. 30°-35° E., N. 40°-45° E., and 

N. 55°-60° E.; N. 10° W., N. 40°-45° W., and N. 60°-70° W.; northsouth, and east-west. The joints of the dominant system extend 

approximately northeast and northwest, east-northeast and westnorthwest. The spacing of the joints varies considerably, ranging 

from less than 1 foot to more than 20 feet, but is usually from 6 to 

15 feet.

The horizontal joints, prominent in all the larger quarries, separate 

the granite into sheetlike masses, which usually have their strongest 

development near the surface, but in some quarries extend to the 

entire depth of working. Nowhere is this better shown among the 

Maryland granites than in the old Guilford and Waltersville Granite 

'Company's quarry in the Woodstock area (Pis. IV, B; VI, B). The 

sheets may vary from a few inches in thickness at or near the surface to 2 to 10 feet at some distance below the surface. In the 

quarries on the Baltimore County side of Patapsco River, at Ellicott City, sheeting extends to the depth of working, more than 90 

feet, and the sheets range in thickness from 2 to 4 feet. In the quarries of the Woodstock area the sheets are from 2 to 6 feet thick, and 

in the quarries of the Guilford area from 3 to 10 feet thick. Approximately the same range in thickness is shown in the Port Deposit 

quarries, one of which has been worked to the extreme depth of 

230 feet.

Some movement in the granite masses is indicated in the slickenside joint surfaces of the larger quarries. Slickensides are especially noticed on some of the joint surfaces in the quarries at Port 

Deposit, Frenchtown, Ellicott City, and Guilford.

a Williams, G. H., op. cit., p. 670.
44 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

SCHISTOSITY.

The Maryland granites, and indeed the granites of the Southern 

States generally, strongly contrast in the amount of foliation secondarily induced in them by pressure metamorphism. The granites of 

Ellicott City, Woodstock, and Guilford show little or no pressure 

effects, but are massive. Those near S}'"kesville, Texas, and Rowlandsville, and the Murdoch Mill area west of Washington are 

slightly foliated, but not sufficiently so to disguise their essential 

features. In the Port Deposit region and in the Broad Branch area 

west of Washington secondary foliation has resulted in a complete 

rearrangement of the constituents," and the rocks are more properly 

designated granite gneisses.

In the Pine}^ Run type, which occupies a considerable area south 

of Laurel and on Potomac River, extreme foliation has obliterated 

most of the original granite features. Concerning this type Williams 

says: 6 "It is only because of the abundance of indistinct masses 

resembling inclusions which are scattered through it that we assume

for this rock an igneous origin."

DIKES.

In some of the granite areas true granite dikes penetrate the rocks 

into which the granite was intruded and are to be regarded as 

apophyses. These are described by Keyes c as being especially well 

developed and exposed in the railroad cut at Dorsey Run, where 

dikes of very light colored, fine-grained granite penetrate gneiss 

and, as shown in the analyses below, are more acidic than the main 

massive granite and also finer grained in texture. The more acidic, 

finer-grained granite dikes also penetrate the more massive granite 

as well as the gneiss. d

Analyses of granite from dikes at Dorsey Run, Md.

. ' Constituents.

Silica (SiO2 )... . .........................................................................

Lime (CaO). ............................................................................

Soda ( Na2 0) ............................................................................

Potash (K2O). ..........................................................................

Water (H2O).. . ............................................... .t ........................

Lithia(Li2 0).... .......................................................................

1.

02.91

19.13

.98

3.20

1.09

4.28

3.94

3.38

.63

100.14

2.

70.45

15.98

.75

1.84

.77

2.60

3.83

3.59

.45

100. 26

1. Typical granite from selected average specimens of the large granite mass; W. F. Hillebrand. analyst; 

Fifteenth Ann. Kept. U. S. Geol. Survey, 1895, p. 722.

2. Selected specimens from the light-colored granite dikes; W. F. Hillebrand, analyst; idem, p. 722.

a Williams, G. H., op. cit., p. 669.

6 Idem, p. 609.

cKeyes, C. R., Fifteenth Ann. Rept. U. S. Geol. Survey, 1895, pp. 722-723.

d Fifteenth Ann. Rept. U. S. Geol. Survey, 1895, pi. xxxvii, fig. 3, p. 694.
U. S. GEOLOGICAL SURVEY BULLETIN 426 PLATE I

PEGMATITE DIKES, MARYLAND. 

A. llchester station. _Z>'. Orange Grove.
GRANITES OF MARYLAND. 45

Granite dikes of dark-gray color and fine-grained texture, not 

exceeding 6 feet in width and striking N. 60° E., penetrate the porphyritic granite of Weber's quarry at Ellicott City. At Port Deposit, 

in the rear of Mr. McClenahan's residence, the granite is penetrated 

by a dike of foliated dark basic rock, 7 feet wide and nearly vertical. 

A second, dike of similar character is exposed in the granite cliffs 

along the path leading from the town to Tome Institute.

PEGMATITE."

Pegmatites and quartz veins are largely developed in the Maryland 

Piedmont region, where they traverse indiscriminately all the formations of both sedimentary and igneous rocks. The pegmatites 

differ from the quartz veins mineralogically in the addition of an 

alkali feldspar and muscovite or biotite. They are essentially very 

coarse crystallizations of quartz and feldspar aggregates, with more 

or less mica. In width they vary from a few inches up to several

hundred feet (PI. Ill, A, B), and can be traced for considerable distances on the surface. They may either break through or cut across 

the schistosity of the inclosing gneisses.

Some of the pegmatites have probably had an origin similar to that 

of the widely distributed quartz veins; others, usually of smaller 

dimensions and wholly inclosed by the granite mass, have probably 

been formed by a process of segregation; while still others seem to 

show equally strong evidence of an intrusive origin. As a rule the 

rock composing the dikes of an intrusive character is a muscovite 

granite, essentially similar to the granite which it intrudes, except 

that it is more acidic. The minerals composing dikes of this class 

are quartz, orthoclase, microcline, albite, muscovite, and a few small 

crystals of red garnet. Williams 6 has shown that these dikes of pegmatite agree closely in composition with the large masses of granite, 

and are quite independent of the character of the rocks which surround them. The Maryland pegmatites, according to Williams, 

belong to the youngest periods of the granitic intrusion and show 

little or no effect of dynamic metamorphism.

The Maryland pegmatites are not especially rich'in unusual minerals. 

They have become of economic importance within recent years for 

their feldspar and quartz (flint) content, especially the feldspar, and 

have been worked in Baltimore, Howard, Harford, and Cecil counties. 

The principal producing area is in the vicinity of Wood stock, Howard 

County, and in the adjacent portion of Baltimore County. As is 

indicated in the analyses below, the feldspar of these dikes belongs 

partly to the potassic and partly to the sodic varieties. 0

a For a detailed description of the Maryland pegmatites and their origin, see Williams, G. II., General 

relations of the granitic rocks in the middle Atlantic Piedmont Plateau: Fifteenth Ann. Kept. U. S. 

Geol. Survey, 1895, pp. C57-684.

6 Idem, p. GS3.

c Mineral Resources U. S. for 1906, U. S. Gcol. Survey, 1907, pp. 1257, 1209. Maryland Geol. Survey, 

Cecil County, 1902, pp. 90, 97,101-103, 217, 218.
46 GRANITES OF SOUTHEASTERN ATLANTIC STATES. 

Analyses of feldspar from Maryland pegmatites.

Constituents.

Silica (SiO2 ). .-................:........-.........-........................-....

Lime (CaO).......... ..........................................................

Potash (K2 0) ..................................................................

1.

65.96

19.53

.24

.18

1.13

12.92

99.96

2.

68.60

19.10

.14

.28

2.09

9.03

99.24

3.

64.62

20.57

Trace

2.36

.14

10.27

1.94

99.90

1. Potash feldspar from quarry of Guilford and Waltersville Granite Company, Woodstock, Howard 

County, Md. Partial analyses of other specimens from the same quarry made at the Maryland agricultural experiment station show 13.2 per cent potash with 1.8 per cent soda, and 13.5 per cent potash with 

1.6 per cent soda. (Quoted by E. S. Bastin, Mineral Resources U. S. for 1906. U. S. Geol. Survey. 1907, 

p. 1259.)

2. Potash-soda feldspar; quarry of Walter F. Patterson, jr., Henryton, Carroll County, Md. Analysis 

by Pittsburg Testing Laboratory (Limited). (Quoted by E. S. Bastin, op. cit., p. 1257.)

3. Soda feldspar, variety albite.from quarry of Sparavetta Mining Company, Chester County, Pa., near 

Sylmar, Md. (Quoted by E. S. Bastin, op. cit., p. 1257.)

QUARTZ VEINS.

Like the pegmatite dikes, quartz veins are numerous over parts of 

the eastern division of the Maryland Piedmont, and the two are as a 

rule closely associated. Many of the veins assume large dimensions, 

and they traverse the formations indiscriminately. Though in many 

places concealed by soil covering, their abundance is indicated locally 

by the innumerable quartz fragments strewn over the surface.

Quartz veins have been observed actually penetrating the granite 

in quarries of two Maryland localities, Frenchtown and Port Deposit, 

Cecil County. They are, however, by no means numerous, and they 

do not exceed 12 inches in width, the average probably being only 

1 or 2 inches. They are apparently more abundant, in the same 

granite, in the high and steep cliffs along the north side of Susquehanna River at and just below the town of Port Deposit. The 

course of the quartz veins in the Frenchtown quarries is N. 60° E.

INCLUSIONS.

Inclusions of foreign rocks, including sedimentary and eruptive 

kinds, incorporated in the granites at Sykesville, Woodstock, Dorseys 

Run, and Garrett Park, were described in some detail by Keyes.a 

They comprise irregular fragments and blocks 9f all sizes and shapes 

identical with the neighboring rocks. For the most part they display 

characteristic border zones of complete alteration with essentially 

unaltered interiors.

 The inclusions were found in greatest abundance in the granite at 

Sykesville. Among the various foreign rock fragments noted by 

Keyes in this granite were limestone, soapstone, pyroxenite, vein 

quartz, and hornblende and biotite gneisses. The granite at Woodo Fifteenth Ann. Kept. U. S. Geol. Survey, 1895, pp. 722,723, 724,726-729,732.
GRANITES OF MARYLAND. 47

stock shows similar phenomena equally well. The incorporated 

fragments are mostly gneiss; many of them are puckered and wrinkled 

and some measure 10 feet. Inclusions of gneiss usually exhibit only 

a very narrow marginal metamorphosed zone. In the small openings 

made in the Garrett Park outcrops, a few miles northeast of Washington, numerous irregular blocks of dark gneiss are in places incorporated 

in the granite. Similar fragments and blocks derived from a near-by 

gneiss are shown in the granite at Dorseys Run.

A chemical analysis, made by W. F. Hillebrand, of the United 

States Geological Survey, of a large assortment of inclusions in the 

granite on Dorseys Run, is given by Keyes: °

Analysis of inclusions in granite from Dorseys Run.

Silica (Si2 0).........'......................................... 57. 33

Alumina (A12 03 )............................................. 15. 31

Ferric oxide (Fe2 03 )........................................... 3.39

Ferrous oxide (FeO)............................................ 8.19

Magnesia (MgO)............................................... 4. 36

Lime (CaO).................................................... 3.95

Soda (Na.,0)......................................'............ 1.22

Potash (K20)................................................. 4.57

Water(H2 0).................................................. 1. 80

Lithia (Li20).................................................. Trace.

p . ______

100.12

In his description of the granitoid rocks which emerge from beneath 

the Coastal Plain south of Laurel and extend across the Potomac 

into Virginia, Williams says: 6

These rocks, though typical gneisses in their structure, are filled with what seem to 

be inclusions of foreign rock, especially of vein quartz and irregular fragments of similar though older gneisses. They may best be studied along the Potomac, between 

Washington and the Chain Bridge, where they are extensively exposed in the great 

quarries. They are also typically shown near the north end of Analostan Island, at 

the Falls of the Patuxent west of Laurel, and along Sligo Branch, Piney Run, and the 

lower portions of Rock Creek, near Washington. They may also be seen to advantage 

where Fourmile and Holmes runs have cut deeply into the Coastal Plain deposits in 

Fairfax County, south of Washington.

BASIC SEGREGATIONS (KNOTS).

Segregations of the ferromagnesian minerals do not seem to be so 

abundant in the Maryland granites as in some of the granites in others 

of the Southern States. A small quarry opening made near Garrett 

Park on the south side of Rock Creek, near the Rockville road, is 

in a light-colored granite poor in ferromagnesian minerals. Keyes c 

reports numerous basic secretions of lenticular shape and various 

sizes in the granite. Occasional dark segregations (knots), few of

o Keyes, C. R., op. cit., pp. 7,22, 723. cQp. clt., p. 730. 

6 Williams, G. H., op. cit., p'. 665.

38971° Bull. 426 10 4
48 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

them exceeding 12 inches in size, were observed by the writer in the 

granite quarries opened at Port Deposit, Frenchtown, Ellicott City, 

Woodstock, and Guilford. They were most abundant in the quarries opened along Patapsco River on the Baltimore - County side, 

opposite Ellicott City. In these quarries many of the knots are 

drawn out parallel to the schistosity of the granite and measure as 

much as 2 feet in length.

The percentage of silica in and the specific "gravity of the basic 

segregations (knots) in the granite at Port Deposit are compared 

with those of other well-known granites on page 30.

PHYSICAL TESTS. 

ABSORPTION TESTS.

Figures obtained by Merrill a showing the relative amount of water 

absorbed by some of the well-known granites and gneisses of Maryland 

are given in the following table:

Absorption tests of Maryland granites and gneisses.

Kind of stone.

Do. ....................................................

Do.....................................................

Do. ....................................................

Weight 

after drying 24 

hours at 

212° F.

Grams. 

351. 33

341. 34

340. 43

340. 45

354. 37

323. 36

Weight 

after immersion 24 

hours in 

water.

Grams. 

352. 22

342. CO

341. 31

341. 24

355. 0/

326. 97

Gain in 

weight.

Grams. 

0.89

.66

.88

.79

.70

3.01

Absorption.

Per cent. 

0..253

.196

.258

.232

.197

1.116

A second set of experiments was conducted by E. B. Mathews 6 on

blocks of the same size (2-inch cubes) as those of the first set.

Absorption teats of Maryland granite and gneiss.

Kind of stone.

Gneiss, Baltimore. .........................

Weight, 

air dry.

Grams.

345. 00

350.70

Weight

after immersion

one hour.

Grams.

350. 65

Weight

after immersion

one day.

Grams.

345. 50

350. 70

Weight

after immersion

one week.

Grams.

350.67

Gain in 

weight.

Grams.

0.05

Absorption.

Per cent.

The tests show that practically no water is absorbed by the specimens. Merrill states that the weather during the experimenting was 

warm (85° to 95° F.), and the humidity was approximately 70 percent.

a Merrill, G. P., The physical, chemical, and economic properties of building stones; Maryland Geol. 

Survey, vol. 2, pt. 2a, 1898, p. 94. 

6Quoted by Merrill, G. P., loc. cit., p. 94.
GRANITES OF MARYLAND. 

MISCELLANEOUS TESTS.

49

Tests to ascertain resistance to freezing were made on 1-inch cubes 

of granite from Port Deposit, Cecil County, and from Great Falls, on 

Potomac River, Montgomery County,Md., with the following results. 0

Freezing tests of Maryland granites.

Locality.

Port Deposit. .......................................................................

Great Falls .........................................................................

Specific 

gravity.

2.009

Loss, In 

grains.

5.05

.35

Merrill states that the inch cubes were immersed for half an hour 

in a boiling solution of sulphate of soda and then hung up to dry, 

this performance being repeated daily throughout the four weeks of 

the experiment. The result is assumed to be analogous to that of 

freezing.

Strength and other physical tests of granite from Port Deposit 

were made by Gillmore b with the following results:

Miscellaneous tests of granites from Port Deposit, Md.

Position.

On bed...

On edge.. 

On bed...

Do...

Cracked.

Pounds.

33,000

Strength 

of specimen.

Pounds. 

79,000

52,400 

66,000

60,000

Strength 

per 

square 

inch.

Pounds. 

19, 750

13,100 

10, 000

15,000

Specific 

gravity.

2.720

2.720 

2.720

2.720

Weight 

of 1 cubic 

foot.

Pounds. 

170

170 

170

170

Ratio of absorption.

0

0 '0

0

Remarks.

black. 

Do. 

Do.

Concerning the following tests, Mathews c states that the specimens were 2-inch cubes carefully prepared and subjected to tests 

under the most uniform conditions:

Strength, absorption, and freezing tests of Maryland granites.

Simple crushing.

Crack.

Pounds.

Break.

Pounds. 

67, 100 

' 79, 200 

86,200 

101,540

Absorption 

gain.

Per cent. 

0.253 

.193

Freezing 

loss.

Per cent. 

O.OOC 

.011

Crushing after 

freezing.

Crack.

Pounds. 

83, 000 

78, 100

Break.

Pounds. 

86,000 

90, 800

oMerrill, G. P., op. cit., p. 105.

6 Gillmore, Reports on the compressive strength, specific gravity, and ratio of absorption of the building 

stones in the United States: Rept. Chief of Engineers for 1875, appendix 2, p. 847; republlshed 8, 37 pp., 

Van Nostrand, New York, 1876. (Quoted by Mathews, E. B., Maryland Geol. Survey, vol. 2,1898, p. 144.)

cMathews, E. B., Maryland Geol. Survey, vol. 2,1898, p. 145.
50 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

Tests made by Messrs. Booth, Garrett, and Blair, of Philadelphia, 

on a 2-inch cube of the granite from Port Deposit gave the crushing 

strength as 84,730 pounds, which is equivalent to 21,180 pounds per 

square inch. a

Mathews 6 reports the following tests on specimens from the Waltersville quarries at Woodstock:

Strength, absorption, and freezing tests on granite from Woodstock.

Simple crushing.

Crack.

Pounds.

79, 700

79, 200

Break.

Pounds.

85,700

83, 420

Absorption

Per cent.

0.258

.232

Freezing

Per cent.

0.011

.029

Crushing after 

freezing.

Crack.

Pounds.

79, 400

86,800

Break.

Pounds.

102, 200

90,300

Mathews c . gives the following results of tests made on the gneiss 

from the extensive quarries on Jones Falls, at the northern limits of 

the city of Baltimore:

Strength, absorption, and freezing tests on gneiss from Jones Falls.

Kind of stone.

Quartzose layers ("blue stone"). .........

Feldspathic layer ("biotite granite").

Crushing.

Crack.

Pounds. 

i6(i, 700 

85,940

78, 600

 Break.

Pounds. 

 70,140 

96,300 

94,200 

103,500

Absorption gain.

Per cent. 

0.197

' i. lie

Freezing 

loss.

Per cent. 

0.028

.052

Crushing after 

freezing.

Crack.

Pounds. 

80,118

63,060

Break.

Pounds. 

118, 000

84, 220

INDIVIDUAL QUARRY AREAS.

GENERAL STATEMENT.

The granitic rocks of Maryland are discussed below by areas under 

(a) granites and (6) gneisses.

Under granites are included the even-granular granites and their 

porphyritic facies and the massive and foliated varieties of both. 

Porphyritic granites are of very minor extent and'are merely local 

facies of the larger even-granular masses. They are represented in 

the Ellicott City, Relay, and Texas areas. Of the massive, evengranular granites, the Guilford and Woodstock areas are the most 

typical. In most of the other areas a foliated or gneissic structure, 

resulting from pressure metamorphism, is more or less developed in 

the granite masses. Granite gneisses, or foliated granites, the most

a Eighteenth Ann. Kept. U. S. Geol. Survey, pt. 5,1897, p. 964. 

b Mathews, E. B., op. cit., p. 156. 

c Idem, p. 164.
GRANITES OF MARYLAND.. 51

typical representatives of which are those of Port Deposit and Frenchtown, are also included under granites.

Under gneisses are included the highly crystalline, banded rocks 

of granitic composition of alternating hornblendic and micaceous 

types, belonging chiefly to the Baltimore gneiss. They are typically 

represented at the western and northern limits of the city of Baltimore about two principal centers, Gwynns Falls and Jones Falls.

GRANITES.

ELLICOTT CITY AREA. 

GENERAL STATEMENT.

As indicated on the map (PI. I), the Ellicott City granite area comprises an irregular L-shaped mass, which has an extreme length of 

about 5 miles in an east-west direction and a. width varying from

one-half mile to 2 miles. On the north, west, and south the granite 

mass is bordered by a large gabbro area, and on the east by gneiss. 

Much of the area is overlain by the Coastal Plain gravels and clays 

of Lafayette and Potomac ages. All the streams in the area have 

cut through this thin covering of recent sediments into the underlying older crystalline rocks, allowing the ready determination of the 

boundaries of the granite, gabbro, and gneiss. The best exposures 

of the granite occur along the gorge of Patapsco River at Ellicott 

City, where quarries have been opened.

The quarries are located on both sides of Patapsco River in Baltimore and Howard counties, about 9 miles west of Baltimore, and the 

granite in which they occur extends as far east as Ilchester on the 

east side of-the river, but only as far as Grays siding on the west side. 

On the east or Baltimore County side of the river the granite has a 

decided foliated or gneissic structure, but on the west or Ellicott City 

side, in Howard County, the granite is massive and of porphyritic 

texture. The date of opening of the quarries is unknown, but was 

probably some time in the latter part of the eighteenth century. 

The foliated granite from the quarries opened opposite Ellicott City, 

on the Baltimore County side, was used in building the Cathedral in 

Baltimore, in 1806 to 1812 and 1815 to 1821. This was doubtless 

one of the most important stone structures in the United States at 

the time of its construction.

DESCRIPTIONS OF QUARRIES.

BALTIMORE COUNTY.

Several quarries opened in the steep and moderately high granite 

cliffs along the east side of Patapsco River have been operated nearly 

opposite Ellicott City. The largest of these, known as the Gaiiher 

quarry, comprises' two large openings that adjoin each other and
52 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

have been worked back from the river into the granite cliffs, with an 

elevation from the base to the top of about 75 feet. (See PL IV, A.)

The rock is a biotite granite of medium dark blue-gray color and 

medium grain. Its structure is decidedly foliated or schistose, 

though much less pronouncedly so than that of the granite gneiss at 

Port Deposit and French town; and its original granite characters 

are still apparent. Hand specimens of the granite show abundant 

fine granules of yellow epidote closely associated with the biotite. 

Irregular grains of brownish allanite are also apparent in the hand 

specimens. Because of its richness in epidote and allanite Keyes 

classified this granite and some of the granites from the Port Deposit, 

Woodstock, Dorseys Run, and Ilchester localities as allanite-epidotebearing granites.

The granite consists of soda-lime feldspar (oligoclase), potash 

feldspars (orthoclase and microcline), quartz, and biotite, together 

with accessory zircon, apatite, hornblende, allanite, epidote, and 

secondary chlorite and epidote. Intergrowths of the feldspar and 

quartz in more or less rounded grains are of common occurrence. 

The feldspar is partly cloudy and opaque from alteration, and the 

larger individuals inclose small rounded grains of feldspar and quartz. 

Allanite and epidote occur as parallel growths. Partial granulation 

of the quartz and feldspar into fine mosaics from pressure metamorphism is pronounced.

The structure of the granite both in the quarry and in the hand 

specimens is schistose or foliated. Vertical joints strike N. 40° E. 

and N. 60° to 70° W. Many joints of the N. 40° E. course observe 

southeast (70°) and northwest dips. Some joints of the N. 60° to 

70° W. course show curved faces. Horizontal joints, separating the 

granite into sheetlike masses of varying thickness, are well developed 

to the entire depth of the quarry opening about 75 feet. The 

vertical joints are spaced at intervals of 2 inches to 6 feet, and the 

horizontal joints give sheets from 2 to 4 feet thick at the bottom of 

the quarry: Slickensides developed on the surfaces of some of the 

vertical joints indicate movement in the granite mass. 

. There are at this locality numerous pegmatite dikes ranging from 

a fraction of an inch to more than 12 inches thick, with an average 

thickness of less than 6 inches. These, cut the granite indiscriminately, but most of them apparently conform to a N. 30° W. course. 

They contain biotite as the principal mica, with a flesh-colored feldspar and quartz as the chief constituents. Dark-colored segregations (knots), chiefly of biotite with some feldspar and quartz, much 

elongated or elliptical in shape, are abundant. These range up to 

more than 2 feet in length and usually show pronounced foliation 

parallel to that of the inclosing granite.
U. S. GEOLOGICAL SURVEY BULLETIN 426 PLATE IV

A. GAITHER'S GRANITE QUARRY, ELLICOTT CITY, MD.

GUILFORD AND WALTERSVILLE GRANITE COMPANY'S QUARRY NEAR WOODSTOCK, MD.
GRANITES OF MARYLAND. 53

The granite is decayed from the surface downward to a depth that is 

more than 20 feet in some places, but is usually much less.

The quarries on the Baltimore side of Patapsco River, in the Ellicott City area, were idle when examined in 1908 and had not been 

worked for some time.

HOWARD COUNTY.

The Weber quarry, opened in moderately high cliffs along the Baltimore and Ohio Railroad on the opposite side of Patapsco River from 

the Gaither quarry, is the principal quarry in the Ellicott City area 

in Howard County. The opportunity for shipment is excellent, as 

the quarry is so close to the Baltimore and Ohio Railroad that cars 

are readily loaded by turning the derrick boom.

The granite is a porphyritic biotite granite of dark-gray color and 

medium grain and is massive. Its mineral composition is essentially 

the same as that of the granite of the Gaither quarry already described. 

The minerals are soda-lime feldspar (oligoclase), potash feldspar 

(microcline and orthoclase), quartz, very little muscovite, and accessory zircon, apatite, and allanite. Secondary minerals are chlorite 

and epidote. Intergrowths of feldspar and quartz are numerous. 

Many of the larger feldspar individuals inclose small, rounded grains 

of feldspar and quartz.

The feldspar phenocrysts are distributed without orientation 

through the granite groundmass. They show both crystal (idiomorphic) and noncrystal (allotriomorphic) boundaries, are in places 

twinned on the Carlsbad law, are of a pronounced red color, and contain abundant inclosures of biotite. The idiomorphic phenocrysts 

are usually flat-tabular in outline and are as much as \\ to 2 inches 

long. a

Jointing is prominent and irregular and necessitates the working of 

the irregular masses into the desired shape by hand after quarrying. 

There are at least four sets of vertical joints; the principal set strikes 

N. 60° E. Slickensides characterize many of the joint surfaces. 

Horizontal joints are emphasized in the granite mass in the upper 

portion of the quarry. Dark basic segregations (knots) occur, but are 

not abundant.

A dike of even-granular biotite granite, 6 feet thick, of dark bluegray color and fine grain, penetrates the porphyritic granite in a 

N. 60° E. course. A thin section of the dike granite showed sodalime feldspar (oligoclase), potash feldspar (orthoclase and microcline), quartz, and biotite, together with accessory apatite and zircon 

and secondary chlorite and epidote. Intergrowths of feldspar and 

quartz are abundant.

The Weber quarry was the only quarry operating in the Ellicott 

City area at the time of examination in 1908.

a See Maryland Geol. Survey, vol. 2, 1898, PI. XI, for reproduction of a polished surface of a block of 

porphyritic granite from the Weber quarry.
54 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

GUILFORD AREA. 

GENERAL STATEMENT.

The Guilford granite area, located in Howard County, a few miles 

southwest of the Ellicott City area, is of large size and irregular outline, as shown on the map (PL I). It is bordered on the north and 

west by the Baltimore gneiss and on the east by the gabbro. It is also 

coyered in part by the gravels and clays of the Coastal Plain.

The granite from this area differs from that of the other areas in 

the State in containing both light mica (muscovite) and dark mica 

(biotite). Muscovite occurs as a subordinate constituent in some of 

the other Maryland granites, but not so abundantly nor characteristically as in the granite of this area.

The granite of the Guilford area varies from a coarse-grained 

granite of red color at the Guilford Granite and Stone Company's 

quarry through a medium-grained reddish-gray granite at the Penny 

quarry to a fine-grained medium-gray granite at the Maryland Granite 

Company's quarry. This last-named type is the one most extensively 

quarried, because it possesses durable qualities that give it a wide 

range of uses.

The quarries are located on Little Patuxent River about 5 miles 

northwest of Annapolis Junction and about 2 miles from the nearest 

railroad point Savage Factory. They were opened about 1834 and 

were worked almost continuously until the/outbreak of the civil war 

in 1860. Very little work was done from 1860 to 1893, but in 1893 

the quarrying industry was revived and has continued to the present 

time.

 DESCRIPTIONS- OF QUARRIES.

Four quarries, located close together on Little Patuxent River,

have been opened. These are, in order of importance, the Maryland 

Granite Company's quarry, Guilford and Waltersville Company's 

quarry, Pemiy quarry, and Guilford Granite and Stone Company's 

quarry.

The Maryland Granite Company's quarry is on the east side of 

Little Patuxent River 2 miles north of Savage Factory and about 5 

miles northwest of Annapolis Junction. It is the principal quarry 

in the Guilford area and was the only one operating at the time of 

examination in 1908.

The rock is a muscovite-biotite granite of medium-gray color and 

of even, fine grain, with biotite uniformly disseminated and in excess 

of muscovite. It consists of potash feldspar (orthoclase and microcline), soda-lime feldspar (oligoclase), quartz, biotite, and muscovite, 

together with accessory zircon and apatite and secondary chlorite, epidote, muscovite, and kaolinite. Intergrowths of feldspar and quartz 

are numerous. The larger feldspar grains show inclosures of feldspar
(SBANITES OF MARYLAND. 55

and quartz. The stone takes a fine polish, the durability of which is 

favored by the smallness of the biotite scales.0 A chemical analysis 

of this granite is given in column 3 of the table on page 42. The 

percentages of soda and potash show that the rock contains nearly 

equal amounts of the potash and soda-lime feldspars.

The quarry measures about 500 by 300 feet and has a depth of 

about 100 feet. The average depth of stripping is about 10 feet. 

The sheets, 3 to 10 feet thick, are approximately horizontal and 

tapering lenticular. Vertical joints strike north-south and eastwest, recurring at wide intervals. Many of the joint surfaces are 

slickensided, indicating movement in the granite mass. There are- a 

few dark basic segregations (knots), the largest observed not exceeding 6 inches long by 3 inches wide. No pegmatite dikes were 

noted.

The product is used chiefly for monuments, though much of it is 

used for general building purposes in the dressed and rough states, 

largely in the rough. Much of the coarse waste is worked into paving 

blocks. Very little of the stone is used for curbing and no crushed 

stone is produced.

The principal markets are in Maryland and Pennsylvania. Shipments have been made as far west as St. Louis and Chicago, north to 

New York, and South to Atlanta.

The Guilford and Waltersville Granite Company's quarry is on the 

east side of Little Patuxent River a short distance from the Maryland-Granite Company's quarry. Work had been suspended sometime prior to the writer's examination in 1908.

The rock is a muscovite-biotite granite of medium^gray color and 

of even, fine grain, with biotite uniformly disseminated and in excess 

of muscovite. This granite appears to be identical in composition, 

color, and texture with that of the Maryland Granite Company's 

quarry, and is equally well adapted to the same uses.

The Penny quarry is on the north side of Little Patuxent River 

about 300 feet northeast of the Maryland Granite Company's quarry. 

The quarry was nearly filled with water at the time of the writer's 

examination in 1908, but during its activity it was operated by the 

Maryland Granite Company.

The quarry is a small one, less than 100 feet square and less than 

50 feet deep. The granite is a biotite-muscovite granite of medium 

pinkish-gray color and medium-coarse grain. Its feldspar contrasts 

strongly in color with that of the Maryland Granite Company's 

granite in having a pronounced pinkish cast. The rock is also 

of coarser texture and differs in composition, muscovite being in 

excess of biotite. It consists of potash feldspar (orthoclase and

a See Maryland Geol. Survey, vol. 2,1898, PI. XVI, for reproduction of a polished surface of a block of 

this granite.
56 GBANITES OF SOUTHEASTERN ATLANTIC STATES.

microcline), soda-lime feldspar (oligoclase), quartz, muscovite, and 

biotite, together with accessory apatite, and zircon and secondary 

chlorite. Microcline and orthoclase are present in nearly equal proportion; the latter is intergrown with a second feldspar as microperthite. The feldspar shows very general alteration. The larger 

feldspar individuals inclose rounded grains of other feldspar and 

quartz. Intergrowths of feldspar and quartz are observed.

Vertical joints strike north-south and east-west. Many of their 

surfaces show slickensides. Segregations (knots) and pegmatite 

dikes were not observed in the granite.

The Guilford Granite and Stone Company's quarry is on- the opposite (west) side of Little Patuxent River from the Maryland Granite 

Company's quarry. It comprises three small openings, the largest 

one of which is about 75 by 60 feet and 50 feet deep. The object of 

the company was to produce crushed stone, and a large crusher was 

erected and operated near the quarry. Operations were suspended 

about four months prior to the writer's examination in March, 1908.

The rock is a biotite-bearing muscovite granite of pronounced 

reddish color and coarse grain. The feldspar which imparts the red 

color to the granite contrasts strongly with the dark glassy quartz. 

The granite of this quarry is similar in composition to that of the 

three other quarries in the Guilford area described above, except 

that muscovite is the principal mica and is greatly in excess of the 

biotite. The rock consists of potash feldspar (orthoclase and microcline), soda-lime feldspar (oligoclase), quartz, muscovite, and very 

little biotite, together with accessory apatite and zircon. Potash 

feldspar is in excess of soda-lime feldspar, and both are considerably 

altered. Orthoclase is intergrown with a second feldspar as microperthite. Intergrowths of feldspar and quartz occur.

The granite differs from the other granites quarried in the Guilford 

area in being coarser grained and of a more pronounced red color 

and in having a larger preponderance of muscovite over biotite-.

Closely spaced vertical joints are prominently developed. There 

are several sets, intersecting at approximately right angles and 

recurring at such short intervals as to render the quarrying of dimension stone very doubtful.

WOODSTOCK AREA. 

' GENERAL STATEMENT:

The Woodstock granite area is located in the extreme southwest 

corner of Baltimore County, about 2 miles north of Woodstock, on 

the Baltimore and Ohio Railroad, in the Patapsco River valley. The 

area lies about 25 miles a little north of west of Baltimore. As indicated on the map (PL I), the granite forms an isolated oval-shaped 

area scarcely 2 miles in extent from northeast to southwest and 1
GRANITES OF MARYLAND. 57

mile from northwest to southeast. Although small, this area is 

economically one of the most important in Maryland.

The granite is entirely surrounded, by the Baltimore gneiss, of preCambrian age, into which it is intruded. No dikes or apophyses of 

the granite have been observed penetrating the surrounding gneiss, 

but that the gneiss is older than the granite is shown by the large 

number of inclusions of the gneiss incorporated in the granite. These 

are described in some detail on pages 46-47.

The systems of horizontal and vertical joints are prominently 

developed in these quarries, especially in the Guilford and Waltersville 

(Pis. IV, B, and VI, B) and the Weller quarries.

A chemical analysis of the granite from Woodstock is given in 

column 4 of the table on page 42. A noteworthy item in this analysis 

is the large percentage of soda, which indicates the presence of much 

soda-lime feldspar.

The granite bowlders first attracted attention to this area and 

operations were begun about 1832-33. The principal demand at 

first was that by the Baltimore and Ohio Railroad for stone for bridge 

and culvert work. One of the most important of the early contracts 

for the granite from Woodstock was that for the Baltimore customhouse about 1873-74.

DESCRIPTIONS OF QUARRIES:

Several extensive quarries have been operated in the Woodstock 

area. These are the Guilford and Waltersville Granite Company's 

quarry, the Fox Rock quarry, the Weller quarry, and the Atherton 

quarry. The first two are the most important and extensive and, 

together with the Atherton, which had only recently been opened, 

were operating at the time of the writer's examination in March, 1908. 

The village of Granite is located within the quarry area. A railroad 

spur 2 miles long connects the quarry of the Guilford and Waltersville 

Granite Company with the main line, of the Baltimore and Ohio 

Railroad at Putney & Riddle's bridge, about 1 mile east of Woodstock.

The Guilford and Waltersinlle Granite Company's quarry is the 

largest quarry in the area. The opening is roughly circular in outline, 

measuring about 500 by 600 feet, and is worked to an average depth 

of about 12 feet. (See PL IV, B.}

The rock is a biotite granite of medium-gray color and medium 

grain. Because of slightly increased biotite the granite is a fraction 

darker in color than the gray granite at Guilford and is of slightly 

coarser texture.a The granite consists of potash feldspar (orthoclase 

and microcline), soda-lime feldspar (oligoclase), quartz, and biotite, 

together with accessory zircon, apatite, and allanite and secondary

a See Maryland Oeol. Survey, vol. 2, 1898, pi. XIII, for a reproduction of a polished surface of a block 

of the granite from this quarry.
58 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

chlorite, epidote, and muscovite. . Orthoclase is partly intergrown with 

a second feldspar as microperthite. A part of the feldspar shows considerable alteration in some of the thin sections. Intergrowths of 

feldspar and quartz are abundant. The quartz shows strain shadows 

and is in places fractured from pressure metamorphism.

The sheets measure from 1 \ to 6 feet in thickness and are approximately horizontal (PI. VI, .5). There are two principal sets of vertical joints, striking about northeast-southwest and northwestsoutheast, and several minor sets having different courses. Many 

of the joint faces are "curved irregularly. They are spaced at sufficiently wide intervals to permit the quarrying of blocks of almost 

any size. The rock contains some thin pegmatite dikes. A very few 

dark segregations (knots), of biotite chiefly, the largest rarely exceeding 12 inches in length, were observed.

Physical tests made on specimens of this granite to determine 

absorption, compressive strength, and freezing loss, the results of 

which are given on pages 48, 50, show it to be a most durable stone. 

A chemical analysis is given on page 42 (No. 4).

The product is used chiefly for general building purposes, in both the 

rough and the dressed states. Other uses are for monuments, paving 

blocks, some curbing, and crushed stone (mostly for concreting). 

It is shipped to Maryland, Pennsylvania, New York, Delaware, 

Washington, D. C., and occasionally to Virginia and Ohio.

The Fox Rock quarry is the oldest one in the area and has been 

worked to an extreme depth of 96 feet. The rock is a biotite granite 

of medium-gray color and medium grain. It is entirely similar in 

color, texture, and composition to that of the Guilford and Waltersville 

quarry described above. It consists of potash feldspar (orthoclase 

and microcline), soda-lime feldspar (oligoclase), quartz, biotite, and

scant muscovite, together with accessory zircon, apatite, and allanite and secondary chlorite, "muscovite, and epidote. The feldspars 

are partly intergrown in microperthitic structure, and some of them 

are cloudy and opaque from alteration. Intergrowths of feldspar 

and quartz are shown.

Vertical joints strike N. 55° E., N. 10° W., and N. 50° W., spaced 

at intervals of 8 inches to 4 feet and more. There are a few pegmatite dikes of small thickness. Occasional dark segregations (knots), of 

biotite chiefly, occur in the granite. The thickness of the decay at 

the surface ranges up to more than 15 feet in places.

The principal uses made of the product are for general building 

and monumental work and for street curbing and paving blocks. 

No crushed stone is produced. The product is shipped to Pennsylvania and West Virginia and to various points in Maryland. Occasionally it has been shipped as far west as Indiana and as far north as 

New York.
U. S. GEOLOGICAL SURVEY BULLETIN 426 PLATE V

A. WELLER QUARRY, NEAR WOODSTOCK, MD.

Showing elongated concentric shells of granite.

Ji. LONG GRANITE COMPANY'S QUARRY, NEAR OGLESBY, GA. 

Showing concentric weathering,

WEATHERING OF GRANITE.
GRANITES OF MARYLAND. 59

The Wetter guarry is adjacent to the Guilford and Waliersville 

quarry on the west. It was the only quarry in the area not operating at the time of examination; in March, 1908. It had apparently 

been idle for some time, as the opening, which is a large one, probably 

300 feet long by 100 feet wide and 70 feet deep, was nearly filled with 

water, and very little could be seen of the actual quarry conditions. 

(See PI. V.)

The rock is a biotite granite of the same color, texture, and composition as that at the Guilford and Waltersville and the Fox Rock 

quarries, already described. The effects of weathering along vertical 

and horizontal systems of joints are probably the most characteristic 

to be found within the State. Keyes a has described it as follows:

The quarry ledge has the appearance of a great wall of cyclopean masonry, layer 

upon layer of huge blocks, rising one upon another with the regularity and precision 

of human workmanship. The separate blocks are more or less oblong in shape, and 

often measure 15 to 20 feet in length and from 2 to 8 feet in height. They are all 

more or less rounded, the spaces between the different bowlders being filled with 

incoherent granitic sand, derived from the decomposed edges and the sides of the 

blocks. It is quite evident .that the granitic mass was originally everywhere jointed, 

and that atmospheric decay took place much faster on the edges and corners than 

on the flat sides of the great fragments, thus quickly rounding and forming them 

into bowlders like those found throughout drift areas. The sandy matrix is usually 

from 5 to 10 inches in thickness. . The interior of the bowlders is perfectly fresh, 

and affords the best of rock for building purposes. As decomposition progresses the 

amount of interstratified sand greatly increases, and the blocks become proportionately 

smaller.

The Atlierton guarry is a short distance west of the Guilford and 

Waltersville quarry. It was opened about eighteen months prior 

to the writer's examination in March, 1908, in bowlder exposures of 

the granite.

The rock is a biotite granite and is entirely similar in color, texture, 

and composition to that of the other quarries in the Woodstock area, 

already described. It is likewise equally suited for the various uses 

made of the granite from the Guilford and Waltersville quarry (p. 58).

POUT DEPOSIT AREA.

Probably the Maryland granite which is best known outside of 

the State is that quarried in Cecil County, near the northern limits 

of the town of Port Deposit, on the northeast side of Susquehanna 

Biver. The value of this granite was early recognized, and it was 

quarried for foundation stone for the oldest colonial dwellings. 

Though it was worked in a small way for many years, the quarrying 

industry may be said to date from the years 1816 and 1817, when 

stone was quarried for the bridge built across Susquehanna River. .

a Fifteenth Ann. Kept. U. S. Geol. Survey, 1895, p. 725.
60 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

The only quarries operated in this area are those of the McClenahan 

Granite Company, 1 mile northwest of Port Deposit, immediately 

on the northeast side of'the Susquehanna. (See PI. VI, A.) The 

quarries are opened in the nearly vertical granite wall (cliff) which 

extends for some distance along the northeast side of the river, and 

measures about 200 feet from the base to the top. A number of 

very extensive openings have been worked in the wall along the 

river front within a distance of 3,000 feet. The natural advantages 

for quarrying and shipping at this point would, indeed, be difficult 

to excel. The average depth of the quarry is 200 feet, with an 

extreme depth of 230 feet, and in one exposure it is opened to a 

depth of 15 feet below the river level. The depth of stripping on 

the surface varies from 1 to 25 feet.

The rock is a biotite granite gneiss (foliated granite) of light bluishgray color and medium grain. Its schistose, or foliated structure, is 

pronounced and is highly characteristic. 0 The principal minerals 

are soda-lime feldspar (oligoclase), potash feldspar (orthoclase and 

microcline), quartz, and biotite, -with 'accessory apatite, zircon, 

titanite, allanite, garnet, tourmaline, and magnetite. The secondary 

minerals are muscovite, hornblende, epidote, chlorite, and occasionally calcite. The quartz and feldspar occupy well-defined areas, 

which show crushing and recrystallization into a mosaic, as a result 

of the dynamic forces, which have modified the original granite. 

The feldspars show less perfect granulation than the quartz. Acidic 

plagioclase, the extinction angles of which place it between AbgAr^ 

and Ab2Ant , so that it corresponds to oligoclase, is the dominant 

feldspar. The microcline has been derived, probably, in part at 

least, from orthoclase by pressure. The shreds of biotite are orientated and lie in approximately parallel lines, thus producing the 

gneissoid structure of the granite gneiss. The lines of mica shreds

are not straight and continuous, but are arranged in more or less 

disconnected and overlapping bands.

A chemical analysis of the granite gneiss from Port Deposit is 

given on page 42. The analysis indicates that soda is in excess of 

potash, thus confirming the apparent predominance of plagioclase 

over orthoclase and placing the granite with the quartz monzonite

typeThe course of the foliated or gneissoid structure is N. 35° E. 

Vertical joints strike N. 35° E., N. 60° E., N. 70° W., and north-south. 

Zones of close jointing occur at intervals in the direction of the 

N. 70° W. set, and to a less extent in the N. 35° E. set. The N. 35° E. 

joints show a dip of as. much as 58° N., 35° W. The spacing between 

joints varies from a fraction of an inch up to 15 feet, and is in general sufficiently great to allow the extraction of dimension stone.

a For description see Maryland Geoi. Survey, vol. 2, 1898, pp. 138-147; Pis. VIII, IX.
U. S. GEOLOGICAL SURVEY BULLETIN 426 PLATE VI

A. McCLENAHAN GRANITE COMPANY'S QUARRY, PORT DEPOSIT, MD.

» T!rp?ra/<-' ' . TT\

.~ FV A 4,«K -«u«**i

B. GUILFORD AND WALTERSVILLE GRANITE COMPANY'S QUARRY, GUILFORD, MD.
GRANITES OF MARYLAND. 61

Movement in the granite mass is indicated in slickensided surfaces 

of many of the joint planes. Pegmatite dikes were not observed, 

but a few narrow veins of quartz up to 6 and 12 inches wide penetrate the granite gneiss in the quarries and are more abundant in 

the steep, high cliffs of granite in and below the town of Port Deposit. 

A few dark segregations (knots) of small and large size occur.

Tests (see p. 49) of the crushing strength (over 20,000 pounds per 

square inch), the absorption capacity (0.19 to 0.25 per cent), and 

the freezing loss establish the durability of the granite gneiss under 

most circumstances. This is further confirmed by a study of its 

mineralogical and chemical composition and of the stone itself under 

natural conditions in the quarries.

The product of the quarries is shipped as far west as Chicago 

and Cincinnati and as far north as New England; but the principal 

market-is in Pennsylvania. No shipments have been made south 

of Norfolk, Va. The quarries are favorably located for shipment 

by water and rail routes.

The principal use made of the product is for general building 

purposes, in both the rough and the dressed states. It is largely 

used for bridge and ashlar work and, as crushed stone, for various 

purposes, such as for ballast, macadam, and concrete, in chemical 

filtering, and in fertilizers.

FllENCHTOWN AREA.

Near Frenchtown, about 4 miles southeast of Port Deposit, in 

Cecil County, is another body of granite gneiss similarly situated. 

The rock is of the same general character as that quarried at Port 

Deposit. One quarry has been opened at the east end of the suspension bridge of the Baltimore and Ohio Railroad over the Susquehanna, on the northeast side of the river. It is reported to have been 

opened during the construction of the railroad bridge, but quarrying 

did not assume importance until 1894. The cold-storage warehouse 

and an extension of the Baldwin Locomotive Works in Philadelphia 

were built from the Frenchtown rock.

The rock is a biotite granite gneiss (foliated granite) of gray color 

and medium grain. It is probably a shade darker in color than the 

granite at Port Deposit because of the prevailingly darker color of the 

biotite. Its microscopical characteristics are the same as those of the 

granite gneiss at Port Deposit (p. 60). The chief minerals are sodalime feldspar (oligoclase), potash feldspar (orthoclase and microcline), quartz, and biotite, with accessory apatite, zircon, and allanite. 

The secondary minerals are chlorite, epidote, muscovite, garnet, and 

kaolinite. Granulation of the quartz and feldspar into fine mosaics 

and orientation of the biotite along parallel lines, producing gneissoid 

or foliated structure, are the most characteristic. dynamic mo.difica-
62 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

tions of the original granite. The foliated or schistose structure of 

the granite gneiss is not so strongly developed as in the Port Deposit 

rock, but the two are closely similar in color, texture, and composition.

In 1908 the dimensions of the opening were approximately 300 by 

75 feet by 30 feet deep. Two prominent sets of vertical joints are 

developed at approximately right angles to each other, striking N. 

60° E. and N. 40° W., with a wide range in dip. The surfaces of 

some of the joints are smooth and polished and are coated with a 

thin veneer of dark-greenish to yellowish micaceous material, resulting from motion in the granite mass. Horizontal joints, separating 

the rock into sheetlike masses of varying thickness, are most pronounced in the upper portions of the quarry. Decay is shown 

prominently along the vertical and horizontal joints near the surface, 

in the gaping of the joints and in the hydration and oxidation of the 

rock minerals. Scattered quartz veins striking N. 60° E. and varying 

in width from a fraction of an inch to 6 inches penetrate the granite 

gneiss. There occur, also, a few dark segregations (knots) of small 

dimensions.

At the time of examination in 1908 most of the product was worked 

into blocks for paving. It is capable, however, of a wide range of 

uses. Its principal markets are reported to be in Pennsylvania and 

Maryland. The transportation facilities are very good, and are 

similar to those at Port Deposit.

Other, masses of similar, granite gneiss (foliated granite), less 

favorably located for commercial purposes, occur on either side of 

Susquehanna River in the vicinity of Port Deposit.

MINOR GRANITE AREAS.

In addition to the five principal areas already described, there are 

a number Of minor granite areas in the State which have been worked 

from time to time to supply the local demands. Of these minor areas 

the most important are Dorsey Run, on the Baltimore and Ohio 

Railroad between Ellicott City and Woodstock; Sykesville, on the 

Baltimore and Ohio Railroad west of Woodstock; Garrett Park and 

Brookville, a few miles northwest "of Washington; Franklinville, on 

Little Gunpowder River, 3 miles north of Bradshaw; Benson, in 

Harford County; Baldwin station, in Cecil County; Texas, about 12 

miles north of Baltimore; and Relay, 9 miles southwest of Baltimore. 

No quarries have been opened in the Texas and Relay areas.

DORSET RUN AREA.

The Dorsey Run area comprises a small oval-shaped granite mass 

located on Patapsco River a few miles northwest of Ellicott City. 

It is surrounded on all sides by dark-colored Baltimore gneiss. The 

relations'of the granite to the gneiss are well shown in a cut of the
. GRANITES OF MARYLAND. 63

Baltimore and Ohio Railroad 400 feet in length and 40 to 50 feet in 

height.0

The rock is a biotite granite of dark color and is massive, even 

grained, and homogeneous in texture. Allanite and epidote are 

abundant accessory constituents, and the granite is classed by 

Keyes as an allanite-epidote granite which differs but little from the 

other allanite-epidote granites of the region. Biotite is much altered to 

chlorite. Orthoclase, abundant plagioclase (oligoclase), and variable 

microcline compose the feldspathic constituent. Much of the quartz 

is crushed and fractured, and the feldspar is peripherally granulated 

from pressure metamorphism. Chemical analyses of the granite and 

of the lighter-colored, more acidic granite dikes, regarded as probable 

apophyses from the main mass, are given on page 42.

According to Mathews the granite was first used on the Baltimore 

and Ohio Railroad to protect it against the encroachment of Patapsco 

River. Several small quarries have been opened since, but had not 

been operated for some time prior to the writer's visit in 1908.

SYKESVILLE AREA.

The Sykesville granite area is one of the largest in the State. 

Except in the vicinity of Washington and for a short distance northward on the east side, the granite is entirely surrounded by the 

Wissahickon mica gneiss, of probable pre-Cambrian age. According 

to the recent map of the Maryland Geological Survey and as shown 

on the map accompanying this report (PI. I), the granite is prolonged 

southward into Virginia.

The rock is a biotite granite of gray color and fine grain. Its 

principal minerals are orthoclase and plagioclase (oligoclase), quartz, 

and biotite. The biotite is Considerably altered to chlorite and the 

feldspars to scales of colorless mica and kaolin. Large plates of 

muscovite are aboundant in some sections. Muscovite is partly 

secondary. A few garnets occur in several' of the thin sections. 

Pressure effects are pronounced in the granulation of the feldspar 

and quartz, more especially the quartz, and as a rule the granite is 

more or less foliated.

A quarry opened in 1888 for paving blocks, a few hundred rods 

below the railway station, showed a large number of inclusions of 

irregular fragments of foreign rocks of all sizes and shapes incorportated in the granite. Keyes says: 6 "Among the fragments noted 

may be mentioned those which were originally limestone, soapstone, 

pyroxenite, vein quartz, hornblendic, and biotitic gneisses."

At present no quarries are in operation in the Sykesville granite area.

n See Fifteenth Ann. Rpt. U. S. Geol. Survey, 1895, PI. XXXVII, flg. 3, for a diagrammatic section of 

this cut.» 

6 Fifteenth Ann. Kept. U. S. Geol. Survey, 1895, p. 720.

38971° Bull. 426 10 5
64 GEANTTES OF SOUTHEASTERN ATLANTIC STATES. 

GARRETT PARK-BROOKVILLE AREA.

Extending westward along Potomac River and northward from 

Washington, in Montgomery County, Md., and the northwestern 

portion of the District of Columbia, are extensive areas of granitic 

rocks. According to Williams and Keyes the rock types have been 

largely derived from original granites by dynamic metamorphism and 

over most of the district are now more properly called granite gneisses. 

Extreme foliation has obliterated most of the granitic features, but 

the abundance of indistinct masses, which resemble inclusions, 

scattered through the granite gneiss in places, led Williams to assume 

for the rock an igneous origin. Within this large district are included 

the Cabin John Bridge, Murdoch Mill, Broad Branch, Garrett Park, 

Rock Creek, Brookville, Sligo Branch, and Piney Run localities 

referred to by Williams and Keyes.0

The principal rock type is a foliated biotite granite or granite 

gneiss, containing hornblende as an important constituent in some 

localities. The feldspar constituent comprises usually the potash 

varieties (orthoclase and some microcline) and the soda-lime variety 

(oligoclase). The biotite-bearing granite ranges from fine to medium 

grained in texture, and from light to dark gray in color. The typical 

hornblende granite is exposed for some distance along the Rockville 

road about 2 miles north of Garrett Park. It is of dark color and 

contains about equal amounts of hornblende and biotite. Analyses 

of the biotite type of gneiss along.Potomac River, in Montgomery 

County, Md., are shown in columns 11 and 12 of the table on page 42, 

and of the foliated granite in the District of Columbia in column 13 of 

the same table.

The gradation of the different facies of the granitic rocks of this 

area into each other is stated by Williams as follows: b

III the large granite area extending from Tridelphia southward to Brookville, in 

Montgomery County, the rock grades from a dark basic granite resembling a digrite to 

one which is very light colored and acid. In the Murdoch Mill granite area, west of 

Washington, gradual passages into a diorite facies are frequent, while the same thing 

takes place, with the development of still more basic varieties, in the granite area 

which extends southward from Falls Church, in Fairfax County, Va. The most striking example of gradual passage from one igneous type into another is, however, to be 

found in the wide belt which crosses the Potomac River at Cabin John Bridge. This 

originates near the southern portion of the Frederick sheet, above Bethesda Park, as a 

normal gabbro similar to that occurring near Baltimore; and as it passes south ward it 

gradually becomes more acid, developing hornblende in the place of pyroxene, and 

thus merging into a diorite. Still farther south the diorite becomes biotitic, its feldspar more acid, while a little quartz commences to show itself. After the passage of 

the river the rock becomes a hornblende granite and, without any break in the continuity of the mass, is developed along Pimmit Run as a typical granite.

"Fifteenth Ann. Kept. U. S. Geol. Survey, 1893-94 (1895), pp. 665, 669, 670-C71, 729-730. 

& Idem, p. 671.
GEANITES OF MARYLAND. 65

The recently published map a of the Maryland Geological Survey 

differentiates the rock types in this region as follows: A large granite 

heel extending westward and northward from Washington to Sykesville, in Carroll County, Md., west of Baltimore; diorite and gabbro 

areas, chiefly diorite, within the granite, extending northward from 

the Potomac and only a short distance northwest of Washington; 

and a small area of Baltimore gneiss in contact with the granite on the 

east side and a short distance north of Washington. From the southern border of the Baltimore gneiss to Potomac River the eastern limits of the granite are concealed beneath the Coastal Plain formations, 

and the entire granite mass is surrounded by the Wissahickon mica 

gneiss on the west and north sides and for most of the distance on the 

east side.

A number of quarries have been operated within the area. The 

first was opened at Brookville about the beginning of the last century

and was operated in a small way at intervals up to 1881. A second 

quarry was opened at Brookville in 1850. Several small quarries, 

opened in the granite exposures along Rock Creek at Garrett Park, 

have been worked at intervals to supply the local demand. Perhaps 

the most extensive quarry in Montgomery County was opened in 

1850 near Cabin John in a schistose granite of dark-gray color. The 

total production of stone from this quarry was very large, the product being used principally for general building purposes, foundations, 

arid road metal.

FRANKLINVILLE AREA.

The Franklinville granite area is located partly in the counties 

of Baltimore and Plarford, northeast of the city of Baltimore, and 

is traversed in a southeastward course by Little Gunpowder River. 

It is partly covered by Coastal Plain sediments, and is in contact 

with gabbro on the south and west sides and with Baltimore gneiss 

on the north side. The rock is a foliated biotite granite resembling 

that quarried at Port Deposit, although somewhat darker and more 

foliated.

A quarry opened at Franklinville, on the Little Gunpowder, 3 miles 

north of Braclshaw, has supplied local demands. Mathews states 

that large curbing blocks might be obtained easily, as blocks 11 by 2 

by 1 foot have been quarried.

BENSON AND BALDWIN STATION.

Mathews reports that a little granite is quarried in the town of 

Benson, Harford County, and near Baldwin station, Cecil County. 

The operations have been greatest at the latter locality, where the 

quarry was first opened in 1842 in a schistose granite. The writer 

did not visit either of these two localities.

a Maryland Geol. Survey, vol. 6,1906.
66 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

TEXAS AREA.

The Texas area, situated about 12 miles north of Baltimore, comprises an oval-shaped granite mass between 4 and 5 square miles in 

extent. It is surrounded chiefly by the Cockeysville marble, except 

at the northwest corner, where it is in contact with the Wissahickon 

mica gneiss. A second thin band "of the gneiss extends for some "distance along the margin on the east side between the granite and the 

marble.

The main body of the rock is a biotite granite with a distinct porphyritic f acies along the western margin. It is composed of the essential minerals feldspar (including orthoclase with about equal amounts 

of oligoclase and microcline), quartz, and biotite. Biotite is much 

altered to chlorite and epidote and the feldspars to a light-colored 

mica. Zircon and apatite are the principal microscopic accessory 

minerals. Pressure effects are pronounced in the quartz and feldspar, and the rock presents, both in thin sections and in hand 

specimens, a distinct gneissoid appearance. The porphyritic portions of the mass along the western margin may be designated an 

augen gneiss.

No quarries have been opened in the Texas granite area. '

RELAY AREA.

A "Small area of granite lies on Patapsco River in the vicinity of 

Relay, 9 miles southwest of Baltimore. The rock is a biotite granite 

of dark-gray color, rather coarse grained, more or less porphyritic 

in texture, and somewhat foliated from pressure metamorphism. 

Biotite, here and there intergrown with shreds of muscovite and considerably altered to chlorite, is orientated along parallel directions. 

The quartz is much crushed and fractured and the feldspar exhibits 

pronounced peripheral granulation. Orthoclase and some plagioclase

(oligoclase) make up the feldspar content. The feldspar phenocrysts 

usually exhibit crystal boundaries. This granite resembles, microscopically, that quarried at Ellicott City, a short distance up the

river.

GNEISSES.

INTRODUCTORY STATEMENT.

The Baltimore gneiss, mapped by the Maryland Geological Survey 

as extending along the eastern slope of the Piedmont in several welldefined areas between Susquehanna and Potomac rivers, is the oldest 

formation in the State and is of Archean age. It is described by the 

Maryland Survey as follows: a

 The easternmost of these Baltimore gneiss occurrences is within the area of Cecli 

County, east of the Susquehanna River, and extends from this point south westward, 

widening to an area of 5 miles or more in breadth where it is overlain by Coastal Plain

oClark, W. B., and Mathews, E. B., Maryland Geol. Survey, vol. 6, 1906, pp. 106, 107.
GRANITES OP MARYLAND. 67

deposits in Harford County. This formation is limited on either side by igneous 

rocks. A northern outlier a mile or less in width extending for several miles southwestward from the Susquehanna River probably represents a detached portion of 

this larger mass lying a little to the south.

The second area of Baltimore gneiss is found in an anticlinal dome, 15 miles long 

and 5 miles broad, lying on either side of the Northern Central Railroad 10 miles south 

of the Mason and Dixon line and -20 miles north of Baltimore. Three smaller areas 

occur in the vicinity of Baltimore. Two of these are portions of anticlinal domes 

which are either completely inclosed by overlying sediments or cut off by faults and 

igneous rocks, while the third, underlying the northwestern part of Baltimore City, 

is entirely surrounded by gabbro and other igneous masses and is overlain in great 

measure by the Coastal Plain deposits.

The rocks in each of these areas, consist of highly crystalline gneisses composed of 

quartz, feldspar, and mica, with accessory minerals, which are so distributed as to 

produce well-marked, gray-banded gneisses, the individual bands of which vary 

from a fraction of an inch to several feet, the average thickness, however, being quite 

slight. Some of these bands are highly quartzose, resembling a micaceous quartzite; 

others are rich in biotite or hornblende, producing dark schists, which in a hand 

specimen are indistinguishable from metamorphosed igneous masses. Within the 

areas of Baltimore gneiss are also numerous small bodies of metamorphosed granites 

and more basic' igneous rocks, which have been intruded into the gneiss and subsequently metamorphosed until they are practically indistinguishable from it.

Extensive quarries have been opened in the Baltimore gneiss and 

worked for very many years on the north and west sides of the city 

of Baltimore, grouped about two centers, Jones Falls and Gwynns 

Falls.

JONES FALLS QUARRIES.

The quarries on Jones Falls, at the northern limits of the city of 

Baltimore, were opened probably before the beginning of the last 

century. A published record in 1811 states that the gneiss was quarried on both sides of Jones Falls.0 The first quarries opened, situated 

probably on the right bank of the stream, were worked until about 

1830. The quarries opened on the left bank are reported to have 

been continuously operated from the date of opening until the present 

time. The principal quarries in operation at the time of examination 

in 1908 were the Atkinson, Curley-Schwind, and Peddicord.

The rock is a banded gneiss of variable color, texture, and composition. The bands range in thickness from 2 or 3 inches to 5 or 6 

feet, and are usually rather uniform for considerable distances. They 

dip to the northwest at an angle of about 45°, but flatter and steeper 

dips are not uncommon. The variation in color is from very light 

gray to blue-black, being dependent on the amount of biotite or hornblende present. Probably a blue-gray is commonest, and this has 

given rise locally to the term "blue stone" among the quarrymen and 

in the trade. In texture the rock ranges from fine to medium grained. 

In many of the beds the component grains are of approximately the 

same size, producing a rock of uniform texture.

oMathews, E. B., op. cit., p. 162.
68 GRANITES OP SOUTHEASTERN ATLANTIC STATES.

The gneiss is highly variable in composition, ranging from essentially a hornblende gneiss on the one hand to a biotite gneiss on the 

other. Both biotite and hornblende, more especially the former, 

are subject to wide variation in amount. In the mica-bearing gneiss, 

which is probably the most abundant facies, the rock may be composed almost entirely of quartz, with very little mica and feldspar, 

or it may be made up of quartz, feldspar, and mica (biotite) in nearly 

the proportions of a very acidic granite. In the hornblende-bearing 

facies of the gneiss the very dark, blue-black bands are composed 

largely of hornblende with very little feldspar or quartz. Among 

the secondary minerals occurring in the gneiss are epidote and garnet, 

less commonly fibrolite, cyanite, and staurolite. Many thin sections of 

the light-colored bands show the constituent grains to be somewhat 

rounded and not interlocked as in igneous rocks, suggesting that the 

gneiss is probably of sedimentary origin, and it is so regarded by the 

geologists of the Maryland Geological Survey.

In some quarries the rock is thoroughly decayed in places to a 

depth of 25 feet and more. Usually two sets of vertical joints are 

developed at approximately right angles to each other. Their 

courses are N. 30° E. and N. 40° W. The surfaces of some, of the 

joints are slickensided, indicating movement. These quarries are 

well known for the large number of minerals that coat the surfaces 

of some of the joints (p. 32). Pegmatite dikes ranging from an 

inch to several feet across cut the gneiss in places. For figures of 

tests to determine crushing strength, absorption, and freezing loss, 

see pages 48, 50.

The product of these quarries is used principally in the city of 

Baltimore for paving and curbing, chiefly the latter, and in the form 

of crushed stone.

GWYNNS FALLS QUARRIES.

The quarries along Gwynns Falls, near the western limits of the 

city of Baltimore, were not opened for about fifty years after those 

along Jones Falls. Systematic work dates from about 1850 and has 

continued to the present time. The principal quarries'in the area 

are the John G. Schwind quarry, on Edmondson avenue, and the 

Leonard quarry, a little farther west on Gwynns Falls. In addition 

to these two, there are a number of smaller quarries in the immediate 

vicinity. The rock is essentially the same in all and is closely similar 

to that quarried along Jones Falls. Quarrying operations extend 

from the dam south of Edmondson Avenue Bridge for a distance of a 

mile or more southward, along the west side of Gwynns Falls.

The rock is an irregular gneiss showing variations of color, texture, 

and composition similar to those of the gneiss quarried along Jones 

Falls. The general strike of the beds is N. 45° E., and the average
GRANITES OF MARYLAND. 69

dip is 30° NW. Much steeper dips are observed in places, resulting 

from irregularity of the folding. The average thickness of the beds 

ranges from 1 to 4 feet. In composition the rock ranges from a hornblende gneiss to a biotite gneiss, with wide variation shown in the 

amount of hornblende and biotite, especially the latter. The lightercolored layers are composed essentially of quartz, much or little feldspar, and very little biotite, closely resembling a light-colored, very 

fine-grained granite. Some bands are more feldspathic and micaceous 

than others and likewise vary in the degree of lamination. The-lighter 

beds furnish the most desirable grade of stone.

Two principal sets of vertical joints, nearly at right angles to each 

other, strike N. 55° E. and N. 50° W.; minor jointing is developed in 

other directions. The joints are spaced at intervals ranging from a 

few inches to several feet, but are not so close as to prevent the 

quarrying of dimension stone. Numerous minerals, such as laumontite, stilbite, etc., listed on page 32, are distributed along the faces of 

some of the joints.

Pegmatite dikes of very large dimensions intersect the gneiss in 

places. The principal mica in the pegmatites is the light-colored 

potash variety, muscovite. Abundant large and small red garnets 

occur in the pegmatite shown in the figure. (See PL III.)

Like the material already described as characteristic of the Jones 

Falls quarries, the product from these quarries has a wide range of 

uses. Some of it is reported to have been furnished for many wellknown buildings in Baltimore. Part is used for foundations; much 

of it is worked into paving blocks; and the quarry waste is utilized in 

the form of crushed stone for various purposes.

OTHER GNEISS QUARRIES.

Besides the large quarries on Jones Falls and Gwynns Falls, 

described above, there are smaller scattered quarries in the vicinity 

of Baltimore which have been worked to supply a local demand. 

The principal ones are opened along Herring Run, near Hall Spring; 

at Ivy; and along the upper course of Gwynns Falls, near McDonogh. 

Mathews reports that the material from these quarries is similar to 

that obtained from those on Jones Falls and Gwynns Falls, and is 

used locally for paving blocks, sills, steps, and curbing. The principal 

use made of the product, however, is for road metal in the construction of the highways radiating from Baltimore.
CHAPTER III.

THE GRANITES OF VIRGINIA. 

THE VIRGINIA PIEDMONT REGION.

The Piedmont province in Virginia, a part of the eastern crystalline area which extends southwestward from New York to northcentral Alabama, stretches eastward from the Blue Ridge to the 

western margin of the Coastal Plain and widens southward. Lack 

of systematic study of the Virginia Piedmont region forbids more 

than a most general statement of its geology. The rocks occupying the region are the oldest in the State, and, except in the Triassic 

areas, they are all crystalline. Rogers mapped the crystalline rocks 

of the region as Archean, but more recent studies reveal the fact 

that a part of them are as late as Ordovician in age. The rocks 

comprise sedimentary and igneous masses so greatly altered through 

metamorphism that many of them bear but slight resemblance to 

the original rocks. They constitute a complex of schists, gneisses, 

and granites, with local areas or belts of slates, quartzites, and limestones. This complex is further intersected by intrusions of basic 

eruptive rocks belonging, so far as they have been studied, to the 

diabasic, dioritic, and gabbroic types. To the east of Danville, in 

the extreme southern part of the region, is an extensive area of 

altered andesite and acidic porphyries, and their associated pyroclastic rocks (tuffs), which extends into North Carolina and is 

regarded as pre-Cambrian in age.

Over the eastern, northern, central, and southern parts of the 

Piedmont are areas of Triassic shale, sandstone, and conglomerate. 

The northern and eastern areas of these rocks are extensive.

DISTRIBUTION OF THE GRANITES.

In Virginia the granites are limited to the crystalline area described 

above and comprise both massive and schistose types. The schistose 

granites (gneisses) are widely distributed throughout the Virginia 

crystalline area, forming one of the dominant rock .types. Only a 

small part of this area has yet furnished first-grade quarry material, for 

over most of the area the granites have been rendered schistose from 

metamorphic action and are not desirable for use in the higher grades

70
U. S. GEOLOGICAL SURVEY BULLETIN 426 PLATE VII

/ Washing ton

RAPP AHA1W O

.

FLUVANNA/

UC KIN G

\ Buckinghau

APPOMATTOX

"NO T\T O "

Charlotte 

o

HAR L OTTEx

\r)NevvportNews

S0Me of W^ht

PriacessAnne^ 

I NORFOLK

LEGEND

Fal line

QUARRIES

1-5 Potomac River

6 Trip

7 Hoffman &. Miller

8 Annandale (?)

9 Cartwright &. Davis

10 Hazel Run

i i Richmond Granite Co.

12 Old Dominion Iron and Nail Works 

(Belle Island)

13 Netherwood

14 Wray

15 Donald

16 McGranigan

17 Granite Development Co.

18 Old Dominion (Middendorf)

19 Mclntosh

20 Krimm

21 Old Dominion Granite Co.

22 Westham

23 Smith

24 Winston & Co.

25 McCloy

26 Philadelphia

27 Middendorf

28 Tidewater Quarry Co.

29 McGowan

30 Cook

31 Lassiter

32 Petersburg Granite Co.

33 Cowherd

34 Wingo

35 State test farm 

36, 37 Lynchburg

38 Kenbridge

39 Occoquan

40 Occoquan Stone and Lumber Co.

MAP OF VIRGINIA, SHOWING DISTRIBUTION OF GRANITE QUARRIES.
GRANITES OF VIRGINIA. 71

of work. There are, however, many localities capable of furnishing 

granite of superior quality for general building and monumental 

purposes. The principal areas which have produced and are now 

producing granite of superior quality are distributed in a north-south 

direction along the eastern margin of the crystalline region. They 

include the Petersburg area, the Richmond area, and the Fredericksburg area. The granite from quarries in these areas has an established reputation and has been shipped more or less to all the States 

and. the principal cities south of New England. In addition to these 

there are several minor areas capable of yielding granite suitable for 

general building purposes, but in none of them has the stone more 

than a strictly local use, and it has not been placed on the market. 

The location of the principal granite quarries in the State is shown 

on the map (PI. VII).

SCIENTIFIC DISCUSSION.

MINERAL COMPOSITION.

Conforming with well-known granites elsewhere, the Virginia rocks 

are mixtures of feldspar and quartz, with biotite as a third essential 

component in the most important areas. Muscovite in subordinate 

amount usually accompanies the biotite in all the granite areas of the 

State, and it becomes a principal constituent in the granite of the 

Hazel Run area, west of Fredericksburg. Hornblende is an important constituent in only a part of the granites of the Falls Church 

area, southwest of Washington, and it is almost unknown in the 

granites of the other areas. It is essentially absent from the economically most important granites of the State.

In the unique variety of granite known as unakite, occurring in 

the Blue Ridge near Luray, in Page and Madison counties, and near 

Troutdale, in Grayson County, epidote is a principal constituent 

and the ferromagnesian silicates are nearly or entirely absent. The 

epidote is entirely a secondary mineral.

The feldspathic constituent of Virginia granites is composed of 

plagioclase (oligoclase), orthoclase, and microcline in variable amount. 

In some places microcline may equal or even exceed orthoclase in 

amount. One of the most striking features in the mineralogical 

composition of these rocks is their richness in plagioclase (oligoclase), 

and to a less extent in microcline. Both oligoclase and microcline, 

however, are subject to variation, and in a few thin sections examined 

their poverty was a noticeable feature. It seems probable that a 

part of the microcline in the Virginia rocks has developed in part 

from orthoclase by pressure metamorphism.

Besides the above-named minerals the granites contain apatite, 

zircon, titanite, magnetite, and some other minerals.
72 GRANITES OF SOUTHEASTERN ATLANTIC STATES. 

CHEMICAL COMPOSITION.

The chemical composition of the Virginia granites in the Richmond, 

Petersburg,-and Fredericksburg areas is shown in the table of analyses 

below:

Chemical analyses of Virginia granites. 0- 

[Wm. M. Thornton, jr., analyst.]

Constituents.

Silica (SiOj)...... ...................

Alumina ( A12 03 ) .....................

Lime (CaO). .........................

Soda (Na2 0) .........................

Potash.(KsO)........................

Water (H2 0)- at 110° C.............

Water (H2 0)+ at 110° C .............

Phosphoric acid (P2 O6 ) ..............

1.

72.27

14.30

1.16

.97

.70

1.50

3.40

5.00

.04

.25

.31

Tr.

.21

.02

100. 25

2.

71.51

13.82

1.76

1.20

.80

1.79

3.64

4.63

.17

.31

.33

.03

Tr.

.30

100. 29

3.

71.19

14.01

1.66

1.29

.44

2.04

3.56

4.45

.04

.33

11

.02

Tr.

.34

99.72

4.

70.83

12.70

2.67

1.36

.53

1.88

3.49

4.83

.07

.34

.41

.03

Tr.

.33

99.47

5.

69.48

13.95

2.82

1.70

1.10

2.81

3.65

3.45

.04

.50

.47

.03

Tr.

.49

100. 49

6.

69.44

15.46

1.31

1.43

1.01

2.11

3.97

4.25

.07

.29

.48

.03

Tr.

.22

100. 07

7.

69.29

14.07

2.59

2.03

1.32

2.76

2.89

2.87

.06

.37

10

.08

Tr.

.26

99.09

8.

68.45

10.00

5.71

2.59

3.26

6.20

1.98

1.18

.18

.62

.20

.05

Tr.

.25

100. 67

a. Watson, T. L., Bull. Virginia Geol. Survey No. 1-A, 1909, p. 81.

1. Meclium-textured medium-gray biotite granite. Westham granite quarries, 4.5 miles west of Richmond, Chesterfield County.

2. Medium-textured medium-gray biotite granite. Lassiter and Petersburg Granite Company's quarries, Petersburg, Dinwiddie County.

3. Fine-grained dark blue-gray biotite granite. McGowan, Netherwood, and Donald quarries, Chesterfield County, and Mitchell & Copeland quarry, Henrico County, near Richmond.

4. Medium-coarse medium-gray biotite granite. Netherwood, State (Old Dominion), Granite Development Company, Krimm, and Middendorf quarries, Chesterfield County, near .Richmond.

5. Fine-grained dark blue-gray biotite granite. Cartwright & Davis quarries, near Fredericksburg, 

Spottsylvania County.

6. Medium-textured medium-gray biotite granite. Mclntosh quarry, Chesterfield County, 5 miles west 

of Richmond.

7. Medium-coarse gray biotite granite gneiss. Middendorf (Belt Line Railway) quarry, near Manchester, 

Chesterfield County.

8. Medium-coarse gray biotite granite gneiss. Cartwright & Davis quarries, near Fredericksburg, 

Spottsylvania County.

The high percentage of soda in the Virginia granites has been 

commented on above. Soda molecularly exceeds potash in every 

analysis, indicating the predominance of soda-lime feldspar over 

potassic feldspar, a fact which places the Virginia granites with the 

quartz monzonites.

KINDS OF GRANITE.

Like the granites of the southeastern Atlantic States in general, 

the granites of Virginia vary in structure from massive to schistose, 

and in texture from even granular to porphyritic. On this basis 

three types of rocks are distinguished: (1) Massive even-granular 

granites, (2) porphyritic granites, and (3) schistose granites or granite 

gneisses.. The granite gneisses were derived from the massive granites, from which they differ principally in the pronounced schistose 

structure secondarily induced by dynamic metamorphism.

On the basis of mineral composition the Virginia granites are divisible into the following leading types: (1) Biotite granite, which 

usually carries a little muscovite in addition to the biotite, and under
GRANITES OF VIRGINIA. 73

which a majority of the granites of the State may be grouped, including the Richmond and Petersburg areas and most of the Fredericksburg area; (2) muscovite granite, of which the Hazel Run area, 1 

mile west of Fredericksburg, is the only typical representative yet 

known; (3) hornblende-biotite granite, represented by a part of the 

granites occurring southwest of Washington in the Falls Church area, 

Fairfax County, and near Saxe, Charlotte County; and (4) epidote 

granite (unaldte), of which there are only two known localities, one 

in the Blue Ridge at Milams Gap, near Luray, in Page and Madison 

counties, and the other near Troutdale, in Grayson County.

In addition to these types pegmatites, coarse crystallizations of 

quartz and feldspar with subordinate mica, in dikelike form, abundantly penetrate the finer granites and associated crystalline rocks 

over much of the Piedmont region. Aplite is represented only in the 

granite of the Richmond area, and here principally on the western 

border of the Richmond basin, near Midlothian.

NATURE OF THE GRANITE OUTCROPS.

Rock decay is somewhat profound over all parts of the Piedmont 

region, and the rocks are generally concealed beneath a variable 

thickness of the loose residual material. Exposures of the moderately fresh granite, however, are by no means uncommon, and because 

of their favorable location and topographic relations they usually 

afford desirable quarry sites. These exposures lie usually along the 

major stream courses in the form of both high and low steep slopes 

bounding the streams, and on the surface they are usually of a bowldery character. This is particularly true in the stream beds, where 

the exposures are almost invariably made up of large and small 

bowlders. Outcrops of this character are strikingly developed along 

James, Appomattox, and Rappahannock rivers in the vicinity of 

Richmond, Petersburg, and Fredericksburg. In these areas the 

quarries have been largely opened in the steep slopes immediately 

facing the rivers.

On the smaller streams the exposures are low and more in the form 

of true ledges, which may or may not be of bowldery character. The 

exposures on the interstrearn areas are in the nature of low, flatsurfaced masses, and the extent of the exposed granite varies greatly 

in the outcrop. Prominent granite domes, such as Stone Mountain 

in Georgia and North Carolina, do not occur in the Virginia region.

EVEN-GRANULAR GRANITES.

The even-granular granites are economically the most important 

in Virginia. Five types are distinguished: (1) The medium-gray 

biotite granite of the Richmond-Petersburg area, (2) the dark blue-
74 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

gray biotite granite of the Richmond-Fredericksburg area, (3) the 

light-gray muscovite granite of the Fredericksburg area, (4) the 

dark-gray hornblende-biotite granite of the Falls Church area, and 

(5) the yellowish-green and pink epidote granite known as unakite. 

The differentiation of these five types is based on certain differences 

which are best brought out under the individual descriptions.

MEDIUM-GRAY BIOTITE GRANITE OF THE RICHMOND-PETERSBURG AREA.

The medium-gray granite has been quarried for many years in the 

vicinity of Richmond and Petersburg. (For description of individual 

quarries, see pp. 88-106.) It extends over parts of three counties 

Dinwiddie, Chesterfield, and Henrico. It is a biotite granite, in 

many places containing a little muscovite, and the mineral grains 

(anhedra) range in size from 1 to 5 millimeters. Variation in the 

size of the anhedra within the limits given is a noticeable feature of 

this type of granite in the quarries around Richmond and Petersburg. Its principal minerals are quartz, orthoclase, microcline, plagioclase near oligoclase, biotite, a little muscovite, titanite, magnetite, 

apatite, zircon, and rutile. The secondary minerals are chlorite, 

epidote, a light-colored mica, and kaolin. An important feature in 

the mineral composition of this granite is its large content of plagioclase, which either equals or is greater than the potash feldspar. It 

occurs in large, stout laths, and is always characterized by polysynthetic twinning striae in basal sections. Extinction angles measured 

against the twinning striae usually indicate a plagioclase near oligoclase. Microcline is variable in amount, and may either equal or 

exceed orthoclase. Twinning on the Carlsbad law is generally visible 

among the feldspars, both in thin sections and in hand specimens of 

the rock. Microperthitic intergrowths of the feldspars are seen in 

most of the thin sections studied. Many of the larger feldspars contain 

microscopic inclusions of other minerals (micropoikilitic), the inclosures consisting of quartz and other feldspars.

Rutile needles are abundant in some of the quartz. Granophyric 

intergrowths (mutual penetrations) of the quartz and feldspars are 

very abundant in the thin sections studied, indicating overlap in the 

period of formation of these minerals. The quartz intergrowth is 

not restricted to any single species of feldspar, but seems to be of 

about equal development in the orthoclase, microcline, and plagioclase species.

Biotite is the third essential constituent; it is deep brown and 

strongly pleochroic. It is distributed through the rock in single 

long and stout shreds and as small aggregates. This constituent is 

subject to some variation both in size of shred and in amount; the 

rock becoming, according to quantity of biotite, either lighter or
GKANITES OF VIRGINIA. 75

darker in color. Under the microscope numerous inclusions of the 

older minerals are seen in the biotite, among the most important of 

which are zircon, apatite, and magnetite. In most of the thin sections 

a little primary muscovite is intimately associated with the biotite, 

here and there as a parallel growth; in places the two micas penetrate 

each other, always preserving sharp and clear-cut boundaries. Much 

chlorite occurs as an alteration product of the biotite. Epidote, 

though not abundant, is usually present in many of the sections, 

always as an alteration product from the interaction of the biotite 

and feldspars, and is associated with the biotite.

Titanite is present to a minor extent in many of the sections, 

mostly as irregular grains and aggregates, but in part as rhombic 

crystals. The tint varies from nearly colorless to reddish brown, 

with noticeable pleochroism in the deeper hues.

Pressure-metamorphic effects are clearly defined in all the thin 

sections of granite of this type. They are more strongly marked in 

the granite from the Petersburg portion of the area than in that from 

Richmond. Under the microscope the pressure effects are shown in 

an optical disturbance of the quartzes and feldspars, more marked in 

the former, in the form of a wavy or undulous extinction; in a fracturing of the quartz and feldspar, which is rather strongly developed in 

some of the plagioclase individuals of thin sections from the Petersburg area; and lastly in peripheral shattering or granulation of the 

larger quartz and feldspar individuals in the granite from the Petersburg area. Also, in several sections, biotite shreds were noticed 

broken across, and in still other cases the folia were markedly curved 

or bent.

At the Netherwood quarry, several miles west of Richmond, this 

granite is typically shown and in some of the largest quarried blocks 

dressed up during the summer of 1905 a distinct schistosity was discernible. As a rule, however, the rock from this quarry and from 

the Richmond area in general belonging to this type appears entirely 

massive. In the Petersburg part of the area the dynamic effects are 

the most pronounced, both in the thin sections and in the hand specimens, and a tendency toward a rough parallel arrangement of the 

minerals schistosity is shown on close examination of the rock in 

nearly every opening.

The State, War, and Navy Building in the city of Washington was 

constructed from granite of this type obtained near Richmond; and 

the stone, which has been extensively quarried in the vicinity of 

Richmond and Petersburg, is used in most of the territory south of 

New England for building purposes.
76 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

DARK BLUE-GRAY BIOTITE GRANITE OF THE RICHMOND-FREDERICKSBURG AREA.

The dark blue-gray granite does not differ essentially in mineral 

composition, from the light-gray rock just described, although the 

two bear no resemblance to each other in hand specimens. The 

dark blue-gray rock is much more finely crystalline, the anhedra 

averaging less than 0.5 millimeter in size. The biotite is uniformly 

distributed through the granite in minute irregular shreds which 

impart the pronounced dark-blue color to the rock. Like the lightgray type this is a biotite granite containing a very little muscovite 

associated with the biotite. Plagioclase and microcline, in quantity 

and occurrence, are similar in both the dark-blue and the light-gray 

granites.

Microscopically the two types are unlike in the degree of pressure 

effects indicated. The dark blue-gray granite is entirely massive, 

and the only effects of pressure metamorphism discernible in the 

thin sections are those of undulous extinction of and local fractures 

in the quartz. In the Fredericksburg portion of the area the rock 

is a shade darker in color than most of the same type in the Richmond portion. The texture is the same for the two localities, but in 

the quarries near Richmond there is a perceptible variation in the 

depth of the blue-gray color.

The dark blue-gray granite is quarried in the vicinity of Richmond 

and Fredericksburg for monumental stock. Uniformity in color and 

texture make it a most desirable granite for this purpose.

LIGHT-GRAY MUSCOVITE GRANITE OF THE FREDERICKSBURG AREA!

Light-gray granite occurs about 1 mile west of Fredericksburg on 

Hazel Run. It is made up of anhedra averaging about 2 millimeters 

in size and is essentially a muscovite granite containing considerable 

biotite closely associated with the potash mica (muscovite), distributed through the rock. It somewhat resembles the light-gray biotitebearing muscovite granite of Stone Mountain, Ga. Here and there a 

crystal of red garnet is observed in the rock.

The effects of dynamic metamorphism are manifested in the rock 

in a thinly foliated structure which is discernible only on close examination. Thin sections of the granite show quartz, orthoclase, microcline, plagioclase (oligoclase), muscovite, biotite, apatite, rutile, and 

zircon. Chlorite and muscovite are the principal secondary minerals. Muscovite is partly primary and partly secondary. Microcline and plagioclase are present in large amount. Intergrowths of 

the feldspars and of the feldspars with quartz are numerous. Micropoikilitic structure in the larger feldspar individuals is strongly 

marked. Partial orientation of the mica along parallel directions, an
GRANITES OF VIRGINIA. 77

occasional bent and broken muscovite shred, fractured quartzes with 

wavy extinction, and the perfect granulation of the quartz-feldspar 

individuals are pressure effects plainly marked in the thin sections.

DARK-GRAY HORNBLENDE-BIOTITE GRANITE OF THE FALLS CHURCH

AREA.

The granites in the vicinity of Falls Church, Fairfax County, are of 

two varieties. One is a medium to finely crystalline rock and contains dominant biotite with some muscovite as a third essential constituent, and is similar in mineral composition to the Richmond types 

of granite. The other, a light and dark speckled rock, is a fraction 

more coarsely crystalline and is a hornblende-biotite granite; except 

for the small granite area near Saxe (p. 112), this is the only hornblende granite yet found in the State, and its affinities somewhat 

closely ally it with quartz diorite. It is closely associated in the field

with diorite masses on the one hand and with foliated mica granites 

on the other; the associated diorites are partly altered to metadiorites. 

Petrographically it more properly belongs with the granodiorites, 

differing from the diorites proper in containing more quartz and 

potash feldspar. Thin sections show quartz, plagioclase, orthoclase, 

green and brown hornblende, biotite, apatite, rutile, and the secondary minerals epidote, sericite, garnet, chlorite, and kaolin. Hornblende is one of the most abundant constituents and in places it 

completely incloses shreds of the biotite. Microcline does not occur. 

Plagioclase is probably slightly more abundant than orthoclase. 

Pressure effects are indicated in the optical disturbance of the 

quartz and feldspar in fractures crossing the quartz, in the curved and 

bent lamellae of a part of the plagioclase, and in the marked distortion 

of the cleavage angle of the hornblende.

YELLOW-GREEN AND PINK EPIDOTE GRANITE UNAKITE.

Unakite derives its name from the Unaka Mountains in western 

North Carolina and eastern Tennessee, where it was first observed.a 

Until very recently knowledge of it in Virginia was limited to a single 

locality Milams Gap, in the Blue Ridge, near Luray, but it has 

lately been noted near Troutdale, Grayson County. b The mineral 

composition of the rock from the Virginia and North Carolina-Tennessee localities places it among the granites with epidote as an essential constituent, but according to the analysis by Phalen c of specimens from Milams Gap the rock is relatively basic for a granite.

The rock is a moderately coarse but irregular crystallization of red 

feldspar, quartz, and green epidote. Irregular crystallization of the

o Bradley, F. H., Am. Jour. Sci.,3cl ser., vol. 107,1874, pp. 519,520.

6 Watson, T. L., Am. Jour. Sci., 4th ser., vol. 22, 19CG, p. 248.

c Phalen, W. C., Siriithsonian Misc. Coll., vol. 45,1904, pp. 306-316.
78 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

rock is shown in its range from masses that are more than two-thirds 

red feldspar through all gradations to masses composed of quartz and 

epidote without feldspar (epidosite) 0. Thin sections of the unakite 

from Milams Gap show epidqte, orthoclase, quartz, iron oxides, zircon, 

and apatite. The epidote is secondary, replacing pyroxene and feldspar, both plagioclase and orthoclase.

The unakite-bearing rock at Milams Gap is, according to Phalen, a 

hypersthene akerite (hypersthene-quartz-diallage syenite), a coarsegrained dark grayish-green aggregate consisting essentially of feldspars and black pyroxenes. Thin sections of the syenite reveal the 

following minerals: Orthoclase, plagioclase, orthorhombic and monoclinic pyroxene, quartz, microcline, iron ore, apatite, and zircon, with 

the alteration products epidote, chlorite, and sericite. Hornblende is 

essentially absent in the thin sections. Phalen regards the unakite as 

having originated from the akerite by hydrometamorphism aided by 

dynamic disturbances.

The following analyses of the unakite and the unakite-bearing rock 

(akerite) are quoted from Phalen (p. 313):

Analyses of unakite and akerite from Milams Gap, Virginia. 

[W. C. Phalen, analyst.]

Constituents.

Si02 a -.--...-.---------.-----.--- ....................:..............................

A12 03 . ..............................................................................

FeO

MgO. .................................................................................

CaO. ................................................................................

Na2 0 ................................................................................

K2O ................................................................................ i-ijO. ................................................................................

p,o& .. .............................................................................

MnO. .........................................................,:...................-

Unakite.

58.32

15.77

6.56

89

09

11.68

OO

4. 01

1.73

.48

.13

99.98

Hypersthene 

akerite.

CO. 52

 16. 99

.60

6.53

1 r)9

2.83

3.91

.88

.74

.25

Trice

93.42

PORPHYRITIC GRANITE.

Unlike the crystalline region of North Carolina and Georgia, 

Virginia contains few porphyritic granites. The best developed 

and most typical area in the State is that bounding the eastern 

margin of the Richmond coal basin near Midlothian, 13 miles west 

of Richmond, and extending about 20 miles in a north-south direction. It marks the western limits of the even-granular granite 

quarried around Richmond and Petersburg. The porphyritic and 

even-granular granites are both biotite granites and differ from 

each other only in texture.

a Phalen, W. C., op. cit., p. 312.
GRANITES OF VIRGINIA. 79

The rock in the vicinity of Midlothian is a coarse biotite granite, 

the porphyritically developed mineral of which is potash feldspar. 

The phenocrysts are of large size, in part twinned on the Carlsbad 

law, as a rule idiomorphic and flat tabular in habit and are orientated in a general north-south direction from flowage of the rock. 

The ratio of phenocrysts to groundmass is variable. The porphyritic 

texture with variations is traced as far north as Gayton, Henrico 

County, and as far south as Winterpock, Chesterfield County. The 

evidence seems clear that the porphyritic granite underlies in part 

the eastern portion of the Richmond coal basin, but its relations to 

the crystalline rocks on the west can not be stated, for the line of 

contact is concealed beneath the cover of Newark rocks of the coal 

basin.

No quarries have been opened in the porphyritic granite.

GNEISSES.

INTRODUCTORY STATEMENT.

Gneisses of granitic composition make up one of the principal 

rock types in the Virginia Piedmont complex. Many of these 

gneisses were derived from original massive granites, and they are 

usually of the mica variety. In mineral composition the granite 

gneisses are essentially identical with the massive granites, except 

that hornblende is associated with biotite in the gneisses of the 

Richmond and Fredericksburg areas. In some of the thin sections 

hornblende is largely in excess of the biotite. The gneisses differ 

from the granites principally in having a banded structure, produced 

through pressure metamorphism. The banding may be fairly 

regular, but as a rule it is very irregular; in either case the rock is 

composed of alternating bands of light and dark minerals. The 

individual bands may vary much in thickness. The structural 

features of the rock of this type in the Virginia area render it unsuitable for use in any except the rough grades of work, and it is but little 

quarried in the State.

Between the entirely massive granite and the typical granite 

gneiss intermediate grades of schistosity are easy of differentiation 

over parts of the Virginia region. This undoubtedly means that 

in some of the areas a less schistose granite may grade into a more 

schistose granite. In other areas this interpretation is not possible, 

for the massive granites are sharply defined structurally from the 

schistose granites, and wherever contacts were found it was entirely 

clear that the massive rock was younger and had been intruded into 

the schistose rock.

38971° Bull. 426 10 6
80 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

GNEISS OF THE RICHMOND-FREDERICKSBURG AREA.

The gneiss is the oldest of the granitic rocks in the Richmond and 

Fredericksbiirg area, and it is invaded by both the medium-gray and 

the dark blue-gray massive granites. Figure 3 shows the relationbetween the dark blue-gray granite and the gneiss at the McGowan 

quarry south of Manchester. Similar relations prevail between the 

granite and the gneiss in the Cartright & Davis quarries 3 miles 

northwest of Fredericksburg. The period of deformation, inducing 

the schistose structure in the gneiss, preceded that of the intrusion

of the massive granite, as shown 

by the fact that the massive 

granites cut across the schistQsity of the gneiss and contain inclusions of the gneiss 

which preserve perfectly the 

gneissic structure.

The gneiss is a hornblendebiotite gneiss of medium-coarse 

texture and irregular banding. 

It is much coarser in texture 

than the granites and consists 

of irregular alternating bands 

of essentially the dark and 

light minerals. Its principal 

minerals are quartz, orthoclase, 

plagioclase, hornblende, and 

biotite, with accessory titanite 

and apatite. Chlorite occurs 

as an alteration product from

biotite. 

A thin section of one of the

dark bands showed a preponderance of brOWn and green

horn blende with less black mica (biotite), largely altered to chlorite. 

Some potash feldspar (orthoclase) and soda-lime feldspar (oligoclase), 

quartz, and much titanite were present. Microcline does not occur. 

The principal accessory minerals noted in the granite are also present in the gneiss.

Thin sections of one of the coarse-textured, light-colored bands 

of the gneiss showed the minerals to be quartz, potash feldspar (orthoclase) and soda-lime feldspar in nearly equal amounts, a little black 

mica (biotite), and several pieces of nearly colorless hornblende. 

Microcline is not present.

FIGURE 3. Contact of hornblende-biotite gneiss with 

granite at McGowan quarry, south of Manchester, Va.
U. 6. GEOLOGICAL SURVEY BULLETIN 426 PLATE VIII

A. GNEISS QUARRY NEAR LYNCHBURG, VA. 

Showing regular banding of the gneiss.

B. COOK QUARRY, NEAR PETERSBURG, VA. 

Photograph by H. Ries.
GRANITES . OF VIRGINIA. 81

The gneiss, which is older than the granite, differs essentially 'from 

the latter in having a banded or schistose structure; in the presence 

of hornblende, which exceeds biotite in amount in some of the thin 

sections; in the absence of microcline a mineral always present in 

the massive granites; and in coarseness of texture. It is unsuited for. 

the higher grades of work for which granite is used, but for other 

uses it will probably serve equally well. Though good quarry sites 

are procurable, the gneiss has not been quarried.

GNEISS OF LYNCHBURG, VA.

Extending from the north and east limits of the city of Lynchburg 

is an extensive body of gneiss cut across by James River and lying 

partly in Amherst County and partly in Campbell County. Its 

limits are unknown. Excellent exposures are found along James 

River and some of its tributaries near the city. Numerous quarries have been opened and the product is used for general building 

and street purposes in Lynchburg. The quarries are located iilong 

the north side of the James, in Amherst County, opposite Lynchburg, 

where the river has cut directly across a broad anticline of the gneiss; 

and to the southeast of Lynchburg, in Campbell County, along the 

tributaries of the James.

The rock is a biotite gneiss of dark blue-gray color and fine grain. 

It is of doubtful origin, and in places appears to be composed of 

alternating layers of gneiss and schist of a prevailing gray color. 

Quartz and mica are the predominant minerals in the schist. The 

gneiss splits readily into slabs, is hard but easily dressed, and is very 

resistant to atmospheric agents.

The quarries opened about 1 mile south of Lynchburg are located 

in beds forming the southeastern limb of the anticline. The gneissic 

bands are very regular and even as a rule, vary in thickness from 6 

inches to several feet, and dip 45° S. (See PL VIII, A.) They are cut 

by a well-developed system of joints striking N. 5°-10° W. Pegmatite dikes, composed in essential part of pink feldspar with some 

quartz, are in places developed parallel to the banding. Along the 

planes of banding very thin, finely crinkled laminas of sericite mica, 

in part chloritic, occur locally.

GNEISSES OF FAIRFAX AND ALEXANDRIA COUNTIES.

Extending southward from Potomac River and covering much of 

Fairfax and Alexandria counties are two extensive 'belts of gneiss, 

of which one is a metamorphosed granite and the other is of doubtful 

origin. The former, granite gneiss, is of fairly uniform color and 

texture; the latter is rather irregular in color, texture, and composition.
82 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

The granite gneiss has been quarried from time to time for local 

use from the ledges along and on the south side of the Potomac. 

When fresh the rock is a dark bluish-gray gneiss of rather fine grained, 

uniform texture. The principal minerals are quartz, orthoclase, 

plagioclase, muscovite, and biotite, with small amounts of garnet, 

chlorite, hornblende^ tourmaline, and pyrite.

The gneiss of doubtful origin, designated by Keith the Carolina 

gneiss, is composed of alternating layers of gneiss and schist of a prevailing gray color, dark bluish gray when fresh. The bands vary in 

thickness. Quartz and mica are the predominant minerals in the 

schist; quartz, feldspar, and mica in the gneiss. So far as the writer 

is aware the Carolina gneiss has not been quarried in this area.

OTHER GNEISS AREAS.

Gneiss has been quarried also in Fluvanna, Bedford, Franklin, and 

Pittsylvania counties. These are feldspar-quartz-mica gneisses. The 

Virginia gneisses are usually well adapted to the rougher grades of 

work, such as for certain kinds of street work, for concreting and 

ballast, for retaining walls and foundations, and for road material. 

Where quarries have thus far been opened, the product has been used 

strictly for local purposes.

STRUCTURAL RELATIONS IN THE RICHMOND-FREDERICKSBURG

AREA.

GENERAL STATEMENT.

Three types of rocks of granitic composition are represented in the 

Richmond area; two are massive granites; the third is a schistose 

granite or granite gneiss. The two massive granites are designated 

the medium-gray granite and the dark blue-gray granite. Three

periods of intrusion are represented, in the following order, beginning 

with the earliest: (1) The granite gneiss; (2) the medium-gray granite; and (3) the dark blue-gray granite. This succession is plainly 

indicated in the field.

CONTACTS.

The numerous quarries worked in the vicinity of Richmond afford 

excellent opportunity for studying the contacts between the fresh 

granites of the three types named above. As noted in the descriptions of the three types (p. 80), the differences in color, texture, and 

structure render them easy of differentiation. Not one of the large 

number of contacts examined has shown the presence of contact 

minerals. Several of the contacts show inclosures of the older granite 

in the newer one. At one of the contacts between the medium-
GRANITES OF VIRGINIA. 83

gray and the dark blue-gray granites in the Netherwood quarry the

younger or dark blue-gray granite contains numerous irregular fragments of varying size of the medium-gray

granite, as shown in figure 4. Other exposures in the same quarry reveal the true

relations of the two granites. As shown in

figure 5 the dark blue-gray granite invades

the gray granite in two separate, nearly

vertical dikelike arms.

The same relation of these two types is 

equally well shown in the dark blue-gray 

granite penetrating the medium-gray granite in the Philadelphia quarries, at the 

head of the settling basin, near Richmond

(fig. 13). 

At the McGowan quarry, several miles

SOUth Of Richmond (fig. 3), aild at the Cartwright & Davis quarries (fig. 14), 3 miles

north of Fredericksburg, contacts between

granite gneiss and dark blue-gray granite are beautifully shown. At

both places the granite cuts directly across the schistosity of the gneiss.

quarry, near Richmond, Va.,

°f the grayin

APOPHYSES.

At the Cartwright & Davis quarries, 3 miles north of Fredericksburg, 

the sloping floor of the granite gneiss in one of the openings contains 

numerous large and small dikes or tongues of the dark blue-gray 

granite penetrating the gneiss (fig. 14). These have the texture, color, 

arid composition of the parent mass, and they conform in part with 

the schistosity of the inclosing gneiss and in part cut directly across

'^Sfc^G^

FIGURE 5. Relations of blue to gray granite, as shown at Netherwood quarry, near Richmond, Va.

it. Similar conditions exist at the McGowan quarry, several miles 

south of Richmond. The Fredericksburg quarries furnish the best 

illustration of granite tongues penetrating from the parent mass into 

the inclosing rock.
84 GRANITES OF -SOUTHEASTERN- ATLANTIC STATES.

INCLUSIONS.

The inclusions correspond, in composition and otherwise, with the 

inclosing rock and plainly represent fragments of the country rock 

torn off during the intrusion of the granite containing them. In the 

Richmond-Fredericksburg area the dark blue-gray granite in some of 

the quarries contains inclusions of the massive light-gray granite 

(fig. 4) and of the gneiss (PI. XII, B}. The foliation of the gneiss 

inclusions is entirely preserved. No appreciable metamorphism was 

observable at the contacts of the inclosing granite and the inclusions.

BASIC SEGREGATIONS (KNOTS).

Dark-gray or black segregations of the iron-magnesian minerals 

principally, biotite usually, and less quartz and feldspar have scant

development in the more productive granite areas of Virginia. The composition of 

the knots corresponds entirely with that 

of the inclosing granite, except that biotite 

is very largely in excess. The granites of 

Richmond, Petersburg, and Fredericksburg show comparative freedom from 

knots. Where observed in the quarries 

around these cities the knots were invariably of small size, usually an inch or less 

in diameter, and oval. A stronger tendency 

toward the formation of minute segregations of biotite is shown in the dark bluegray granite near Fredericksburg than in 

the granite around Richmond and Petersburg.

J J ,. ..In the hornblende-biotite granite and FIGURE 6. Banded aplite-pegmatite _ °

dike in blue granite at McGowan the diorite of the Falls Church area, in 

quarry, south of Richmond, va. Fairfax County, both large and small,

nearly black, oval-shaped knots are common. In some of the undeveloped exposures of the rock the knots are so numerous and so large 

as to disfigure the stone.

JOINTS.

The Virginia granites are intersected by three systems of joints 

a vertical set, a diagonal set, and a horizontal set. These may be 

widely or closely spaced. Usually the spacing is sufficiently wide to 

admit of dimension stone being quarried. The vertical set of joints 

is in general more strongly developed than the diagonal; some of the 

granite masses are cut by both sets.

Measurements of the joint courses made in the quarries can be 

summarized as follows: Two sets of joints whose planes lie in the
OF VIRGINIA. 85

northeast and southwest quadrants compose the major jointing, and 

the minor sets strike east-west and north-south. The strike of the 

joint planes in the northeast and northwest quadrants shows the 

limits of variation to be N. 5° E. or W. to N. 80° E. or W. Only a 

few of the planes strike east-west and north-south.

The inclined joints are less abundant than the vertical ones, and 

they dip at angles varying from 20° to 82°. The dips are toward the 

northeast, east, southeast, northwest, and southwest. Plates X, A, B, 

and XI, A, show the two systems of vertical and inclined joints. 

Some movement in the granite masses since the formation of the 

joints is indicated in the development of slickensides on the joint 

surfaces. Polished and striated surfaces are fairly abundant.

As a rule, joints approximating horizontality in position are strongly 

developed in the 

granites of Virginia. Probably 

the most noteworthy exception 

is the granite exposed in the quarry 

of the Richmond 

Granite Quarrying 

Company, where 

vertical jointing is 

well developed but 

horizontal jointing 

is not apparent. 

The thickness of 

the sheets produced by this set. 

of joints varies

orpqtlv rnnfnncr FIGURE 7. Contact between blue and gray granites, showing pegmatite 

,_, btlLiy, ^ i clllgmg cutting both, at Netherwood quarry, west of Richmond, Va.

from 6 inches to

several feet. Ordinarily the planes separate the granite into thinner 

sheets at or near the surface and into thicker sheets at greater 

depth. (See PI. XI, B.)

DIKES.

APLITES.

Aplites are uncommon in the Virginia granite areas, and have been 

noted by the writer only in the Richmond area. A banded aplitepegmatite dike of small dimensions, shown in figure 6, penetrates 

the dark blue-gray granite of the McGowan quarry, south of Richmond. In the vicinity of Midlothian, 13 miles west of Richmond, 

the porphyritic biotite granite is cut by a number of small aplite 

dikes. Where these have been observed they are plainly of an intrusive nature, cutting the granite proper and not the inclosing gneisses.
86 GRANITES OF SOUTHEASTEKN ATLANTIC STATES.

PEGMATITES.

Pegmatites are abundantly developed in the Richmond-Fredericksburg areas, and some of them are of large size. Only in one or

two places do they 

seriously interfere 

with quarrying operations. They are 

of granitic composition and no unusual 

or rare minerals 

have. been noted in 

them; they cut alike 

the granites and 

gneisses. They have 

been worked to a 

moderate extent in 

several places in the 

Richmond area, but 

they have not yet 

become of economic 

importance.

The pegmatites 

consist of coarse aggregates of feldspar 

and quartz with

FIGURE 8. Faulted pegmatite intersecting blue granite at Donald more Or less black 

quarry, near Richmond, Va.

muscovite. In the Fredericksburg quarries of dark blue-gray granite, 

where the pegmatites are particularly abundant, massive granular 

magnetite and large and small perfect red crystals of garnet are not 

uncommon constituents. The dodecahedron and trapezohedron are 

the commonest forms of the garnet. 

The feldspar exhibits a variety of 

colors from opaque white and pink 

to a decided medium green, the 

former two being the prevailing 

shades. An acidic plagioclase is 

present in some of these dikes.

The numerous quarries in the 

Richmond area afford excellent 

opportunity for studying the pegmatites and some interesting data 

bearing on their comparative age relations have been obtained. It

FIGURE 9. Pegmatite cutting across schistosity 

of grai»te gne'ss at Middendorf quarry, west 

of Manchester. Va.
U. S. GEOLOGICAL SURVEY BULLETIN 426 PLATE IX

A. MONUMENTAL GRANITE, DONALD QUARRY, NEAR RICHMOND, VA.

Photograph by H, Ries.

21. PEGMATITE DIKES CUTTING GRANITE; DONALD QUARRY, NEAR RICHMOND, VA, 

Photograph by H. Ries. - .-..
GRANITES OP VIRGINIA. 87

has been shown above that there are three granites, including the 

granite gneiss, in this area, representing as many periods of intrusion. 

The order of these intrusions, beginning with the oldest, has been 

shown to be (1) granite gneiss, (2) light-gray granite, and (3) dark 

blue-gray granite. As shown in figures 3, 7, and 10, the granite of 

each intrusion was accompanied by the formation of pegmatitic material. Some of the pegmatites intersecting the dark blue-gray granite, 

the latest of the granite intrusions, also penetrate the light-gray 

granite and, locally, the earliest of the intrusions, granite gneiss. 

These conditions are well illustrated in figures 3 and 7, which 

show the latest formed pegmatites intersecting the dark bluegray granite, the light-gray granite, and the granite gneiss. 

Figure 3 shows a pegmatite 

associated with the earliest granite (granite gneiss), abruptly cut 

off by the intrusion of the later 

dark blue-gray granite into the 

granite gneiss. Those pegmatites which are characteristically 

associated with the dark bluegray granite intersect one another 

in such manner as to indicate earlier and later formation. Figure 

8, which shows this feature, also 

shows that the older or intersected pegmatite is faulted along 

the younger or intersecting pegmatite.

The pegmatites that intersect 

the granite gneiss may coincide 

with the schistosity, as in figure 

3, or may cut across the schistosity, as in figure 9. Figure 10, sketched from a portion of the Richmond Granite Quarrying Company's quarry, illustrates the irregularities of form and width of many of the pegmatites. Plate IX, B, 

shows pegmatite cutting the dark blue-gray granite in a quarry near 

Richmond.

Where observed the pegmatites are sharply defined from the 

inclosing rock; they show no banding parallel to the walls; their composition is essentially similar to that of the inclosing granite; and 

they are massive without evidence of pressure metamorphism.

FIGURE 10. Pegmatites showing irregularities of 

outline and width at Richmond Granite Quarrying Company's quarry, 4$ miles north of Richmond, Va.
88 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

This massive character has an important bearing on the question 

of the relative periods of formation of the pegmatites and the granite gneiss which they intersect. If the gneiss represents an original 

massive granite, which seems reasonably sure, it must follow that the 

massive pegmatites which characterize it were formed after the 

period of deformation which induced the banded or schistose structure in the gneiss. Again, this series of pegmatites must have formed 

prior to the periods of intrusion of the light-gray and the dark bluegray granites, as shown in figure 3.

Pegmatite dikes assume large dimensions in many of the Virginia 

Piedmont counties. The economic value of these bodies has been 

proved in Amelia, Bedford, Hanover, Henry, and Nelson counties. 

As indicated in the analyses below, the feldspar of the Virginia 

pegmatite dikes is, with one exception, potassic.

Analyses of feldspar from Virginia pegmatites.

Silica (SiOj). ........'...................................................

Potash ( K2 0) ..........................................................

1.

04.12

10.84

2.28

.32

.20

1.88

13. 34

99.04 

2.504

2.

05.37

18.74

.13

.27

2.49

12.98

99. 98 

2.501

3.

67. 00

21.72

.03

1.59

10.01

.38

100. 79 

2.618

4.

03.25

20.33

1.35

12.85

97.78

1. Potash feldspar from pegmatite dike near Amelia Court-house, Va.; C. C. Page, analyst.

2. Potash feldspar from pegmatite dike near Amelia Court-house, Va.; E. B. Sloan, analyst.

3. Albite feldspar from pegmatite dike near Amelia Court-house, Va.; R. Robertson, analyst.

4. Potash feldspar from pegmatite dike near Bells, Bedford County, Va.; Golding Sons Co., analyst.

INDIVIDUAL QUARRY AREAS.

PETERSBURG AREA. 

GENERAL STATEMENT.

The Petersburg granite area includes the extreme northeastern 

portion of Dinwiddie County and the contiguous southeast corner of 

Chesterfield County. The area is crossed by Appomattox River 

near Petersburg, and quarries are operated to the north and south of 

the stream. The principal quarries, shown on the map (PI. VII), 

include the Lassiter and Petersburg Granite Company's quarries, 

on the west side of Petersburg, and the Cook quarry, on the north 

side.

The granite of this area, as shown in the quarries, varies in texture 

from fine to medium, and in color from light to medium gray. It is a 

biotite granite and a little muscovite is'usually associated with the
GRANITES OF VIRGINIA. 89

biotite in variable amount. Thin sections of granite from the individual quarries show some variation in the ratio of the mineral constituents, more especially that of biotite to muscovite, and that of the 

different species of feldspar. In descending order the principal minerals are potash feldspar (orthoclase and variable niicrocline), 

soda-lime feldspar (oligoclase), quartz, biotite, and muscovite, with 

accessory magnetite, titanite, apatite, and zircon, and secondary 

chlorite, white mica, and epidote. An occasional grain of pyrite is 

observed in some of the sections, but in such minute quantity as to 

be entirely negligible as a deleterious constituent in the rock.

Plagioclase (soda-lime feldspar) may equal or in places exceed 

orthoclase (potash feldspar) in amount. Excess plagioclase over 

potash feldspar is indicated in some of the thin sections cut from 

specimens of granite from the Cook quarry. Microcline varies 

greatly in amount, but is usually subordinate to both orthoclase and

plagioclase. Intergrowths of the different feldspars with one another 

and of quartz with feldspar and twinning of the feldspars on the 

Carlsbad and albite laws are common microstructures to all the thin 

sections. Biotite, partly altered to chlorite, is subject to some 

variation, both in size of shred and in amount, the rock being, according °to the proportion of biotite, either lighter or darker in color. The 

granite from the Cook quarry contains less biotite than that from other 

quarries in the area, and is accordingly lighter in color. The effects 

of pressure metamorphism, shown principally in the peripheral granulation of the quartz and feldspar, occasional bent and fractured plagioclase, undulous extinction and fracturing of the quartz, and a 

tendency toward orientation of the minerals, especially mica, are 

rather strongly indicated in the thin sections of the granite from 

this area.

The stone from the quarries in the Petersburg area is of excellent quality and is used for monuments, general building, and 

street work. It is of homogeneous texture and good permanent 

color, and contains no harmful mineral. The joint planes are 

widely spaced, readily permitting the quarrying of dimension stone.

DESCRIPTIONS OF QUARRIES.

The Cook quarry is located about 2 miles north of Petersburg, immediately on the west side of the Seaboard Air Line Railway, within 

300 feet of the crossing of this road by the Belt Line. Some stone 

was quarried as early as 1837, but extensive quarrying was not 

begun until 1887. PL VIII, B, shows a view in the quarry.

The rock is a biotite granite of light-grayish color and mediumTine, even grain. It consists of potash feldspar (orthoclase and 

microcline) and soda-lime feldspar (oligoclase) in nearly equal amount
90 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

(the oligoclase exceeding the potash feldspars in one section), quartz, 

and black mica (biotite), associated with a sprinkle of white mica 

(muscovite), together with accessory magnetite and titanite, and secondary chlorite and epidote. Biotite is present in smaller amount 

than in the granite of other quarries in this area, and the color of 

the rock is correspondingly lighter. Pressure effects are manifest in 

peripheral mashing or granulation of the quartz and feldspars.

The sheets at this quarry average from 2 to 9 feet in thickness and 

are approximately horizontal. Pegmatites do not occur. Joints in 

a small exposure above the quarry strike N. 30° to 50° E. In the main 

quarry opening the joints strike N. 50° to 70° E. and N. 10° to 55° 

W., and vary in dip from vertical to as much as 65°. The sap does 

not exceed 4 to 6 inches in thickness. In places oxidation along 

joint surfaces extends to the depth of working.

The granite is admirably adapted to the uses made of it, winch 

comprise general building purposes; street work of all forms, including blocks, curbing, and crushed stone; and wall, bridge, and culvert 

work in the rough and dressed state. A crusher is operated at the 

quarry for working up the quarry waste, mainly for concrete work. 

The largest-size waste is made into paving blocks, the second into 

rubble paving, and the balance is crushed for concrete. The product 

is shipped as° far north as New York and as far west as Cincinnati, 

but practically no shipments are made south of Virginia.

The Lassiter quarries, comprising three or four openings made close 

together, are located about 1% miles west of Petersburg, immediately 

on the line of the Virginia Passenger and Power Company, within a 

quarter of a mile of the Seaboard Air Line Railway. Some stone is 

reported to have been quarried here more than fifty years ago. 

During the summer of 1906 two of the openings were being operated 

by separate parties.

The rock is a biotite granite of medium dark-gray color and medium 

fine grain. The feldspar has a decided pinkish cast. The minerals, 

in descending order of abundance, are feldspar (the potash varieties, 

orthoclase and microcline, and the soda-lime variety, oligoclase, the 

latter in amount but slightly less than orthoclase and microcline), 

quartz, black and white micas (biotite and muscovite), with accessory titanite, magnetite, apatite, and zircon and secondary chlorite 

and epidote. Crushing effects are strongly marked in peripheral 

granulation of the quartz and feldspar and in occasional bent and 

fractured plagioclase individuals. Thin sections of the sap (partly 

decayed granite) show a somewhat advanced stage of decay in the 

principal minerals, which are extensively discolored by yellow iron 

oxide liberated from the iron-bearing minerals.

Joints intersecting the granite in the Walsh opening strike N. 70° 

to 80° E., N. 15° to 30° W., and east-west, and dip 70° S. The joint
GRANITES OF VIRGINIA. 91

surfaces are slickensided from subsequent movement and are coated 

with a greenish altered mica. Joints measured in one of the other 

openings strike N. 70° E. and N. 20° to 70° W. and dip from vertical 

to about 80° ESE. Pegmatite dikes, from 1 inch to 5 or 6 inches wide, 

composed mostly of pinkish feldspar and less quartz, with little or no 

mica, intersect the granite. These are not so abundant as to interfere 

with quarrying. The joints are usually widely spaced, and blocks of 

granite 20 feet and more in length are frequently quarried. The 

depth of stripping necessary will average about 5 feet, being greater' 

in some places and less in others. The partly decayed granite (sap) 

is likewise variable in thickness and will probably average several 

inches.

The granite works well under the hammer and is susceptible of a 

high polish. It is extensively used in the monument and building 

trades, principally in

the former. The quarry «> __ J?urface 

waste is broken up and 

used for rubble. As 

monumental stock this 

granite is used in Virginia and adjoining 

States and as far west 

as Denver, Colo., and as 

far north as Pennsylvania and New Jersey.

The Petersburg Granite Company's quarries,

COmDrisinff two nrin- FIGUKE ll. Section at the Petersburg Granite Company's 

\ ° . \ quarry No. 2,2 miles west of Petersburg, Va. cipal openings about

three-quarters of a mile apart, are located about 2 miles west of 

Petersburg and about half a mile west of the Lassiter quarry, immediately along the line of the Petersburg Passenger and Power Company. The two openings are designated No. 1, known as the 

Asylum quarry, and No. 2, known as the Dibble quarry. About 

5 feet of stripping, comprising sand, gravel, and decayed granite, 

must be removed before the quarrying of fresh granite can begin 

(fig. 11). The openings are large and are made in fiat surface 

exposures of the granite.

The rock is a biotite granite of medium texture and medium-gray 

color. It consists, in order of abundance, of potash and soda-lime 

feldspars (orthoclase, variable microcline, and much oligoclase), quartz, 

black and white mica, (biotite and muscovite), with accessory magnetite, titanite, apatite, and zircon and secondary chlorite, epidote, 

and muscovite. Muscovite is closely associated with the biotite and 

is partly primary and partly secondary. Intergrowths of the feld-
92 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

spars with each other and of feldspar with quartz are numerous. 

Pressure effects are plainly marked in the thin sections, in the way 

common in. the granite of the other quarries in this area, as already 

described.

Pegmatites occur only here and there and are of slight dimensions. 

The best-developed joints and the only ones measured strike N. 10° 

to 25° W. and dip from 55° to vertical. A few very small segregations (knots) of black mica (biotite) were observed in the granite. 

True sheeting does not occur, and the stone appears in the quarry in 

nearly massive form. The joints are widely spaced, and dimension 

stone of almost any size is obtainable.

During the summer of 1906 quarry No. 1 was being operated under 

lease by a Baltimore firm (Guilford and Waltersville Granite Company), and the stone used almost exclusively for building purposes in 

Petersburg. Some of it is used for .coping in cemetery work. Quarry 

No. 2 has not been worked for six years or more. A large quantity 

of the granite has been quarried and used for various purposes.

The Petersburg Passenger Company's quarry, located at the dam 

across Appomattox River, 7 miles west of Petersburg, was opened 

and operated for local purposes during the summer of 1905.

RICHMOND AREA. 

GENERAL STATEMENT.

The Richmond granite area,, including parts of Chesterfield and 

Henrico counties, in the immediate vicinity. of the cities of Richmond 

and Manchester, is the largest producing area in the State. Figure 

12, a generalized section about 15 miles long through Richmond and

w

Richmond coal basin

Coal

FIGURE 12. Section from Richmond west to Midlothian, Va., and beyond.

Midlothian, shows the relations of the granite to the Coastal Plain 

formations on the east and to the Newark rocks of the Richmond coal 

basin on the west.

The quarrying of granite in this area began in the early part of the 

last century, and a large number of quarries have been opened and 

worked since that time. The quarries are opened chiefly in the granite bluffs along James River, extending in a general westerly direction
GRANITES OF VIRGINIA. 93

from the city of Richmond for a distance of more than 5 miles. 

Quarries have been opened to a smaller extent north and south of 

Richmond, in the low granite ledges exposed along the smaller streams 

and in flat-surface exposures on the interstream areas. Many of the 

quarries are very extensive and have been worked to a depth of 

nearly 200 feet. In some of these the depth reached in quarrying is 

below the river level. The quarries are well located with reference to 

transportation facilities and admit of easy working.

The location of this granite area, at the head of navigation on James 

River, affords water transportation either north or south.

KINDS OF GRANITE.

Mineralogically, the granites of the Richmond area are mica granites, but on a textural and color basis two kinds are distinguishable 

a medium-grained light-gray granite and a fine-grained dark blue-gray 

granite. This distinction is recognized commercially, and accordingly two grades of the stone are quarried, each differing in the principal use made of it. The coarser-textured light-gray granite, elsewhere described by the writer as the Richmond-Petersburg light-gray 

granite,0 is admirably suited for general building purposes. The 

finer-textured dark blue-gray granite, described as the RichmondFredericksburg dark-blue granite,6 is extensively used for monument 

stock. (See PI. IX, A.} Both are homogeneous even-granular granites possessing good working qualities.

The coarser light-gray granite is the older of the two and is penetrated in several of the quarries by dikelike masses of the finer dark 

blue-gray granite. Figures 4, 5, and 7 show the structural relations 

between the two granites as exposed in the Netherwood quarry 

west of Richmond.

STRUCTURAL FEATURES.

The structural relations of the two granites in the Richmond, area 

have been stated above. Both granites are intruded into an irregularly banded hornblende-bearing biotite gneiss of granitic composition.

Joint structure and pegmatite dikes are well developed in the 

granites of this area. Each of these structures is described in some 

detail on pages 84-88. The joint planes are usually spaced sufficiently far apart to permit the quarrying of stone of almost any size, 

and the pegmatites are rarely numerous enough to cause waste in 

quarrying.

oBull. Geol. Soc. America, vol. 17,1906, pp. 526-528. 

ft Idem, pp. 528-529.
94 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

MINERAL COMPOSITION.

The two types of granite distinguished above do not differ essentially in mineral composition, although they bear little or no resemblance to each other in the hand specimens. Both are biotite granites, locally containing a little muscovite. The coarser light-gray 

type consists of anhedra which range in size from 1 to 5 millimeters. 

Variation in the size of anhedra here given is a noticeable feature 

in the rock of this type in the quarries opened around Richmond and 

Petersburg. The dark blue-gray granite is more finely crystalline 

and its anhedra are more uniform in size, averaging less than 0.5 

millimeter.

The principal minerals in the two types are orthoclase, micfocline, 

plagioclase near oligoclase, quartz, biotite, a little muscovite, titanite, 

magnetite, apatite, and zircon. The usual alteration minerals occur, 

chief among which are chlorite, muscovite, and kaolin. Quartz and 

either of the feldspars present are frequently intergrown in granophyric structure. Microcline or plagioclase may either equal or 

exceed orthoclase in amount. These granites usually contain much 

plagioclase, which occurs in large, short laths and is characterized 

by the twinning striae in basal sections. Extinction angles measured against the twinning strise usually indicate a plagioclase near 

oligoclase. Twinning on the Carlsbad law is .common among the 

feldspars, both in thin sections and in hand specimens.

Biotite, the third essential constituent, is brown in color and 

strongly pleochroic. Its distribution in the fine-grained, dark bluegray granite is probably more uniform than in the light-gray rock, 

and in the latter it is subject to some variation, both in size of shred 

and in amount. In both types a little primary muscovite is as a rule 

intimately associated with the biotite, locally as parallel growths; 

and in places the two micas penetrate each other, always preserving 

sharp and clear-cut boundaries. Chlorite occurs as an alteration 

product of the biotite. Epidote is not abundant but appears in 

many of the sections as an alteration product from the interaction of 

the biotite and the feldspars; it is usually associated with the biotite.

The remaining minerals occur only in very subordinate amount 

and present no special interest.

.Pressure effects of the usual kind are pronounced in the thin sections of the light-gray granite, and are only slightly discernible in 

the thin sections of the dark blue-gray type. They are more marked 

in the granite from the Petersburg part of the area than in that from 

the Richmond area proper.

Some of the large blocks of the light-gray granite, quarried at the 

Netherwood quarry during the summer of 1905, showed a fairly well 

developed schistose structure. Ordinarily the rock belonging to this 

type from this quarry and from the Richmond area in general appears
U. S. GEOLOGICAL SURVEY BULLETIN *26 PLATE X

JOINTING IN NETHERWOOD QUARRY, NEAR RICHMOND, VA. 

A. In gray granite. B. In blue-gray granite, which intrudes the gray. Photographs by H. Ries.
GRANITES OF VIRGINIA. 95

massive. In the Petersburg area the pressure effects in the granite 

of the same type are most pronounced in the thin sections and a 

tendency toward parallel arrangement of the minerals is indicated 

in an incipient schistose structure.

DESCRIPTIONS OF QUARRIES.

The Richmond area includes about twenty-five quarries. Of this 

number less than ten were being operated during 1905 and 1906. 

These were the McCloy, McGowan, Mclntosh; Middendorf, Netherwood, Richmond Granite Company, Winston & Co., and Wray. 

Some of the others have not been worked for many years, and in 

part they include the most extensive openings in the area. This is 

particularly true of the Westham and the Old Dominion Granite 

Company's quarries.

CHESTERFIELD COUNTY (SOUTH OF JAMES RIVER).

The Netkerwood quarry is opened in the high granite bluff On the 

south side of James River about 2£ miles southwest of Richmond. 

It is one of the largest quarries in the Richmond area, and is reported 

to have been worked as early as 1845.

Two types or gracfes of granite, the structural relations of which 

are shown in figures 4, 5, and 7, are quarried, both of which are biotite 

granites. One is a medium-textured, light-gray rock; the other a 

fme-textured dark blue-gray rock. They are essentially similar in 

mineral composition. The principal minerals are feldspar (orthoclase, microcline, and plagioclase, in variable amounts), quartz, 

biotite, and a little muscovite. Chlorite, epidote, kaolin, and a 

light-colored mica are secondary minerals derived from the alteration of the biotite and feldspars. 'The feldspars all show intergrowths 

with quartz. Accessory titanite, apatite, and zircon occur. An 

occasional garnet was noted in all the sections, of the fine-textured, 

dark blue-gray granite. Pyrite is rare; it occurs sparingly along 

the joint surfaces and occasionally in the granite, but nowhere in a 

harmful amount.

The quarry has a working face of about 65 feet. Though located 

only a short distance from James River, its greatest depth is considerably above the stream level and the drainage is good. The 

stripping consists of about 2 feet of red clay.

The sheets are from 2 to 6 feet thick. Vertical joints strike 

N. 45° to 65° E. and N. 15° to 75° W. (See PL X, 4, B.) The surfaces 

of some of the joints show slickensides and are coated to some degree 

in places with pyrite, which shows the movement in the striated and 

flattened masses of the mineral. Coarse pegmatite dikes up to 12 

inches and more in width cut the granite irregularly. Dimension 

stone is readily obtained and little or no waste is occasioned by tho 

pegmatites.

38971° Bull. 426 10 7
96 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

The granite has an extensive market in and out of the State and is 

used for general constructional and monumental purposes, curbing, 

blocks for paving, and crushed stone in all uses made of it. Its principal use is for building and city street work, for which the light-gray 

type is mostly used. The dark blue-gray, fine-textured granite takes 

a fine polish and it is a desirable stone for monumental stock.

The Wray quarry, opened in the high granite bluffs on the south 

side of James River, is located about 3 miles southwest of Richmond 

and about half a mile west of the Netherwood quarry. It has been 

operated since 1895 for monumental stock exclusively.

The rock is a biotite granite of medium dark color and fine, even 

grain. Its minerals are potash feldspar (orthoclase and microcline), 

soda-lime feldspar (oligoclase), quartz, and biotite. The rock contains accessory apatite and titanite, and secondary chlorite and a 

light-colored mica. Intergrowths of the quartz with the feldspars 

and of the feldspars with one another are noted. Twinning structure 

in the feldspars is marked.

The joints strike east-west and north-south and are so spaced as to 

admit of dimension stone being quarried. (See PI. %I, A.} Slickensides are developed along the surfaces of the joints, indicating some 

movement along these directions. Several pegmatite veins or dikes 

up to 3 inches wide occur.

This granite is practically limited in sale to the principal cities in 

the State for monument stock.

The Donald quarry is located similarly to the Netherwood.and Wray 

quarries, on the south side of James River about 500 yards east of the 

Belt Line railroad bridge. It is a short distance west of the Wray 

quarry and farther up the river.

The rock is a biotite granite of fine, even grain and in large part of 

dark blue-gray color. A zone 6? feet wide of very light gray granite,

containing little or no biotite, -of the same fine, even-grained texture 

as the dark blue-gray rock is exposed near the west half of the quarry. 

The contacts made by the two granites are entirely sharp and distinct. The minerals of the dark blue-gray granite are potash and 

soda-lime feldspars (orthoclase, microcline, and oligoclase in variable 

proportion), quartz, ancl biotite, with rarely a scale of muscovite. 

The feldspars are twinned and are intergrown partly with one another 

and partly with quartz. Accessory apatite and titanite occur and 

some secondary chlorite and light-colored mica are developed in 

some of the thin sections. The zone of light-gray granite differs from 

the dark blue-gray only in the amount of biotite present.

The granite is traversed by joints which strike north-south, eastwest, N. 50° to 60° E., and N. 55° W. Slickensides developed along 

many of the joint surfaces indicate some subsequent .movement along
U. S. GEOLOGICAL SURVEY

A. WRAY QUARRY, WEST OF RICHMOND, VA. 

Showing joint systems. Photograph by H. Ries.

It. McGOWAN QUARRY, SOUTH OF MANCHESTER, VA. 

Showing sheeting. Photograph by H. Ries.
GBANITES OF VIRGINIA. 97

these directions in the granite. Pegmatite dikes, ranging in thickness 

up to 12 inches and more, are somewhat numerous in.parts of the 

quarry and traverse the granite in nearly all directions (PL IX, B}. 

In several places intersecting of the dikes has resulted in slight displacement (faulting) of the intersected by the intersecting dike, as 

shown in figure 8.

The quarry has not been worked for several years.

The McGranigan quarry is about three-eighths of a mile east, of 

Granite, a station on the Southern Railway, and about one-eighth of 

a mile west of the Belt Line railroad bridge. The quarry comprises 

the stripping of an irregular sloping granite surface to a maximum 

depth of 20 feet, extending back from the water's edge of James River.

The rock is a biotite granite of medium-gray color and medium, 

even grain. Its minerals are potash feldspar (orthoclase and microdine), soda-lime feldspar (oligoclase), quartz, and biotite, with accessory apatite and zircon. The feldspars are partly altered to a little 

kaolin and a light-colored mica. Chlorite and epidote are noted to 

some extent as secondary minerals.

Joints strike N. 25° E. and N. 65° W. Several pegmatite dikes of 

small dimensions intersect the granite. There are a few knots of 

small size. This quarry has not been worked for some years.

The Granite Development Company's quarries comprise a number of 

small openings several hundred yards west of the McGranigan quarry 

and about one-fourth, mile east of Granite station. The rock is a 

biotite granite of the same color, and texture as that of the McGranigan quarry. Its mineral composition is the same, with perhaps sodalime feldspar in larger amount. The principal vertical joints strike 

north-south and N. 65° E.

The Hawlcins quarry, reported to have been one of the first quarries 

opened in the Richmond area, is located between James River and 

the Southern Railway, a few paces east of Granite station. The rock 

is a biotite granite of medium, even grain resembling that of the 

Granite Development Company's quarries. Quarrying was confined 

to the stripping of a gently sloping granite surface to only a shallow 

depth. It is said that much of the stone was used in the form of riprap 

for river work about Williamsburg, Portsmouth, Norfolk, and. other 

towns in eastern Virginia. This quarry has been idle for many years.

The Old Dominion Granite (Middendorf) quarries comprise two 

large openings very close together, located several hundred yards 

south of west from Granite station. The openings are .extensive, 

affording every evidence that large quantities of stone have been 

quarried from them, but they have not been worked for some years, 

and at the time of examination in 1906 they were nearly filled with, 

water.
98 GEANITES OF SOUTHEASTERN" ATLANTIC STATES.

The rock is a biotite granite of medium-gray shade and medium, 

even grain. Vertical joints strike N. 60° E. and N. 5° W. Pegmatite dikes traverse the granite in places, but they are not numerous 

enough to cause waste in quarrying. Small, irregular knots are 

developed to a minor degree.

The Krimm quarry is located several hundred yards southwest of 

the Old Dominion Granite (Middendorf) quarries. The quarry has 

not been worked for some years, and it was nearly filled with water at 

the time of examination in 1906. A mantle of light-gray decayed 

granite and soil, 8 to 12 feet thick, must be stripped before the fresh 

granite is reached.

The rock is a biotite granite of similar color and texture to that 

of the Old Dominion Granite (Middendorf) quarries. Its minerals 

are potash feldspar (orthoclase and microcline), soda-lime feldspar 

(oligoclase), quartz, and biotite, with scattered muscovite shreds, 

and secondary chlorite, epidote, and light-colored mica.

The joints strike N. 55° to 65° E. and N. 15° W., the latter set being 

somewhat more closely spaced than the former. Very few pegmatite dikes were noted.

The Mclntosh quarry, formerly known as "flat rock," has been 

operated for about twenty years and is one of the most extensive 

working quarries in the State. It is located about three-eighths of 

a mile southwest of Granite, a station on the Southern Railway 5 

miles west of Richmond.

Two types of granite are represented. The principal and dominant 

type is a biotite granite of medium-gray color and medium-coarse 

grain. Its minerals are potash feldspar (orthoclase and microcline), 

soda-lime feldspar (oligoclase), quartz, and biotite, together with 

accessory apatite, zircon, and ilmenite and secondary chlorite, epidote, 

and colorless mica. An occasional grain of pyrite occurs. Orthoclase is intergrown with plagioclase as microperthite. Intergrowths 

of feldspar and quartz as micropegmatite, feldspar twinning on the 

Carlsbad law, and micropoikilitic structure in some of the larger 

feldspar individuals are common. The second type of granite is a 

biotite granite of dark blue-gray color and fine-grained texture. In 

mineral composition it conforms entirely with the dominant, mediumgray granite just described.

The quarry opening measures about 250 feet long by 125 feet 

wide and 45 feet deep. Stripping, where necessary, varies up to 8 

feet in thickness.

The sheets are curved and range from a few inches to 5 feet in 

thickness. There is some "toeing in," owing to the overlapping of 

lenses. Vertical joints strike N. 85° E., N. 10° W., N. 60° to 65° W., 

and north-south, and are spaced at intervals of a fraction of an inch 

up to 6 feet and more. Many of the joint faces are slickensided and
A. McGOWAN QUARRY, SOUTH OF MANCHESTER, VA. 

Photograph by H. Ries.

B. GNEISS INCLUSION IN GRANITE AT McGOWAN QUARRY, NEAR MANCHESTER, VA. 

Photograph by H. Ries.
GRANITES OF VIRGINIA. 99

are coated with a reddish mineral substance. At the south end of 

the quarry the granite shows pronounced schistose structure and 

close jointing.

The product is used principally for street purposes in the form of 

curbing and blocks, for general building purposes, and for crushed 

stone, mainly in concreting. It has had a moderate use in monuments.

The Wesfham quarries, comprising a large number of openings 

along the south side of James River in Chesterfield County, are about 

4 miles a little north of west from the city hall in Richmond. The 

openings are made in the escarpment extending for a distance of 

about a mile along the river front. Several more recent openings 

have been worked a short distance from the river to the south and 

southwest of the old quarries.

The rock is a biotite granite of medium-gray color and medium, 

inclining to coarse, even grain. The. minerals are potash feldspar 

(orthoclase, with variable but usually much microcline), soda-lime 

feldspar (oligoclase) in considerable quantity, quartz, and black 

mica (biotite), with a few intergrown shreds of white mica (muscovite) and accessory titanite, magnetite, zircon, and apatite. The 

feldspar shows some alteration to kaolin and a colorless mica, and 

the biotite is partly altered to chlorite. Epidote occurs as an alteration product. The feldspars show some intergrowths with quartz, 

are twinned on the Carlsbad and albite laws, and contain rounded 

inclosures of quartz and feldspar.

These are among the largest if not the largest quarries in the Richmond area and supplied the stone from which the State, War, and 

Navy building in Washington, D. C., was constructed. The largest 

openings average about 800 by 200 feet by 180 feet deep. The 

depth of the quarries is considerably below the river level. Quarrying was suspended about 1897. When active, 500 to 800 men were 

employed and the granite was marketed extensively outside of the 

State.

In the larger openings the vertical joints strike N. 60° to 65° E. 

and N. 15° to 60° W. The size of stone quarried was limited to the 

capacity for handling the stone. Dark-gray knots are noted to a 

slight extent in places.

The McGowan quarry is located in Chesterfield County about 2 

miles south of Manchester and about 300 yards east of the Petersburg 

turnpike. (See PI. XII, A.) It has been worked continuously for 

about thirteen years and the stone is used exclusively for monumental 

stock! The quarry waste is worked into blocks for paving.

The rock is a biotite granite of dark blue-gray color and fine, even 

grain. Its minerals are potash feldspar (orthoclase with some 

microcline), soda-lime feldspar (oligoclase), quartz, black mica
100 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

(biotite), a few shreds of white mica (muscovite), together with 

accessory apatite, zircon, and titanite. Filaments of rutile are 

abundant in the quartz. Secondary minerals are chlorite, epidote, 

and a colorless mica. The feldspars are intergrown with each other 

and with quartz, and they are twinned on both the Carlsbad and the 

albite laws.

The sheets, from 4 to 6 feet thick, are thinnest at the top. (See 

PL XI, B.) Vertical joints are not so conspicuously developed and 

are spaced at wide intervals, striking N. 80° E. and N. 30° W. Pegmatite dikes, ranging in thickness up to 5 feet, cut the granite indiscriminately. The principal feldspar in these dikes is orthoclase, 

containing rounded inclosures of other feldspars and quartz. Black 

mica (biotite) is sparingly present. A single aplite-pegmatite 

dike was noted, the relations of which are shown in figure 6. A 

thin section of the aplite showed predominant plagioclase (oligoclase), the potash feldspars (orthoclase and microcline), and quartz, 

with an occasional reddish garnet. Some large blocks, measuring 

several feet across, of a banded granite gneiss were inclosed in the 

granite (fig. 3; PL XII, B}. A thin section of the gneiss revealed 

orthoclase and plagioclase (oligoclase) in about equal amount, quartz, 

biotite, and hornblende, with accessory apatite and titanite and 

secondary chlorite.

An average depth of about 5 feet of stripping of soil and granite 

decay is necessary. The granite takes a fine polish, and it has an 

extensive sale as monumental stock in many States.

The Middendorf quarry is located west of Manchester, on the Belt 

Line Railway, about 760 feet north of the Petersburg turnpike. 

Several acres of ground has been stripped to a depth of about 25 

feet.

The rock is a banded biotite granite gneiss of gray color and

medium to coarse, even grain. Its minerals comprise about equal 

amounts of potash feldspar (orthoclase) and soda-lime feldspar 

(oligoclase), quartz, and biotite, with some microcline, occasional 

muscovite, and the usual accessories.

The joints strike N. 65° E. and N. 45° W. and have slickensided 

surfaces indicating subsequent movement in the granite mass. Pegmatite dikes up to several feet thick are numerous; in direction they 

may coincide with or cut across (fig. 9) the banding of the gneiss and 

in dip may vary from nearly vertical to nearly horizontal. .The 

average strike of the gneiss banding (schistosity) is N. 65° E.

The product is used locally for ballast and paving blocks, largely 

the former.

The Tidewater Quarry Company's quarry is located 2 miles southeast 

of Manchester, immediately on the west side of James River and 

about 500 yards from the Seaboard Air Line Railway. The quarry
GRANITES OF VIRGINIA. 101

was opened prior to the civil war and was last worked in 1905. The 

stone was shipped by water, being loaded by derricks directly from 

the quarry into the boats.

The rock is a biotite granite of medium-gray color and mediumfine, even grain. The minerals are potash feldspar (orthoclase and 

microcline in about equal amounts), soda-lime feldspar (oligoclase), 

quartz, biotite, and scattered muscovite scales, together with accessory apatite, zircon, and rutile and secondary chlorite and epidote. 

The feldspars are considerably altered. The orthoclase is intergrown, in part, with a plagioclase.

The principal direction of vertical jointing is N. 10° W. Several 

zones of very close jointing occur, but in other parts, of the quarry 

the joints are spaced at intervals sufficiently wide to permit the 

quarrying of dimension stone. Pegmatite dikes of varying thicknesses traverse the granite.

Stripping of 5 to 12 feet is necessary. The quarry has been 

worked to a depth of 30 to 40 feet. During its last period of working 

the stone was shipped to Norfolk, Hampton, Old Point, and Newport 

News, in the form of crushed rock for roads and for use in foundations 

and granolithic work. A No. 7£ Gates crusher was operated at the 

quarry for crushing and sizing the stone.

The Old Dominion Granite Company's quarry, formerly known as 

the State quarry and now owned by Mr. Middendorf, is located about 

300 yards N. 30° E. of Granite station and about 100 yards north of 

the Southern Railway. The quarry comprises two large openings 

within 100 paces of each other and a smaller one lower down on 

James River. The largest opening is 600 by 225 feet by 100 feet 

deep. The larger openings were worked for some time by the State, 

hence the name State quarry. Neither of the openings has been 

worked for some years.

The rock is a biotite granite of medium-gray color and of mediumcoarse, even grain. The minerals are potash feldspar (orthoclase 

with much microcline), soda-lime feldspar (oligoclase), quartz, and 

biotite, with a little muscovite, accessory apatite, zircon, magnetite, 

and titanite, and secondary chlorite, kaolin, and epidote. The 

feldspars are partly clouded from alteration. Much microperthite is 

present.

Several thin sections of the altered granite (sap) were examined. 

The principal changes were opacity of the feldspars from kaolinization; the liberation of much yellow hydrated ferric oxide as a stain 

from the iron-bearing minerals, biotite and iron ores; and more or 

less spacing along the cleavages of the feldspars and the sutures of 

the individual minerals, the first stage in crumbling or granulation.

The granite in the large openings is parted horizontally into sheets 

of varying thickness near the top, which pass below into massive
102 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

granite. Vertical joints strike N. 55° E. and north-south. Pegmatite dikes up to several inches in thickness and a few small knots 

occur.

A large mass of banded gneiss was observed on the lower side of 

the large opening. Whether this is an inclusion in the granite or an 

exposure of the country rock (gneiss) in contact with the granite it 

was impossible to determine, because of failure to reach it for examination. A stripping of 3 to 8 feet of decayed granite and soil is 

necessary.

Old Dominion Iron and Nail Works quarry, comprising two openings near together which were opened in April, 1902, is located on 

Belle Island between the cities of Richmond and Manchester.

Two types of granite are represented. The principal one is a 

biotite granite of medium light-gray color and irregular mediumcoarse grain. The second is a biotite granite of dark blue-gray color 

and fine grain. The principal minerals in both types are potash and 

soda-lime feldspars, quartz, and biotite.

The larger opening is 480 feet long by 100 feet wide and 65 feet 

deep. The depth of stripping at the center is 15 feet, with a 50-foot 

face of granite below. The second opening, made in dark blue-gray 

granite, is a small one and was not being worked at the time of the 

writer's visit in October, 1908.

In the large opening vertical joints are widely spaced, and their 

faces are slickensided. Very few pegmatite dikes occur, and most are 

of small width. Basic segregations (knots) up to 6 and 8 feet in 

length are present. The coarse-textured light-gray granite is irregularly banded in places, a feature especially noticeable near the contact with the fine-grained dark blue-gray granite which penetrates 

it along the contact in well-defined dikes or apophyses, and is accordingly the younger. A uniformly fine-grained light reddish-gray 

aplite dike, 2 inches thick and having a nearly horizontal position, 

is observed in an apophysis of the dark-gray granite near the contact 

with the coarse gray granite.

Vertical joints in the fine-textured dark blue-gray granite of the 

small opening strike N. 50° to 60° E. and N. 30° W., and are spaced at 

intervals varying from less than 1 foot up to 6 feet. Pegmatite dikes 

occur, ranging from 1 to 8 inches in thickness, usually averaging 1 to 2 

inches. The feldspar of the small dikes is white; that of the 8-inch 

dike is of a pronounced red color. Biotite is the mica associated 

with the feldspar and quartz in these dikes. Knots were not observed 

in the granite of this opening.

The product is used almost entirely in the form of crushed stone 

for concrete and ballast. A little of it has been used for road making 

and for paving blocks. Two crushers, a No. 6 Gates and a No. 4 

McCulloch, are operated at the quarry. The stone is quarried by 

blasting.
GRANITES OF VIRGINIA. 103 

HENRICO COUNTY (NORTH OF JAMES RIVER).

The Richmond Granite Quarrying Company's quarry is located 4£ 

miles north of Richmond and about 250 yards east of the Richmond, 

Fredericksburg and Potomac Railroad. A spur track is operated 

between the quarry and the main line of the railway. l]he quarry, 

opened about eighteen years ago in a bowldery exposure of the granite, 

measures 500 by 100 feet by 50 feet deep.

The rock is a biotite granite of medium-gray color, and medium, 

even grain, consisting of potash feldspar (orthoclase and microcline 

in approximately equal amount), soda-lime feldspar (oligoclase) 

quartz, and black mica (biotite), together with accessory apatite, 

zircon, and titanite, and secondary chlorite and kaolin. Plagioclase 

nearly equals in amount the potash feldspars. A thin section of the 

decayed granite (sap) shows the feldspars partly altered to kaolin and 

much stained from the liberation of yellow hydrous iron oxide derived

from the alteration of the iron-bearing minerals. Much of the biotite 

is altered to chlorite.

The granite is not sheeted, but is massive for the entire depth of 

the quarry. Vertical joints strike N. 30° to 35° E., N. 10° to 70° W., 

and east-west. The dip varies from vertical to 35° SE. The joints 

are spaced from 2 to 8 feet or more apart. The joint surfaces usually 

display well-developed slickensides. Pegmatite dikes up, to 8 inches 

in thickness and of irregular outline (fig. 10) traverse the granite, 

but are not very numerous.

A second opening, about 400 yards east of the main quarry, in a 

similar exposure of the granite, was begun late in the summer of 1905.

The stone is shipped to various points in Virginia, Maryland, and 

Pennsylvania, and to Washington, D. C. It is used for building and 

monuments and for street work in the form of blocks and curbing. 

The waste is crushed and sized at the quarry for crushed stone.

The Smitli quarry, opened in the bluff facing James River, is located 

at the 5-mile locks west of Richmond, within a few feet of the canal. 

It was worked many years ago and was last operated in 1903 for riprap 

used in the river.

The rock is a biotite granite of gray color and medium-coarse, even 

grain. The minerals are potash feldspar (orthoclase with much 

microcline), soda-lime feldspar (oligoclase), quartz, and black mica 

(biotite), with accessory apatite, iron ore, and zircon and secondary 

chlorite, epidote, kaolin, and a colorless mica. Intergrowths of 

quartz with feldspar and of the feldspars with each other (microperthite) are abundant. The feldspars contain rounded inclosures of 

quartz and other feldspars.

The quarry has a working face of 40 to 50 feet. The sheets vary 

from 4 to 10 feet in thickness. Vertical joints strike N. 30° E. and 

N. 5° to 30° W. Slickensides are developed along the joint-plane
104 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

surfaces. In parts of the quarry decay extends to the entire depth 

of the opening. The product shows little or no evidence of oxidation, 

but is mostly a light-gray granitic sand formed chiefly by physical 

decay granulation.

Winston & Co.'s quarry, formerly known as the Mitchell & Copelaud quarry, is located at the settling basin, about three-quarters of a 

mile east of the Smith quarry. Mitchell & Copeland first opened the 

quarry many years ago and operated it for a period of twelve years. 

Winston & Co. began working the quarry about 1900 to supply 

crushed stone and riprap for the construction of the settling basin. 

The quarry is opened in the bluff facing James River on the north side, 

and measures 200 by 200 feet by 75 to 100 feet deep.

The rock is a biotite granite of light to medium gray color and 

medium-coarse even grain. The minerals are potash feldspar 

(orthoclase with much microcline), soda-lime feldspar (oligoclase), 

quartz and black mica (biotite), together with accessory apatite, 

titanite, magnetite, zircon, and muscovite. Secondary chlorite and 

epidote occur, the latter sparingly.

The granite is separated into horizontal sheets, which are thick and 

massive at the bottom of the quarry and thinner near the top. Vertical joints strike N. 30° to 70° E., N. 5° W., and eastwest. Pegmatite dikes up to several feet in thickness intersect the granite, but are 

not numerous.

The stone obtained for building the settling basin was quarried by 

blasting with powder and dynamite. It was conveyed by tram cars 

and overhead cranes from the quarry to the crusher near by.

The Philadelphia quarries, comprising three large openings close 

together, are located at the extreme east end of the-settling basin, less

than a mile south of east 

from Winston & Co.'s 

quarry, about 100 yards 

north of James River, on 

the north side of the ChesFIGUKE 13. Section at Philadelphia quarries, near Richmond, Qrip ol nnrl OViin 

Va., showing relations between the blue and gray granites. apeaKe d,I!U VJ111O

way. The quarries were

last worked about seventeen years ago, and at the time of the writer's examination the openings were so nearly filled with water that 

not much information could be obtained from a study of them.

Two grades of granite were quarried one of medium-gray color and 

medium-coarse grain, the other of dark blue-gray color and fine 

grain. The relations of these two granites are shown in figure 13. 

The fine-grained dark-gray granite is intruded into the coarser, 

lighter-gray granite. Mineralogically the two granites are essentially alike; they are biotite granites.
OF VIRGINIA. 105

The fine, even-textured granite contains potash feldspar (orthoclase 

and microcline in nearly equal amount), soda-lime feldspar (oligoclase), quartz, and black mica (biotite), with accessory apatite, magnetite, and occasional scales of muscovite. The medium-gray and 

medium, even-textured granite contains potash feldspar (orthoclase 

with much microcline), variable soda-Jime feldspar (oligoclase), 

quartz, and black mica (biotite), with accessory apatite, zircon, and 

magnetite. The secondary minerals are chlorite, kaolin, and a lightcolored mica. The feldspars exhibit the usual twinning and are 

intergrown with one another and with quartz.

The openings are reported to have been worked to a depth of 90 

feet. Vertical joints strike N. 20° to 70° E. and N. 20° to 45° W. 

Slickensides are developed along the joint surfaces and the jointing is 

sufficiently spaced to allow the quarrying of dimension stone. The 

granite is intersected by pegmatite dikes, but these are not numerous.

The city hall in Richmond was built in part from the granite of 

these quarries. Much of the product was shipped to Washington, 

D. C., and to Philadelphia for use as a building and street stone.

The McCloy quarry, opened in a flat-doming surface exposure of 

granite, is located about 300 yards from the James River branch of 

the Richmond, Fredericksburg and Potomac Railroad, and about a 

quarter of a mile west of the new reservoir. The quarry opening 

covers nearly an acre of ground, .worked to an average depth of less 

than 18 feet.

The rock is a biotite granite of medium dark-gray color and fine, 

even grain. Its minerals are potash feldspar (orthoclase with much 

microcline), soda-lime feldspar (oligoclase), quartz, and black mica 

(biotite) intergrown with occasional shreds of white mica (muscovite), together with accessory apatite, zircon, and magnetite. Secondary chlorite and a light mica occur. The orthoclase is intergrown in part with a plagioclase.

The granite is massive and is not sheeted horizontally. The vertical joints strike N. 10° to 75° E. and N. 5° to 85° W. and clip from 

vertical to 55° NW. A minor set of joints strikes north-south. Slickensides are developed along the joint planes. Very few pegmatite 

dikes were observed, and these measured less than an inch in thickness.

The granite is decayed in places to a depth of 3 or 4 feet, and this 

material must be removed before the fresh stone can be obtained. 

The principal uses made of the product are for monuments and building and for street work as blocks and curbing. The quarry waste 

is crushed and utilized for street concrete or cement work. The 

product is marketed in a number of States. The quarry has been 

worked for about eight years.
106 GBANITES OP SOUTHEASTERN ATLANTIC STATES. 

FREDERICKSBURG AREA. 

INTRODUCTORY STATEMENT.

The" Fredericksburg area includes the region west and north of the 

city of Fredericksburg in Spottsylvania and Stafford counties. The 

granite exposed along Rappahannock River northwest of Fredericksburg extends across the river for some distance into Stafford County, 

but no quarries have yet been opened in that county.

Two types of granite have been quarried in the Fredericksburg 

area one a very light gray, medium-textured muscovite granite, 

the other a dark blue-gray, very fine textured biotite granite. The 

latter is identical in texture and composition with the fine-grained 

dark blue-gray granite quarried .in the Richmond area and extensively used for monument stock. The granite in the Fredericksburg 

area is a shade darker in color than the granite in the Richmond area; 

it is an excellent monumental stone and has wide use for that purpose. 

The dark blue-gray granite of the Richmond and Fredericksburg 

areas has been described elsewhere."

DESCRIPTIONS OF QUARRIES.

Hazel Run quarry. A light-gray muscovite granite of medium 

texture is exposed along Hazel Run, a tributary of Rappahannock 

River, about a mile west of Fredericksburg. It resembles somewhat 

the light-gray muscovite granite of Stone Mountain, 16 miles east of 

Atlanta, Ga., which has been and is used so extensively for general 

building purposes. In the spring of 1879 an opening was made in 

the exposure immediately on the south side of Hazel Run, about a 

mile west of Fredericksburg, and enough stone was quarried to build 

the Presbyterian Memorial Chapel in Fredericksburg. None of the 

Stone has been quarried since. The joint planes are widely spaced; 

the best-developed ones strike N. 75° W. and north-south.

Thin sections of the granite show potash feldspars (orthoclase and 

microcline), soda-lime feldspar (oligoclase), quartz, the white and 

black micas (muscovite and biotite), apatite, rutile, and zircon. 

The principal secondary minerals are chlorite and muscovite, the 

former derived from the alteration of the biotite. Muscovite is 

partly primary and partly secondary. Biotite is very subordinate 

in amount. Microcline and plagioclase are abundant. Intergrowths 

of the feldspars and of the feldspars with quartz are numerous. 

Partial orientation of the mica along parallel directions, an occasional bent and broken muscovite shred, fractured quartz with 

wavy extinction, and the perfect granulation of the quartz-feldspar 

individuals are pressure effects plainly marked in the thin sections.

a Watson, T. L., Lithological characters of the Virginia granites: Bull. Geol. Soc. America, vol. 17, 

1906,p. 528.
GRANITES OF VIRGINIA. 107

On close examination a thinly foliated structure is discernible in 

hand specimens of the rock and an occasional red garnet may be 

seen.

Cartwright & Davis quarries. About 3 miles northwest of Fredericksburg the granite is exposed along the Rappahannock in steep 

bluffs and low bowlder ledges, which offer good quarry sites. On 

the Spottsylvania County (south) side of the river the Cartwright & 

Davis quarries are opened in the granite bluffs immediately along 

the river. Numerous openings have been worked, extending along 

the river front for half a mile or more.

The rock is a biotite granite of dark blue-gray color and finegrained texture. In color it is a shade darker than the rock of the 

same type in the Richmond area. It consists of potash feldspar

FIGURE 14. Sketch in Cartwright & Davis quarry, near Fredericksburg, Va , showing relation of

granite to gneiss.

(orthoclase and some microcline), soda-lime feldspar (oligoclase), 

quartz, black mica (biotite), and accessory muscovite, apatite, rutile, 

and zircon. The feldspar is partly intergrown with quartz in granophyric structure, indicating overlapping of the periods of formation 

of the' two minerals. Orthoclase and plagioclase are present in 

nearly equal amounts, but microcline is very scant. The quartz 

contains abundant threadlike inclusions of rutile, and the biotite is 

largely altered to chlorite.

The granite is intruded into an irregular hornblende-biotite gneiss 

(fig. 14) The general strike of the schistosity of the gneiss is N. 25°. 

to 40° E. The granite is cut by several sets of joints so spaced as to 

admit of the stone being quarried in blocks of any size. The strike
108 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

of the principal joint planes in the quarry openings is north-south, 

dipping 40° E.; N. 60°'to 80° E., dipping 10° to 30°; and N. 20° to 

80° W. Pegmatites are abundantly developed in places and occasion considerable waste in quarrying.

The granite is quarried exclusively for the monument trade. The 

monuments have an extensive market both in and out of the State. 

The granite takes a fine polish, the durability of which is favored by 

the uniformly small size of the biotite scales. No dimension stone 

is sold in the rough, but it is all worked up at the yards near the 

northern limits of Fredericksburg, where the equipment is ample 

for all grades of polished and dressed work. The stone is conveyed 

from the quarries to the yards by canal. A crusher is operated at 

the yards for sizing the waste, which is utilized for local purposes.

FAIRFAX COUNTY AREA. 

INTRODUCTORY STATEMENT.

A complex of igneous rocks, largely altered, comprising chiefly 

granite, granite gneiss, gabbro, and diorite, mapped by Williams and 

Keith as Archean,0 extends southwestward from Maryland and the 

District of Columbia across the Potomac into Fairfax County, Va., 

passing immediately west of Washington. This rock complex has 

been extensively altered by metamorphism.and much of the original 

massive material has been rendered schistose. Massive granites and 

basic igneous rocks occur within the area, but they are subordinate 

in extent to their schistose equivalents. Because of the structure, 

rocks of the schistose class are less desirable for commercial purposes 

than the massive types. Granite gneiss is the most abundant rock 

type and many portions of it furnish good material for foundations and 

similar rough work. It is easy to quarry and is strong and durable. 

In many places it contains pyrite, unfitting it for ornamental use. 

Rock is also quarried from the less schistose portions of the granite 

masses at a number of places in the county. It is homogeneous, of 

even texture and good color and works out readily into stones of 

moderate size. Some portions of the rock in the Falls Church 

area are colored by pink feldspar.

. DESCRIPTIONS OF QUARRIES.

Granite has been quarried in Fairfax County to a small extent in 

the vicinity of Falls Church and Annandale, strictly for local use.

PALLS CHURCH AND VICINITY.

The granites in the vicinity of Falls Church are of two varieties. 

One is a medium to fine grained rock and contains dominant biotite,

a Washington folio (No. 70), Geol. Atlas U. S., U. S. Geol. Survey, 1901.
GRANITES OF VIRGINIA. 109

with some muscovite as a third essential component. The ratio of 

muscovite to biotite is variable, but muscovite occurs in considerable 

amount at a few places. The microscope shows that the granite of 

this type contains principally orthoclase and quartz, some niicrocline, 

and a small but variable amount of soda-lime feldspar (oligoclase), 

with biotite and muscovite and the usual accessory minerals. The 

biotite is largely altered to chlorite and the muscovite is, in part, at 

least, secondary. An occasional garnet is noted in some of the thin 

sections. Pressure effects of the usual kinds are plainly seen oil 

microscopic examination.

The second variety of granite occurring near Falls Church, a light 

and dark colored rock, is more coarsely crystalline than that just 

described and is a hofnblende-biotite granite. It is somewhat 

closely allied to quartz diorite and is closely associated in the field 

.with diorite masses on the one hand and with foliated mica granite 

011 the other. It more properly belongs with the granocliorites, differing from the diorites proper in increased quartz and potash feldspar.

Thin sections show quartz, plagioclase, orthoclase, green and brown 

hornblende, biotite, apatite, rutile, and the secondary minerals epidote, sericite, garnet, chlorite, and kaolin. Hornblende is one of 

the most abundant constitutents, and in places it completely incloses 

shreds of the biotite. Microcline does not occur. Plagioclase feldspar is probably a little more abundant than orthoclase. Pressure 

effects are indicated in the optical disturbance of the quartz and 

 feldspar; in fractures crossing the quartz; in curved and bent lamellae 

of a part of the plagioclase; and in the marked distortion of the 

cleavage angle of the hornblende.

The Trip quarry, located about a mile south of Falls Church, has 

supplied considerable stone for local use, principally for foundations 

and buildings. The rock is a massive granite of medium grain and 

variable light-gray color, depending on the amount and distribution 

of the mica present. Several sets of joints are developed which 

usually cut the granite at close intervals and limit the size of stone 

that can be quarried. The directions of these joints are N. 10° to 80°E. 

and N. 10° to 80° W. The Presbyterian and Catholic churches at 

Falls Church were constructed of the granite in the rough from this 

quarry.

ANNANDALE AND VICINITY.

The granite quarried several miles west of Annandale is a mediumgray, medium-grained, massive biotite granite, intermediate in color 

and texture between the Richmond light-gray and dark blue-gray 

types described on pages 74-76. It is similar in mineral composition to the Richmond types. Orthoclase is the dominant feldspar. 

Considerable microcline is present, but plagioclase is less abundant 

than elsewhere. A sprinkle of idiomorphic sections of garnet is noted.
110 GEANITES OF SOUTHEASTERN ATLANTIC STATES.

Crushing effects are discernible under the microscope in the partial 

granulation of the quartz and feldspar, with the fine mosaic filling the 

interspaces of the unrnashed portions of the two minerals.

The Iloffman & Miller quarry, located about 2 miles west of Annandale, is opened at about water level directly on the west side of 

Accotink Creek. The opening was made in a bowlder ledge exposure. 

Stripping of 8 to 10 feet of soil and red clay is necessary for the 

quarrying of fresh granite. The strike of the joint planes is northsouth and N. 50° to 80° W.; they are spaced widely enough to permit the quarrying of dimension stone.

BLUE RIDGE REGION. 

GENERAL DISCUSSION OF THE GRANITES.

In the northern Blue Ridge of Virginia granite has wide distribution, extending from Maryland across the Potomac southward for 

some distance southeast of Front Royal. As a rule, the granite areas 

are distributed in long, narrow belts, which vary in width up to 6 miles. 

The outcrops of granite increase in number and extent southward 

from-the Potomac in Virginia.

According to Keith,a the mineralogical composition of the granite 

is fairly constant over large areas. Six varieties are distinguished, 

each having a considerable areal extent. The essential minerals 

given by Keith are quartz, orthoclase, and plagioclase feldspar. By 

the addition to these of biotite, garnet, epidote, blue quartz, and 

hornblende, five types are formed. Texturally the granite ranges 

from coarse to very fine grained. Keith gives the following microscopic description of the different types: 6

Epidote granite, 3 miles west of Aldie, Va., is composed of fine-grained quartz, 

plagioclase, orthoclase, and biotite both unaltered and altered to chlorite. Accessory

minerals are magnetite, a little eipdote, and some doubtful allanite. Another specimen from the same locality shows a coarse holocrystalline mass of quartz, orthoclase, a 

little plagioclase, and epidote. The epidote is both granular and'crystalline and is 

associated with quartz (rarely feldspar) in groups of crystals. A third specimen from 

the same locality shows epidote in bunches of crystals and as inclusions in the feldspar.

Garnetiferous granite from the Potomac River 1 mile east of Harpers Ferry shows 

quartz, orthoclase, plagioclase, garnet, epidote, and apatite; all except the last two 

are in large crystals. Dynamic action has caused considerable alteration of feldspar to 

quartz, muscovite, and chlorite, and cracks in the quartz, which are cemented with 

chlorite. A specimen from the granite 4 miles southwest of Hillsboro, Va., contains 

quartz, plagioclase, orthoclase, pink garnet, magnetite, and a little chloritized biotite.

Granite from 1 mile northwest of Browntown, Va., shows quartz, orthoclase, plagioclase, hornblende, a little biotite, magnetite, and, along the feldspar cleavage, chlorite. 

Another specimen from the same locality shows the same minerals in larger crystals. 

A third specimen contains a large amount of garnet in rude crystals and fragments, a 

little apatite and pyrite, and but very little orthoclase.

a Fourteenth Ann. Rept. U. S. Geol. Survey, pt. 2, 1894, p. 299; Harpers Ferry folio (No. 10), Geol. 

Atlas U. S., U. S. Geol. Survey, 1894. 

& Fourteenth Ann. Rept. U. S. Geol. Survey, pt. 2,1894, p. 300.
GRANITES OF VIRGINIA. Ill

The biotite variety is far the most common. The biotite is always small in amount 

and often absent, so that the rock has a prevailing light-gray color. Its minerals are 

quartz, orthoclase, plagioclase, biotite, magnetite, and usually a little secondary 

muscovite and chlorite from feldspar decomposition.

The varieties of granite characterized by blue quartz do not differ under the microscope from other varieties containing biotite. As a macroscopic constituent, however, 

the blue quartz is very striking, and the brilliancy of its color renders it noticeable 

wherever seen. It occurs both'as original crystals disseminated through the mass 

and as veins and patches.

The granite of the Blue Ridge region is usually light gray in color 

and has been extensively altered by pressure. According to the 

degree of alteration the rock is granite, gneiss, or quartz schist. No 

quarries have been opened in the granite, but where bowlders could 

be obtained without much labor they have been worked up and the 

granite used locally.

UNAKITE.

The name unakite was applied by Bradley* in 1874 to a variety 

of granite from the Unaka Mountains in North Carolina, composed 

of the essential minerals yellow-green epidote, pink feldspar, and 

quartz. Unakite has since been noted at two localities in Virginia 

(1) at Milams Gap, near Luray, in Page and Madison counties,6 , in 

the Blue Ridge of northern Virginia, and (2) about 2£ miles south of 

Troutdale, Grayson County,0 in the Blue Ridge region of southwestern Virginia.

The mineral composition of the unakite from the Virginia and 

North Carolina-Tennessee localities places it among the granites, 

with epidote as an essential constituent, but, according to an analysis 

by Phalen, quoted below, of specimens from Milams Gap, Virginia, 

the rock is relatively basic for a granite.

In the Milams Gap locality the unakite is a moderately coarse but 

irregular crystallization of red feldspar, quartz, and green epidote. 

Irregular crystallization of the rock is shown in the variation from 

masses composed of more than two-thirds of the red feldspar through 

all gradations to masses composed of quartz and epidote without 

feldspar epidosite.d Thin sections of the unakite from Milams Gap 

show epidote, orthoclase, quartz, iron oxide, zircon, and apatite. The 

epidote is here secondary, as in the other localities, replacing pyroxene 

and feldspar, both plagioclase. and orthoclase. The unakite from 

Grayson County, Va., shows deeper-colored feldspar and epidote 

than that from Milams Gap. Analyses of the unakite and the unakite-bearing rock at Milams Gap are given on page 78.

a Bradley, F. H., Am. Jour. Sci:, 3d ser., vol. 7,1874, pp. 319, 320.

6 Merrill, G. P., Stones for building and decoration, 1903, p. 80. Phalen, W. C., Sniithsonian Misc. Coll., 

vol. 45,1904, pp. 306-316.

c Watson, T. L., Am. Jour. Sci., 4th ser., vol. 22, 1906, p. 248. 

d Phalen, W. C., op. cit., p. 312.

38971° Bull. 426 10 8
112 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

The strikingly beautiful combination of colors produced by the 

peculiar green of the epidote and the pink or rose red of the feldspar 

makes the rock especially desirable for use, when polished, in certain 

forms of interior ornamental work. Should the rock be found to 

exist in quantity, the quarrying of it would certainly prove profitable.

AREA IN NOTTOWAY AND PRINCE EDWARD COUNTIES.

In the northwest corner of Nottoway County and in the adjacent 

portion of Prince Edward County is a promising area of massive gray 

granite of fine-grained texture and uniform color, which has been 

opened and quarried for local use at a single point in each county. 

The granite is exposed at the surface in flat-doming masses and as 

bowlders. This'area lies close to the Southern and the Norfolk and 

Western railways, which afl'ord ready transportation facilities.

The Wingo quarry, in Nottoway County, located between Jennings 

and Jetersville on the east side of the Southern Railway, was operated on a small.scale some years ago for ballast. The rock is a finegrained, massive, medium-gray biotite granite of uniform color and 

texture.

In the vicinity of Rice Depot, Prince Edward County, granite was 

quarried some years ago for use in bridge construction along the 

Norfolk and Western Railway.

CHARLOTTE COUNTY.

The State Test Farm quarry is located on the state farm on the 

southeast side of the Richmond and Danville division of the Southern 

Railway, near Saxe station. A very small amount of stone has been 

quarried here from a bowlder-ledge exposure strictly for local use.

The granite is a hornblende-biotite granite of pronounced red color

and medium grain. It has a marked schistose structure imparted by 

the orientation of hornblende and biotite. Very small miarolitic 

cavities occur in the granite. The feldspar is entirely of red color, to 

which is due the pronounced red color of the rock. Hornblende is 

considerably altered in places, partly to chlorite and epidote and 

partly to iron oxide.

The stone quarried from this outcrop was used in the construction 

of bridges over some of the small streams in the neighborhood.

FLUVANNA AND GOOCHLAND COUNTIES.

The Cowherd quarries are located on the north side of James River, 

along the James River division of the Chesapeake and Ohio Railway, partly in Goochland County and partly in Fluvanna County, at 

Columbia.
GRANITES OF VIRGINIA. 113

Quartz vein 

\

Granite gneiss

V'|'l/v'<-./'

The rock is a biotite granite gneiss of medium dark-gray color, fine 

grain, and fine, regular, straight banding. Its principal minerals are 

feldspar (potash and soda-lime varieties), quartz, and biotite.

A steep slope paralleling the river and the railroad for a distance of 

1,500 feet has been worked by irregular stripping. No work has been 

done on the Fluvanna County side for more than twenty-five years. 

On the Goochland County side quarrying operations were suspended 

about 1900.

The strike of the schistosity (gneissic banding) is N. 45° E. The 

vertical joints are widely spaced, striking N. 10° E., N. 35° W., and 

N. 55° W. Quartz veins of irregular bulbous shape, varying from a 

fraction of an inch up to 

2 feet in thickness, are 

nu merou s. These a r e 

seamed with knife-edge

layers of biotite altered 

to chlorite occupying 

central and contact positions, which both cut 

across and conform with 

the schistosity of the inclosing granite gneiss. 

That these veins were 

formed prior to the period of deformation inducing schistosity in the 

inclosing rock is shown in the fracturing of many of the quartz 

masses in directions coincident with that of the schistosity, as indicated in figure 15. A few knots up to 6 or 8 feet long occur.

LUNENBUllG COUNTY.

The Kenbridge quarry, located on the north side of the Virginian 

Railway, near Kenbridge, in Lunenburg County, was opened about 

five years ago to supply crushed stone for railroad ballast. The 

writer has not visited the quarry, but specimens of the rock show it 

to be a biotite granite gneiss of medium color and texture.

PKINCE WILLIAM COUNTY.

Several granite quarries are opened close together immediately on 

the northwest side of Occoquan Creek, opposite Occoquan village, in 

Prince William County (PL VII). The rock is a thinly foliated biotite granite of medium gray color and texture. It is used principally 

in the form of crushed stone for concrete, and locally for building. 

The rock is crushed and sized at the quarry and shipped to Washington, D. C., for use in concrete,

FIGURE 15. Quartz vein in Cowherd quarries, Columbia, Va., 

showing jointing coincident with schistosity of inclosing gneiss.
114 GRANITES OF SOUTHEASTERN ATLANTIC STATES. 

OTHER GRANITE AREAS.

In addition to the areas described above, many other counties of the 

Virginia crystalline region contain granite that is suitable for general 

building and other purposes, but in none of these has it been developed. 

So far as these undeveloped areas have been examined, the granite 

conforms to one or the other of the types of the developed areas. 

They are prevailingly mica granites, containing biotite either with or 

without muscovite, fine to medium in texture, and usually some 

shade of gray in color.
CHAPTER IV.

THE GRANITES OF NORTH CAROLINA. 

DISTRIBUTION OF THE GRANITE.

Granites are distributed over about one-half the total area of North 

Carolina, but -the productive part of this area is considerably less. 

Openings from which some granite has been quarried have been made 

in most of the counties in which granite occurs, but only a few quarries 

are being systematically worked at present.

Geographically, granites are distributed over parts of each of the 

three larger physiographic provinces of the State the Coastal. Plain, 

the Piedmont Plateau, and the Appalachian Mountains. The areas 

are fewer and smaller in the Coastal Plain region, and more numerous 

and larger in the Piedmont Plateau region, where granite forms one of 

the dominant rock types.

For convenience of description the granites and gneisses may be 

divided into the following belts, the location of which is indicated on 

the accompanying map (PI. XIII):

I. The Coastal Plain region.

II. The Piedmont Plateau region.

(1) The northeastern Carolina granite belt.

(2) The Carolina metamorphic slate and volcanic belt.

(3) The Carolina igneous or main granite belt.

(4) The Western Piedmont gneiss and granite belt. 

III. The Appalachian mountain region.

This division of the State into belts is essentially the same as that 

adopted by the State Geological Survey, and the map is the one compiled from the records of the State Survey to accompany Nitze and 

Hanna's report on the gold deposits of North Carolina.

SCIENTIFIC DISCUSSION.

KINDS OP GRANITE.

On the basis of texture and structure three types of granite are 

distinguished (1) the massive even-granular (normal) granites; (2) 

the porphyritic granites; and (3) the banded or schistose granites 

(granite gneiss). Field and laboratory study develops close similarity 

of mineral composition in the three types. The even-granular and 

porphyritic textures represent different phases of the same rock mass.

115
116 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

The granite gneisses differ essentially from the massive granites in 

having a pronounced schistose structure, induced by pressure metamorphism.

On the basis of mineral composition, the granites of North Carolina, 

are divisible into four principal types (1) biotite granite, which may 

or may not contain a little muscovite (usually scant muscovite is 

present), to which most of the granites of the State belong, including 

those of the Mount Airy, Dunns Mountain, and Greystone areas; 

(2) hornblende-biotite granite, represented by a part of the granites 

in the northern and southern parts of Mecklenburg County; (3) muscovite granite, with or without biotite, represented by a small area 

near Warren Plains, in Warren County; and (4) the epidote granite 

(unakite) of Madison County, N. C., and Cocke County, Term.

MINERAL COMPOSITION.

The granites of North Carolina conform in mineral composition to 

those of the other States in the southern Appalachian region. There 

are mixtures of feldspars and quartz, with biotite as the third essential 

mineral in the most important areas. Muscovite in association with 

biotite is present in small amount in many of the biotite granites of 

the State, and it is an important component in the area near Warren 

Plains, in Warren County. Hornblende is an important constituent 

in a part of the granites near and east of Daviclson, and 5 miles south 

of Charlotte, in Mecklenburg County. It is sparingly noted in the 

biotite granite near Elm City (Toisnot), in the extreme northern part 

of Wilson County. It does not occur in the commercially more 

important granites of the State. Epidote is a principal constituent of 

the granite known as unakite, in Madison County. The epidote is 

entirely secondary.

The feldspathic constituent includes orthoclase, microcline, and 

acidic plagioclase, either oligoclase or albite or both. In. most places 

the soda-lime feldspar exceeds in amount the potash feldspars, but in 

others it may be equal or less. As a rule, the North Carolina granites 

are relatively rich in plagioclase. Microcline is variable in quantity 

and in places is entirely lacking.

The common accessory minerals include apatite, zircon, titanite, 

magnetite, ilmenite, and here and there other minerals in very 

sparing amounts.

CHEMICAL COMPOSITION.

Very few chemical analyses of North Carolina granites have been 

made. Those available are from widely separated areas, and, though 

not so complete with respect to all the constituents as the presentday analyses, they serve to indicate two important points the 

acidity and the character and ratio of the feldspathic constituents.
U. S. GEOLOGICAL SURVEY

BULLETIN 426 PLATE XIII

A/ xS^^H'. E>^ 

Jefferson.

/ HALIFAX

HendersonviB

O L, V I

LEGEND

Granite quarries

(numbers refer to list)

Granite, diorite, and other

rocks, largely igneous

Gneiss, granite, and other rocks

of both sedimentary and igneous

Metamorphic slates and schists

including volcanic rocks

Fall line

.ion Co.

East of fall line: Coastal Plain formations 

(sands, clays, marls). West of fall line: 

Triassic sandstones and shales; metamorphic quartzites, schists, limestones, etc., 

of unknown age

QUARRIES

1 Elm City (Toisnot)

2 Contentnea Creek

3 City (Raleigh)

4 Penitentiary

5 Seaboard Air Line Railway

6 Old Greystone

7 New Greystone

8 Greystone Granite and Construct!

9 Middleburg

10 Paschal 

M Walker

12 City (Greensboro)

13 Gamble

14 Modlin

15 Maston

16 Charles

17 Concord 

,8 Sink

19 Hartman &. Hodge

20 Duncan'&. Floyd

21 McCauless (Dunns Mountain Granite Co.)

22 Rowan Granite Co.

23 Balfour Quarry Co.

24 Consolidated Granite Co.

25 Phillips Mountain

26 Powlers Mountain

27 Reid (City)

28 Balfour Quarry Co.

29 City (Charlotte)

30 Gastonia

31 Jenkins

32 North Carolina Granite Co.

33 DuBose

34 Owenby

35 Montford

36 County (Buncomoe)

37 City (Asheville )

38 Balfour Quarry Co.

39 Name not known.

40 McNeely

41 Breed

42 Biddell

GEOLOGIC MAP OF NORTH CAROLINA SHOWING DISTRIBUTION OF GRANITE QUARRIES. 

Based on maps of North Carolina Geological Survey, Bulletin 2, 1906.
GEANITES OF NOETH QABOLINA. 117 

Partial analyses of North Carolina granites.

Constituents.

Silica (Si02 ). .. . ........................................................

Lime (CaO). ...........................................................

Soda (Na2 0) ...........................................................

Potash (KjO) ..........................................................

1.

75.14

.93

5.82

2.57

2.

70.70

2.96

4.50

2.45

3.

69.28

2.20

2.76

4.

66.01

1.44

5 nfi

3.16

1. Pink granite from Pink Granite Company's quarry, Dunns Mountain, Rowan County: First Bienn. 

Rept. North Carolina Geol. Survey, 1893> p. 89.

2. Light-gray granite from Mount Airy quarry, Surrey County: Ide'm, p. 94.

3. Gray granite from City quarry, Raleigh, Wake County: Geology of North Carolina, vol. 1,1875, p. 122.

4. Gray granite from Johnson quarry, near Mooresville, Iredell County: First Bienn. Rept. North Carolina Geol. Survey, 1893, p. 87.

STRUCTURAL FEATURES.

JOINTS.

With possibly one or two exceptions, the North Carolina granites 

are characterized by a strong development of vertical joints, which 

break the rocks into polygonal blocks of different sizes. The most 

noteworthy exception is the extensive granite area near Mount Airy, 

Surrey County, in which vertical jointing is not visible. Measurements of the vertical joints were made in all the openings and quarries of granite in the State, and the results show four sets the major 

joints, whose planes lie in the northeast and northwest quadrants, 

and two minor sets, whose planes strike east-west and north-south. 

The major joints vary in strike from N. 10° E. or W. to N. 80° E. or 

W. Of the total number of vertical joints measured 56 lie in the 

northeast quadrant, 45 in the northwest quadrant, 19 have a northsouth strike,~and 16 east-west.

The surfaces of the vertical joints usually show smooth, somewhat 

polished and striated faces, which indicate some movement in the 

granite masses since the formation of the joints. Striae are developed 

in a thin coating or skin of yellow to yellowish-green mineral, which 

probably is damourite in most places, but locally, epidote, or a mixture 

of the two derived frojn certain original minerals of the granite, and 

caused probably by the rubbing together of the two sides along the 

plane.

BASIC SEGREGATIONS (KNOTS).

The distribution of knots in the granite is subject to much variation. From some quarries they are entirely absent, in others they 

occur only here and there, and in others still they are so abundant 

as to disfigure the granite and preclude its use in certain higher 

grades of work. The knots vary in size from a fraction of an inch 

to more than a foot across. They are of irregular outline, varying 

from those that are roughly oval or round to those that are greatly 

elongated.
118 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

DIKES.

Genetically, the intersecting materials are of two kinds true 

dikes and true veins. These are strongly contrasted in some places, 

and everywhere they show differences to some degree in both texture 

and composition.

BASIC IGNEOUS DIKES.

Dikes of basic igneous rocks, chiefly diabase or its altered form, 

penetrate the granites of most of the important areas in the State. 

Thinly schistose dikes of amphibolite, composed largely of hornblende with accessory feldspar and quartz, are common in some of 

the quarries.

The widest dikes exposed in the granite openings do not exceed 

50 feet and many are less than 6 feet. Where a number of dikes are 

exposed the intervals between them vary greatly. Within a zone of 

12 to 15 feet two or more dikes may occur, always parallel and coincident with the vertical joints in that direction. More commonly, 

however, the intervals at which the dikes intersect the granite are 

considerably greater. The dip of the dikes is vertical or departs only 

a few degrees from the vertical, a feature likewise characteristic of 

the joints. . The following table makes clear the relationship between the 

strike of the dikes and that of the vertical joints:

Strikes of dikes and vertical joints in granites of North Carolina.

Locality.

Jamestown, £ mile southeast of ...............

Lilesville, J mile north of .....................

County.

Guilford.........

.....do............

Wake..:..........

Strike of 

dikes.

N. 40° E..

N on0 !?

N.40°W..

N. 15-20°

W.

N.20°E...

N.20°W..

Strike of joints.

N dft° v \r 3^_t;n o w

20° W.'' . '' 

N. 40° W.. N. 20° E.

N. 20° W., N. 70° E.

N. 20° W., N. 70° E.,

north-south.

GRANITE DIKES.

True granite dikes of normal composition and usually of fine 

grain are numerous in certain areas, but only one or two have been 

observed penetrating the granite masses. In the main granite belt 

of the Piedmont region dikes of this character, penetrating the surrounding rocks, are common, and are regarded as apophyses from the 

granite masses. As a rule, they are irregular in outline and fine 

grained, and are composed of quartz and light to pink feldspar, with 

mica subordinate, if present at all. They range from a few inches to 

several feet in thickness.
U. S. GEOLOGICAL SURVEY

A. PEGMATITE VEIN WITH QUARTZ CENTER. 

Harris clay mine, northeast pit, 2^ miles north of Bryson, N, C.

13. WHITESIDE MOUNTAIN, A GRANITE DOME, JACKSON COUNTY, N. C.
GRANITES OP NORTH CAROLINA. 119

The principal localities where the granite dikes have been noted are 

northeast of Concord, in Cabarrus County, for several miles along the 

Concord-China Grove road; near Concord and to the east along the 

Mount Pleasant road; along the east and west roads leading out of 

Salisbury, a short distance from the town; 5 miles west of Barber 

Junction, near Elm wood, Iredell County; in the cuts of the Southern 

Railway near Lexington, Davidson County; and in the railroad cuts 

north and south of High Point, Guilford County.

PEGMATITES.

Pegmatite dikes intersect the granite in most of the quarries in the 

State. They are so abundant in parts of some quarries that dimension stone is difficult to obtain. This is especially true of the granite 

in the Raleigh City quarries, where hardly a block of granite can be 

quarried that is entirely free from the quartz-feldspar dikes, a feature 

strikingly shown in the state capitol in Raleigh, built of this stone. 

In some quarries pegmatites are but sparingly developed, and in others 

they are entirely absent.

Where observed they are characterized by the usual coarse texture, 

and are composed principally of feldspar and quartz with subordinate 

stout platy black biotite (PI. XIV, A). The feldspars are partly 

pink and partly white in color, are highly lustrous, with a good 

cleavage development, and are commonly twinned on the Carlsbad 

law.0 Feldspar is the most abundant constituent, the quartz locally 

diminishing to a very subordinate amount. Biotite is usually present 

in large, stout platy forms, in some places irregularly distributed 

between the feldspar and quartz, in others distributed along a central 

axis in the vein or dike. Muscovite has been observed in the pegmatite bodies only occasionally, and tourmaline, garnet, and the rarer 

minerals associated with some pegmatite dikes are strikingly absent.

Some of the pegmatites are very extensive, though usually narrow, 

apparently deep seated, and of aqueo-igneous origin. Others are of 

minor extent and are surrounded entirely by the granite, being probably true veins of segregation. In the Raleigh City quarry, where 

the only true aplite dikes have been observed, the aplite and pegmatite are associated as banded aplite-pegmatite. As a class the pegmatites are irregular in outline, conforming to no definite or fixed 

direction, but cutting the granite at random and at all angles..

In the Raleigh City quarry, the Carrigan quarry, 3 miles northeast 

of Mooresville, Iredell County, and the Walker quarry, 1$ miles 

southeast of Ridge Summit station, Guilford County, many of the 

pegmatites intersect one another, producing a faulted condition of 

several inches displacement.

o See analyses of feldspars, p. 170.
120 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

APLITES.

Aplite dikes have been observed at only one locality in the State, 

the City quarry at Raleigh, where they number less than half a dozen 

in all. They do not exceed 6 inches in width, and most of them are 

not more than 2 inches. Some of them are in contact with pegmatite 

on one side and the inclosing granite on the other. Megascopically, 

the aplite is very light in color, being composed of a fine-grained 

crystallization of quartz and feldspar, through which are irregularly 

distributed subordinate minute flecks of black biotite.

Microscopically, the aplite is strikingly similar in mineral composition to the inclosing granite, except that it is much finer grained 

and contains a much smaller proportion of biotite and plagioclase 

feldspar. The mineral composition places it with the potash aplites.

QUARTZ VEINS.

Quartz veins of small dimensions cut the granite in a number of 

quarries, usually where pegmatite intrusions are strongly developed. 

The two sets of intersecting bodies are more or less closely associated. 

The quartz veins are not numerous in any of the openings, and as a 

rule they do not measure more than a few inches across.

Quartz veins of large dimensions are numerous over the crystalline 

area of the State. Many of them are readily traced over the surface 

for considerable distances by the partly disintegrated outcrops and 

the abundant fragments which litter the surface. In cross section 

they vary from 25 feet to several hundred yards. In some localities 

the veins form true fissure veins, are metalliferous, and mark many of 

the most important gold and copper mines in North Carolina

RELATIONSHIP BETWEEN THE JOINTING AND THE BASIC DIKES.

Careful measurement and tabulation of the vertical joints and the 

dikes of basic igneous rocks show a marked parallelism in certain 

directions between the joints and dikes. The planes of most of the 

joints and the strikes of most of the dikes are in the northeast and 

northwest quadrants. Moreover, in nearly every quarry where basic, 

dikes are exposed the strike of the dikes and that of the joints for a 

given direction is coincident, apparently indicating that in those 

places, at least, the jointing has exercised some influence on the cutting direction of the dikes. Not only is this true for the dikes penetrating the granite in the quarries, but it is also true of the- Triassic 

sandstone belt, where the same relation between the joints and the 

dikes is shown. Whether this statement will apply in general to the 

dikes beyond the limits of the fresh-rock exposures it is not possible 

to say, as the jointing is entirely obscured by the deep residual decay 

covering the fresh rock, but presumably it does.
GRANITES OF NORTH CAROLINA. 121

Probably the basic dikes, so far as they have been observed, do not 

belong to a single period of intrusion but are to be referred to different 

ages. The observations recorded denoting coincidence in the directions of dike and joint include both the massive, unaltered, igneous 

intrusive rock and the perfectly schistose, more or less altered, basic 

dike. If these observations are correct, clearly the jointing in the 

granites preceded the intrusion of the basic rocks forming the dikes.

INDIVIDUAL QUARRY AREAS.

E VE N-GB ANTJL AB GBANITE S. 

DISTRIBUTION.

Granites of even-granular type have wide distribution and compose 

the bulk of the granites occurring in North Carolina. They range 

from massive to partly schistose rocks, are fine to medium in texture,

rarely coarse, and are pink to gray in color, the prevailing color being 

light to medium and dark gray.

Mineralogically, the even-granular granites are mixtures of potash 

feldspar (orthoclase chiefly, with variable microcline), palgioclase 

(oligoclase or albite), and quartz, with a variable quantity of biotite 

and, in several areas, some additional hornblende as the characterizing accessories. The prevailing large amount of plagioclase feldspar 

in the rocks is a noteworthy feature; rarely does this constituent sink 

to very subordinate proportions; usually it .is approximately equal 

to or even exceeds the potash feldspars. In many areas the poverty 

of the rocks in the ferromagnesian constituent is a striking feature, a 

fact well illustrated in the extensive and important granite area 

known as Dunns Mountain, in Rowan County.

The even-granular granites are described below under (1) Coastal 

Plain granites; (2) Piedmont Plateau granites; and (3) Appalachian 

Mountain granites.

COASTAL PLAIN GRANITES. 

GENERAL STATEMENT.

In places near the boundary between the Coastal Plain with the 

Piedmont Plateau, but extending well, within the Coastal Plain, the 

thin veneer of loose unconsolidated sands and gravels has been 

stripped from the surface, exposing small, irregular, somewhat elongated areas of the crystalline rocks. Many of these areas are composed either wholly or in part of granites of good quality. This stripping of the Coastal Plain sediments from the crystalline rocks has 

taken place mostly along the courses of the larger streams. In such 

areas the granitic rocks are usually exposed in ledge and bowlder form 

and as flat-surfaced masses, a short distance back from the stream.
122 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

Some of the schists and gneisses composing parts of the inliers of 

crystalline rocks are derived from original igneous masses. They 

include both acidic and basic types.

The principal areas of even-granular granite, lie in Wilson, Edgecomb, and Nash counties to the east of Raleigh. In each of these 

counties small openings have been made in the granites and some of 

the rock has been quarried for local use. None of the openings, 

however, are sufficiently large to be called quarries, and no systematic 

work has yet been undertaken, though the granite is'of good quality, 

is readily accessible, and can be easily worked.

The rocks are massive biotite granites, in one place hornblende 

bearing, varying from fine to coarse grained in texture and from gray 

to pink in color. Jointing is usually well developed, intersecting the 

rock in three general directions northwest, northeast, and northsouth. The granites are younger than the schists and gneisses into 

which they have been intruded, as shown by the nature of the contacts, in the partial decay of the rocks, and by their massive structure 

as contrasted with the completely schistose structure of the surrounding rocks.

The granites of the North Carolina Coastal Plain region occur in 

three principal areas (1) the Contentnea Creek area; (2) the Elm 

City area; and (3) the Rocky Mount and Springhope area.

DESCRIPTIONS OF QUARRY AREAS.

CONTENTNEA CREEK AREA.

About 3 miles south of Wilson granite is exposed in large bowlders 

and flat-surfaced masses for several miles along and near Contentnea 

Creek. A small opening was made some years ago near the creek 

where it is crossed by the Wilmington and Weldon Railroad.

The rock is a biotite granite of pinkish-red color and coarse grain, 

with a marked porphyritic tendency. Feldspar is largely in excess 

of the other minerals. The larger feldspar individuals are 1 to .2 

inches long and are pinkish in color, exhibiting good cleavage development and twinning on the Carlsbad law. The f eld spathic constituent 

has been estimated to amount to 82 per cent, proportioned as follows: 

Orthoclase, including a little microcline, 50 per cent; plagioclase 

(albite), 32 per cent. Quartz is the next most abundant mineral. 

Biotite is only sparingly present and is largely altered to chlorite. 

Accessory apatite and magnetite and secondary kaolin, calcite, and 

a light-colored mica are present.

The vertical joints strike N. 50° E., N. 70° W., and north-south. 

No veins nor segregations were observed. The granite takes a good 

polish.
GRANITES OF NORTH CAROLINA. 123

ELM CITY (TOISNOT) AREA.

The Elm City area is located in the extreme northern part of Wilson 

County, 3 miles north of Elm City. The granite.is exposed in the 

form of bowlder outcrops, and one opening has been worked to an 

average depth of about 30 feet. The decayed granite, which requires 

stripping for the quarrying of fresh rock, averages 6 to 8 feet in depth.

The rock is a biotite granite of light-gray color and medium-coarse 

grain. The minerals are potash feldspars (orthoclase and a little 

microcline), much soda-lime feldspar (very acidic oligoclase), quartz, 

and biotite with occasional hornblende, together with accessory zircon, 

apatite, a little titanite, and ilmenite and secondary chlorite, kaolin, 

and light-colored mica.

The vertical joints, rather closely spaced, strike N. 40° E. and 

N. 80° W. and have slickensided surfaces. A dike of very fine 

grained amphibolite schist carrying much pyrite penetrates the granite, 

striking approximately northwest and southeast and ranging from 

4 to 20 feet in thickness. Quartz veins trending north and south 

also cut the granite. Two of these veins, observed on the west side 

of the quarry, are about 12 inches wide and are wrapped with films 

of hornblende.

The poor working qualities of the granite, coupled with the close 

jointing and the numerous veins, render the stone imsuited for general constructional purposes.

ROCKY MOUNT AND SPR1NGHOEE AREA.

About- a mile north of Rocky Mount, in Edgecombe County, bowlder outcrops and small fiat-surfaced exposures of granite can be 

traced along Tar River for some distance westward into Nash County. 

The granite is associated with crystalline schists which were derived 

in part from original igneous rocks. Contacts between the granite 

and the schists were not observed, but the field evidence clearly suggests that the granite is the younger rock.

At the cotton mill on Tar River, 1 mile north of Rocky Mount, 

several small openings were made in the granite some years ago. The 

rock is a biotite granite of gray color and medium grain. Its minerals 

are potash feldspars (orthoclase and microcline in about equal amount), 

soda-lime feldspar (oligoclase), quartz, and black mica (biotite), with 

accessory apatite, zircon, and magnetite and secondary chlorite and 

epidote.

The vertical joints strike northeast-southwest, N. 30° W., N. 80° 

W., and north-south. The joints cut the granite at intervals which 

vary from only a few inches in some places to many feet in others. 

Pegmatite dikes, ranging in thickness -from a fraction of an inch to 

more than 6 inches, intersect the granite. All gradations exist between 

veins containing mostly feldspar to those containing mostly quartz.
124 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

PIEDMONT PLATEAU GRANITES. 

GENERAL STATEMENT.

. The North Carolina Piedmont region is composed of a number of 

belts, approximately parallel to one another and crossing the State 

in a general northeast-southwest direction (PI. XIII), composed as a 

rule of unlike rocks of different ages.

The granites and gneisses of commercial importance in North Carolina are most widely distributed within the Piedmont Plateau region, 

where they occur in considerable variety and abundance. They are 

biotite bearing, with additional hornblende in several areas, and muscovite in very subordinate amount if present at all. Some shade of 

gray prevails, though pink is largely characteristic of certain areas.

In most places the granite is of good quality and readily accessible, 

and as a rule it can be easily worked. Numerous quarries have been 

opened over many parts of the plateau region, to which the granite 

industry of the State is confined almost exclusively.

The Piedmont Plateau granites are described below under four 

geologic divisions (1) the northeastern Carolina granite belt, comprising the counties of Wake, Franklin, Vance, Granville, and Warren; (2) the metamorphic slate and schist and volcanic belt; (3) the 

central granite belt, including Mecklenburg, Gaston, Cabarrus, Iredell, Rowan, Davie, Davidson, Forsyth, Guilford, and Alamance 

counties; and (4) the western gneiss belt, comprising the counties of 

Surry, Wilkes, Alleghany, Alexander, and Cleveland.

NORTHEASTERN CAROLINA GRANITE BELT. 

INTRODUCTORY STATEMENT.

The position and limits of the northeastern Carolina belt are shown

on the map (PL XIII). It comprises parts or the whole of five counties, located in the extreme northeastern portion of the North Carolina Piedmont region, extending northward from Raleigh. With but 

few exceptions the granites show a partial schistose structure. Biotite, the chief accessory mineral, is variable in quantity, imparting 

accordingly either a light or a dark gray color to the rock. In places 

the feldspars are of a pronounced pinkish hue and with the subordinate amount of biotite present the rock assumes more or less of a 

mixed pinkish-gray color. The granites are prevailingly even granular, though a porphyritic tendency is somewhat emphasized in places 

They do not differ essentially in mineral composition, although hand 

specimens of the granite from different portions of the area may show 

no resemblance to each other.
GEANITES OF NOETH CAROLINA. 125 

FRANKLIN COUNTY.

Granite exposures are numerous over the middle and eastern portions of Franklin County, especially in the vicinity of Louisburg, the 

county seat. Usually the rock is'deeply decayed, though fairly fresh 

granite is exposed in large bowlder outcrops and small irregular surfaced masses. Porphyritic granite occurs at one or two places. Quarries have not been opened at any locality in the county, but several 

small openings have been made along Tar River at Louisburg for 

stone to supply a local demand.

The rock-is a biotite granite of light-gray color and even, fine to 

medium-coarse grain. In places the feldspars have a pronounced 

pinkish tint, imparting a similar color to the granite. The minerals 

are orthoclase, microcline, acidic plagioclase, quartz, biotite, muscovite, apatite, zircon, iron oxide, chlorite, and kaolin. Orthoclase is 

the dominant feldspar, with little microcline but much acidic plagioclase. A thin section from a specimen 3£ miles west of Louisburg^ 

differed in composition from that above given in the absence of microcline and in containing a smaller amount of plagioclase.

The vertical joints are spaced at irregular intervals, close together 

in some places, but as a rule sufficiently far apart to yield dimension 

stone. On the road near the Louisburg bridge the joints strike N80° E., N. 20° W., and north-south.

GRANVILLE COUNTY.

Granite bowlders of light-gray color and medium grain occur in the 

vicinity and to the east of Oxford, the county seat of Granville county. 

No quarries have been opened, but some of the larger bowlders have 

been split and used locally for curbing and foundation stone and for 

other purposes.

VANCE COUNTY.

The granite of Vance County is perhaps among the best known 

in North Carolina, and some of the quarries compare favorably 

with the most extensive ones elsewhere in the State. The area 

is a large one, confined principally to the central and eastern parts 

of the county. Quarries are worked at several places in the county 

along the Seaboard Air Line Railway, chiefly at and near Greystone 

and Middleburg stations. The quarries at Greystone have been 

worked almost continuously since they were opened, about thirty 

years ago. Those near Middleburg have only recently been opened. 

Several years ago a little of the granite was quarried at Henderson 

the county seat, for use on the streets.

The granite has been used mostly for street purposes in the form 

of blocks, for coping and bridges, and to a less extent as a building 

stone. It has been shipped to numerous places in Virginia and
126 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

North Carolina, especially in the eastern parts of the two States. 

The quarry waste is used for macadam and ballast.

Greystone area. The Greystone quarries, located at Greystone, 

a station on the Seaboard Air Line Railway, are the largest and best 

known in eastern North Carolina. As shown in the individual 

descriptions, the rock is a schistose granite that is admirably suited 

for street purposes, for which there has been a large demand over 

the eastern Carolina-Virginia territory.

The principal quarries are the Old Greystone, New Greystone 

and those of the Greystone Granite and Construction Company 

and the Seaboard Air Line Railway.

The rock is a biotite granite of gray to pinkish-gray color and 

fine to medium grain. The schistose structure, apparent in the 

hand specimens, is usually indicated in the thin sections. Orientation is less apparent in the light-colored minerals than in the biotite. 

The principal minerals are orthoclase, microcline, plagioclase (oligoclase), quartz, biotite, a little muscovite, zircon, and apatite. 

Much chlorite and kaolin and a light-colored mica are developed 

from the alteration of the biotite and feldspars. The feldspars are 

more or less clouded from irregular patches and areas of kaolin and 

minute scales of a light mica. Intergrowths of quartz and feldspar 

are frequent.

The Old Greystone quarry, the largest in the county, is located 

near the depot at Greystone and was continuously worked for fifteen 

years from the date of opening, about thirty years ago. The quarry 

opening covers about 2 acres and is worked to an average depth 

of 35 feet.

The rock is a foliated biotite granite of fine grain and pronounced 

porphyritic tendency. It is dark gray in color, with a pinkish 

cast imparted by the prevailing pink-colored feldspars.

The decayed granite at the surface, including soil, averages about 

3 feet in thickness, but is as much as 15 feet in places. Near the 

top of the opening the granite weathers into thin horizontal sheets, 

which become much less well defined lower down, attaining near 

the bottom a thickness of 12 feet or more. Vertical joints striking 

R[. 60° E. cut. the granite at irregular intervals, in some places being 

spaced close together, in others at wide intervals. Slickensides are 

developed on the surfaces of the joints. Dikes of pegmatite and of 

fine-grained granite are somewhat numerous, varying in thickness 

from a fraction of an inch to many inches and conforming as a rule 

to a north-south direction. Small, irregular, roughly rounded, 

dark-colored segregations (knots) chiefly of biotite occur here and 

there.

The New Greystone quarry, opened in 1902, is about 150 yards, 

west of the Old Greystone quarry. It averages less than 12 feet
GEANITES OF NORTH CAROLINA. 127

in depth. The fresh rock is covered to a depth of 3 to 6 feet with 

soil and decayed granite.

The rock is a biotite granite similar in all respects to that of the 

Old Greystone quarry, except that the schistosity is less marked. 

The vertical joints strike N. 5° to 10° E. and N. 60° E. Occasional 

small grains of pegmatite cut the granite.

The Greystone Granite and Construction Company''s quarry is about 

three-fourths of a mile northwest of the depot at Greystone. The 

hill slope back of the quarry rises about 25 to 30 feet above the 

opening. The quarry was first opened in 1889 and was worked 

constantly for about six years, but has been idle for some time. 

At the time of working it was well equipped with the necessary 

modern machinery for quarrying and handling the stone, and a 

spur track was,laid and operated between Greystone and the quarry. 

The opening is a large one; it averaged nearly 250 feet each way 

and was worked to a depth of about 25 feet.

The opening -shows along the face a zone of decayed material 

from the surface downward for 2 to 10 feet, composed largely of a 

granite soil of red to light-gray color and thin, partly decayed, 

nearly horizontal sheets of moderately firm rock. As in the Old 

Greystone quarry, the horizontal parting planes are less well defined 

down in the fresh rock, although they are variable, separating the 

rock into layers or sheets 8 or 10 feet thick.

The granite, is essentially the same as that of the Greystone quarries 

already described. It is somewhat lighter in color, but has a pinkish 

tone. It ranges from fine to medium grain in texture and is 

distinctly schistose in a general north-south direction. The feldspars 

average larger than the other mineral constituents, are white or of 

light color, and show the usual porphyritic tendency.

Two sets of vertical joints of about equal development and intersecting at right angles cut the granite in approximately north-south 

and east-west directions. These are spaced sufficiently far apart 

to admit the quarrying of blocks of any desirable size. Pegmatite 

dikes 6 to 8 inches across penetrate the granite and strike in a general 

north-south direction. Small irregular knots of black mica are 

noted here and there in the rock.

The Seaboard Air Line Railway quarry is about 2 miles northeast 

of Greystone station. In all several acres of surface has been stripped 

to a moderate depth over the gentle slopes on both sides of a small 

stream. The quarry was opened about 1896. A spur track is laid 

from the main line near Greystone to the quarry, a distance of about 

1J miles.

Three rather strongly contrasted phases of the granite are developed in the quarry. One, which comprises the main body of the 

rock, is the typical granite of the Greystone area, dark gray with a 

38971° Bull. 426 10 9
128 GRANITES OF SOUTHEASTERN ATLANTIC SjTATES.

faint pinkish tone and generally fine grained. In the hand specimens the schistose structure is much less marked than in the Greystone rock proper, and it exhibits a pronounced porphyritic tendency. Another phase is a medium-textured, uniformly light-pink 

granite containing a much smaller amount of biotite than the phase 

just described. The rock is decidedly schistose in structure and 

highly feldspathic, and the biotite is distributed along roughly parallel disconnected bands of knife-edge thickness. As nearly as could 

be determined, the width of this zone as exposed in the opening is 

not less than 600 feet, with a north-south direction. The porphyritic tendency is not shown in this phase of the granite. A third 

phase is a dark blue-gray biotite granite, generally finer grained than 

the other two and containing a larger amount of biotite. This phase 

of the rock is usually developed between the pink and the gray granite as a narrow zone from 2 to 6 feet across.

The three phases of the granite are alike schistose in structure, 

the schistosity striking north and south; and the jointing is likewise 

continuous through them in the same general directions. The quarry 

is not sufficiently developed to show conclusively the exact relations 

and significance of these three variations in the rock, but such data 

as were available seemingly indicate that they are phases of the same 

rock and not separate intrusions. The differentiation was possibly 

begun with the cooling of the magma and completed by the intense 

dynamic metamorphism to which the granite has been subjected. 

Indeed, banding on a small 'scale, due to metamorphism, differentiating the rock into dark and light-colored bands, is distinctly 

noticeable in some parts of the quarry.

Vertical joints intersect the granite, striking north-south, eastwest, and northwest-southeast. The joints in the east-west direction form the major set and their surfaces are usually slickensided 

after the fashion of those in the Old Greystone quarry described 

above. Pegmatite dikes varying from 1 inch to more than 6 inches 

across and mostly striking N. 10° E. are numerous.

The stone quarried from this opening is reported to have been used 

for ballast and for street purposes.

One other exposure of the granite near Greystone station, between 

the main track of the railroad and the New Greystone quarry, was 

recently opened to a small extent, but was soon abandoned on account 

of the numerous veins and the irregular texture of the rock.

Middleburg area. Two quarries, near together, have been opened 

on the west side of the Seaboard Air Line Railway, 1 mile west of 

Middleburg station and about 3 miles north of Greystone. The granite is essentially the same as that quarried at Greystone. On the 

whole it probably contains a very little more biotite and is correspondingly darker. The feldspars are chiefly light in color nearly
GRANITES OF NORTH CAROLINA. 129

white, with the barest pinkish cast. The rock is fine grained, displaying a marked porphyritic tendency in the feldspathic constituent. The biotite is distributed in fine black shreds along parallel 

lines arranged in the direction of their longer axis. Hand specimens 

from the two openings are indistinguishable.

The rock is a biotite granite, distinctly schistose, and composed of 

the same minerals in practically the same proportions as the granite 

at Greystone. Feldspar predominates, consisting of the potash varieties, orthoclase and microcline, with microperthitic intergrowths, 

and an acidic plagioclase. Some alteration to kaolin and muscovite 

is indicated in the cloudy and opaque areas over the feldspar surfaces. Micropoikilitic structure in the potash feldspars is common 

and Carlsbad twinning is occasionally observed. Intergrowths of 

quartz and feldspar, indicating the overlapping of the periods of separation from the magma of these two minerals, are common. Biotite 

is largely altered to chlorite and it is identical in occurrence and 

microscopic properties with that in the granite at Greystone. The 

microscopic accessories are the same in the granite from the two 

areas.

The first quarry was opened in 1899. The opening averages about 

400 by 199 feet, and has been worked to an average depth along the 

quarry face of 25 feet. A 22-foot quarry face is developed lengthwise of the opening, covered at the top by an average depth of about 

4 feet of soil derived from the decay of the granite.

Only one set of joints cuts the granite; they strike east and west, 

and are spaced some distance apart, less than half a dozen planes 

being visible in the entire quarry. Very few seams were noted. A 

tendency toward banding is indicated in places, separating the rock 

into alternating darker and lighter layers in a direction N. 20° E., 

which is the prevailing strike of the schistosity.

The rock is a biotite granite of dark-gray color and fine grain. 

It contains perhaps a slightly larger proportion of 'biotite than that 

quarried at Greystone. The feldspars are mostly white and show 

much less of the pink color so characteristic of the former area.

A second opening was made in 1903 in an outcrop of the same 

granite 100 yards south of the quarry described above. The jointing 

and schistosity are the same in the two openings.

WAKE COUNTY.

The principal exposures of granite in Wake County in which openings have been made are in the Raleigh area and the Wyatt-Rolesville 

area.

Raleigh area. The only quarries worked in the Raleigh area are 

within the eastern limits of the city of Raleigh, about 1£ miles from
130 GRANITES OF SOUTHEASTERN ATLANTIC STATES. '

the statehouse. Two large openings near together were first made 

more than seventy-five years ago. From 1833 to 1836 stone was 

quarried to build the statehouse. The north opening, which is the 

larger, is 850 feet long in a north-south direction, 75 feet wide, and 

30 to 35 feet deep. The south opening is 330 feet long, 75 feet wide, 

and 25 feet deep.

The rock is a biotite granite of medium-gray color and even, fine 

grain. It is not entirely massive, but displays a partial schistose 

structure. The minerals are the potash feldspars (orthoclase and 

microcline in nearly equal amounts), an excess of acidic plagioclase, 

quartz, black mica (biotite), and a little white mica (muscovite), 

together with accessory apatite and zircon and secondary chlorite, 

epidote, and colorless mica. Intergrowths of the feldspar and quartz 

are common. Peripheral granulation of the quartz and feldspar is 

indicated, being a result of mechanical stress or pressure. A partial 

chemical analysis of this granite is given on page 117.

An average depth of about 3 feet of deep red clay derived from the 

decomposition of the granite is exposed at the top of the openings. 

Below this is a zone of less advanced decay, 10 feet thick, exposing 

partly decayed granite in thin sheets. Within this zone the rock along 

the horizontal parting planes and the vertical joints is broken down 

into light-red granitic clay and the middle portion of the sheets is 

composed of moderately hard though deeply decayed granite. Below 

this second zone of weathering the granite is hard and fresh to the 

depth of working.

Joints occur at fairly close intervals, but the planes are not so close 

as to prevent the quarrying of dimension stone. The principal 

joints strike approximately east and west and their surfaces are 

slickensided.

Pegmatite dikes up to several feet in thickness are very abundant. 

Dimension stone free from these dikes can not be obtained, as attested 

by the stone used in the statehouse. Slight faulting is shown in some 

of the dikes, with an extreme displacement of 6 inches. A single 

dike of banded aplite-pegmatite was observed. Thin sections show 

it to be a potash aplite.

Along the west side of the north opening is a large diorite mass 

sharply defined from the granite and cut in all directions by pegmatites and true granite veins, much crumpled and contorted. The 

pegmatites are largest in the diorite mass but are large also in the 

granite on the east side of the quarry. The line of contact between 

the granite and the diorite seems to be sharp but exceedingly irregular. The exact relations between the diorite and the granite were 

not plain. Thin sections show the rock to be a quartz diorite, composed of the principal minerals hornblende, plagioclase feldspar, and 

quartz.
GRANITES OF NORTH CAROLINA. ' 131

At the state prison, 1£ miles west of the capitol, a quarry 300 to 

350 feet in diameter and worked to a depth of 60 feet was opened in 

1868 to furnish stone for the foundations and walls of the prison 

building. The rock is a biotite granite gneiss of irregular color and 

texture. The vertical joints strike N. 80° W. and north-south.

Wyatt-Rolesville area. The Wyatt-Rolesville granite area is about 

14 miles north of Raleigh and about 4 miles south of Wake Forest, 

extending eastward from Wyatt, a station on the Seaboard Air Line 

Railway, to Rolesville, a distance of about 5 miles. Flat-surfaced 

outcrops several acres in extent are exposed near Wyatt station 

and near Rolesville. As indicated below, the granite is biotite bearing, but differs in some respects from that farther south in the Raleigh 

area. No quarries have been opened.

The rock is a biotite granite of light-gray to pinkish-gray color and 

fine to medium grain. Muscovite is more plentiful in the granite at

Wyatt station and the feldspar is of a pinkish cast over the entire 

area. Thin sections of the granite near Rolesville showed the minerals to be orthoclase, microcline, acidic plagioclase, biotite, occasional muscovite, apatite, and zircon and secondary chlorite, kaolin, 

and iron oxide. Microcline is variable in quantity, nearly equaling 

the orthoclase in one section. Plagioclase nearly equals potash feldspar in amount in some sections and is considerably less in others.

Pyrite and garnet are both present in the granite at Wyatt, the 

latter locally in considerable quantity. Pyrite appears also in the 

granite at Rolesville. Vertical joints in the granite at Wyatt strike 

N. 20° E., N. 80° E., and north-south, and at Rolesville N. 20° E. 

and east-west. The spacing between the joints varies but is usually 

sufficiently great to yield dimension stone. Pegmatite dikes ranging 

in thickness from a fraction of an inch to several niches cut the granite 

in places.

WARREN COUNTY.

The most important exposures of granite in Warren County are 

found at Warrenton, the county seat, and to the north and northwest 

of Wise siding, on the Seaboard Air Line Railway. Some stone has 

been quarried in each locality.

Near the west limits of Warrenton an irregular dark-gray biotitehornblende gneiss has been quarried for local use. It is not a desirable rock for any but the rougher grades of work. Vertical joints 

strike N. 60° E. and N. 30° W. Scattered crystals of pyrite are 

noted in the rock.

About a quarter of a mile east of the Richmond division of the 

Seaboard Air Line Railway, 1 mile northwest of Wise siding, a 

muscovite-bearing biotite granite is quarried for general building 

and street purposes.
132 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

The rock is a medium light-gray massive biotite granite of medium 

grain. Biotite is regularly distributed through the rock; much red 

garnet is present in places, and, indeed, is so abundant in some of the 

hand specimens that it imparts a mixed pink and gray color to the 

rock. The principal minerals are potash feldspar (orthoclase and 

and microcline), soda-lime feldspar (oligoclase), quartz, biotite, and 

a little muscoyite, together with the accessories apatite, zircon, 

titanite, and rutile and secondary chlorite and light-colored mica.

About 2 miles north of Warren Plains a small opening was made 

some years ago in a light-colored muscovite granite. It is of even, 

fine-grained texture, and is composed of orthoclase, much acidic 

plagioclase, a little microcline, and muscovite. Some garnet and 

iron oxide occur. The vertical joints strike N. 10° E., N. 45° E., and 

N. 60° W. and are too closely spaced, as a rule, to permit the quarrying of reasonably good dimension stone.

SUMMARY OF .GRANITES OF NORTHEASTERN CAROLINA BELT.

Within the five counties composing this belt there are large workable areas of different grades of granite suited for nearly all classes of 

work in which granite is used, except for monumental stock. Systematic quarrying has been limited chiefly to areas in two counties the 

Raleigh area in Wake County and the Greystone and Middleburg 

area in Vance County. Granite outcrops are fairly numerous and 

are usually of sufficient size to admit of quarries being opened without 

much surface stripping. The vertical joints are rarely spaced so 

close as to prevent the quarrying of dimension stone. Pegmatite 

dikes are so abundant in one or two localities as to make it impossible 

to obtain dimension stone free from them.

The granites show but slight variation in mineral composition over 

the entire belt. With one exception they are biotite granites containing occasional muscovite and, in two places, hornblende. They 

range from fine to medium grained in texture, with a porphyritic 

tendency in places. Structurally they vary from massive to schistose 

rocks. In color they are some shade of gray, with a pronounced 

pinkish tone, imparted by a pink feldspar, over much of the area.

METAMORPHIC SLATE AND VOLCANIC BELT.

The belt composed of metamorphic slates and schists and altered 

volcanic rocks extends in a general southwesterly direction across the 

middle portion of the State and forms a part of the eastern Piedmont 

region. Its width varies from 8 to 50 miles. It is included between 

the Carolina igneous belt on the'west and the Triassic belt, chiefly, on 

the east.

Rocks of granitic composition and texture have been noted in only 

one county (Orange) within this belt. The principal exposures occur
GRANITES OF NORTH CAROLINA. 133

a short distance to the north, south, and east of Chapel Hill. They 

are biotite granites with much variation in color, texture, and 

structure. Nowhere has the rock been quarried, and except for certain grades of rough work it seems to be of doubtful commercial 

value.

CAROLINA IGNEOUS OR MAIN GRANITE BELT. 

INTRODUCTORY STATEMENT.

The main granite belt of North Carolina, as shown on the map 

(PI. XIII), occupies a nearly central position in the Carolina portion 

of the Piedmont Plateau. It crosses the State in a general northeast-southwest course, beginning at a point east of Danville, Va. ; and 

extending southwestward into South Carolina. In width it probably 

averages from 15 to 50 miles. It is traversed for most of its length 

by the main line of the Southern Railway and is crossed at rather close 

intervals by many of the principal railroads which join the main line 

of the Southern, being thus one of the most accessible areas in the 

State.

The southeast border of the belt can, as a rule, be traced with 

comparative readiness along an irregular line marking the contact 

with the belt of metamorphic slates and volcanic rocks. On the 

northwest it is bounded by an extensive belt of gneisses and schists 

of the western Piedmont region, and the line of differentiation between 

the two belts is less easily determined.

Granite and diorite constitute the two principal rock types of this 

belt. These may be either massive or more or less mashed, squeezed, 

and schistose. They are penetrated by dikes of granite and diabase 

and other basic intrusive rocks. Areas of variable schists are 

scattered over the belt, in many places forming the country rock.

The area is further traversed by very many intersecting quartz 

veins, large and small. These are usually concealed by the deep 

covering of rock decay, but their abundance is indicated by the 

innumerable angular fragments of quartz strewn over the surface.

Two phases of the granite are prominently developed over many 

parts of the area, the porphyritic and the even granular, which nearly 

everywhere grade into each other. A zone of porphyritic granite 

extends in a northeasterly direction through a number of counties 

along the western margin of the belt. This zone and other areas of 

porphyritic granite in the igneous belt are described on pages 164-170'. 

With only one or two exceptions the even-granular granites are biotite 

granites of some shade of gray, and they vary from fine to coarse in 

texture.

Some of the largest and most important granite areas in the State 

are included in the Carolina igneous belt. As a rule, the rocks are 

deeply decayed, but outcrops of nearly fresh granite occur in every
134 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

county within the belt. The decayed material is in general characteristic of the underlying rocks from which it has been derived, and 

the granites can thus usually be traced with considerable accuracy 

by means of. the overlying soil.

The belt includes either the whole or a part of each of the following 

counties, named in order from south to north: Gaston, Mecklenburg, 

Cabarrus, Rowan, Iredell, Davidson, Davie, Forsyth, Guilford, 

Alamance, and Caswell. Granite has been quarried to some extent 

in each of these counties except Caswell.

GASTON COUNTY.

Numerous exposures of granite occur in the central and middle 

eastern portions of Gaston County. The rock is usually deeply 

decayed, yielding a characteristic light-gray soil, by which the granite 

is readily traced.

The rock is a biotite granite of light to medium dark-gray color 

and fine to medium-coarse grain. At Belmont the granite has a 

decided pinkish cast. With only few exceptions, the granites over 

most of the area show a pronounced porphyritic tendency. The 

principal minerals are potash feldspar (orthoclase and microclirie, 

usually in nearly equal amount), soda-lime feldspar (oligoclase), 

quartz, and biotite, with accessory apatite and zircon and secondary 

chlorite, epidote, and a light-colored mica. Soda-lime feldspar is 

lacking in some thin sections of the granite near Gastonia, but is 

present in large amount in the granite near Belmont.

The granite has been quarried for local use from numerous small 

openings in and near Gastonia and from a small opening 3 miles 

northwest of Belmont, a station on the Southern Railway 10 miles 

south of east from Gastonia. As measured in the openings, the vertical joints show the strike of N. 20° to 30° E., N. 40° to 60° E., N. 60° 

to 70° W., N. 80° W., north-south and east-west. Usually not more 

than two sets of joints are developed in any one of the openings, and 

in several only one set was observed. The joints are sufficiently far 

apart to permit dimension stone to be quarried. Slickensides are 

developed on the surfaces of the joints at the opening 3 miles northwest of Belmont.

. A few knots of small size occur, and in several openings pegmatite 

dikes 1 to'2 inches thick were observed.

MECKLENBURG COUNTY.

Granite occurs very generally over Mecklenburg County, but comparatively few quarries have been opened. The areas in which some 

granite has been quarried are the Charlotte area, the Morning Glade 

Church area, and the Davidson area.
GRANITES OF NORTH CAROLINA. 135

. Charlotte area. The Charlotte area includes all known granite 

localities within a radius of 5 or 6 miles of the city of Charlotte. 

Openings have been worked within and just beyond the city limits at 

several places about 4 miles to the east; at Belmont Springs, also on 

the east; and at several places about 5 miles to the south.

The City quarry, located near the freight depot in the southeastern 

part of Charlotte, is 350 by 400 feet and is worked to a depth of 50 

feet. The rock is too extensively crushed and jointed and too 

variable in color and texture to be used for any purpose except for 

road metal and ballast. The product is used principally for macadamizing the city streets in Charlotte.

The rock is a biotite granite of bluish-gray color and generally of 

fine grain. Potash feldspar (orthoclase and microcline) and very 

little plagioclase compose the feldspar content. Two principal sets 

of vertical joints, striking N. 40° E. and N. 35° to 50° W., cut the granite at close intervals. The joint surfaces are slickensided. A series 

of dark-greenish, schistose, fine-grained diabase dikes, varying from 

12 inches to several feet across, cut the granite coincident with the 

N. 40° E. set of joints.

The Oders quarry, just beyond the southeastern limits of Charlotte, comprises two small openings, in a biotite granite of the same 

color and texture as that of the City quarry. The granite is crushed 

and intersected by closely spaced vertical joints, striking N. 10° W. 

and N. 60° W. The product can be used in the form of crushed 

stone.

Several small openings 4 miles east of Charlotte are near the Seaboard Air Line Railway, in a biotite granite of variable texture. 

The granite is more or less schistose and is cut by dikes of diabase. 

The product can be used only for the rougher grades of work.

Bowlder exposures of a hornblende-biotite granite occur over a 

large area on both sides of the Nation Ford road, 5 miles south of 

Charlotte. A number of small openings have been made in different 

places and some of the largest bowlders have been partly worked off. 

The rock is a hornblende-biotite granite of blue-gray color and 

medium grain. The principal minerals are potash and soda-lime 

feldspars, quartz, hornblende, and biotite, with much titaniferous 

magnetite. Hornblende and biotite are partly altered to chlorite. 

Pyrite occurs here and there. Small and large knots are so abundant 

in the Kirkpatrick openings as to render the stone unfit for the better 

grades of work.

At Belmont Springs, 1^ miles east of Charlotte, a dike of quartz 

porphyry, whose width nowhere exceeds 25 feet and which has been 

appropriately named leopardite,0 intersects the biotite granite. 

It is a dense, hard, tough, and compact cryptocrystalline rock,

a Genth, F. A., Am. Jour. Sci., 2d ser., vol. 33,1862, p. 198.
136 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

which breaks with a conchoidal fracture. It is nearly white, tinged 

a faint greenish in places, and is penetrated by long parallel streaks 

or pencils of black color. (See PI. XV.) When broken at right 

angles to the streaks the surface is dotted with rounded irregular 

black spots, varying in diameter from that of a pin head up to half 

an inch. These pencils are entirely absent from some portions of the 

rock and are closely crowded together in others. The rock is composed essentially of a crystalline aggregate of feldspar (potash and 

soda-lime varieties) and quartz, with less colorless mica. Idiomorphic phenocrysts of quartz and feldspar of small size are distributed through the groundmass. The black streaks or pencils 

are composed of the oxides of manganese and iron. The rock is 

susceptible of an excellent polish and could be used with splendid 

effect in inlaid work.

Morning Glade Cliurch area. The Morning Glade Church granite 

area is 10 miles east of Charlotte and 4 miles east of south from Newells 

station. -One of the large bowlders on the Cross place has been 

quarried, and this, constitutes the only development. The rock is a 

biotite granite of light-gray color and medium-grained texture. The 

largest bowlders are from 20 to 30 feet high and proportionately 

large in other dimensions.

Davidson area. The Davidson granite area is located mainly in the 

extreme northern part of Mecklenburg County, but extends northward into Iredell County and eastward into Cabarrus County. Numerous small openings east, south, and southwest of Davi'dson have 

been made at different times to obtain stone for local use, but no 

regular quarries have been worked. The earliest quarrying in the 

area was done prior to the civil war, to obtain stone for foundations, 

steps, and sills in the early buildings of Davidson College. The stone 

was quarried from the immense bowlder outcrops of biotite granite,

on West Fork of Rocky River, 5 miles east of Davidson, located 

partly in Mecklenburg and partly in Cabarrus County.

Two varieties of granite occur in the Davidson area. The dominant 

variety is a biotite granite of light to dark gray color and fine to 

medium grain. The minerals are potash feldspar (orthoclase and 

microline), soda-lime feldspar (oligoclase), quartz, and biotite, with 

ti.tanite, magnetite, apatite, and zircon. Epidote and chlorite occur 

as secondary minerals. Pressure effects are plainly visible in the 

granite from the various openings. At the Knox quarry four sets of 

vertical joints cut the granite, spaced at close intervals and striking 

N. 20° E., N. 45° W., north-south and east-west. The joint planes 

.are slickensided, indicating subsequent movement in'the granite massT?he second variety is a biotite-bearing hornblende granite of 

medium-gray color and medium grain. It is exposed in large bowlders and low ledges along a small stream on the Caldwell place, 1 mile-
F*'*%,**-1k' 

, '* '«*** .- '*V5V*»

^r>A^;

 %<** »*'%jy*r4» ^ibl

i^^^i!il .'. *J*^^*^LM:; ^ ^ *0>^l

LEOPARD1TE (QUARTZ PORPHYRY) NEAR CHARLOTTE, MECKLENBURG COUNTY, N. C. 

A- Section across black streaks. 77. Section along black streaks.
GRANITES OP NORTH CAROLINA. 137

east of Davidson. Some of the stone was quarried many years ago 

for foundations in several of the Davidson College buildings. The 

hornblende is distributed through the rock as irregular grains and 

lath-shaped crystals, measuring as much as If inches long by one-' 

fourth inch wide. The minerals are potash and soda-lime feldspars 

(the latter in excess), quartz, hornblende, biotite, and a little magnetite, with some secondary chlorite and epidote.

The vertical joints strike N. 70° E. and N. 20° W., and are sufficiently far apart for the quarrying of dimension stone. Numerous 

areas of dark-colored knots occur in places, measuring 2 to 10 inches 

in length by 1 to 3 inches across.

CABARRUS COUNTY.

Even-granular granites occur over many parts of Cabarrus County, 

but except at several small openings near Concord no quarrying has 

been attempted. The rock is a biotite granite varying from gray to 

pink in color, fine to medium grained in texture, and massive to 

schistose in structure. The exposures are in the form of bowlders, 

ledges, and flat-surfaced masses.

Four miles southwest of Concord the Balfour Granite Company 

opened a quarry in a large bowldery ledge outcrop of augite-hornblende-biotite syenite of dark-gray color and coarse texture (PI. XVI, 

B]. ' Its principal minerals are orthoclase, microcline, oligoclase, green 

augite (diopside), hornblende, biotite, magnetite, pyrite, and kaolin. 

The feldspar very largely predominates in the form of large, irregular 

bluish-gray grains. The opening is 150 by 225 feet, worked to a depth 

of 25 feet. The vertical joints strike N. 40° E. and N. 40° W., with 

slickensided surfaces. The stone is quarried by blasting and the 

product is used for ballast.

ROWAN COUNTY.

One of the most important granite areas in the State is that near 

Salisbury, in Rowan County. The area marks a nearly continuous 

ridge beginning about 4 miles east of Salisbury and extending southwestward for a distance of more than 12 miles. Numerous quarries 

have been worked in many places on the ridge, and the stone has been 

widely used in North Carolina and. the adjoining States. The first 

quarries were opened many years prior to the civil war and. quarrying 

has been continued at intervals to the present time. Both a lightgray, nearly white granite and a pink granite of uniform color and 

texture and of most desirable quality are quarried on the ridge. "

Dunns Mountain area. Dunns Mountain, 4 miles east of Salisbury, 

forms a part of a conspicuous granite ridge 12 to 14 miles in length, 

trending in a general northeast-southwest direction. The ridge character is more or less apparent throughout its course, but it becomes
GRANITES OF SOUTHEASTERN ATLANTIC STATES.

less well denned toward the southwest. Dunns Mountain is the 

northern part of the ridge and the highest point, its elevation being 

about 900 feet above sea level and about 150 feet above Salisbury. 

Similar but less elevated portions of the ridge are locally known as 

Phillips Mountain, 6 miles nearly south of Salisbury, and Powlers 

Mountain, which forms a part of the extreme southwest extension of 

the ridge, about 9 miles southwest of Salisbury.

Over many parts of the ridge, especially Dunns Mountain proper 

and Phillips Mountain (PI. XVII, A), the granite is exposed in huge 

bowlders 10 to 30 feet high and proportionately large in the other 

dimensions. At other points on the steeper slopes and near the top 

the loose residual material has been stripped from the surface, exposing large and continuous areas of the hard and bare rock surface. At 

still other places, where the ridge character is less pronounced, large 

and continuous flat-surfaced areas of the hard, nearly fresh rock are 

exposed. Over the intervening areas nearly fresh granite outcrops 

in smaller bodies, but the rock is mostly overlain by a variable mantle 

of residual material, from 1 to 10 feet thick, which on account of the 

slope can as a rule be easily stripped. In many places the exposures 

are sufficiently large to yield immense quantities of granite without 

stripping.

Two distinct and important grades of granite are quarried a very 

light gray, nearly white variety, and a decided pink or flesh-colored 

'granite. Both have the same texture and mineral composition 

and are closely similar in other less important particulars. The 

difference in color is shown only in the northeast half of the ridge, 

a distance of 5 miles or more. The granite has more or less of a pronounced pinkish tone over all parts of Dunns Mountain proper, but 

farther south this grades into the light-gray granite. Between 

Dunns Mountain and the village of Faith most of the rock is light 

gray, although several quarries have been worked within these limits 

in the pink granite. From Phillips Mountain, near Faith, southwestward the granite is entirely of the light-gray color.

After a careful study of the area, the writer is convinced that the 

light-gray and the pink granite are phases of the same rock. The 

light-gray granite is as strong and durable as the pink granite, but 

the latter is more desirable for certain classes of high-grade work.

The granite has been extensively quarried and has had a wide use 

both in and out of the State. Beginning at the extreme northeast 

end of Dunns Mountain and extending southwestward the principal 

quarries are those on the north slope of Dunns Mountain, the Dunns 

Mountain (McCanless) quarries, the Rowan Granite Company's 

quarries, the Balfour Quarry Company's quarries, the Consolidated 

Granite Company's quarries, the Phillips Mountain quarries, and 

the Powlers Mountain quarries. Many other small openings have
GRANITES OF NORTH CAROLINA. . 139

been made over the ridge, but practically no stone has been quarried 

from them.

Microscopically the granite is an aggregate of interlocking feldspar 

and quartz, through which is distributed very subordinate biotite. 

Plagioclase equals and in many sections exceeds the potash feldspar. 

Microcline is usually very small in amount. Feldspar intergrowths 

are-numerous. Biotite is sparingly present and is usually either 

partly or entirely altered. Scattered grains of magnetite and garnet 

and a few other minor accessory minerals occur. Pressure effects 

are plainly marked in fine mosiacs of crushed feldspar and quartz, 

and in strain shadows and fractures in the larger individuals. Some of 

the plagioclase individuals are broken across, the parts being separated 

and in some places bent and curved.

On the north slope of Dunns Mountain, 4 miles east of Salisbury, 

a number of quarries have been worked on both sides of the Stokes

Ferry road. Of these the principal ones were worked during 1908 by 

Hartman & Hodge and by Duncan & Floyd, chiefly for dimension 

stone.

The granite is of medium grain and varies in color from faint pink 

to light gray, nearly white. More or less pinkish feldspar is usually 

present. The sap or partially decayed and discolored granite is very 

thin. The vertical joints, which are spaced at wide intervals, strike 

N. 50° to 70° E. and N.25° W. Over the summit andnorth slope of the 

mountain pronounced shear zones of crushed and laminated rock, 

not exceeding 2 feet in width and lying at considerable distances apart, 

are developed in the granite. At the picnic grounds on top of the 

mountain the strike of the shear zones is N. 55° E. The surfaces are 

usually slickensided and coated with a thin veneer of yellowish-green 

mineral substance, which in part is epidote. A partial chemical 

analysis of the granite is given on page 117.

The Dunns Mountain (McCanless) Granite Company's quarries, which 

are 4£ miles southeast of Salisbury, include 45 openings, large and 

small, from most of which no stone has been quarried. Quarrying 

has been confined to three large openings, the largest one of which 

is 267 by 100 feet and 30 feet deep. The sap or partly decayed 

granite exposed in this opening averages 12 to 14 feet in thickness. 

The largest dimension stone shipped averaged 14 feet long by 6 feet 

thick. One hundred pieces, each 6 by 8 by 2 feet, were shipped 

to Reading, Pa.

The granite is light gray in color, the feldspars assuming a pinkish 

 cast in places, and is of medium grain. The two principal sets of 

vertical joints strike N. 15° to 20° E. and N. 30° to 40° W. The planes 

of both sets are slickensided and are spaced at wide intervals.

The principal use made of the stone has been in buildings, as blocks 

and curbing for street purposes, and as macadam and ballast. In
140 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

July, 1908, the granite was- being quarried for blocks to supply a 

Chicago contract. It has been shipped for use to various points in the 

Carolinas, Virginia, and Georgia, to Reading, Pa., and to Washington, 

D. C. The rock works well under the hammer, takes a good polish, and 

is susceptible of fine carved work, as displayed in some completed 

pieces at the quarries.

The Rowan Granite Company's quarries are located within a few 

hundred yards of Granite Quarry station on the Yadkin Railroad, 

about 4^ miles southeast of Salisbury. Some 12 to 15 openings are 

made in different places. The two largest openings are within 200 

yards of each other, they are about 200 feet long by 150 feet wide, 

and are worked to an average depth of 32 feet. (See PI. XVI, A.) 

Dimension stones weighing 70 to 100 tons each, were quarried from 

the southwest opening, quarry No. 2, in the summer of 1903, and 

used in the construction of the dam across Yadkin River.

The rock is a light-gray biotite granite, more or less speckled in 

places with a pinkish feldspar, not so pink nor so uniformly distributed through the rock as to modify the light-gray color appreciably, except at very close range and on close scrutiny. The stone 

possesses good working qualities, dresses well under the hammer, and 

is well suited for the various uses made of it.

Vertical joints break the stone into polygonal blocks of different 

sizes, but the planes are usually spaced far enough apart to permit 

the quarrying of blocks of almost any dimensions. Measurements 

made of the strike of the joints in the principal openings gave the 

following results:

N. 80°E. N.25°E. N. 70° W.

N.65°E. N:20°E. N. 50° W.

N. 45° E. N.15°E. N.45°W.

N.40°E. N. 10° E. N.40°W.

N. 35° E. '

In the two large openings the joints strike as follows: QuarryNo. 1, N. 40° E. and N. 40° W.; quarry No. 2, N. 35° to 45° E. and 

N. 45° to 50° W.

In quarries Nos. 1 and 2 the granite shows in places an advanced 

stage of decay, varying in depth as a rule from 5 to 6 feet, though in 

quarry No. 1 the granite is completely decayed at one point to a 

depth of more than 10 feet. The weathered material at this point 

consists of concentric layers of light-red and gray granitic sand and 

clay. The entire mass is reduced to a soft siliceous clayey material, 

in which the layered structure is completely preserved and which 

can be easily removed with the pick and shovel.

The product has been used as a general building stone, for street 

work in the form of curbing and blocks, as crushed stone for ballast, 

and to a slight extent in monumental stock. It has been shipped
U. S. GEOLOGICAL SURVE

A. ROWAN GRANITE COMPANY'S QUARRY NO, 2, NEAR SALISBURY, ROWAN COUNTY, N. C.

B, BOWLDER OUTCROP OF SYENITE SOUTHWEST OF CONCORD, CABARRUS COUNTY, N. C.
GRANITES OF NORTH CAROLINA. 141

for use to Washington, D. C., to the most important points in Virginia 

and North Carolina, and to a minor extent to several other States.

These quarries were idle at the time of the writer's visit in July, 

1908.

The Balfour Quarry Company's quarries are located less than half 

a mile south of the Rowan Granite Company's quarries, about 5 

miles N. 20° W. of Salisbury and 2 miles northeast of Faith. Two 

openings have been made near together, the smaller one of which 

is in light-gray granite of the same color, texture, and composition 

as that quarried by the Rowan Company described above.

The principal opening, known as the Balfour pink quarry, is in a 

beautiful pink granite, in a ledge exposure having a slope of about 

25°. Practically no soil covers the granite except on the east side, 

where slight stripping is necessary before quarrying. On the southeast side of the opening the partly discolored granite extends for

several feet from the surface downward; on the north side fresh granite 

begins practically at the surface. Oxidation resulting in a reddish 

discoloration of a thin outer layer of the rock is observed along the 

joint surfaces.

Two sets of vertical joints strike N. 10° E. and N. 70° W. and are 

spaced sufficiently far apart to admit of quarrying stone of almost 

any size. The joint surfaces show slickensides. So far as quarrying 

operations have extended in depth, the rock appears to lie in sheets 

which vary in thickness from 2 to 10 feet, with a probable average 

of 8 feet. The rock contains both large and small knots of dark-gray 

color. The feldspar of the knots is of a pronounced pink color and 

in the larger segregations it shows a marked porphyritic tendency.

The rock is a biotite granite of uniform pink color and should prove 

to be an excellent stone for all purposes that require granite of the 

best grades. Its susceptibility to a high polish makes it a most 

desirable stone for monumental and decorative stock. The texture 

is medium grained and is similar to that of the light-gray granite. 

Biotite is very sparingly present and the feldspathic constituent, 

uniformly colored pink, is evenly distributed through the stone. The 

working qualities of the rock are excellent.

Stone from this quarry was used in the building of the Catholic 

University and the new municipal court building, in Washington, 

D. C. This grade of pink granite is in much demand in Chicago 

and other northern and central cities for use as monumental stock. 

During the summer of 1905 the nearly white granite was quarried, 

chiefly for use in paving, and was shipped principally to Cincinnati, 

Ohio. The product from this quarry was used during 1908 for 

monumental stock, building stone, blocks, and crushed stone.

'The Consolidated Granite Company's quarries, 5% miles south of Salisbury, near the village of Faith, include a large number of openings.
142 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

Quarrying is reported to have begun some years prior to the civil 

war. Large areas of fresh granite practically free from decay are. 

exposed and the loose residual material, where present, is of slight 

depth and can be easily removed.

Two grades of granite are quarried a light-gray granite of the 

same color and texture as that quarried by the Kowan Granite 

Company and a pink granite of the same depth of color and texture 

as that quarried by the Balfour Quarry Company.

Vertical joints are strongly developed in the various openings, the 

planes being usually spaced at intervals sufficient to allow the quarrying of stone of any desirable size. Measurements of the joints in the 

openings gave, the following results:

N. 80° E. N. 50° W. North-south.

N.40'°E. . N.40°W. East-west.

N. 10°E. N.30°W.

The PJiiUips Mountain quarries are situated on Phillips Mountain, 

a large, low, conical peak about 1 mile southwest of Faith, which 

marks the southwestward extension of the Dimns Mountain ridge. 

The granite is exposed over the surface of the peak in the form of 

huge bowlder masses in which numerous quarries have been 

worked. (See PI. XVII, A.)

The rock is a biotite granite of very light-gray, nearly white color, 

and medium grain. The color and texture are fairly uniform over the 

area and the granite is a desirable stone for nearly all grades of work. 

Blocks of almost any size can be readily quarried. The stone works 

well under the hammer and is free from blemishes and harmful 

minerals.

The principal quarry operating on Phillips Mountain during the 

summer of 1908 was that of the Peeler Bame Company, which 

extracted stone for building and curbing. -

The Powlers Mountain quarries are situated on a low dome of granite 3 miles southwest of Faith and 9 miles southwest of Salisbury, 

locally known as Powlers Mountain, which marks the southwest 

extension of the granite ridge in Rowan County. It does not exceed 

100 feet in elevation above the surrounding plain. The granite is 

exposed in irregular hummocky surfaces, bare of loose residual material over much of the area but covered in places by a variable depth 

of the weathered product.

The rock is a biotite granite of light-gray color and medium 

grain. It is composed largely of feldspar and quartz, with very subordinate biotite.

Several openings were made in places on the slopes of the dome 

many years ago, and the surface raises were worked off. Examination of these ledges shows the rock to be considerably weathered, 

though still fairly hard and firm. The feldspars present a lusterless
U. S. GEOLOGICAL SURVEY

.1. BOWLDER QUARRY, PHILLIPS MOUNTAIN, NEAR FAITH, ROWAN COUNTY, N. C.

STONE MOUNTAIN, A GRANITE DOME, WILKES COUNTY, N. C
GRANITES OF NORTH CAROLINA. 143

appearance from kaolinization, and entirely fresh hand specimens of 

the rock could not be obtained. Two sets of joints, which strike 

N. 20° E. and N. 70° W., break the granite into blocks of different 

sizes. The N. 70° W. set is especially well developed and cuts the 

granite at closer intervals than the other set.

Woodleaf area. In the northwest corner of Rowan County numerous outcrops of a biotite granite occur in and around Woodleaf station, 11 miles northwest of Salisbury. A little of the granite has been 

quarried from a number of small openings for local use.

The rock is a biotite granite of medium-gray color and fine grain. 

The feldspathic constituent includes orthoclase and microcline, the 

former predominating.

The vertical joints strike N. 20° E. and N. 60° E. Abundant 

pyrite crystals are developed on the surfaces of the joints. There 

are some small dark knots. A slight schistose structure is developed 

in places.

IREDELlj COUNTY.

The Mooresville granite area, located in the southern part of Iredell 

County, furnishes probably the most desirable granite for monument 

stock in the State. A number of quarries have been worked near 

the town of Mooresville, from which the area derives its name.

Both even-granular and porphyritic granites occur. From the 

field evidence it appears that these are not simply textural phases of 

the same rock, but that the even-granular granite is the younger of 

the two and is intrusive into the porphyritic'granite. Both are biotite granites and differ from each other chiefly in texture.

The McNeely quarry, 1 mile northwest of Mooresville, comprises several small openings made in flat bowlder outcrops, worked to a depth 

of less than 10 feet. The granite bears a striking resemblance to the 

dark blue-gray granite at Oglesby, Elbert County, Ga. (pp. 218-223).

The rock is a biotite granite of dark blue-gray color and fine grain. 

Its minerals are potash feldspar (orthoclase and microcline), sodalime feldspar (oligoclase), quartz, and biotite, with accessory titanite, 

apatite, and zircon and secondary chlorite and epidote. Abundant 

feldspar and quartz intergrowths occur. Biotite manifests a tendency to segregate in minute blotches-containing several shreds to the 

area, similar to that of the granite at Oglesby, Ga.

A few knife-edge veins of feldspar were noted in places. Only one 

visible set of vertical joints intersect the granite in the openings, 

striking N. 65° W. The granite is of good quality and is susceptible 

of a high polish.

The Breed quarry, 2 miles southwest of Mooresville, includes two 

openings that have been worked at intervals since 1886. The larger 

opening, about 200 feet in length, is in a"ledge outcrop along a small. 

38971° Bull. 426 10 10
144 GEANITES OF SOUTHEASTERN ATLANTIC STATES.

stream at the base of a moderate hill slope, the top of which rises 

probably 20 to 25 feet higher. Stripping to a depth of 8 to 10 feet 

is necessary in places.

The rock is a biotite granite of dark blue-gray color and fine grain. 

In hand specimens it can not be distinguished from that of the 

McNeely quarry, to which it is similar in mineral composition. A 

partial chemical analysis of the granite from the west (Johnson) 

opening is given on page 117. .

Vertical joints strike east-west, north-south and N. 45° W., the 

last set being less prominent than the first two. About midway of 

the opening a zone of close jointing about 30 feet wide is exposed, 

from which dimension stone can not be quarried. With this exception the joints are usually spaced 18 to 20 feet apart. Horizontal 

joints divide the granite into sheets 3 to 8 feet thick. Beautiful contacts between the fresh even-granular and the porphyritic granites 

are exposed in the east opening.

The Biddell quarry, 3 miles northeast of Mooresville, comprises 

several small openings made in 1891. The product is reported to 

have been shipped to Pennsylvania Jor use as building stone. The 

largest opening is about 150 feet long and is worked to a depth of 

about 15 feet.

The rock is a biotite granite of medium blue-gray color and medium 

to fine grain. The same minerals are present as in the granite of 

the McNeely quarry (p. 143). Microcline is the dominant feldspar. 

There are a few small grains of magnetite.

Vertical joints, striking .north-south and N. 65° E., are spaced at 

wide intervals. Pegmatite dikes, varying in thickness from 1 inch 

to more than 12 inches, cut the granite indiscriminately. These are 

so numerous that hardly a block of the granite of any size can be 

quarried that would be entirely free from them. Light and dark

wavy streaks or bands, suggesting fiowage, appear in places. Because 

of this irregularity and the abundance of pegmatite dikes the granite 

is more restricted in its use than that from the McNeely and the 

Breed quarries.

DAVIDSON COUNTY.

Granites occupy extensive areas over much of Davidson County. 

They are biotite granites of gray color, ranging from even granular 

to porphyritic in texture and from massive to schistose in structure. 

The two textures represent different facies of the same granite mass, 

as the porphyritic granite grades into the even-granular rock of the 

same mineral composition.

The granites have not been regularly worked, but some stone has 

been quarried from time to time at a number of places as needed to 

supply the local demand. The openings are all small and are located 

in the vicinity of Lexington, the county seat, where the rock has been
SURFACE OF ORBICULAR GABBRO-DIORITE, DAVIE COUNTY, N. C.
GRANITES OF NORTH CAROLINA. 145

principally used. The earliest quarrying was done in 1856, when 

stone was taken out on the Conrad and Fritts places, 1£ miles north 

of Lexington, for use in the court-house at Lexington. The minerals 

are potash feldspar (orthoclase), soda-lime feldspar (oligoclase), 

quartz, and biotite, with accessory apatite, zircon, and magnetite and 

secondary chlorite, a colorless mica, epidote, and rutile.

A fine-grained biotite granite of schistose structure has been 

quarried to a small extent 2 miles south of Lexington, on the Sink 

place. The opening is about 100 feet long by 36 feet wide and 25 to 

40 feet deep.

DAVIE COUNTY.

The principal granite areas of Davie County are limited to the eastern half of the county and represent the westward extension of the 

Davidson County granite area. Both even-granular and porphyritic 

granites of the biotite variety are known, No quarries of granite 

have been worked in Davie County.

On the Hairston place, 10 miles west of Lexington, there are exposures of orbicular gabbro-diorite.a The rock is of dark color with a 

greenish cast imparted by the hornblende and diallage. It presents 

a pronounced mottled appearance, being made up of dark-green areas 

of hornblende, varying from an eighth of an inch to several inches 

in diameter, set close together, with the interstices filled with white 

feldspar. (See PL XVIII.) On a polished surface of the stone the 

effect is unique and beautiful, and the rock should prove of value for 

ornamental and decorative purposes.

COUNTY.

The Winston granite area, extending over the south-central portion 

of Forsyth County, is the most important area in the county. Evengranular and porphyritic biotite granites are represented. These 

grade one into the other, representing different facies of the same 

mass of similar mineral composition. No quarries have been regularly worked, but several small openings have been made a few miles 

to the east and south of Winston to supply a local demand for stone 

in Winston-Salem. Quarrying has been limited to the p'orphyritic 

granite, which is described on page 169.

GUILFORD COUNTY.

Of the granite distributed in numerous areas over the northern, 

central, and western portions of Guilford County, but little is specially 

desirable for the higher grades of work. Regular quarries have 

nowhere been worked, but numerous small openings have been 

made to obtain stone of a certain grade for local use. Some stone

a Watson, T. L., Orbicular gabbro-cliorite from Davie County, N. C.: Jour. Geology, vol. 12, 1904, pp. 

294-303.
146 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

has been quarried in five localities the Brown Summit area, the 

Summerfield area, the Friendship area, the Jamestown area, and the 

Greensboro area.

The granites are biotite granites, and with the sole exception of a 

porphyritic granite occurring near Friendship, they are even granular 

in texture and more or less schistose in structure.

Brown Summit area. The Brown Summit area is located near the 

Southern Railway, 10 miles north of Greensboro. On the Walker 

place is a single opening in a light-gray foliated granite, from which 

a little stone was first quarried prior to the civil war.

The rock is a biotite granite, containing much muscovite in places, 

and of variable texture and color. Potash feldspars (microcline and 

orthoclase) and quartz are the principal minerals; soda-lime feldspar 

(oligoclase) occurs but sparingly. The effects of pressure metamorphisni are pronounced in the thin sections.

Abundant pegmatite dikes, most of which strike N. 60° E., penetrate the granite. Some of them intersect, with a displacement of 

several inches. The principal set. of vertical joints strikes N. 60° E. 

and the surfaces of the joints are slickensided. This granite can be 

used only in the lower grades of work.

Summerfield area. Another area is located 12 miles northwest of 

Greensboro, at Summerfield station. Several openings have been made 

to obtain granite for macadamizing roads and for street work in 

Greensboro. The principal openings are on the Hoskins and Gamble 

places, within a mile of Summerfield.

The rock is a biotite granite of variable color, texture, and structure. At the Gamble opening the porphyritic texture predominates 

over the even granular. Soda-lime feldspar (plagioclase) is but 

sparingly present in the thin sections of the granite from both places. 

At the Gamble place dark knots occur in the granite. Vertical 

joints at the Hoskins opening strike N. 10° E. and N. 70° E.

Friendship area, This area lies 10 miles west of Greensboro, near 

Friendship station. The only stone quarried has been the porphyritic granite described on page 169.

Jamestown area: Half a mile southeast of Jamestown, on Bull 

Run, several small openings are made in a porphyritic granite. .The 

rock is dark gray, fine grained, and thinly schistose. It is composed 

of a very fine-grained groundmass of quartz and feldspar with some 

biotite, largely altered to chlorite, much epidote, and a colorless mica, 

in which are embedded porphyritic crystals of oligoclase, orthoclase, 

and quartz. Bluish opalescent quartzes characterize the hand 

specimens of the rock. Vertical joints, striking N. 20° E. and N. 

40° W., cut the granite porphyry at close intervals. A single diabase 

dike, striking N. 40° to 50° W., penetrates the granite porphyry several 

hundred feet north of the opening.
GRANITES OF NORTH CAROLINA. 147

At the Oakdale cotton mills, on Deep River, 1 mile southeast of 

Jamestown, are extensive exposures of granite, which was quarried for 

use in building the cotton-mill dam at that point. It is a biotite granite of gray color and medium grain, somewhat schistose in structure. 

Soda-lime feldspar (oligoclase) nearly equals in amount the potash 

feldspar (orthoclase). Very little microcline is present. Dark knots, 

principally of segregated biotite, of irregular outline and variable 

size, are abundant in the granite. A number of parallel dikes of diabase, striking N. 20° E., intersect the granite at the mill site.

Some granite has been quarried on the Modlin place, 1£ miles southeast of Jamestown. It is a biotite granite of dark-gray color and 

medium grain. Its uniformity of color and texture make it a desirable stone for many purposes. Orthoclase and oligoclase are nearly 

equal in amount. Microcline was not observed in the thin sections.

Greensboro area. Two quarries, one in granite the other in diorite, 

are worked for macadam just beyond the northern limits of Greensboro. The granite is a biotite granite of medium-gray color and 

medium-coarse grain. Nearly equal plagioclase and orthoclase, with 

a little microcline, quartz, and biotite, make up the essential minerals 

in the thin sections.

Vertical joints, spaced at close intervals, strike N. 20° E., N. 50° E., 

and N. 20° W. Slickensides are well developed along the joint surfaces. The granite is further penetrated by dikes of dark greenishblack amphibolite, varying from a few inches to 18 inches in thickness 

and striking N. 20° E. The granite is very uniform in color and 

texture, but dimension stone can not be quarried because of the close 

jointing.

ALAMANCE COUNTY.

Granites of irregular color and texture are found in the vicinity of 

Burlington, the county seat of Alamance County, principally to the 

north, east, and southeast of the town. They are biotite bearing, 

schistose in places, and of little value except for the lower grades of 

work. According to the amount of biotite present the color varies 

from very light to medium and dark gray. In texture the rock ranges 

from fine to moderately coarse.

A number of small openings have been made in places to obtain 

stone for purely local purposes. About 4 miles north of Burlington 

small quantities of the granite have been quarried for window and 

door sills in factories of that vicinity. Two miles east of Burlington 

granite of variable color, texture, and structure has been, quarried for 

use as macadam. Near the southeast limits of Burlington, a small 

quantity of granite has been quarried, but the rock at this point lacks 

uniformity in color and texture.

An area of syenite porphyry is exposed along Haw River and its 

tributaries, at the Altamahaw and Ossipee cotton mills, about 7 miles
148 GRANITES OP SOUTHEASTERN ATLANTIC STATES.

northeast of Burlington. The rock is a compact, exceedingly hard, 

fine-grained, dark-gray syenite porphyry. The feldspar phenocrysts 

are not large nor conspicuously developed in the rock. Named in 

order of abundance the minerals of the groundmass are orthoclase, 

oligoclase, biotite, muscovite, epidote, magnetite, pyrite, and a little 

quartz. Oligoclase, some orthoclase, and less biotite are the porphyritically developed minerals.

Vertical joints strike N. 10° E. and N. 60° to 70° W. A few pegmatite dikes occur. Several small openings have been made and a little 

of the stone has been quarried for use as granite.

WESTERN PIEDMONT GNEISS AND GRANITE BELT.

INTRODUCTORY STATEMENT.

The rocks of the western Piedmont in North Carolina are composed 

largely of schists and gneisses of the mica type. They show considerable variation in composition and texture where examined, and are 

probably in large part of sedimentary origin. Some of the gneisses, 

however, are certainly altered igneous masses whose structural 

resemblances to sedimentary rocks are due to the effects of dynamometamorphism.

Besides these there are areas of both acidic and basic igneous rocks 

invading the gneiss-schist complex. Among the acidic igneous rocks 

are massive and foliated granites that are workable in many parts of 

the belt, the more important areas being in Surry, Wilkes, Alleghany, 

and Alexander counties. There are other granite areas in this belt, 

but so far as known they are of little economic importance.

At present granite quarrying in the belt is limited exclusively to 

Surry County, where, in the vicinity of Mount Airy, one of the largest 

quarrying industries in the State is developed.

Surry County. The principal outcrops of granite in Surry County 

are found in the northern part of the county near the Virginia line, 

in the vicinity of Mount Airy, the county seat. The granite' is 

exposed in flat-surfaced masses in rather an advanced stage of decay, 

immediately to the north and south of Mount Airy, where quarrying 

on an extensive scale has been conducted for some years.

The North Carolina Granite Corporation's (Mount Airy) quarries, 

located less than 1 mile northeast of Mount Airy, were opened in 1889 

and the first shipment of stone from them was made in July, 1890. 

The total shipment of granite from these quarries from 1890, when 135 

carloads were shipped, to 1904, when 1,282 carloads were shipped, was 

13,232 carloads. (See PI. XIX, A, B.}

Quarrying is confined to a 40-acre tract of continuously exposed 

granite over the slope and top of a long hill, which rises about 125 feet
U. S. GEOLOGICAL SURVEY lULLETIN 426 PLATE XIX

MOUNT AIRY GRANITE CORPORATION'S QUARRIES, SURRY COUNTY, N. C.
GRANITES OF NORTH CAROLINA. 149

above the valley bottom. The company holds more than 200 acres 

additional of ground over which granite is exposed. Quarrying has 

extended over practically the entire 40-acre tract, the greatest depth 

of working being about 30 feet.

The rock is a biotite granite of very light gray, nearly white color 

and medium grain. The biotite is not, except in one opening, equally 

distributed through the granite, but is entirely absent from some parts 

of it, is uniformly distributed through others, and shows a marked 

tendency to segregation in still other parts. Quartz-feldspar areas 

of extreme whiteness, ranging from several inches to as many feet in 

diameter, in which biotite is entirely lacking or represented by only 

a few shreds, are common through the granite. This unequal distribution of the characterizing accessory (biotite) renders the granite 

in places less uniform in color than might be desirable for some purposes. The granite that has a uniform color is most pleasing in appearance and forms excellent and desirable stone for all US6S except for 

monumental stock,, for which the contrast of color between the cut and 

polished faces is not great enough.

Microscopically the principal minerals are potash feldspar (orthoclase and microcline), soda-lime feldspar (oligoclase), quartz, and 

biotite, with accessory apatite and zircon, and secondary chlorite, 

epidote, light-colored mica, and iron oxide. Plagioclase feldspar 

exceeds the potash feldspars in amount. Zonary structure and Carlsbad twinning are beautifully developed in some of the feldspars. 

Intergrowths of the feldspars with one another and with quartz are 

abundant. A partial chemical analysis of the granite is given on 

page 117.

The crushing strength of the granite is well shown in the following 

tests, made on specimens of the stone by different parties and at 

different places: a

Crushing siren-jlh of 2-inch cubes cf granite from quarries at Mount Airy, N. C.

M. A

M A

M. A

M A

M A

M A

Marks.

1............................................

10...........................................

13...........................................

10...........................................

Crushed

at 

Pounds.

on 70S

86,460

90 780

en nrifi

74,870

1.

Strain per 

square inch.

Pounds.

Of) dCQ

21,292

22 4(jg

20,086

' Crushed 

1 at 

Pounds.

7Q Qftn

art 3^n

0 1 (lf){\

2.

Strain per 

square inch.

Pounds. IQ 7*sn

OA AOQ

' 20 400

'

20,070

1. U.S. Navy-Yard, Washington, D. C., April 1C, 1890; Charles O'Neil, commander, U.S. N., and Bureau 

of Ordnance, U. S. N.

2. Testing department of the Philadelphia Scale and Testing Machine Works, Philadelphia, Pa., November 4,1895; Ilienle Bros.

a Bull. North Carolina Geol. Survey, No. 2,1906, pp. 155-156.
150 GRANITES OP SOUTHEASTERN ATLANTIC STATES.

The specimens broke suddenly with a.loud report, several large 

pieces and a lot of fine material resulting from each test.

Two tests made by Prof. F. P. Venable, of the University of North 

Carolina, at Chapel Hill, October 24, 1895, as to the capacity of the 

granite from Mount Airy for absorbing water, yielded the following 

result:

Weight, in grams, of water absorbed by granite from Mount Airy, N. C.

'

Weight after being soaked in water 24 hours and then allowed to dry in air 24 hours. ....

1.

830.4

830.8

.4

2.

1,001.7

1, 002. 1

.4

The veins and dikes found in most granites are not seen in the 

Mount Airy quarries, and visible vertical jointing is almost entirely 

lacking.

The company is adequately equipped with all necessary modern 

machinery and appliances for quarrying and handling the stone. In 

1905 a large stone-cutting plant was erected. The stone is carried 

from the quarries to the railway cars by a system of inclined cableways, run by gravity. The limit in size of dimension stone is the 

capacity of the railroad cars. Blocks weighing 20 tons are reported 

to have been frequently shipped from the quarries. (See PI. XX.)

The product is marketed over a large territory, chiefly iii .the 

States south of New York. It is used for general building and 

paving purposes. The quarry waste is utilized for concreting, 

roofs on cotton mills, macadam on streets and roads, ballast along 

the railroads, and granolithic work. All the stone used in the large 

dry dock at Newport News, Va., and the concreting material used in 

the Fort Caswell fortifications, Cape Fear River, North Carolina, came 

from the Mount Airy quarries.

The method of quarrying the granite a consists in drilling a hole 

about 3 inches in diameter perpendicular to the surface to a depth 

equal to the thickness of the stone desired, usually 5 to 7 feet, and 

then firing a succession of light blasts. The operation is begun by 

discharging about one-fourth of a pound of dynamite in the bottom 

of the hole; this small charge pulverizes the stone slightly and 

forms a small chamber. The tamping is then cleaned out and the 

hole is recharged in the same manner, this time, however, with 

about a handful of powder. Small charges of powder are exploded 

in the hole until a small seam has been started at the bottom, extending parallel with the surface. To determine if this has been done, 

a small steel rod bent at the lower end and sharpened to a point is

oBull. North Carolina Geol. Survey, No. 2,1906, pp. 157-160.
GRANITE MONOLITH FROM MOUNT AIRY, SURRY 
GRANITES OF NORTH CAROLINA. 151

passed up and down the hole until the crack is located. After the 

crack has once been started the charges are gradually increased until 

it extends a distance of 75 feet or more from the hole. The use of 

explosives is then discontinued, and a water-tight connection to 

the hole is made by fastening a piece of iron pipe in the hole with 

melted sulphur. To this connection is attached an ordinary hand 

force pump, and water is pumped into the crevice formed by the 

explosives. The crevice is extended by continuous pumping for a 

few hours until, finally it covers an area of perhaps 2 acres and the 

pressure finds vent by tearing the rock out to thin edges on the side 

of the hill. This method is used in the warmest weather, when the 

surface of the rock is naturally somewhat expanded and more easily 

raised. It is very doubtful whether it could be employed during 

cold weather; experience shows that the hotter the weather the 

easier the work. Sheets of stone covering areas of 1 to 2 acres and 

from 6 to 8 feet thick close to the hole are easily raised by this method. 

It is found necessary to clean off a ledge of stone made in this manner 

before attempting to form or raise another sheet on the surface 

below. For this reason the quarry covers considerably more area 

than one having natural seams horizontal sheeting.

In another method now used the sheets are split off with compressed air, which has been found to be even more effective than 

water. The method of employing compressed air, according to Mr. 

Thomas Woodroffe, vice-president of the company, is as follows:

The procedure is the same as that just described, until the crevice 

extends a distance of 75 feet or more from the hole in all directions. 

A pipe is then cemented into the hole and connected by means of .a 

globe valve to an air pipe line from an air compressor. Compressed 

air at a pressure of 70 to 80 pounds is gradually admitted and the 

crack is rapidly extended until it comes out on the hillside. A 

sheet several acres in extent may be raised in this manner, affording 

a bed plane approximately horizontal, to which the quarrymen can 

work, thus obtaining stone of any required thickness." The first time 

this method was used, air under a pressure of 80 pounds was admitted 

into the cavity which had previously been extended to a distance of 

100 feet from the lift hole. The power of the air, however, was too 

great for the easily splitting stone and the cleavage turned abruptly 

to the surface. In the next hole, however, the compressed air was 

admitted very gradually and the stone could soon be heard cracking 

in all directions, and in about half an hour the cleavage came to the 

surface of the hillside about 225 feet from the lift hole. To extend the 

cleavage by means of powder for 100 feet would require from six to 

twelve days and with water from three to five hours, whereas with 

compressed air a larger area was split in half an hour.
152 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

Wilkes and AllegJiany counties. Lying partly in the northeastern 

portion of Wilkes County and partly in the adjacent southeastern 

portion of Alleghany County are numerous closely grouped large 

granite bosses or dome-shaped residual masses. One of the largest 

of these is Stone Mountain (see PL XVII, B), 20 miles slightly east 

of north of Wilkesboro, the county seat of Wilkes County. Some of 

the other large masses are Little Stone Mountain, Cedar Rock, Wolf 

Rock, and Beauty Falls Rock.

These granite masses vary in height from 100 to 600 feet and in 

circumference at the base from 2 to 6 miles. There are eight or ten 

of them, characterized by steep, nearly precipitous slopes rising from 

narrow intervening valleys. Both the tops and the slopes are usually 

covered with a scant veneer of soil, sufficient in many places to 

maintain a fair growth of trees. In some of them, however, the tops 

and the slopes are entirely bare, exposing the hard though partly 

decayed granite.

These residual masses are composed of granite of similar color, 

texture, and composition. It is a biotite granite of light-gray, nearly 

white color and medium grain, a trifle coarser grained than the 

granite from the Mount Airy quarries, which it otherwise closely 

resembles. Fresh specimens of the granite could not be obtained, 

as no quarries have been opened. Dark areas (knots) chiefly of 

segregated biotite, are somewhat abundant in certain portions of the 

granite. Like the granite of the Mount Airy quarries, the rock of 

these bosses is largely free from vertical joints. Less than half a dozen 

joint planes were observed in the Stone Mountain mass; their strike 

was northeast and northwest. In the narrow valleys separating the 

large masses the granite is broken by two principal sets of closely 

spaced vertical joints, which have general northeast and northwest 

strikes.

The western Piedmont belt is composed largely of gneisses of variable composition and texture, which in many places could be quarried 

and used to advantage in certain grades of work. One of the most 

promising bodies of gneiss, commercially, in this belt is Rocky Face 

Mountain, in Alexander County, about 6 miles northeast of Taylorsville, the county seat. This mountain is an elliptical dome-shaped 

mass of granite gneiss rising to an elevation of not less than 500 feet 

above the surrounding plain and measuring several miles around the 

base. It has an approximate northeast-southwest trend and generally steep slopes.

The rock is a biotite granite gneiss of light-gray color and medium 

grain. The banding is of irregular thickness though generally thin.
GRANITES OF NORTH CAROLINA. 153

The principal minerals are potash feldspar (orthoclase and microcline), 

soda-lime feldspar (oligoclase), quartz, and biotite, with the usual 

accessories. Feldspar intergrowths (microperthite) are abundant. 

Red garnet in small grains and crystals is a common mineral in places. 

Recrystallization and crushing of the rock minerals are pronounced 

in the thin sections.

Vertical joints, spaced at wide intervals and of inconspicuous development, strike N. 30° E. and N. 80° E. A few quartz veins, contorted and crushed from pressure metamorphism, penetrate the rock 

in places.

No quarries have been opened, but stone has been stripped from 

the surface in several places for local use. The rock is closely similar 

to the contorted biotite granite gneiss at Lithonia, DeKalb County, 

Ga., and at Beveiiy, Pickens County, S. C., described on pages 197-198, 

253-262, and should prove equally desirable.

APPALACHIAN MOUNTAIN GRANITES.

GENERAL DESCRIPTION.

In North Carolina the Appalachian Mountains include an- irregular 

mountainous region lying between the steep southeastern slope of the 

Blue Ridge and the northwestern slope of the Great Smoky Mountains. The region has an approximate area of 6,000 square miles and 

an average elevation over all parts of its surface of 2,700 feet. Many 

of the peaks rise to elevations of more than 5,000 feet, and Mount 

Mitchell, the highest one, has an elevation of 6,711 feet.ft

The principal rocks are gneisses, granites, schists, slates, limestones, 

quartzites, and conglomerates, cut in places by basic eruptive rocks.

Five of the geologic folios b published by the United States Geological Survey cover a considerable part of the North Carolina mountain province and show that it contains extensive areas of gneiss 

and granite suitable for building stone. With only one exception 

the Whiteside granite, in the southeastern portion of the Pisgah 

quadrangle, covering parts of North and South Carolina the granites 

and gneisses of this region are assigned by Keith to the Archean. 

The granite and gneiss formations in the five quadrangles, with 

their general character and age, are tabulated below.

a Bull. North Carolina Gcol. Survey, No. 2, 190G, p. 104.

b Cranberry (No. 90), 1903; Asheville (No. 110), 1904; Mount Mitchell (No. 124), 1900; Nantahala (No. 

143), and Pisgah (No. 147), 1907.
154 GRANITES' OF SOUTHEASTERN ATLANTIC STATES.

Granite and gneiss formations of Appalachian Mountains in N.orth Carolina.-.

CRANBERRY QUADRANGLE.

Archean:

Beech granite......... Coarse, light-reddish porphyritic granite.

Blowing Rock gneiss. .Chiefly dark coarse porphyritic gneiss. 

. Cranberry granite.... .Mainly granite and granite gneiss.

Roan gneiss........... Chiefly hornblende gneiss and diorite.

Carolina gneiss.........Chiefly mica gneiss and mica schist; includes

other gneisses, granite, and diorite.

ASHEVILLE QUADRANGLE. 

Archean:

Max Patch granite.. ...Coarse or porphyritic, light gray or red.

Cranberry granite.... .Mainly granite and granite gneiss.

Roan gneiss............Chiefly hornblende gneiss and diorite

Carolina gneiss........Chiefly mica gneiss and mica schist; includes

other gneisses, granites, and diorites and

small lenses of marble.

MOUNT MITCHELL QUADRANGLE. 

Archean:

Hendersongranite.... .Porphyritic granite and gneissoid granite.

Cranberry granite..... .Mainly granite and granite gneiss.

Roan gneiss......... ..Chiefly hornblende gneiss and diorite.

Carolina gneiss........ Chiefly mica gneiss and mica schist; includes

other gneisses, schists, granite, diorite, and

small lenses of marble.

NANTAHALA QUADRANGLE.

Archean:

Granite................ Granite and gneissoid,granite.

Roan gneiss........... .Hornblende gneiss, hornblende schist, and

diorite. 

Carolina gneiss........ .Mica gneiss and mica schist.

PISGAH QUADRANGLE. 

Post-Cambrian: - Whiteside granite.....Biotite-muscovite granite, slightly schistose. 

Archean:

Henderson granite.....Porphyritic granite and gneissoid granite.

Roan gneiss........... .Chiefly hornblende gneiss and schist.

Carolina gneiss........ Chiefly mica gneiss and mica schist; includes

other gneisses, granite, and diorite.

The principal characters of these formations, beginning with the 

oldest, as mapped and described by Keith, are briefly summarized 

below.

CAROLINA GNEISS.

The Carolina gneiss, so named because of its great extent in 

North and .South Carolina, is the oldest formation in the region. 

It is the most extensive formation in the mountain region and consists of an immense series of interbedded mica gneiss, mica schist, 

and fine granitoid layers of light or dark gray color. In places 

granite masses up to 100 feet thick cut through the gneiss at all 

angles. These are massive, fine grained, uniform in texture,
GRANITES OF NORTH CAROLINA. ' 155

and of light-gray color, and are composed of quartz, orthoclase, 

and plagioclase feldspar, biotite, and muscovite, the last usually 

in subordinate amount. The mica schists are rarely coarse grained, 

and are composed of quartz, muscovite, a little biotite, and a very 

little feldspar. The granitoid layers contain quartz and feldspar, 

with muscovite and biotite in small amounts; in the light-colored 

bands the biotite and most of the muscovite are lacking. The granitoid, layers and schists alternate in bands varying from a few inches 

up to 50 feet in thickness. Bands similar in composition and from 

one-tenth of an inch to 1 inch thick form the banded gneisses.

As a rule, the Carolina gneiss is too irregular in texture and structure to be of value 'as a building stone. Many of its bands can be 

used for rough work, such as retaining walls, foundations, macadam, 

and ballast. The granite and gneiss bands in the Carolina gneiss are 

quarried in the vicinity of Asheville and are used chiefly for road 

material. The roads in the vicinity, and especially those of Asheville, are constructed of rock from this formation and are reported 

to be very satisfactory.

ROAN GNEISS.

The Roan gneiss, so named from Roan Mountain, on the boundary 

of North Carolina and Tennessee, consists chiefly of hornblende 

gneiss, hornblende schist, and diorite, with some interbedded mica 

schist and gneiss similar to the Carolina gneiss. It is younger and 

very much less extensive than the Carolina gneiss, and as yet has 

proved of no value as a building stone.

CRANBERRY GRANITE.

The Cranberry granite, named from Cranberry, Watauga County, 

N. C., consists of granite of varying texture and color and of schists 

and granite gneisses derived from granite. A broad belt of this 

granite passes diagonally through the Asheville quadrangle, extending 

southwestward through the Mount Guyot quadrangle and northeastward through North Carolina and far into Virginia. Its principal minerals are quartz, orthoclase and plagioclase feldspar, biotite, 

muscovite, and in places hornblende. Minor accessory minerals 

are magnetite, pyrite, ilmenite, garnet, and epidote. Feldspar 

greatly predominates, imparting a light-gray color to the granite, as 

a rule.

. The granite varies from light gray, nearly white, to red in color 

and from a fine, even-grained rock to a coarse-grained porphyritic 

granite in texture and is schistose in structure. The Cranberry 

granite is one of the most desirable in the mountain region of the 

State for building stone, and its areas afford abundant opportunity 

for the location of quarries.
156 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

Southeast of Hayesville, Clay County, in the Nantahala quadrangle, is a belt of biotite granite which Keith states is probably 

to be correlated with the Cranberry granite. It is of fine or medium 

grain, mostly massive but partly gneissoid and schistose in structure, 

and composed chiefly of orthoclase and plagioclase feldspar, quartz, 

biotite, and muscovite, named in the order of abundance. Minor 

accessory' minerals are hornblende, pyrite, magnetite, and garnet. 

This granite is probably too variable hi texture and color and in places 

too schistose to yield desirable building stone.

BLOWING ROCK GNEISS.

The Blowing Rock gneiss derives its name from a large body 

of gneiss exhibited in Watauga County, near Blowing Rock. It 

extends southward into Caldwell County. "The formation consists 

entirely of gneiss of two varieties, one with large, porphyritic crystals, 

the other of very fine, even grain.. The former consists of large orthoclase crystals embedded in a groundmass of feldspar, quartz, 

biotite, and muscovite; the latter consists of the same minerals in 

crystals of uniform size and granitoid appearance. "a The feldspar 

phenocrysts are commonly twinned and range in length up to 3 

inches. Owing to the large amount of biotite present, the gneiss 

is of.dark-gray or blackish-gray color. In some places the porphyritic 

and even-grained gneisses grade into each other; in others they are 

interbedded. Because of its schistose structure the Blowing Rock 

gneiss yields easily worked slabs, which split readily along the planes 

of foliation. Keith mentions this rock as an ornamental stone.

BEECH GRANITE.

A large area of the Beech granite occupies the southwestern portion of Watauga County in Beech Mountain, from' which it derives 

its name, and extends westward into Tennessee. It is a coarsegrained porphyritic granite composed of orthoclase and plagioclase 

feldspar, quartz, biotite, and very little muscovite. Orthoclase is 

the porphyritic mineral, the phenocrysts measuring 2 inches in length. 

Felelspar is largest in amount and usually imparts a light color to the 

rock. Biotite is abundant in the more massive portions of the rock, 

giving a spotted appearance to the granite because of the large size 

of its crystals. Near the border of the area a coarse red granite 

occurs, the red color being due to the pink or red feldspar present 

in the rock. This granite has been squeezed and mashed until it has 

acquired a pronounced gneissoid structure.

MAX PATCH GRANITE.

The Max Patch granite is displayed in ten or more areas hi Madison 

and Haywood counties, N. C., chiefly the former, and extends into 

Cocke and Unicoi counties, Tenn. The largest area surrounds Max

o Pisgah folio (No. 147), Geol. Atlas U. S., U. S. Geol. Survey, 1907, p. 3.
GRANITES OF NORTH CAROLINA. 157

Patch Mountain, from which the formation derives its name, near 

the Tennessee-North Carolina boundary, in the extreme southwest 

corner of Madison County. Keith describes the Max Patch granite 

as follows: 0

The formation consists almost entirely of coarse granite, in places porphyritic and 

iii places of uniform grain. The minerals which compose the rock are orthoclase and 

plagioclase feldspar, quartz, biotite, and a very little muscovite. Accessory minerals 

are magnetite, pyrite, and epidote, the latter being, for the most part, in secondary 

veins and patches. Porphyritic crystals of orthoclase feldspar whose lengths exceed 

1 inch are not infrequently to be seen. These are most common north of Big Laurel 

Creek, where the formations cross the state boundary into Tennessee. The other 

masses, particularly that around Bluff Mountain, are composed of the uniform massive 

variety, which is more characteristic of the formation as a whole. In the porphyritic varieties the feldspars make by far the greatest part of .the rock, giving it a lightgray or dull-whitish color. In the massive parts of the formation biotite is prominent and causes a decidedly spotted appearance by the large size of its crystals.

Another variety of great extent is a coarse red granite. This appears to be a modification of the usual massive rock, from which it differs only in having many red Of 

pink feldspars. These give a very marked red color to the whole rock.

The feldspar is in places partly altered into epidote and saussurite. 

In the extreme stage of alteration the feldspar has been so far replaced by the epidote that this mineral composes one-third or onehalf of the bulk of the rock. This is especially noticeable on Max 

Patch Mountain, but it is by no means restricted to that locality. 

Practically all the feldspars have been so altered in other places. 

Likewise the biotite is altered into chlorite and fibrous hornblende. 

Besides these processes there was a considerable growth of epidote 

in small veins and segregated patches, described under unakite 

below.

Like the Cranberry granite, the Max Patch granite has been 

squeezed and mashed until at many places it has developed a pronounced gneissoid structure. Those portions of the Max Patch 

granite which are marked by red feldspar and yellow-green epidote 

should prove desirable for ornamental stone. The porphyritic portions of the granite also present a striking appearance and might be 

used to advantage for the same purpose. Opportunities for quarrying are abundant, especially along the streams, where fresh rock can 

be readily obtained.

UNAKITE.

A type of granite occurring in this area is the unique and beautiful 

variety known as unakite, composed of yellow-green epidote, dull 

pink or red feldspar, and quartz. It occurs in small narrow veins 

and segregated patches in the Max Patch granite described above. 

The unakite where observed is not uniform in color and composition 

but shows pronounced gradations into a pink feldspathic rock on the

a Asheville folio (No. 110), Geol. Atlas U. S., U. S. Geol. Survey, 1904, p. 4.
158 GEANITES OF SOUTHEASTERN ATLANTIC STATES. '

one hand and a yellow-green epidote rock on the other. The several 

phases of the rock here described usually occur in the same "vein/' 

the unakite proper occupying, as a rule, the middle portion and grading toward the sides, next to the inclosing granite, into either a feldspathic or an epidote rock or both. The typical unakite portions of 

the "veins" show a coarse massive rock of even texture ami of lightpink and green color. "

The exposure best showing the relations between the unakite and 

the Max Patch granite was seen along Roaring Fork, a short distance 

above its entrance into Meadow Fork. At this point the vein character of the unakite was entirely apparent. The other exposures 

examined were almost entirely covered by decayed material which 

obscured the contacts between the unakite and the inclosing rock, 

and therefore revealed little or nothing of the real relations between 

the two.

Microscopically, the unakite-bearing (Max Patch) granite is composed' of orthoclase and microcline in nearly equal proportions, a 

little plagioclase, quartz, a little biotite, zircon, apatite, rutile, magnetite, and a few small grains of pyrite. The secondary minerals 

are a colorless and a green mica, epidote, chlorite, and kaolin. The 

epidote is clearly an alteration product derived from the interaction 

of the ferromagnesian constituent and the feldspar. It occurs in the 

form of minute microscopic granules, thickly crowded together in 

large and small areas in the feldspar, next to. the biotite where that is 

present. The quartz contains innumerable long lines of threadlike 

inclusions of rutile, broken into very many minute segments but 

always perfectly aligned. In addition to the epidote the colorless 

mica derived from the feldspar almost completely obscures, in a few 

places, the original mineral.

Some peripheral shattering is manifested in the small interstitial 

areas and the narrow border zones of a fine-grained mosaic. The 

effect of dynamic forces is further shown in strain shadows and lines 

of fracture in the quartz and feldspar. In some places the larger 

feldspar grains are much fractured and the lines are filled with another 

mineral; in others alteration has progressed along these lines and 

patches of deep-green mica are developed in them.

A thin section of the unakite shows a moderately coarse-grained 

granite composed of orthoclase, quartz, and epidote, with titaniferous 

iron oxide largely altered to leucoxene, rutile inclusions, and secondary 

muscovite. The quartz and feldspar individuals are considerably 

fractured, and they show additional strain shadows with some 

peripheral shattering, indicative of intense dynamic deformation.

The epidote shows, from its mode of occurrence and association in 

the thin sections, that it is entirely a secondary mineral. It occurs 

in large masses composed of minute microscopic granules, many of
GRANITES OF NORTH CAROLINA. 159

them replacing the entire feldspar individuals, and as continuous and 

irregular disconnected bands and areas of large and small size, following the fractures in both the feldspar and the quartz but most extensively developed in the feldspar. The development of epidote along 

the breakage lines can be continuously traced in many places from 

the larger areas or masses replacing the entire feldspar individuals 

across or into contiguous feldspars. In still other places the feldspar 

shows scattered granules of epidote over its surface. All gradations 

between these two extremes of epidotization appear. Hardly any of 

the feldspar in the sections examined was entirely free from some 

epidotization.

Besides epidote, the other (secondary) mineral matter consists 

mostly of quartz, which locally fills the cracks in.the larger quartz 

and feldspar grains made by the fracturing. Some of the less epidotized feldspar shows additional alteration into a colorless mica and

some kaolin. No plagioclase and no ferromagnesian minerals were 

recognized in any of the sections of the imakite.

HENDERSON GRANITE.

The Henderson granite derives its name from the extensive areas 

and exposures of the granite in Henderson County, N. C. It crosses 

the Pisgah quadrangle (Henderson and Transylvania counties) in a 

northeast-southwest direction, in a belt 6 or 8 miles wide, and extends 

southwestward into South Carolina. The granite is composed 

chiefly .of orthoclase and plagioclase feldspar, quartz, muscovite, and 

biotite, named in the order of their abundance. Biotite is usually 

subordinate in amount but is subject to much variation. Both 

porphyritic and even-granular varieties of the granite are common, 

grading into each other. The granite is gray in color and generally 

gneissoid in structure, although small areas of massive rock, usually 

fine or medium grained and containing very little biotite, occur here 

and there. In the gneissoid portions of the porphyritic granite the 

feldspar phenocrysts are drawn out to more than twice their original 

length, few of the unaltered crystals being more than an inch long.

Extensive outcrops of the Henderson granite are common throughout the area, especially near French Broad River, in cliffs and steep 

slopes which afford available quarry sites. Keith states that the 

stone- dresses well and is exceedingly hard and durable. Much of the 

granite has been quarried at the following places on or near the 

French Broad: At Johnson Bridge or Horseshoe, Henderson County; 

several miles north of Hendersonville, at Balfour station, by the 

Balfour Quarry Company; less than 2 miles east of the TransylvaniaHenderson county line, near Etowah, in Henderson County; and 

at several points near Wilson Bridge in Transylvania County. The 

product was used locally in bridges and buildings and for railroad 

ballast and macadam.

38971° Bull. 426 10 11
160 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

WHITES1DB GRANITE.

The Whiteside granite derives its name from Whiteside Mountain, 

where, according to Keith, it forms a series of enormous cliffs. (See 

PL XIV, B.} There are 2 acres of the granite lying on the east 

and west sides of the Henderson County line, extending southeastward into South Carolina and southwestward into South Carolina and 

Georgia. It is a biotite-muscovite granite of light-gray color and fine 

to medium grain, and is generally massive in structure. Because of 

its massive character and because it cuts the other rocks of the region, 

Keith refers it doubtfully to post-Cambrian age and states that it 

may be as late as Carboniferous. Named in the order of their 

importance, the principal minerals are orthoclase and plagioclase 

feldspar, quartz, muscovite, and biotite. Minor accessory minerals 

are magnetite, ilmenite, pyrite, and garnet. Feldspars are the 

dominant minerals. Biotite varies considerably in amount and in 

places is entirely lacking. A porphyritic phase of the granite occurs 

in places along the border portions of the area.

Regarding the economic features of this granite Keith says: a

The Whiteside granite yields excellent stone of a more massive texture than the 

Henderson. Its color is light gray or white, and its grain is medium and very uniform 

through large bodies. It splits out in thick sheets and dresses very. well. Its durability is shown by its enormous cliffs in Table Rock and Lookingglass Mountain. 

Along the Blue Ridge are found the best natural outcrops, but quarries could be developed readily at nearly any locality in the areas. The cover of soil is seldom heavy over 

the rock and weathering is not deep. The stone has been used for dams, chimneys, 

and abutments.

SUMMARY OF THE GRANITES OP THE MOUNTAIN REGION.

Granites are widely distributed over many parts of the mountain

region of North Carolina. As a rule, they are gneissoid in structure

as a result of intense pressure metamorphism, although massive 

forms are by no means uncommon. In color they range from nearly 

white through different shades of gray to deep reddish pink, and in 

texture from fine or medium, even granular, to coarse porphyritic. 

The principal minerals are potash and plagioclase feldspars, quartz, 

biotite, and muscovite, with a little hornblende in places. Much 

epidote and chlorite are present locally as secondary minerals derived 

from the alteration of the feldspars and micas. With but few exceptions the granites are pre-Cambrian in age.

There are in the region extensive areas of gneiss, principally 

micaceous and hornblendic, having variable composition and texture. 

In addition to the rocks of granitic composition, volcanic rocks of 

both acidic and basic types, massive and schistose in structure, are 

found, some of which are of commercial value.

o Plsgah folio (No. 147), Geol. Atlas U. S., U. S. Geol. Survey, 1907, p. 8.
GRANITES OF NORTH CAROLINA. 161

Numerous extensive exposures of the -granite afford desirable locations for quarries. Some of the exposures are accessible and can be 

quarried; other areas are at present inaccessible to lines of railway 

and must remain undeveloped except to supply a strictly local demand.. Many sniall openings have been made in places to supply 

stone for local uses. The product has been used in buildings and 

bridges but mainly for ballast and macadam. Much of the granite 

is suitable for building and ornamental purposes. Dimension stone 

of uniform color and texture can be quarried and some of it is susceptible of a handsome and durable polish.

POBPHYBITIC GRANITES.

GENERAL STATEMENT.

Porphyritic granites are intimately associated in places with the

even-granular granites of the Coastal Plain, Piedmont, and Mountain 

provinces. They are widely distributed, rather extensive areas 

occurring in nine of the Piedmont counties (Cabarrus, Davidson, 

Davie, Forsyth, Franklin, Gaston, Guilford, Iredell, and Rowan) 

and two in the Coastal Plain (Anson and Richmond).

Regular quarries have nowhere been opened in the porphyritic 

granite, but in most of the areas small openings have been made from 

which granite has been quarried to supply a local demand. Reasonably good exposures of the porphyritic granite occur in places, but 

as a rule the rock is more or less deeply decayed and is readily traced 

by the kaolinized feldspar phenocrysts in the residual material.

A striking similarity is shown in the different areas of granite of 

this type. The porphyritic granites of the Coastal Plain and Piedmont provinces are massive in structure, light to dark gray in color, 

and medium to coarse grained in texture., Those of the Mountain 

province are usually more or less foliated as a result of pressure 

metamorphism. The ratio of phenocrysts to groundmass is variable, 

almost every gradation being traceable between normal and evengranular granite, in which phenocrysts are entirely absent, to a typical 

porphyritic granite in which phenocrysts of feldspar predominate.

In mineral and chemical composition the porphyritic granites are 

identical with the even-granular granites, the only essential difference 

being that' of texture. Gradation from one into the other could 

readily be traced in many of the areas, indicating that they are simply different textural facies of the same rock mass.

MICROSCOPIC CHARACTERS.

Microscopically, the porphyritic granites are biotite granites containing the same essential and accessory minerals as the even-granular 

granites. They are mixtures of feldspar and quartz with biotite, 

these minerals occurring in descending abundance in the order named.
162 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

The groundmass ranges from a medium to a coarse-grained biotite 

granite. Orthoclase is usually the dominant feldspar, although 

microcline or plagioclase may equal or in some places exceed it in 

amount. Intergrowths of the potash feldspar with plagioclase 

(microperthite), and with quartz in micrographic structure, are 

abundant. Micropoikilitic feldspars, chiefly from other included 

feldspars, are common. Quartz and biotite are the other essential 

minerals. Apatite, zircon, magnetite, and locally titanite occur as 

accessory minerals. Chlorite, epidote, and a light-colored mica are the 

usual secondary minerals, derived chiefly from the alteration of the 

biotite and feldspars.

Only the potash feldspars, orthoclase, and microcline, are porphyritically developed. They range from white and opaque through 

flesh-colored to pink in color; from 1 inch to 2 inches in length by 

one-fourth to 1 inch in width; from flat-tabular idiomorphic (with 

crystal faces) to irregular rounded allotriomorphic (without crystal 

faces) individuals in outline. Many of them are twinned on the 

Carlsbad law and as a rule they contain inclosures of biotite. The 

flat-tabular idiomorphic forms of white color usually prevail. They 

are generally of conspicuous development, rarely showing gradation 

into the groundmass feldspar, and in a number of specimens a rude 

tendency toward orientation is displayed. Like the phenocrysts of 

the Georgia porphyritic granites, described on pages 216, 238-250, 

those of the North Carolina areas show an origin in place rather than 

an intratelluric origin.

COASTAL PLAIN PORPHYRITIC GRANITES.

ANSON AND RICHMOND COUNTIES.

The Wadesboro-RocldngTiam area, located in the Coastal Plain 

region south of east from Charlotte, near the South Carolina boundary, 

has an east-west length of approximately 14 miles, lying partly in 

Kichmoiid and partly in Anson County. For the extension of the 

same granite into South Carolina see pages 191-193. About 1 mile 

east from the western exposure of the granite the Triassic sandstones 

first appear, overlying unconformably the crystalline schists. The 

area between the granite and the sandstone is composed of crystalline 

schists of variable mineral composition. Irregular stretches of the 

Coastal Plain sands cover the granite over many of its parts. Outcrops of the fairly fresh granite are somewhat numerous, largely in the 

nature of huge bowlders, ledges, and flat-surfaced masses, the last 

containing several acres of surface in the largest exposures. Exposures of the fresh and weathered granite are seen to advantage in the 

cuts of the Seaboard Air Line Railway.
GRANITES OF FORTH CAROLINA. 163

The granite is a coarse-textured, porphyritic biotite granite of 

pronounced pinkish-gray color, tinged a delicate yellowish green 

which is more decided in some places than in others. The rock 

derives its gray color from the presence of black biotite; the pink and 

yellow tints are imparted by the feldspars of those shades. Over 

most of the area the granite lias a peculiar resinous luster imparted by 

the feldspathic constituent.

The groundmass is a medium coarse-grained dark-gray biotite 

granite. Biotite is less abundant in some of the exposures and the 

granite is correspondingly lighter in color. This is especially true of 

the exposures in the cut of the Seaboard Air Line Railway about 1 

mile west of Lilesville. Here the mica occurs in small hexagonal 

plates, deep black in color and highly lustrous. The biotite is distributed through the groundmass as single individuals and aggregates 

occupying distinct areas. In other places the biotite occurs as shreds 

and plates usually crowded close together and freely distributed 

through the groundmass, thus imparting a darker color to the granite.

The phenocrysts are potash feldspars with good cleavage development and having a pronounced pinkish color, in places of a decided 

yellowish cast. Twinning on the Carlsbad law is characteristic. The 

phenocrysts are more or less of idiomorphic form (with crystal outline), 

flat-tabular, and much elongated, although irregular rounded allotriomorphic outlines are rather common among them. They range from 

more than an inch in length with proportionate width down to the 

size of the groundmass constituents, into which they grade in places. 

Inclusions of biotite are somewhat conspicuous in the phenocrysts. 

The ratio of phenocrysts to groundmass is somewhat variable, a 

probable average being, as nearty as could be estimated, about 1 to 3.

Under the microscope thin sections of. the granite show soda-lime 

feldspar (oligoclase) equal to or greater in amount than the potash 

feldspars (orthoclase and microcline). A thin section of the granite 

prepared from the exposure in the Seaboard Air Line Railway cut 1 

mile west of Lilesville showed absence of microcline.

The area is readily accessible, and almost any of the large outcrops 

offer good quarry sites, but less than half a dozen small openings have 

been made. The granite is susceptible of a fine polish, and that 

showing the deep pink and yellowish shades should prove a desirable 

stone for interior work.

Vertical joints are well developed; 1-} miles north of Lilesville the 

granite is cut by three sets of joints striking N. 70° E., N. 20° W., and 

less conspicuously north-south. At the "flat rock," 2£ miles south of 

Wadesboro, two sets of joints are developed, striking N. 30° E. and N. 

60° W. Dikes of diabase, 25 to 300 feet wide and trending northwest, 

penetrate the granite in several places. Black segregated areas or
164 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

>

bunches (knots), chiefly of biotite, are abundantly developed in some 

of the openings. They range from roughly rounded oval areas to 

much-elongated ones in which the length is several times that of the 

width. The largest ones are from 8 to 12 inches long by 2 to 4 inches 

across. Pyrite is sparingly present at the opening 3 miles west of 

Buckingham, where Hitchcock Creek is crossed by the Seaboard Air 

Line Railway.

The granite is deeply decayed in many places, but it is easily traced 

by the partly decayed (kaolinized) broken fragments of the large 

feldspar phenocrysts rather thickly strewn over the surface. Favorable sections for studying the decayed granite occur in the railroad 

cuts 1 mile east and 2 miles west of Lilesville. An advanced stage of 

decay to a depth of 15 to 20 feet is indicated.

FRANKLIN COUNTY.

About 4 miles northeast of Franklinton occur small exposures of a 

porphyritic biotite granite. The rock is coarse grained, light gray, 

and in an advanced stage of decay at the surface. The feldspar 

phenocrysts are large, pink, and more or less idiomorphic in form and 

contain inclusions of biotite. No stone has been quarried. A porphyritic tendency is indicated in the granite occurring west of Louisburg.

The fine-grained biotite granite gneiss (see pp. 125-129) quarried at 

Greystone, Vance County, to the north of the Franklinton porphyritic 

granite area, has a pronounced porphyritic tendency in many of the 

quarries.

PIEDMONT PLATEAU PORPHYRITIC GRANITES. 

GENERAL DESCRIPTION.

Two facies of granite, porphyritic and even granular, are prominently developed over many parts of the plateau region. Usually 

they grade into each other. The even-granular granites of this region 

are described on pages 124-152. A pronounced zone of porphyritic 

granite extends in a northeasterly direction through a number of 

counties along the western margin of the Carolina igneous belt of the 

Piedmont region. It begins to the southwest in Gaston County, near 

Gastonia, the county seat, and passes northeastward through Iredell 

County, where large areas are exposed around Mooresville and Mount 

Mourne; thence to the west of Salisbury, in Rowan County, along 

Yadkin River, in Davie County, and to the southeast of WinstonSalem in Forsyth -County. In Rowan County the porphyritic 

granite has a width of 4 to 8 miles. In places the feldspar phenocrysts almost entirely die out, reappearing within a short distance in 

proportions equaling and locally exceeding the groundmass.
GRANITES OF NORTH CAROLINA. . 165

Where observed within this area the porphyritic granite preserves 

nearly constant characteristics. It is a coarse-grained medium to 

dark gray porphyritic biotite granite. The feldspar phenocrysts are 

persistently marked by idiomorphic outlines and are of large size, 

measuring in extreme cases more than 2 inches in length by 1 inch 

across. They are usually white, though pink feldspars are not uncommon, and they almost invariably contain some included biotite as 

large in size as that of the groundmass constituent. Twinning after 

the Carlsbad law is very common and the cleavage is pronounced. 

Marked orientation of the phenocrysts was not apparent.

In the absence of exposures the porphyritic granite is readily 

traced by its decay. The feldspar phenocrysts are abundantly scattered over the surface in a partly kaolinized condition, and many of 

the individuals are split into smaller fragments along the cleavage 

lines.

A second very prominent area of porphyritic granite, similar to that 

described above, lies in Cabarrus County, north and northwest of 

Concord, the county seat. About 3^ miles southwest of Concord is 

an area of coarse-grained syenite (see p. 137), which possibly grades 

into even-granular and porphyritic granite to the northeast and 

southwest.

DESCRIPTION OF INDIVIDUAL AREAS.

GASTON COUNTY.

Beginning at Gastonia and extending for about 2^ miles eastnortheastward along the Gastonia-Charlotte macadam road is a belt 

of gray coarse-grained porphyritic granite. The feldspars make up 

at least 50 per cent of the rock mass and in places more. The phenocrysts are white, opaque, and large, some of them measuring more 

than an inch in length. They are usually flat-tabular, and idiomorphic in outline and contain biotite inclusions. A tendency toward 

orientation in the phenocrysts is exhibited in places. The rock in 

an advanced stage of decay is exposed in shallow cuts along the road. 

The phenocrysts observe essentially the same position and characteristics in the decayed material as in the fresh rock, except that they 

are dull in luster and largely altered to kaolin. Only one quarry has 

been opened in the porphyritic granite of this area.

The Jerikins quarry, located 2 miles northwest of Gastonia, comprises two openings. The rock is 'a porphyritic biotite granite of 

gray color and medium grain, with a fairly well-defined schistose 

structure developed in a N. 10° E. direction. The granite readily 

splits along this direction into curbing 10 to 12 feet long, for which the 

stone is principally used.

The feldspar phenocrysts are somewhat sparingly distributed; both 

idiomorphic and allotriomorphic forms appear, the former exhibiting
166 GRANITES OF SOUTHEASTERN" ATLANTIC STATES.

flat-tabular outlines and measuring as much as 2 inches long by half 

an inch across. The phenocrysts are further characterized by inclosures of biotite and. are of faint pinkish color.

Thin sections show much lath-shaped plagioclase. Chlorite, a 

colorless mica, iron oxide, and some epidote occur as alteration products derived from biotite. The phenocrysts consist entirely of potash 

feldspar, and the larger individuals are characterized by micropoikilitic structure.

Two sets of vertical joints, spaced at wide intervals, strike N. 20° 

to 30° E. and N. 80° W.

0

IREDELL COUNTY.

Porphyritic granite constitutes the principal type of granite in the 

Mooresville area. It extends east of north from Mooresville along 

the Salisbury road for about 5 miles. To the south, southwest, and 

west 6f Mooresville it has been traced for approximately 3 miles in 

each direction. It is exposed in a number, of large flat-surfaced outcrops near Mount Mourne, 2£ miles south of Mooresville. Over the 

entire area the porphyritic. granite maintains remarkable uniformity 

in both color and texture.

Where exposed the groundmass of the porphyritic granite is a 

biotite granite of dark-gray color and medium-coarse grain. It is 

composed of the essential minerals feldspar, quartz, and biotite.

The phenocrysts are of potash feldspar, usually twinned on the 

Carlsbad law; are chiefly flat-tabular and idiomorphic in outline; 

range from one-half inch to 2 inches in length by one-eighth to threeeighths of an inch across; and are either white or pink. As a rule 

the phenocrysts do not grade into the groundmass constituent, and 

are without marked orientation so far as observed, though at several 

exposures a slight tendency toward it was somewhat apparent. 

The phenocrysts contain included biotite, much of it in bodies as 

large as that of the groundmass. The ratio of the phenocrysts to the 

groundmass is approximately 1 to 1, with but little variation from 

this in any of the outcrops examined.

In the fresh rock many of the phenocrysts are of a pronounced 

pinkish color, but in the weathered granite they are entirely white and 

opaque from partial l^aolinization. Over much of the area the 

granite is more or less -deeply decayed, and the texture of the rock is 

preserved in the deca}red material. In such material the phenocrysts 

are usually white and unstained and with the loose scattered crystals 

over the surface they afford a means of readily tracing the underlying 

fresh granite.

The best exposures of the fresh porphyritic granite are north of 

Mount Mourne and at the Breed quarry, 1£ to 2 miles southwest of
GRANITES OF NORTH CAROLINA. 167

Mooresville. Outcrops of the partly or completely decayed rock are 

numerous over the entire area.

A small opening was made in a flat-surfaced exposure of the 

porphyritic granite half a mile north of Mount Mourne, where a little 

stone was quarried prior to the civil war. Microscopically, the 

minerals of the rock at this locality are potash feldspar (niicrocline 

and orthoclase), soda-lime feldspar (oligoclase), quartz, and biotite. 

Titanite, apatite, and magnetite occur as accessory minerals, together 

with a little secondary chlorite and epidote derived from the alteration of biotite. Microcline is the porphyritically developed feldspar 

and exhibits micropoikilitic structure. Intergrowths of quartz and 

feldspar are numerous.

At this point the porphyritic granite is cut by a dike of fmetextured dark blue-gray biotite granite similar to the even-granular 

granite quarried near Mooresville, described on page 143. The dike 

is irregular in outline, varying from 6 to 12 inches across, with a 

general northeast strike, and is regarded as an apophysis from the 

main body of the granite quarried near Mooresville.

The Breed quarry, 2 miles southwest of Mooresville, shows beautiful 

contacts between the fresh porphyritic granite and the even-granular 

granite. Thin sections of the porphyritic granite from the Breed 

quarry are identical in mineral composition with the Mount Mourne 

porphyritic granite described above. The field relations of the two 

granites in this area strongly indicate that they are not different 

facies of the same rock mass, grading one into the other, but that 

the even-granular granite is intrusive into the porphyritic granite, 

and is therefore younger."

CABAKRUS COUNTY.

Landers, a station on the main line of the Southern Railway in the 

extreme southern part of Rowan County, near the Cabarrus County 

line, is adopted for the name of a large area of porphyritic granite 

exposed over the middle northern part of Cabarrus County.

On Schulenberger Branch, where crossed by the Concord road, 

about three-fourths of a mile south of Landers, there are flat-surfaced 

exposures of a porphyritic biotite granite of gray color and mediumcoarse grain. The rock can be traced continuously by scattered 

small outcrops of the moderately fresh granite and its residual 

material to a point within 4 or 5 miles north of Concord. The proportion of groundmass to phenocrysts is large and the porphyritic 

feldspars are white or very light in color. The phenocrysts exhibit 

both idiomorphic and allotriomorphic outlines, without apparent 

orientation. They are composed of potash feldspar and those of 

irregular outline pass by decreased size into the similar groundmass

a Bull. North Carolina Gcol. Survey No. 2,1900, pp. 88, 89.
168 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

constituent. Biotite inclusions are common in the phenocrysts and 

twinning on the Carlsbad law is prevalent.

A thin section cut from a specimen of the porphyritic granite 5£ 

miles north of Concord indicated a biotite granite composed principally of potash feldspar (orthoclase and microcline), much soda-lime 

feldspar (oligoclase), quartz, and biotite. The biotite is much 

altered to chlorite and is in places crowded with inclusions." The 

feldspar contains a considerable proportion of small included particles 

of black iron oxide. Crystals of titanite are noted here and there in 

the thin sections.

N.o openings have been made in the porphyritic granite. The 

vertical joints are spaced at wide intervals. Scattered dark-colored 

areas of biotite (knots) and local thin veins of feldspar are observed 

in the rock. Pyrite is sparingly developed in small scattered grains 

and crystals-, but it has not been noted in sufficient amount in any 

exposures to injure the stone seriously.

ROWAN COUNTY.

Beginning about 2 miles northwest of Salisbury, on the Wilkesboro 

road, is an extensive belt of coarse-grained porphyritic biotite granite, 

which can be traced continuously by its residual material northwestward along the road to a distance of about 8 miles from Salisbury. 

The porphyritic granite grades in many places into an even-granular 

granite of the same composition. Exposures of the fresh rock were 

observed only at a point about 3 miles northwest of Salisbur}7", immediately on the road, where a small opening had been made and a little 

of the stone quarried for macadam.

The groundmass of the rock is a biotite granite of moderately darkgray color and medium grain. The phenocrysts are composed of 

potash feldspar, usually idiomorphic in outline and twinned on the 

Carlsbad law. As a rule, they are very large, from, 2 inches or 

more long by one-half to 1 inch wide. They contain inclusions of 

biotite and in one or two places show a tendency toward orientation.

The rock is deeply weathered into a light-gray granitic sand, in a 

few places deeply colored by staining from iron oxide. The large 

phenocrysts, more or less kaolinized, are rather thickly strewn over 

the surface and offer a very sure means of tracing the rock. Some of 

them are split into smaller pieces along the cleavage directions, distributed through the decayed granite in the same position as in the 

fresh rock.

DAVIDSON AND DAVIE COUNTIES.

About 3£ .miles west of Lexington, on the Mocksville road, partly 

decayed light-gray biotite granite of fine to coarse grain, with a slight 

porphyritic tendency in places, is exposed. Within a short distance
GRANITES OF NORTH CAROLINA. 169

westward the rock becomes typically porphyritic and can be continuously traced along the road by means of its decayed material in 

Davie County to Advance and beyond, a distance of 18 miles west of 

Lexington. Exposures of the fresh granite were not seen, but the 

porphyritic texture of the fresh granite is preserved in the decayed 

product. In color the decayed granite ranges from light gray to 

yellowish red, with the feldspar phenocrysts still intact but much 

kaolinized. In the lighter-colored residual material the biotite has 

suffered but little alteration, but in the deeper-colored areas much 

chemical alteration of this constituent is evident.

The phenocrysts are mostly of large size and flat-tabular to irregular in outline, and they exhibit the usual Carlsbad twinning. Inclusions of biotite are conspicuous.

The decayed material indicates a porphyritic biotite granite, of 

medium-coarse grain, resembling in all respects the porphyritic 

granite of Gastoii, Iredell, Cabarrus, and Rowan counties described 

above.

FORSYTH COUNTY.

About 5 miles south of Winston, near the Lexington road, an opening was made in porphyritic granite and the stone quarried for use in 

Winston-Salem.

The rock is a porphyritic biotite granite of light-gray color and 

medium-coarse grain. Most of the feldspar phenocrysts are 

roughly rounded and of irregular outline, and by decrease in size 

grade into the same groundmass constituent. Many of the phenocrysts, however, show idiomorphic, flat-tabular outlines, one-half 

inch in length by one-eighth inch across; they exhibit Carlsbad twinning and contain biotite inclusions.

The principal minerals are potash feldspar (orthoclase and microcline), soda-lime feldspar (oligoclase), quartz, and biotite. Secondary 

muscovite, chlorite, and epidote, with a slight sprinkling of minor 

accessories, complete the list of minerals. In the larger feldspar 

individuals the micropoikilitic texture is well developed, the inclosed 

minerals consisting largely of feldspar. Intergrowths of quartz and 

feldspar and of feldspars with each other are freely distributed through 

the thin sections.

The vertical joints strike N. 50°'E. and N. 45° W. A slightly 

foliated structure is developed in the granite in places.

GUILFORl) COUNTY.

The Guilford County granite area is a large one, extending from 

Summeriield to Friendship, a distance of 10 miles, and lying about 10 

miles northwest and west of Greensboro. Several small openings 

have been made in the vicinity of Summerfield and Friendship to 

supply a local demand for stone.
170 GRANITES OF SOUTHEASTERN" ATLANTIC STATES.

The rock is a porphyritic biotite granite of variable gray color and 

medium to coarse grain. It grades into the even-granular granite at 

a number of points. The principal minerals are orthoclase, some 

microcline, plagioclase in variable amount, quartz, and biotite. 

Apatite, zircon, and titanite are the primary accessories, and chlorite 

and colorless mica the secondary minerals. The feldspar phenocrysts are both-irregular, roughly rounded in outline and flat-tabular, 

half an inch to 2 inches long by half an inch wide, and many of them 

are twinned on the Carlsbad law.

Several dikes of diabase penetrate the granite between Summerfield and Friendship.

SUPPLEMENTARY NOTE. In the table below are given the percentages of silica, 

alumina, lime, soda, and potash in feldspars quarried from pegmatite dikes in North 

Carolina."

Analyses of North Carolina feldspars.

Silica (SiO2 )...............-.

Soda(Na2 0) ................

Potash (K2 0). ..............

1.

64.25

18.34

.08

5.95

11.66

2.

63.52

21.20

3.62

9.50

3.

63.55

20.20

6.65

8.73

4.

62. 95

19.66

7 64

8.39

5.

64.75

19.24

7.85

7.55

6.

65.15

19 04

.12

7.00

7.28

7.

64.55

99 9(1

1.41

7 91

3 94

8.

64.85

19 90

None

10.04

2 91

9.

65. 18

21.60

64

8.35

.04

1. Young mine, Dobag, Yancey County.

2. Irby mine, near Spruce Pine, Mitchell County.

3. Ray mine, near Burnsville, Yancey County.

4. Averys Meadow mine, Plumtree, Mitchell County.

5. Tolly Bend mine, near Micaville, Yancey County.

6. Flat Rock mine, Flat Rock, Mitchell County.

7. Charlie Robertson mine, near Micaville, Yancey County.

8. Wiseman mine, near Spruce Pine, Mitchell County.

9. Cloudland mine, near Bakersville, Mitchell County.

oPratt, J. H.. Economic paper No. 6, North Carolina Geol. Survey, 1902, pp. 49-50.
CHAPTER V. 

THE GRANITES OF TENNESSEE.

The occurrence of granite in Tennessee is limited to the extreme 

middle-eastern and northeastern portions of the'State, immediately 

along the North Carolina boundary, in the rugged mountain belt. 

The areas, including the westward extensions of some of the principal ones in western North Carolina, are of mirior extent. They 

include the Cranberry and Beech granites and Carolina gneiss in 

Carter and Johnson counties,0 and the Max Patch and Cranberry

granites in Cocke and Sevier counties. 6 According to Keith these 

are all of Archean age. They are described in some detail on pages 

153-161.

Owing to the meagerness of the areas of granite and the general 

character of the granite itself, it is very doubtful if granite quarrying 

will ever assume any great importance in this State. At present 

the areas are somewhat inaccessible and much of the granite is not 

suitable for the better grades of work. Merrill states that quarries 

of a coarse dull-pink biotite granite have been opened recently on 

Ripshin Mountain, on Doe Rlver. c

a Keith, Arthur, Cranberry folio (No. 90), Geol. Atlas U.'S., U. S. Geol. Survey, 1902. 

& Keith, Arthur, Asheville folio (No. 110), Geol. Atlas U. S., U. S. Geol. Survey, 1904. 

c Merrill, G. P., Stones for building and decoration, 3d ed., New York, 1903, p. 83.

171
CHAPTER VI. 

THE GRANITES-OF SOUTH CAROLINA.

THE SOUTH CAROLINA CRYSTALLINE REGION.

The South Carolina crystalline region embraces a roughly triangular 

area which is included within the fall line on the southeast, Savannah 

River and the northeastern boundary of Georgia on the southwest 

and west, and the southern boundary of North Carolina on the north. 

The fall line, characterized by extreme irregularity, extends in a 

general southwestward direction across the State, passing through 

or near Chesterfield, Kershaw, Camden, Columbia, and Trenton, S. C., 

and Augusta, Ga. (See PL XXI.)

The extreme northwestern portion of the crystalline region comprises a narrow belt (part of the Blue Ridge), not exceeding 30 miles 

wide, of mountainous topography, the higher peaks rising to an elevation of 3,500 feet. Between this mountainous belt on the northwest 

and the fall line on the southeast is included the greater portion of the 

crystalline region, the Piedmont province, which does not essentially 

differ from the parts of the same province to the northeast and southwest. Its principal features are the broad, rolling upland surface, 

the valleys carved in the upland, and the minor residual masses which 

rise above the upland.

According to Sloan, the higher elevations of the Piedmont region 

range from 700 to 900 feet above sea level and the beds of the major 

streams are 200 feet lower (500 to 700 feet). The surface gradually 

lowers toward the fall line to elevations of less than 120 feet in the 

major valley bottoms to 680 feet on the upland between Savannah and 

Congaree rivers, and to 597 feet between Wateree and Pedee rivers.0

The major rock types of the South Carolina crystalline region are 

similar to those of the southeastern Atlantic crystalline region in 

general, as described on pages 35-37. They include both igneous 

and sedimentary masses, usually much altered from metamorphism. 

The principal types comprise micaceous and hornblendic gneisses and 

schists, granites, and slates, with numerous masses of crystalline 

limestone, chiefly dolomitic, and quartzite. Surface, volcanic rocks 

and their pyroclastic equivalents (tuffs), especially the latter, much

i* Sloan, Earle, A catalogue of the mineral localities of South Carolina: Bull. South Carolina Geol. 

Survey, ser. 4, No. 2, 1908, p. 408.

172
U. S. GEOLOGICAL SURVEV BULLETIN 426 PLATE XXI

1

, C KERO 

\

NBURGTZ5

Z3 LANGASTE

U N I O

' NEW B

LAND V<

C A L HX) U N

C {LA RENND ON

eB U R G

LEGEND

Fall line

QUARRIES

Ford

Jackson

Whiteside

Excelsior (Southern Granite Co.)

Taxshaw

Stewart

Rion (Winnsboro Granite Co.)

Anderson (Winnsboro Granite Co.)

Leiper-Davis

Blair

Strother

Smiths Branch (County)

Lipscomb (Morris &. Co.)

Ross

Casparis Stone Co.

17 Bates

Whittle

Level

Spears (Baxter)

Leitzsey

Flatrock

City (Union)

Lockhart

Pacolet Granite Co. (Johnson)

"eystone Granite Co.

tntrekin

Cold Point Granite Co.

Benjamin

Edgefield

Bordeaux

Hanckel

Beverley

Lays Mill

Tunnel Hill

MAP OF SOUTH CAROLINA, SHOWING LOCATION OF GRANITE QUARRIES.
GRANITES OF SOUTH CAROLINA. 173

altered from metamorphism, are extensively developed in places. 

Intrusions in the form of dikes of acidic and basic composition cut 

the rocks of this crystalline complex. With 'the exception of the 

massive granites and the dikes of igneous rocks, the rock types 

mentioned above are greatly altered by metamorphic changes arid 

usually show pronounced schistose structure.

At Hornsboro, in Chesterfield County, is a small area of Triassic 

(Newark) rocks composed of brownish-red to gray sandstones, penetrated by dikes of diabase. This is an extension into South Carolina 

of the Wadesboro, N. C., area of Newark rocks.

DISTRIBUTION OF THE GRANITES.

The granites of South Carolina are limited to the crystalline area, 

which includes the whole or a part of Abbeville , Anderson, Cherokee, 

Chester, Chesterfield, Edgefield, Fairfield, Greenville, Greenwood,

Kershaw, Lancaster, Laurens, Lexington, Newberry, Oconee, Pickens, 

Richland, Spartanburg, Saluda, Union, and York counties. Some 

granite has been quarried usually a very small quantity strictly 

for local use in one or more localities in each of those counties, and 

during the summer of 1908 quarrying operations were in progress in 

nine of them. The principal producing areas were Columbia, in Richland County; Lexington, in Lexington County; Edgefield, in Edgefield County; Winnsboro, in Fairfield county; Heath Springs, in 

Lancaster County; and Beverly, in Pickens County.

SCIENTIFIC 'DISCUSSION.

MINERAL COMPOSITION.

The granites of South Carolina are mixtures of feldspar and quartz, 

with biotite as the third essential component. Muscovite as a primary 

constituent is practically absent in many of the granites. It occurs 

as a very subordinate constituent, associated with biotite, in a part 

of the granites of Edgefield, Fairfield, Oconee, and York counties, and 

as a principal constituent in a reddish-gray granite found near Liberty Hill village in Kershaw County. Hornblende has been noted in 

the granite of only one locality, 1 mile south of Winnsboro, on the 

Winnsboro-Rockton road. Thin sections of this granite reveal sufficient hornblende to designate the granite a hornblende-bearing 

biotite granite.

The feldspars include nearly equal mixtures of potassic- (orthoclase 

and microcline) and lime-soda (plagioclase) varieties. Orthoclase 

is the dominant potassic feldspar, with microcline equal to or 

greater in amount in some sections and entirely absent in others. 

Microperthite, an intergrowth of orthoclase with a second feldspar 

(plagioclase), is very constantly present. Plagioclase is usually 

present, in most places being equal to or greater in, amount than the
174 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

potassic feldspar. This is shown by the high soda content in the 

table of chemical analyses given below, and is confirmed by the microscopic study of thin sections of the granites.

The granites contain, besides the principal constituents enumerated 

above, accessory apatite, zircon, magnetite, titanite, and rutile, 

together with secondary chlorite, epidote, and a light-colored mica, 

and locally some other minerals.

CHEMICAL COMPOSITION.

The subjoined analyses of even-granular and porphyritic granites 

and granite gneisses show the range in composition of the South Carolina granites. A study of the analyses indicates that these granites 

correspond closely in chemical composition with the granites of the 

southeastern Atlantic States in general. In conformity with the 

other granites described in this report the South Carolina rocks are 

soda-rich granites (quartz monzonites). In 13 of- the 19 analyses 

soda (Na20) approximately equals or is but slightly less than potash 

(K2 0), in five soda exceeds potash, and in only one is there a great 

excess of potash .over soda. On the basis of potash-soda ratio the 

South Carolina granites correspond more closely to quartz monzonites 

than to normal granites.

Another feature shown by these analyses is the constant presence 

of titanium in very appreciable amount, ranging in the form of Ti02 

from a minimum of 0.24 per cent to a maximum of 0.84 per cent. 

Manganese and phosphorus are also reported in every analysis, either 

in traces or in larger amounts.

Chemical analyses cf South Carolina granites.'1

$\Oi.. .............. \ho3 . ..............

FesOs... ............

FeO ................

MgO................

CaO. ...............

Na2 0 ...............

K2O ................

Ti02 ... .............

MnO................

P2 05 . ...............

S03 . ................

1.

68.70

15 49

1.10

3.73

.86

1.70

3.09

3.36

.81

.84

Trace.

.13

99. 51

2.

68. 71

15.41

1.85

1.59

1.25

1.64

3.48

4.61

60

Trace

Trace.

99.46

3.

68.80

1 c 70

2.14

1.57

1.16

1.G4

3.45

4.54

.33

.45

Trace.

Trace.

Trace.

99.81

'.'.

68.90

, 15.75

1.16

1.49

.74

2.66

4.76

3.49

.18

.36

TrsjcG

Trace.

99.49

5.

69. 52

16.77

.95

1.56

.75

1.82

3.43

4.10

1.43

.36

Trace

Trace.

99.69

0.

69.74

10 79

| 3.64

.22

1.54

5.39

4.98

99.23

7.

70.11

15.76

/ 1.07

\ 1.76

.62

1.84

3 3Q

4.27

.45

.45

Tr&cG

Trace.

99.72

8.

70.20

H 99

1.14

1.24

.48

9 14

5.39

4.82

90

.24

Trace.

Tr&cG

Trace.

100. 20

9.

70. 54

14. 56

1.06

.78

1 00

3 97

5.37

27

.60

Trace

Trace

.06

100. 11

10.

14. 89

.75

1.24d 1?

9 no

.19

Trace

Trace

Trace.

99.88

a. Sloari, Earle, op. cit;., pp. 167-225, 250-255.

1. Porphyritic biotite granite, Clouds Creek, 4.7 miles north of Batesburg, Saiuda County.

2. Porphyritic biotite granite, Flatrock (old Dekalb granite), Kershaw County.

3. Biotite granite, Cold Point station, Laurens County.

4. Biotite granite, Jackson quarry, 0.5 mile north of Clover, York County.

5. Biotite granite, Leitzsey quarry, 5 miles northeast of Newberry, New'kerry County.

6. Biotite granite, Andersori quarry (Winnsboro Granite Company), 8.5 miles from Rion, Fairfield 

County.

7. Biotite granite, Excelsior granite quarry, 5.2 miles south west of Heath Springs, Lancaster County.

8. Biotite'granite, Flatrock quarry, 2 miles north of Carlisle, Union County.

9. Biotite granite, Benjamin quarry, 4 miles east-northeast of Greenwood, Greenwood County.

10. Muscovite-bearing biotite granite, Whiteside quarry, 2 miles west of Filbert, York County.
GRANITES OF SOUTH CAROLINA.

Chemical analyses of South Carolina granites Continued.

175

Si02.................

AlaOa......... .......

FfyOa.. .............

FeO.......... .... -..

MgO. ...............

CaO .................

Na2 0 ................

KS 0. ........ ........

TiOs................

MnO .................

P2 0s......... ......

S03 .................

11.

70.90

]5.25

1.52

1 . 53

.63

2.40

4.32

2.85

.17

.42

99. 99

12.

71.20

17. 04

] 3.48

.11

2.32

4.70

.63

13.

72.19

14. CO

f .70

\ 1.80

.84

1.88

3.46

3.94

.18

.48

.16

9«. on

14.

72.22

14.51

.1.28

1.52

.58

1.32

3. 21

4.30

.52

.24

99. 70

15.

73. 20

| 1.24

.38

1.36

.55

0.89

09. 07

10.

02.34

17.22

I 2.49

1.30

3.28

5.28

5.14

.28

.60

99.08

17.

65. 72

17.22

1.70

2. 67

1.45

2.80

3.68

3.80

.35

.72

Trace.

.08

100. 19

18.

08. 15

14.30

2.49

1.04

2.80

3.80

3.84

.28

.00

.11

Trace

99.85

19.

73.10

13.82

93

1. 43

.51

1.72

3.04

5.06

.23

.24

Trace

100.08

11. Muscovite-bearing biotite granite, Blair quarry, 0.4 mile east of Blair, Fairfield County.

12. Biotite granite, Keystone Granite Company's quarry, 2.5 miles north of Pacolet, Spartan burg County.

13. .Biotite granite, Ross quarry,- near Columbia, Lexington County.

14. Biotite granite, Southern Granite Company's quarry, 0.8 miles southwest of Heath Springs, Kershaw

15. Biotite granite, Riqn quarry (Winnsboro Granite Company), Rion, Fairfield County.

16. Biotite granite gneiss, Hanckel quarry, 1.7 miles southwest of Pendleton, Anderson CoHllty.

17. Biotite granite gneiss, Ware Shoals, Laurens and Abbeville counties.

18. Biotite granite gneiss, Beverly quarry, Beverly station, Pickens County.

19. Biotite granite gneiss, Bates quarry, near Batesburg, Lexington County.

TYPES OF GRANITE.

GENERAL STATEMENT.

The granites of South Carolina, in common with those of the southeastern Atlantic States in general, vary in structure from massive 

to schistose and in texture from even granular to porphyritic. 

Accordingly, three types of the rocks may be distinguished: (1) 

Even-granular massive granites, (2) porphyritic granites, and (3) 

schistose or foliated granites or granite gneisses.

The even-granular and porphyritic granites are textural variations 

of the same rock mass and are locally present in the same quarry, 

but in such places the porphyritic texture is likely to be of a less 

pronounced type than is observed elsewhere. The granite gneisses 

were derived from massive granites, from which they differ principally 

in the pronounced schistose structure secondarily induced in them by 

dynamic metamorphism.

As described above, under "Mineral composition/' the South Carolina granites are, with one exception, mica granites, and are prevailingly biotite granites. Sloan a reports the occurrence of both 

augite and hornblende granites in the State, but remarks that they 

are of doubtful commercial value, especially the augite granite. 

The writer did not observe the occurrence of either one of these types.

On the basis of mineral composition, then, the South Carolina 

granites are divisible into (1) biotite granite, which may contain 

little or no muscovite in addition to biotite, and under which the 

greater part of the granites of the State may be grouped; (2) musco-

« Sloan, Earle, op. c|(;., pp. 170-171. 

38971° Bull. 426 10 12
176 GRANITES OF SOUTHEASTERN ATLANTIC. STATES.

vite-bearing biotite granite, of which there are only a few representatives; and (3) muscovite granite, of which the single occurrence near 

Liberty Hill village, Kershaw County, is the only representative yet 

observed.

EVEN-GRANULAR GRANITE.

Even-granular granites have wide but variable distribution throughout the crystalline area of the State. They vary from fine to medium 

grained, being rarely coarse grained. Hardly without exception they 

are of some shade of gray in color; light, medium, and dark blue-gray 

shades are common. In many localities a part of the feldspathic constituent is of slight or pronounced red color and imparts a mixed 

reddish-gray color to the rock, the depth of which is proportional to 

the intensity of the red of the feldspar.

With but few exceptions the granites are biotite granites. Muscovite, though present in.places, is very subordinate, and. hornblende is 

practically lacking. The principal minerals are orthoclase, microcline, plagioclase (oligoclase), quartz, biotite, a little muscovite, magnetite, apatite, and zircon. Titanite is a common accessory in many 

localities. The usual secondary minerals occur, chief among which 

are chlorite, epidote, muscovite, and kaolin. These are the normal 

minerals in granite and are so familiar that details are unnecessary 

here.

Micropegmatitic intergrowths of the quartz and the feldspars are 

common, indicating that the period of formation of the quartz clearly 

began before that of the feldspar closed. Orthoclase is the dominant 

potash feldspar, but microcline, which is usually present but variable 

in amount, may exceed it. Carlsbad twins are frequently seen both 

in thin sections and in hand specimens of the rocks. The plagioclase 

is invariably characterized by polysynthetic twinning striae. Extinction angles of the plagioclase usually indicate oligoclase. The presence 

of considerable lime in the analyses tends to confirm the microscopic 

study. Microperthitic intergrowths of the feldspars are indicated in 

most of the thin sections studied. Many of the larger feldspar individuals are micropoikilitic, the inclosures consisting of both quartz 

and feldspar.

Biotite, though always present, is subject to some variation in 

amount. It is of deep-brown color and strongly pleochroic. It is 

usually altered to chlorite and less commonly to epidote; both minerals 

are present, chlorite being the more abundant. Muscovite, where 

present, is somewhat closely associated with biotite.

Magnetite, apatite, zircon, and titanite are the most common primary accessories. Much of the magnetite shows crystal boundaries 

and it occurs locally in irregular crystalline grains. The apatite and 

zircon present no noteworthy features. Titanite is present in many
GEANITES OF SOUTH CAROLINA. 177

of the sections, both as irregular grains and aggregates and as rhombic 

crystals. It varies from nearly colorless to reddish brown, with 

noticeable pleochroism in the deeper-colored individuals.

POHPHYRITIC GRANITE.

Porphyritic granites are common over many parts of the South 

Carolina crystalline region, but extensive continuous areas of them in 

which pronounced porphyritic texture is developed are apparently 

less numerous than in Georgia and North Carolina. Though porphyritic texture is freely developed in many of the granite areas, it 

either grades within rather short intervals into the more dominant 

even-granular texture or else is not of a pronounced type. In some 

areas the ratio of phenocrysts to groundmass is very small that is, 

the phenocrysts are not abundant and are scattered irregularly at 

wide intervals through the groundmass. In other areas where the 

phenocrysts are abundant they may grade into the groundmass feldspar, thus imparting to the rock a less pronounced porphyritic texture 

than if the phenocrysts were sharply differentiated. There are 

exceptions, however, and typical porphyritic granites occur in which 

the phenocrysts are sharply defined from the similar groundmass 

constituent.

Like the even-granular granites into which they grade, the porphyritic granites are biotite granites and differ from the former only 

in texture. The porphyritically developed mineral is potash feldspar. 

The phenocrysts vary in size, form, and color. They rarely exceed 

1 inch in length, are both of irregular (allotriomorphic) and regular 

(idiomorphic) outline, and are white or pink in color. They are in 

places twinned on the Carlsbad law, and inclusions of biotite in them 

are common. Marked orientation of the phenocrysts has not been 

observed in any of the areas.

GRANITE GNEISS.

The gneisses quarried in South .Carolina and described in this 

bulletin have closely similar chemical and mineral compositions to 

the jnassive granites. The principal minerals are orthoclase (largely 

microperthite), microchne, soda-lime feldspar (oligoclase), quart/, 

biotite, a little muscovite, apatite, zircon, titanite, and secondary 

chlorite and epidote. Granulation of the quartz and the feldspar is 

usually pronounced, and orientation of the biotite is shown. The 

only essential difference between the gneisses and the massive granites 

is a structural one the gneisses are schistose. For these reasons and 

from the field evidence, these gneisses are believed to have been derived from original granites and are therefore designated granite 

gneisses.
178 GEANITES OF SOTJTHEASTEKN ATLANTIC STATES.

The banding of the gneisses may be fairly regular, but as a rule it is 

rather irregular and highly contorted; in either case the bands are 

alternating ones of light (chiefly feldspar and quartz) and dark (chiefly 

biotite) minerals. The individual bands are subject to considerable 

variation in thickness. Like the massive granites, the gneisses vary 

in color and texture.

Both even-granular and porphyritic textures are common, the 

latter in places imparting a true augen gneiss appearance to the rock. 

The porphyritic mineral is invariably a potash feldspar, commonly 

microcline, and locally it is of pronounced reddish or pink color.

Of the numerous granite gneisses occurring in the State, probably 

that quarried by the Greenville Granite Company at the Beverly 

quarry, in Pickens County, is one of the most typical. It very 

closely resembles the well-known contorted biotite granite gneiss 

extensively quarried at Lithonia, Ga. (pp. 253-262), and a similar 

one composing Rocky Face Mountain in Alexander County, N. C. 

(pp. 152-153).

STRUCTURAL FEATURES OF THE GRANITES. 

DIKES.

Dikes of granitic composition in the South Carolina quarries are 

of two kinds extremely fine-grained granite (aplite) and very 

coarse grained granite (pegmatite). Dikes of basic composition, 

chiefly diabase, have also been observed penetrating the granites in 

a number of localities, but have not been noted at any of the quarries, 

though they occur not uncommonly in the granite quarries of North 

Carolina (p. 118).

APLITE.

Aplite dikes are present only here and there in the South Carolina 

granites. They have been noted by the writer only at the Smith 

Branch (County) quarry, near Columbia; the Anderson quarry, 5 miles 

west of Rion, in Fan-field County; and theCasparis Stone Company's 

quarry, near Lexington.

At the Smith Branch quarry aplite dikes, ranging in thickness 

from a fraction of an inch to 4 feet, are rather numerous. In color 

they are reddish brown, and in texture are so dense and fine grained 

that the mineral particles can not be distinguished with the unaided 

eye. The largest dike, 4 feet wide, is exposed on opposite sides of the 

opening (about 50 feet wide) and trends in a northeast-southwest 

direction, observing a general southwesterly steep dip. It consists 

of potash feldspar (orthoclase chiefly, with some microcline), sodalime feldspar (oligoclase), quartz, a little biotite, accessory apatite, 

and secondary chlorite and epidote.
GBANITES OF SOUTH CAROLINA, 179

At the Anderson quarry there are several aplite dikes which 

range in thickness from 1 to 12 inches. Most of these are associated 

with pegmatite dikes, as banded aplite pegmatite, after the fashion 

shown in figures 16 and 17, page 188. The aplite proper is very 

fine grained and light gray, with scant biotite visible to the unaided 

eye. The aplite consists of potash feldspar (microcline and orthoclase, partly perthite), some soda-lime feldspar (oligoclase), quartz, 

very little biotite and muscovite, accessory zircon, and secondary 

chlorite and epidote. Muscovite is partly secondary.

At the Casparis Stone Company's quarry a single aplite dike 2 

inches wide was noted. The dike is very fine grained and light 

gray and contains no mica visible to the naked eye.

PEGMATITE.

Pegmatites are present in great numbers in some quarries and

practically absent in others. They do not attain very large size, 

ranging from a fraction of an inch to 18 inches in width, but are 

usually narrow. -Nowhere do they seriously interfere with quarrying 

operations. They are of granitic composition, consisting of the 

usual coarse crystallizations of feldspar and quartz, with subordinate 

mica, usually biotite, though some muscovite is commonly present. 

In the Peek quarry, near Pacolet/ black tourmaline is a constituent 

of some of the pegmatites.

The feldspar of the pegmatites is generally white but locally of 

reddish or pink color. It shows good cleavage development and is 

twinned on the Carlsbad law. It is the most abundant constituent 

and is composed usually of potash feldspar (orthoclase or microcline, 

or both) and a less amount of acidic soda-lime feldspar.

The pegmatites apparently do not conform to any fixed direction 

or directions of strike, but show great variation. In the large 

exposures of granite on the Adams place near Clover, York County, 

faulting of the pegmatites was observed at one point, the displacement amounting to about 12 inches.

Over parts of the crystalline area, notably in Abbeville, Anderson, 

Greenville, Oconee, and Pickens counties, the pegmatites assume 

large dimensions, being 9 to 20 feet thick. Several of these dikes 

have become of economic importance within recent years for their 

mica and feldspar content, more especially the mica. As is indicated 

in the analyses below, the feldspar of these pegmatites belongs to the 

potassic variety.
180 GRANITES OF SOUTHEASTERN ATLANTIC STATES. 

Analyses of feldspar from South Carolina pegmatites.®

Si02 . ........................................ v . ................

A12O3 ..........................................................

CaO ...........................................................

MgO ...........................................................

Na2O ..........................................................

KS 0 ...........................................................

Ti02 . ..........................................................

P2 05....... ....................................................

SOS .. ..........................................................

1.

60 79

.18

.24

.23

11.01

1 90

.09

99. 73

2.

62. 26

20.41

.31

.19

.78

1.41

12.71

1 ^4

99.61

3.

65.60

19.45

.71

.18

.13

2.02

11.34

.63

Trace.

100. 19

4.

67.30

18.21

79

.14

.14

2.41

11.14

.06

Trace.

100. 19

oSloan, Earle, op. cit., pp. 142-149.

1. Potash feldspar from the Miller place, 8.5 miles S. 23° E. of Greenville, Greenville Comity, S. C.

2. Potash feldspar from point 12.5 miles northwest of Walhalla, Oconee County. S. C.

3. Potash feldspar from point 3.7 miles N. 71° W. of Pickens, Pickens County, S. C.

4. Potash feldspar from old powder mill, Oconee County, S. C.

QUARTZ VEINS.

Quartz veins are exceptional in the South Carolina granite quarries 

but have general though variable distribution throughout the crystalline area of the State. The few small ones observed in several of 

the quarries are unimportant and do not merit description. The 

quartz veins- attain considerable size in many localities beyond the 

quarry limits, notably near Saluda in Saluda County, Oldtown in 

Newberry County, Ridgeway in Fan-field County, and Kings Creek 

in Cherokee County.

JOINTS.

Two systems of joints intersect the granite of the South Carolina 

quarries a vertical set and a horizontal set. These not everywhere 

have the same degree of development, nor are the two systems present 

in all the quarries.

VERTICAL JOINTS.

The most common type of joint has an approximate vertical position, but joints with other inclinations (50° to 60°) occur. As a rule 

the joints are straight, but here and there they are curved or show other 

irregularities. The spacing of the joints varies greatly. The large 

number of measurements made indicate that the spacing of the 

joints, where well developed, is usually between 2 feet and 8 feet. 

In some quarries, however, zones of close jointing were observed, 

and the spacing was measured in inches. In others the joints were 

30 to 50 feet or more apart.

Measurement made by compass of the strike of .joint courses at 

fourteen South Carolina granite quarries yielded the folio wing results:

N. 5°-10° E. 

N. 20°-35° E. 

N. 40°-50° E. 

N. 60°-70°E.

N. 3°-10°W. 

N. 20°-35° W. 

N.45°-60° W. 

N. 65°-80° W.

East-west. 

North-scmth.
 GRANITES OF SOUTH CAROLINA. 181

In the northeast quadrant the joints which extend approximately 

north-northeast and east-northeast are of about equal development; 

in the northwest quadrant those which extend approximately westnorthwest form the dominant system. Only a few of the joints 

measured extend east-west and north-south.

HORIZONTAL JOINTS.

Horizontal joints which, in general, follow the surface configuration of the rock are less commonly developed in the granite of the 

South Carolina quarries than at the quarries of the other Southern 

States. In some of the South Carolina quarries no horizontal joints 

were observed. This system of joints is especially well developed in 

the quarries of Morris & Co., near Columbia; the Keystone and Peek 

quarries, near Pacolet; and the Benjamin quarry, north of Greenwoocl. They are apparently surface phenomena and diminish in 

number rapidly with increasing depth. The spacing between the 

joints is invariably closest nearest the surface, ranging from a few 

inches to 8 feet.

SLICKENSIDES.

Polished and striated or grooved faces (slickensides) characterize 

many of the joints at the quarries, indicating movement in the rocks. 

This movement may have been caused by more or less faulting along 

the joint directions; if so, further evidence of it is lacking, as discontinuity in the granite masses along the joints has not been observed. 

A thin veneer or coating of white, reddish, and yellowish mineral 

substance is developed on the faces of many of the joints. It is 

derived probably from the original granite minerals by the rubbing 

of the walls on 'each other.

BASIC SEGREGATIONS (KNOTS).

Dark basic segregations (knots),, so common in granite and 

believed to have formed from the cooling magma, have but scanty 

development in most of the South Carolina granites. They were not 

observed at all at many of the quarries, and only here and there at 

the other quarries with perhaps one or two exceptions. They are of 

small size, ranging from 'a fraction of an inch to several inches across, 

and usually of irregular oval outline. They are invariably of darker 

color and finer grain than the inclosing granite and are composed of 

dominant biotite with less quartz and feldspar.

INCLUSIONS.

Inclusions of foreign (country) rock incorporated into the granite 

during its intrusion are exceptional in the South Carolina quarries. 

The only such inclusion noted by the writer is at the quarry of the
GRANITES Of SOUTHEASTERN ATLANTIC STATES.

Cold Point Granite Company, near Cold Point station, in Laurens 

County. In the main quarry opening is a mass of thinly but perfectly foliated, nearly black biotite gneiss about 30 feet long and 15 

feet wide. It is entirely surrounded by the massive granite, and 

where observed the contacts between the two rocks are pronounced 

and sharp. The gniess inclusion is composed essentially of dominant 

black lustrous biotite, white feldspar, and a little quartz. It has a 

pronounced porphyritic texture in places.

PHYSICAL TESTS. 

SPECIFIC GRAVITY AND ABSORPTION.

Tests of the specific gravity and the ratio of absorption of the 

South Carolina granites have been made by Eaiie Sloan, of the South 

Carolina Geological Survey, as follows:

Specific gravity and ratio of absorption of South Carolina granites.'1

Rock.

Do.......................

Porphyritic biotite granite . . .

Do...... .................

Do.......................

Do. ......................

Do.......................

Do.......................

Do.......................

Do.......................

Do.......................

Do.......................

Do.......................

Do.......................

Porphyritic biotite granite.. . . DO.........:.............

Do.......................

Do.......................

Do.......................

Do.......................

Locality.

6.8 miles S. 45° W. of Heath Springs,Kershaw County.

Flat Rock, Cleyburn, Kershaw Comity. .......

Specific 

gravity.

2.65

2.05 

2.73 

2.04 

2.65 

2.03 

2.06 

2.66 

2.68

2.65 

2.64

2.62 

2.66 

2.62 

2.63 

2.66 

2.65 

2.66

2.68 

2.66 

2.68 

2.72 

2.64

Ratio of absorption.

0.344 

63.41 

.405 

.57 

.389 

.314 

.247

.292 

.440 

.338 

.360 

.408 

.43 

.310 

.380 

.129

.288 

.398 

.321 

.304 

.202

o Sloan, Earle, op. cit., pp. 174-225. 6 Probably a misprint for 0.341.

Examination of the table shows the range in specific gravity to be 

from 2.62 in the massive fine-grained granites of Fairfield County to 

2.73 in the coarse-grained porphyritic biotite granite of Clouds Creek, 

Saluda County, and in ratio of absorption from 0.129 in the porphyritic granite of Kershaw County to 0.57 in the massive finegrained granite of Newberry County.

COMPRESSIVE STRENGTH.

Tests to ascertain the compressive or crushing strength have been 

made, so far as the writer is aware, on very few of the South Carolina 

granites. Through the courtesy of Mr. B. H. Heyward, general
OF SOUTH CAEOLINA. 18$

manager of the Winnsboro Granite Corporation, the results of four 

tests made by the United States Ordnance Department to determine 

the compress!ve strength of the gray granite of the Kion quarry are 

given below.

Compressive strength tests of granite from Rion quarry, South Carolina.

Dimensions.

Height.

Inches.

3.55

3.53

3.54

3.50

Compression 

surface.

Inches.

3. 41x3. 54

3. 57x3. 51

3. 50x3. 53

3. 54x3. 54

area.

Sq. in.

12. 07

12. 53

12.30

12.53

First 

crack.

Pounds.

317, 000

350, 000

350,000

305,000

Ultimate strength.

Total.

Pounds.

380, 000

309, 900

417,000

325,000

Per square 

inch.

Pounds.

31,980

29, 520

33,740

25, 940

Sloan fl gives the minimum, maximum, and average results of four 

tests made by the United States Ordnance Department to determine 

the compressive strength of the blue granite of the Anderson quarry, 

as 24,700, 26,080, and 25,585 pounds per square inch, respectively.

Tests to determine the compressive strength of the Keystone Granite Company's gray granite, near Pacolet station, in Spartanburg 

County, gave 21,420 pounds per square inch.6

INDIVIDUAL QUARRY AREAS.

/ .. DISTRIBUTION.

The map (PI. XXI) shows the location of the principal quarries 

or prospects, which include 33 separate openings. Of these 11 were 

operated in 1908. The principal quarries are on or near railroads. 

A few are located some distance from the principal railroad lines, but 

most of these are connected with the main lines by spur tracks. The 

names and locations of these quarries are given in the subjoined list.

Granite quarries in South Carolina. 

Name.

Quarries operating during 1908.

Pany)- ,

Whittle (Moore Creek) ......................

County.

Fairfield ..........

Laurens. ..........

.....do............

Location.

2 miles south of Columbia.

4 miles northwest of Batesbure.

a Sloan, Earle, op. cit., p. 210. i> Idem, p. 198.
184 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

Granite quarries in South Carolina Continued.

Name.

Quarries operated prior to J90S.

Flat Rock. ..................................

Oro. ........................................

Shelor....... :...............................

County.

Fail-field ..........

Abbeville.........

York..............

Edgefield.........

York..............

.....do............

Fail-field ..........

.....do............

York..............

Location.

GrG6nvillc

2.5 miles, N. 20° W., of Pacolet.

1 mile west of Walhalla.

DESCRIPTIONS CF QUARRIES. 

ABBEVILLE COUNTY.

The Bordeaux quarry is located several hundred feet north of Bordeaux station. The writer was unable to visit this quarry, and the 

description which follows is taken from Sloan's report. a The principal type of rock is a biotite granite gneiss of gray color and fine 

grain, but a fair proportion of the quarry face is a massive granite of 

light-gray color and fine grain. The minerals are potash feldspar 

(orthoclase and microcline), a little soda-lime feldspar (oligoclase), 

quartz, biotite, and muscovite, together with accessory apatite and 

magnetite and secondary chlorite and kaolin. Pegmatite dikes and 

knots occur. The quarry has not been worked for some time.

The Ware Shoals Manufacturing Company's quarry is located at 

Ware Shoals, on Saluda Kiver, about 6 miles northeast of Donalds: 

The rock is a biotite granite gneiss of gray color and fine grain. The 

principal minerals are potash feldspar (microcline and orthoclase), 

soda-lime feldspar (oligoclase), quartz, and biotite, with accessory 

apatite, zircon, and magnetite. A chemical analysis of the granite 

quarried adjacent to the power house at Ware Shoals is given on 

page 175 (No. 17). According to Sloan the absorption ratio of this 

granite is 0.321 and the specific gravity 2.68.

ANDERSON COUNTY.

No granite has been quarried in Anderson County in recent years.

The Hanckel quarry, about 2 miles southwest of Pendleton, was last

worked, according to the owner, C. Hanckel, about fifty years ago, to

aSloan, Earle, op. cit.,pp. LS2-1S3
GRANITES OF SOUTH CAROLINA. 185

supply stone for the construction of culverts and bridges on the Blue 

Ridge Railway. The rock varies from a porphyritic biotite granite 

of reddish-gray color and medium-coarse grain to a biotite granite 

gneiss of light-gray color and fine grain. The principal minerals are 

potash feldspar (orthoclase and microclme), soda-lime feldspar 

(oligoclase), quartz, biotite, and accessory apatite, titanite, and magnetite. The porphyritic feldspar is reddish and is commonly twinned 

on the Carlsbad law. A chemical analysis of this granite is given on 

page 175 (No. 16). According to Sloan the absorption ratio of the 

porphyritic granite is 0.288 and of the granite gneiss 0.448. The 

specific gravity of the granite is 2.68.

CHESTERFIELD COUNTY.

The Oro quarry is located 9 miles west of Ruby. The rock is 

reported to be a biotite granite of red-gray color and of coarse-grained 

to porphyritic texture. According to Sloan the feldspars are red, 

imparting a similar color to the granite, and partial alteration to 

epidote (epidotization) in some portions of the rock affords a greenish 

tint which heightens the effect. The granite has a specific gravity of 

2.66, and is said to be susceptible of an excellent polish.

EDGEFIELD COUNTY.

The Edgcfidd quarry is about 0.5 mile north of the EdgefieldTrenton Railway, 3 miles east of Edgefield, and about the same 

distance from Trenton. The rock is a biotite granite of uneven 

color, usually pinkish gray, and medium grain. Its principal minerals 

are potash feldspar (orthoclase and microcline), soda-lime feldspar 

(oligoclase), quartz, a little biotite, apatite, and garnet. The feldspar has a faint reddish cast. The quartz is decidedly smoky and 

ranges from minute grains up to irregular masses an inch or more 

across. Biotite occurs in very subordinate quantity. Red garnets 

are visible in the hand specimens.

The quarry is about 700 feet long from north to south by about 100 

feet wide and from 50 to 60 feet deep. The abundant quartz streaks 

or masses in this granite render it unsuitable for dimension stone. 

The product has been used principally for government'jetty work at 

Charleston and Georgetown, S. C.

On the west side of the town of Edgefield an irregular muscovitebearing biotite gneiss of dark-gray color and porphyritic texture has 

been quarried. The porphyritic feldspars are without distinct crystal 

boundaries, usually show good cleavage, and are pink in color.

FAIRFIELD COUNTY.

The granites of Fairfield County, especially those of the Rion and 

Anderson quarries of the Winnsboro Granite Corporation, are probably the South Carolina granites best known beyond the limits of the
186 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

State. They are mica granites but show variation in color and texture 

and are naturally grouped commercially into those most desirable for 

(a) building stone and (&) monumental stock. The product from 

the Rion quarry (gray granite) is used chiefly as a building stone; that 

from the Anderson quarry (blue-gray granite) is used exclusively 

for monuments. . These two quarries were the only ones operating in 

Fairfield County at the time of examination in July, 1908.

The Rion quarry is located at Rion, 5£ miles southwest of Winnsboro, and is connected by a standard-gage spur track with Rockton, 

a station on the Columbia, Spartanburg and Asheville division of the 

Southern Railway 4£ miles to the east. (See PL XXII, A.}

The rock is a biotite granite of light-gray color and medium grain. 

Its minerals are potash feldspar (orthoclase, in large part intergrown 

with plagioclase as microperthite, and microcline), soda-lime feldspar 

(oligoclase), quartz, and biotite, together with accessory apatite, 

zircon, and iron oxide and secondary chlorite, epidote, and colorless 

mica. Intergrowths of feldspar (microperthite) and of feldspar and 

quartz (micropegmatite) are abundant. The potash feldspar shows 

Carlsbad twinning. Inclosures of irregular rounded quartz, feldspar, 

and quartz-feldspar intergrowths (micropegmatite) are numerous in 

the larger feldspar individuals. The soda-lime feldspar shows more 

alteration than the potash varieties, chiefly into kaolin and colorless 

mica.

The following chemical analysis of the granite was made by Booth, 

Garrett & Blair, of Philadelphia, for the corporation:

Analysis of granite from Rion quarry.

Silica (Si02 ).................................................. 73. 26 1

Alumina (A1 2 03 ).............................................. 15. 39

Iron oxide (Fe2 03 )............................................. i. 24

Magnesia (MgO).............................................. .38

Lime (CaO)... : ........................................... ; .. 1.36

Soda (Na2 0)................................................... .55

Potash (K2 0)................................................. 6. 89

99. 07.

The specific gravity is 2.62. Tests of the compressive strength are 

given on page 183.

The quarry was opened about 1883, but systematic quarrying did 

not begin until fifteen years later. The quarry face is 300 feet long 

and 20 feet deep. (See PL XXII, B.) There is no stripping in the 

direction of working of the present quarry face. In other places the 

granite is decayed to a depth of 3 to 6 feet.

The principal set of vertical joints, striking approximately north 

and south, with a dip of 65° E., are widely spaced. Their faces are 

slickensided, and in places there is an abundant development of pyrite.
U. 3. GEOLOGICAL SURVEY

A. RION QUARRY OF WINNSBORO GRANITE CORPORATION, NEAR WINNSBORO, S. C.

B. NEAR VIEW OF QUARRY FACE IN RION QUARRY, NEAR WINNSBORO, S. C.
GRANITES OF SOUTH CAEOLINA. 187

Knots are abundant in a few places and are of irregular shapes 

(rounded to much elongated, stringer-like forms) and sizes. -

The working qualities of the granite are excellent and it is splendidly adapted to architectural work, for which it has had an extensive 

sale, as indicated in the following list of prominent structures in which 

it has been used: United States court-house and post-office buildings, 

Wilmington, N. C., Asheville, N. C., Statesville, N. C., and Opelousas, 

Ala.; post-offices, Charleston, S. C., Durham, N. C., Chill ico the, Ohio, 

Traverse City, Mich., Florence, S. C., and Charlottesville, Va.; bank 

building, Goldsboro, N. C.; Fidelity Title and Trust Company Building and Hussey Building, Pittsburg, Pa.; New Land Title and Trust 

Company Building, Philadelphia, Pa.; United States custom-house, 

Baltimore, Md.; building No. 1, commandant's office, navy-yard, 

Charleston, S. C.; Fairmont Trust Company, Fairmont, W. Va.; and

Empire Bank Building, Clarksburg, W. Va.

In addition to its principal use in architectural work, the product 

is used for monument bases. The dry docks at Charleston, S. C., were 

built of this stone, 200,000 cubic feet being used. Extensive cutting 

and polishing yards are operated at the quarry.

The Anderson quarry is about 6 miles west of Rion, and is connected 

by a standard-gage track via Rion with Rockton, on the Southern 

Railway (Columbia, Spartanburg and Asheville division).

The rock is a biotite granite of dark blue-gray color and fine grain. 

It is closely similar to the dark blue-gray granites at Oglesby, Ga., 

(p. 218); at Heath Springs (Excelsior quarry), S. C. (p. 191); and at 

Richmond and Fredericksburg, Va. (p. 76). Of these, the granite at 

Heath Springs is the finest grained. The minerals of the Anderson 

rock are potash feldspar (orthoclase and much microcline), sodalime feldspar (oligoclase), quartz, and biotite, together with accessory 

apatite, zircon, and magnetite and secondary chlorite and colorless 

mica. The orthoclase is partly intergrown with plagioclase as 

microperthite; the oligoclase is altered in part to a white mica and 

kaolin and the biotite to chlorite. Intergrowths of quartz and feldspar (inicropegmatite) occur. Carlsbad twinning is observed in the 

potash feldspar.

The following analysis of the granite was made by Booth, Garrett 

& Blair, of Philadelphia, for the corporation:

Analysis of granite from Anderson quarry.

Silica (Si02 )............... 1................................... 69. 74

Alumina (A12 0:) )-............................................. 13. 72

Iron oxide (Fe,0.;)............................................. 3. 64

Magnesia (MgO)................................................ .22

Lime (CaO).................................................... 1. 54

Soda (Na2 0)..................................................: 5. 39

Potash (K20)................................................. 4. 98

99.23
188 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

V

Pegmatite

N- N Pegmatite \

f -^~ -

/T-L x-- Gra n i te / 7, ^- N""/

FIGURE 16. Banded aplitepegmatite at Anderson 

quarry, near Riou, S. C.

The specific gravity is 2.64. Four tests of compressive strength 

of granite from the Anderson quarry, made by the United States 

Ordnance Department, gave the following results: Maximum, 26,080 

pounds per square inch; minimum, 24,700 pounds; average, 25,585 

pounds.

The quarry, opened about 1898, comprises a number of openings 

made in a large granite boss which rises to an elevation of nearly t 

100 feet above Mill Creek. The angle of slope 

averages from 10° to 20°, flatter in some places 

and steeper in others. No stripping is required 

over much of the boss.

The vertical joints strike N. 20° E., N. 35° to 

40° E., N. 45° to 50° W., and N. 80° W. and are 

spaced at varying intervals. Several zones of 

close jointing were observed in places where 

the granite had not been opened. Pegmatite 

dikes, from a fraction of an inch to 8.inches 

thick and composed of white feldspar, glassy 

quartz, and scant biotite, occur in the granite. 

Aplite dikes, up to 12 inches thick, of lightgray color and fine grain and containing scant 

biotite, are also present. In some places the aplites and pegmatites 

are banded, as shown in figures 16 and 17. The principal banded 

aplite-pegmatite in the large opening strikes N. 65° W. There are 

a few small knots composed entirely of biotite.

The granite is uniform in color and texture, possesses good working 

qualities, is susceptible of a high polish, and is 

admirably adapted to monumental purposes. 

The product is used chiefly for monumental 

Stock, and is reported to have been so used in 

twenty-four States.

The Strother quarry is located half a mile south 

of Strother, on the east side of the Columbia, 

Spartanburg and Asheville division of the Southern Railway, with which the quarry is connected by a spur track. The rock is a biotite 

granite of light-gray color and irregular fine to 

coarse grain. Its minerals are potash feldspar 

(microcline and orthoclase), soda-lime feldspar 

(oligoclase), quartz, biotite, a little muscovite, 

and accessory apatite and magnetite. The 

product has been used for rubble masonry at the Charleston navy-yard. 

The Blair quarry is about half a mile east 'of Blair, a station on the 

Columbia, Spartanburg and Asheville division of the Southern Railway. The rock is a biotite granite of gray color and fine grain, with 

a porphyritic tendency in places. The minerals are the same as those

-'\Granite v "To

Pegmatite\-

FIGURE 17. Banded aplitepegmatite at Anderson 

quarry, near Rion, S. C.
GEAN1TES OF SOUTH CAROLINA. 189

at the Strother quarry. A chemical analysis of this granite is given 

on page 175 (No. 11). Its specific gravity is 2.66. A few pegmatite 

dikes and knots occur in the granite.

The Leiper-Davis quarry, comprising two openings about 500 feet 

apart, is located about 5 miles northeast of Alston, close to Little 

River. The rock is a biotite granite of medium-gray color and 

medium-fine grain. The principal minerals are potash and soda-lime 

feldspars, quartz, and biotite. The granite possesses good working 

qualities, is susceptible of a good polish, and was extensively used at 

one time for monumental stock.

The Stewart quarry is located about 2| miles west of Rockton. 

The rock is a biotite granite of light-gray color and medium-fine 

grain. The principal minerals are potash and soda-lime feldspars, 

quartz, an^ biotite. The quarry had not been worked for some time 

prior to the writer's visit in July, 1908, and very little could be seen. 

The granite is reported to contain numerous knots of large and 

small size.

About a mile south of Wimisboro, immediately on the WinnsboroRockton highway, are exposures of a hornblende-bearing biotite 

granite of slightly pinkish medium-gray color and medium grain. 

Much titanite is visible in the hand specimens. This granite is the 

only one of those examined by the writer in the State in which hornblende is present. The minerals are potash feldspar (orthoclase and 

microcline), soda-lime feldspar (oligoclase), quartz, biotite, and 

hornblende, together with accessory titanite, apatite, zircon, and 

iron oxide and secondary chlorite, kaolin, and light-colored mica. 

Plagioclase is in excess of potash feldspar. Intergrowths of feldspar 

(microperthite) and of feldspar and quartz (micropegmatite) are 

common. Irregular rounded inclosures of feldspar and quartz are 

contained in. some of the larger "feldspar individuals. Feldspar 

twinning on the Carlsbad law is shown.

GREENVILLE COUNTY.

The only granite quarried in Greenville County has been a small 

quantity obtained from the western slope of Paris Mountain, about 

6 miles north of Greenville, the county seat, by the Paris Mountain 

Granite Company, of Greenville. The rock is a biotite granite of 

gray color, medium-fine grain, and indistinct gneissoid structure. 

The minerals are potash feldspar (microcline and orthoclase), sodalime feldspar (oligoclase), quartz, biotite, muscovite, and accessory 

apatite, titantite, and magnetite. Titanite is visible in hand specimens of the granite. Quartz and feldspar'are locally intergrown in 

micropegmatitic structure. The granite apparently possesses good 

working qualities under the hammer and chisel. According to Sloan 

its specific gravity is 2.72 and its ratio of absorption 0.304.
190 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

A somewhat similar granite is exposed on the southern slope of 

Piny Mountain, about 2 miles northeast of Greenville, within 300 

yards of the Atlanta and Charlotte division of the Southern Railway. 

This rock is a biotite granite of gray color, medium grain, and 

gneissoid structure. It has not been developed.

GREENWOOD COUNTY.

The Benjamin quarry, comprising a number of openings in bowlders 

and bowlder-ledge exposures grouped rather close together, is about 

4 miles east-northeast of Greenwood and less than a mile north of 

Quarry station.

The rock is a biotite granite of medium-light pinkish-gray color 

and dense, medium-coarse grain. The feldspars in the hand specimens have a decided light-pink color. The minerals fare potash 

feldspar (microcline and orthoclase, the latter partly microperthite), 

soda-lime feldspar (oligoclase), quartz, and biotite, together with 

accessory titanite, zircon, apatite, and iron oxide and secondary 

chlorite, epidote, and light-colored mica. The quartz contains 

threadlike inclusions of rutile. Microcline and oligoclase are the 

dominant feldspars. Much accessory titanite occurs. Small areas 

of micropegmatitic intergrowths of quartz and feldspar are shown.

A chemical analysis of the granite is given on page 174 (No. 9). 

The specific gravity is 2.65.

The sheets are from 4 to 8 feet thick, and the vertical joints are 

widely spaced. The decay is usually deep, necessitating at the two 

largest openings a stripping of several feet. The quarry had not 

been worked for some time prior to the writer's examination in July, 

1908.

KERSHAW COUNTY.

Practically no quarrying of granite has been attempted in Kershaw 

County. Mica granites of excellent grade, possessing good working 

qualities and susceptible of a high polish, occur in the northwestern 

part of the county in the vicinity of Liberty Hill post-office.

About 7 miles southwest of Heath Springs and about ! £ miles 

southeast of the Excelsior granite quarry, in Lancaster County, are 

exposures of a biotite granite of medium-gray color and fine grain, 

similar to that quarried by the Southern Granite Company at the 

Excelsior quarry. The minerals are potash feldspar (microcline 

and orthoclase), soda-lime feldspar (oligoclase), quartz, biotite, a 

little muscovite, together with accessory apatite and magnetite and 

secondary chlorite, kaolin, and iron oxide. Oligoclase and microcline are the dominant feldspars, the former showing considerable 

alteration, principally to kaolin. A chemical analysis of this granite, 

according to Sloan,a is given here for reference.

oSloan, Earle, op. cit., p. 219.
GRANITES OF SOUTH CAROLINA. 191

Analysis of granite 7 miles southivest of Heath Springs.

Silica (Si02 ).................................................. 72.22

Alumina (A12 03 )............................................. 14. 51

Ferric oxide (Fe203 )......................................... 1. 28

' Ferrous oxide (FeO)......................................... 1. 52

Magnesia (MgO)............................................. .58

Lime (CaO)................................................. 1. 32

Soda (Na20)................................................ 3.21

Potash (K2 0)................................................ 4. 30 .

Ignition.................................................... .52

Manganese oxide (MnO)..................................... Trace.

Titanic oxide (Ti02 )........................................... .24

Phosphoric oxide (P205 )., ...............i.... ^............... Trace.

99.70

The specific gravity is 2.63. This granite is uniform in color and 

texture, works well under the hammer and chisel, ,is susceptible of a 

high polish, and is one of the most desirable granites in the State for 

monumental purposes.

About half a mile north of Liberty Hill post-office, on the property 

of Mrs. Richards, is an outcrop of red-gray muscovite granite of 

medium-fine grain. Its principal minerals are oligoclase, orthoclase, 

microcline, quartz, muscovite, very little biotite, and accessory apatite. Soda-lime feldspar (oligoclase) is the principal feldspar and 

is considerably altered to kaolin.

The granite, of Flatrock (old Dekalb granite), near Cleyburn, 

has been quarried to a moderate extent. It is a biotite granite of 

red-gray color and coarse-grained porphyritic texture. The principal minerals are orthoclase (partly microperthite), oligoclase, quartz, 

and biotite, with accessory apatite and magnetite. A chemical 

analysis of this granite is given on page 174 (No. 2). The specific 

gravity is-2.65.

LANCASTER COUNTY.

Two grades of granite occur in Lancaster. County, but are limited 

principally to the southern, part of the county, near the Kershaw 

County line. One is a biotite granite of dark-gray color and fine 

grain, and is used chiefly for monumental stock; the other is a biotite 

granite of coarse-grained porphyritic texture. Only the dark-gray 

fine-grained granite has been quarried to any great extent. Both 

are described below.

The Excelsior quarry of the Southern Granite Company, including 

two openings made in 1902, is located about 6 miles by rail (6£ miles 

by wagon road) southwest of Heath Springs, near the Kershaw 

County line. The rock is a biotite granite of dark blue-gray color and 

fine grain. Its minerals are potash feldspar (orthoclase and microcline), soda-lime feldspar (oligoclase), quartz, and biotite, together

38971° Bull. 426 10 13
GEANITES OF SOUTHEASTERN ATLANTIC STATES.

with accessory apatite, zircon, and iron oxide and secondary chlorite, 

epidote, colorless mica, and kaolin. The orthoclase is intergrown in 

part with plagioclase. Much microcline is present. Intergrowths of 

quartz and feldspar as micropegmatite occur. A chemical analysis 

of this granite, as reported by Sloan, 0 is given below.

Analysis of granite from Excelsior quarry.

Silica (Si02 ).................................................. 70.11

Alumina (A1 208 )--........................................... 15. 76

Ferric oxide. (Fe2 03 )........................................... 1. 07

Ferrous oxide (FeO)........................................... 1.76

Magnesia (MgO)................................................ .62

Lime (CaO).^...............................'................. 1.84

Soda (Na20).................................................. 3.39

Potash (K20)................................................ 4. 27

Ignition...................................................... .45

Manganese oxide (MnO)....................................... Trace.

Titanic oxide (Ti02 ). -........................................ .45

Phosphoric oxide (P203 )...................................... Trace.

Sulphuric oxide (S03 )........................................ Trace.

99.72

The specific gravity is 2.66.

The main-quarry opening is worked to a depth of 35 feet. Prior to 

its opening in 1902 many of the numerous large granite bowlders 

exposed over most of the tract of 1,093^ acres were quarried.

Vertical joints are few and widely spaced in the lower opening, 

which was being worked in July, 1908. They strike N. 3° W. and

 N. 80° W., and are sufficiently far apart to permit the quarrying of 

columns 25 to 60 feet long. Many 25-foot columns used in the construction of the president's house near the quarry were examined, 

and one 58 feet 5 inches long was loaded on the car at the time of the

 writer's visit. The joint faces are slickensided and coated with a

whitish mineral substance, indicating some movement in the granite 

mass. Vertical joints in the abandoned opening on top of the knoll 

are rather numerous, striking N. 20° E., N. 10° W., and N. 45° W., 

and, as a rule, are closely spaced. Their faces are slickensided and 

coated with a reddish mineral substance. Here and there a pegmatite dike less than 1 inch thick is observed and there are a very few 

knots.

The granite is entirely uniform in color and texture, possesses good 

working qualities, is susceptible of a high polish, and is especially 

adapted to high-grade monumental stock, for which it is now used 

exclusively. The product has been shipped as far north as Brooklyn, 

N. Y., and west to Denver, Colo., and Portland, Oreg.

The quarry is connected with Heath Springs, on the Southern Railway, by a standard-gage railway track.

a Sloan, Earle, op. cit, p. 222.
U. S. GEOLOGICAL SURVEY

A. BOWLDER OUTCROP OF GRAY GRANITE, RION QUARRY, FAIRFIELD COUNTY, S. C.

/>'. BOWLDER OUTCROP OF COARSE-GRAINED GRANITE 3 MILES SOUTHWEST OF HEATH

SPRINGS, S. C.

C. BARED SLOPE OF GRANITE GNEISS, BEVERLY QUARRY, BEVERLY STATION, PICKENS

COUNTY, S. C.
GRANITES OF SOUTH CAROLINA. 193

Beginning about 1£ miles southwest of Heath Springs and extending for a considerable distance along the highway to the Excelsior 

quarry is a coarse-grainedporphyriticbiotite graniteof a mixed greenish-yellow and reddish-gray color, similar to that near Lilesville, 

Anson County, N. C., described on page 162. As shown in Plate 

XXIII, B, the granite is exposed in places in large bowlder outcrops. It has not been quarried, but its color and texture are such 

as to render it of value as a decorative stone. Its minerals are potash 

feldspar (orthoclase and microcline), much soda-lime feldspar (oligoclase), quartz, and bio tite, together with accessory apatite, zircon, 

and iron oxide and secondary chlorite, epidote, a little colorless mica, 

and kaolin. The potash feldspar shows Carlsbad twinning. The 

plagioclase feldspar, which is equal to or greater in amount than the 

potash feldspar, is partly altered. ' -

Sloan a has described porphyritic bio tite granite of. coarse grain 

from two other localities in Lancaster County 6£ miles west of 

Jefferson and 6£ miles northeast of Kershaw. The granite west of 

Jefferson is reported to have been used formerly for millstones.

LAURENS COUNTY.

Two grades of granite are quarried in Laurens County, one a finegrained massive granite of light pinkish-gray color, the other a coarsegrained granite gneiss of medium dark-gray color. The granite is 

quarried at Cold Point station, south of Laurens, and the granite 

gneiss at Graycourt station, a little west of north from Laurens.

The Cold Point Granite Company's quarry, opened in 1904, comprises a principal opening and several smaller ones. It is located on 

the west side of the railroad less than half a mile north of Cold Point 

station. The rock is a biotite granite of light reddish-gray color and 

fine grain. The feldspar is of faint though marked reddish color. 

Biotite is present in small amount. The minerals are potash feldspar (orthoclase and microcline, the former largely microperthite), 

soda-lime feldspar (oligoclase), quartz, and biotite, together with 

accessory apatite, titanite, and zircon and secondary chlorite, epidote, 

and colorless mica. The orthoclase is intergrown with plagioclase. 

The larger feldspar individuals inclose irregular grains of quartz and 

feldspar.

According to Sloan 6 the absorption ratio of this granite is 0.344 

and the specific gravity 2.65. A.chemical analysis of the granite is 

given on page 174 (No. 3).

In the main quarry opening, worked to a depth of 40 feet, occurs 

an inclusion, 15 by 30 feet, of a thinly foliated dark (nearly black) 

gneiss. It is composed of dominant black lustrous biotite and some

a Sloan, Earle, op. cit., pp. 224-225. >> Idem, p. 190.
194 GRANITES OF SOUTHEASTER ATLANTIC STATES.

white feldspar and quartz and in places shows a partial porphyritic 

texture. The granite is sheeted in places near the surface but grades 

into massive rock at slight depth. The vertical joints strike-N. 50° 

E. and N. 70° E. and are spaced at varying intervals. Some pegmatites and knots occur. From 4 to 6 feet of stripping is necessary in 

places. A No. 5 Austin crusher is operated at the quarry for crushing 

and sizing the stone. Blasting is employed for breaking down 

(quarrying) the rock. The product, in the form of crushed stone, 

blocks, and curbing, is used almost exclusively in the State.

The Entrekin quarry is located less than a mile east of Graycourt 

station. The rock, is a biotite granite gneiss of medium dark-gray 

color and coarse.grain. Its minerals are potash feldspar (orthoclase 

and microcline), soda-lime feldspar (oligoclase), quartz, and biotite, 

together" with accessory apatite and zircon and secondary chlorite 

and epidote. Intergrowths of quartz and feldspar (micropegmatite) 

in small irregular areas are noted. There is considerable granulation 

of the quartz and feldspar, forming distinct areas of finer-grained 

mosaics. The quartz and feldspar further show strain effects in 

undulous extinction and fractures. The white feldspars, smoky 

vitreous quartz, and black lustrous biotite contrast strongly in the 

hand specimens. The resemblance of the granite gneiss from this 

quarry to that of the Beverly quarry (p. 197) is very striking. The 

minerals are segregated into alternating dark (dominant biotite) and 

light (dominant feldspar and quartz) bands, of irregular thickness and 

more or less contorted. Pegmatite dikes, quartz veins, and knots 

occur. The product is used principally for curbing, lintels, etc.

LEX1NGTON COUNTY.

The granite quarries in Lexington County are near Columbia, in 

Klchland County, and near Lexington, the county seat, 12 miles 

west of Columbia.

The Boss quarry is about 2 miles south of Columbia, on the opposite 

side of Congaree River from Morris & Co.'s (Lipscomb) quarry. The 

quarry is a large one, but at the time of examination, in July, 1908, it 

was idle and nearly filled with water. Preparations were then in 

progress for draining it preparatory to resuming operations for a 

contract to supply stone for government jetty work. The rock is a 

biotite granite of gray color and fine to coarse grain. Two facies of 

the granite are represented, similar to those at Morris & Co.'s quarry 

(p. 198). A chemical analysis of the granite is given on page 175 

(No. 13). Its specific gravity is 2.68. "

The Casparis Stone Company's quarry, opened about 1902, is located 

about 1£ miles N. 75° E. of Lexington station and about 300 yards' 

north of the Columbia and Augusta division of the Southern Railway. 

The rock is a biotite granite of light reddish-gray color and medium
GEANITES -OF SOUTH CAROLINA. 195

grain, with a pronounced porphyritic tendency in places. The feldspars are pinkish and are in places elongated and flat tabular in 

outline. The granite from this quarry resembles that from the 

Smith Branch (County) quarry, near Columbia, except that it is of 

finer-grained texture. Its resemblance to the granite from the Bates 

quarry, in Saluda County, is also very striking. The minerals are 

potash feldspar (orthoclase and microcline), soda-lime feldspar (oligoclase), quartz, biotite, and a little pyrite, with secondary chlorite, 

epidote, colorless mica, and kaolin. The feldspars show considerable 

alteration. Biotite is partly altered to chlorite. Intergrowths of 

the feldspars with each other (microperthite) and of the feldspars 

with quartz (micropegmatite) are indicated.

The quarry is of circular shape, about 200 feet in diameter and 50 

feet deep. The vertical joints strike N. 5° to 10° E., N. 35° E., and N. 

20° W.; several minor sets were not measured. They dip at various

angles and are so closely spaced as to prevent the quarrying of 

dimension stone. The joint faces are slickensided and coated with 

a reddish mineral substance. An aplite dike 2 inches thick, of lightgray color and fine grain, was noted. Pegmatites and knots were not 

observed. From 1 foot to 5 feet of stripping is required.

The product is used chiefly in the form of crushed stone; in July, 

1908, it was used for government jetty work at Savannah, Ga.. The 

quarry is connected with the Lexington station by a standard-gage 

track.

NEWBERRY COUNTY.

. Extending north, northeast, and northwest from the town of Newberry is an extensive area of granite. The exposures are chiefly in 

the form of large and small bowlder masses, which have been worked 

in many places to supply the local demand for stone in buildings and 

monuments. No extensive quarries have been opened, the work done 

consisting in the quarrying of some of the larger bowlders, in places 

to considerable depth below the surface.

The three quarries described below are the most recently operated 

ones and are worked when a local demand for stone arises. Other 

similar openings of long standing have been made at several places 

in the Newberry granite area.

The Leitzsey quarry, opened in a bowlder exposure of granite, is 

about 5 miles northeast of Newberry. The rock is a biotite granite 

of medium-gray color and fine grain. Its minerals are potash feldspar 

(orthoclase, largely microperthite, and microcline), soda-lime feldspar 

(oligoclase), quartz, biotite, and very little muscovite, together with 

accessory apatite, zircon, and magnetite and secondary chlorite, 

epidote, colorless mica, and kaolin. Orthoclase is intergrown with 

plagioclase as microperthite. Small roundish areas of quartz-feldspar
196 GEANITES OF SOUTHEASTERN ATLANTIC STATES.

intergrowths (micropegmatite) are common. A chemical analysis of 

this granite is given on page 174 (No. 5). Its specific gravity is 2.65.

The vertical joints strike N. 45° E. and N. 70° W., and are widely 

spaced. A few pegmatites, 1 to 2 inches thick, occur. The working 

qualities of the granite are good and it is susceptible of a very high 

polish. The product has been used extensively for monuments.

The Spears (Baxter} quarry, comprising two openings in large 

bowlder exposures of the granite, is about 4 miles northeast of Newberry. The rock is a biotite granite of medium-gray color and fine 

grain. The minerals are potash feldspar (orthoclase, chiefly microperthite and microcline), soda-lime feldspar (oligoclase), quartz, and 

biotite, together with apatite, zircon, and magnetite and secondary 

chlorite, epidote/ colorless mica, and kaolin. The orthoclase is intergrown with a second feldspar (plagioclase). Numerous small rounded 

areas of quartz-feldspar intergrowths (micropegmatite) occur. Some 

of the feldspar shows zonal structure' twinning on the Carlsbad law 

is noted.

The vertical joints are widely spaced. Several pegmatite dikes, a 

fraction of an inch to 1£ inches thick, occur. Knots were not 

observed. The granite works well under the hammer and chisel and 

is susceptible of a high polish. The product has been used locally in 

buildings and in monuments.

The Level quarry, opened in large bowlder exposures of granite, is 

about 3£ miles northwest of Newberry and about half a mile northwest of the Columbia, Newberry and Laurens Railway. An old 

opening of very long standing, filled with water at the time of examination in July, 1908, is near by. The rock is a biotite granite of 

medium-gray color and fine grain. Its minerals are potash feldspar 

(orthoclase, chiefly microperthite, and microcline), so.da-lime plagioclase (oligoclase), quartz, and biotite, together with apatite and zircon and secondary chlorite, colorless mica, and kaolin. The orthoclase is intergrown with soda-lime feldspar. The oligoclase shows 

considerable alteration to a colorless mica and kaolin. Pegmatites 

and knots were not observed. The granite is susceptible of a high 

polish and works well under the hammer.

OCONEE COUNTY.

Gneisses which afford strong evidence of having been derived from 

original granites by metamorphic processes, chiefly granulation and 

recrystallization, are extensively distributed over parts of Oconee 

County. A quarry was opened in an exposure of the gneiss near 

the state line and stone was obtained for use as piers and abutments 

in the Southern Railway bridge over Tugaloo River.

At Tunnel Hill and Lays Mill, about 6 miles northwest and 7 miles 

northeast of Walhalla, respectively, are exposures of biotite gneiss of 

medium-gray color and fine grain. The porphyritic texture is usu-
GRANITES OP SOUTH CAROLINA. 197

ally distinct, imparting an augen effect to the gneiss; the porphyritic 

mineral is pink microcline. Muscovite is usually present, associated 

with the biotite. These minerals show marked orientation, to which 

is due the banding of the gneiss. Thin sections of the rocks from 

these localities indicate derivation from porphyritic granites, chiefly 

by granulation and recrystallization.

PICKENS COUNTY.

The Beverly quarry, operated in 1908 by the Greenville Crushed 

Stone Company, is located at Beverly station, on the northwest side 

of the Atlanta and Charlotte division of the Southern Railway. The 

railroad extends along the southeastern base of the doming ridge in 

which the quarry is opened. The rock is a contorted biotite granite 

gneiss of medium to dark gray color and medium grain. It consists of 

white potash feldspar (orthoclase and microcline), white soda-lime 

'feldspar (oligoclase), clear or barely smoky quartz, black mica (biotite), and a little white mica (muscovite), together with accessory 

titanite, zircon, apatite, and iron oxide and secondary chlorite, 

epidote, and colorless mica. Orthoclase is partly intergrown with a 

second feldspar as microperthite. Microcline shows evidence of 

having been derived in part from orthoclase. Micropegmatite intergrowths as small areas are indicated, and some of the larger feldspar 

individuals show micropoikilitic structure (inclosures of rounded 

quartz chiefly). Granulation of the quartz and feldspar is pronounced and orientation of the biotite is usually well marked. In 

the hand specimens much titanite is visible in association with the 

biotite. Here and there pyrite is noted.

The following analysis of granite gneiss from the Beverly quarry, 

quoted from Sloan's report,* will indicate the general chemical composition of the rock:

Analysis of granite gneiss from the Beverly quarry.

Silica (S102 ).................................................. 68.15

Alumina (A1 2 03 )............................................. 14. 30

Ferric oxide (Fe2 03 )............................................ 2. 44

Ferrous oxide (FeO)........................................... 2. 49

Magnesia (MgO)............................................... 1. 04

Lime (CaO)................................................... 2. 80

Soda (Na 2 0).................................................. 3.80

Potash (K20)................................................ 3. 84

Ignition...................................................... .28

Titanic oxide (Ti02 ).......................................... .60

Manganese oxide (MnO)....................................... .11

Phosphoric oxide (P205 )...................................... Trace.

Sulphur oxide (S03 )........................................... Trace.

99.85

oSloan, Earle, Bull. South Carolina Geol. Survey, ser. 4, No. 2, J908, p. 181.
198 GEANITES OF SOUTHEASTERN ATLANTIC STATES.

The specific gravity is 2.66. Sloan gives the absorption ratio as 

0,398.

The quarry was opened about 1894 and is approximately 300 by 405 

feet, with a vertical face of 80 feet, the greatest depth of working. 

Sheeting does not occur and pegmatites and knots have very scanty 

development, only a few small ones being observed. There is no 

stripping. (See PL XXIII, 0.)

The vertical joints are widely spaced. The principal set trends 

N. 60° E. with dips of N. 50° E. and N. 58° W. Slickensides are 

developed on the joint faces, and are coated locally with a yellowish 

mineral substance, indicating movement in the granite mass since 

the formation of the joints.

The rock is composed of alternating more or less continuous dark, 

(dominant biotite) and light (dominant feldspar and quartz) bands 

of variable thickness and highly contorted. As a rule the dark bands 

are much thinner and less continuous than the light ones. A marked, 

tendency toward porpliyritic texture is observed in places, imparting 

to the rock somewhat the appearance of an augen gneiss. The 

granite gneiss from the Beverly quarry closely resembles a similar 

granite gneiss quarried at Lithonia (p. 253) and Odessadale (p. 262), 

Ga., and Rocky Face Mountain (p. 152), Alexander County, N. C. 

The Beverly rock is coarser grained than that of the Georgia localities.

This quarry, located directly on the railroad, possesses excellent 

advantages for operating. The entire product is crushed at the 

quarry and is used principally for concrete work and roofing gravel.

HIGHLAND COUNTY.

The granite quarries in Richland County lie near the city of Columbia, on the south and northwest sides. The granites are mostly concealed beneath a thin cover of the Coastal Plain gravel, sand, and 

clay, and in position are very similar to those of areas in North Carolina, Virginia, and Maryland on the north and in Georgia on the south.

The Morris & Co. (Lipscomb) quarry, opened about 1883, is located 

about 1£ miles south of Columbia, on the east side of and near Congaree River. Two facies of the granite, which usually grade into 

each other without sharp definition, occur in the quarry. The dominant one is a biotite granite of medium-gray color and medium-coarse 

grain, with a pronounced porphyritic tendency in places. Its minerals are potash feldspar (orthoclase and microcline), soda-lime feldspar (oligoclase), quartz, and biotite, together with accessory apatite, 

zircon, and iron oxide and secondary chlorite, epidote, light-colored 

mica, and kaolin. A part of the feldspar is twinned on the Carlsbad 

law. Some of the larger feldspar individuals inclose irregular rounded 

grains of quartz and feldspar. Micropegmatite areas are numerous.
GBANITES OF SOUTH CAROLINA. 199

The second facies is a biotite granite of medium dark-gray color and 

fine grain. Here and there porphyritic feldspar is conspicuously developed and twinned on the Carlsbad law. The minerals are the same 

as in the dominant facies just described. Carlsbad twinning and 

micropoikilitic and micropegmatitic structures are common.

The quarry is a large one, measuring approximately 750 by 500 

feet and 50 to 75 feet deep. The sheets, 6 inches to 4 feet thick, are 

horizontal and grade into massive granite with increasing depth. 

The vertical joints strike north-south, N. 70° E., N. 10° W., and 

N. 50° W., and as a rule are spaced at intervals of 2 to 4 feet. The 

joint faces are slickensided, being coated with a reddish to greenishyellow mineral substance. Pegmatite dikes, from a fraction of an 

inch to 6 inches thick, are common. The feldspar of the pegmatite 

dikes is white; biotite is present, though very subordinate in amount.

Knots occur but rarely.

The granite is of good quality and is suitable for a wide range of 

uses. It has had an extensive use in government jetty work. The 

entire product at present goes into crushed stone, the average production of which during the summer of 1908 was between 4,000 and 

5,000 tons a month. A large crushing plant is operated at the quarry.

The Smith Branch (County} quarry is located on the north side ofSmith Branch, about 300 yards west of the Seaboard Air Line Railway and about 2 miles N. 25° W. of Columbia. The rock is a biotite 

granite of mixed reddish-gray color and coarse grain. The feldspars 

are of a pronounced pinkish color and much of the quartz is of the 

dark smoky variety. Both of these minerals are larger in size than 

the biotite. The minerals are potash feldspar (orthoclase and microcline), soda-lime feldspar (oligoclase), quartz, and biotite, together 

with accessory apatite and magnetite and secondary chlorite, epidote, 

colorless mica, and kaolin. The, soda-lime feldspar is equal to or 

greater than the potash feldspar. Twinning on the Carlsbad law is 

noted.

The quarry is roughly circular in shape, measuringt approximately 

50 by 60 feet and 40 feet deep. The decayed granite extends to a 

depth of 10 to 15 feet. The vertical joints strike N. 60° E., dip about 

50° NW., and are widely spaced. The joint faces are slickensided, 

being coated with a yellowish mineral substance. Brownish-red 

aplite dikes of exceedingly dense, fine-grained texture, without visible 

mica, are rather abundant. The largest one, a dike 4 feet thick, 

strikes northeast and dips to the southeast. The mineral composition is identical with that of the inclosing granite orthoclase, a little . microcline, much oligoclase, quartz, a little biotite, accessory apatite, 

and secondary chlorite and epidote. The potash feldspar is apparently in excess of the soda-lime feldspar.
200 GBANITES OF SOUTHEASTERN ATLANTIC STATES.

SALUDA COUNTY.

The only granite area in Saluda County in which quarries have 

been opened is in the extreme southeast corner of the county, near 

the Lexington County line, extending northward from a point half a 

mile north of Batesburg to and beyond Clouds Creek, a distance of 

5£ miles. In this area are large exposures of granite, chiefly in 

bowlder and flat-surfaced masses. Variation in texture, color, and 

structure is observed. A decided porphyritic tendency is very generally shown. No systematic quarrying has been attempted in this 

area, the openings are small, and the consumption of the product is 

local.

The Bates quarry includes numerous small openings widely separated, located from half a mile to a mile north of Batesburg. The 

rock is a biotite granite of pinkish-gray color and medium to coarse 

grain. The feldspars are of larger size than the other components 

and impart a porphyritic appearance to the rock. They are of irregular outline and are partly pink in color. A partial parallel arrangement of the bi'otite is discernible in places and the granite shows an 

indistinct foliation. The minerals are potash feldspar (orthoclase 

chiefly and microcline), soda-lime feldspar (oligoclase), quartz, and 

biotite, together with accessory apatite, zircon, and iron oxide and 

secondary chlorite, epidote, mica, and kaolin. Abundant quartzfeldspar intergrowths (micropegmatite) occur. A partial peripheral 

granulation of the quartz and feldspar is shown and a rude orientation 

of the biotite is noticeable.

In one opening the rock is a typical granite gneiss of gray color and 

fine grain. It is identical in mineral composition with the granite, 

except that some muscovite is present. A chemical analysis of the 

gneiss is given on page 175 (No. 19). The specific gravity is 2.64.

The Whittle quarry includes several small openings on the south 

side of Moores Creek, about 4 miles northwest of Batesburg. The 

rock is a porphyritic biotite granite of dark-gray color and coarse 

grain. The quartz has a decided bluish opalescent cast and the 

groundmass feldspars are dark gray. As a rule the feldspar phenocrysts are of irregular outline, roughly rounded, the largest measuring 

about 2^ by If inches. They inclose biotite and are of white to gray 

color. The minerals are potash feldspar (microcline and orthoclase), 

soda-lime feldspar (oligoclase), quartz, and biotite, with secondary 

colorless mica, chlorite, iron oxide, and kaolin. The feldspar and 

biotite show some alteration, the former to mica and kaolin, the latter 

to chlorite and iron oxide. The orthoclase is partly intergrown with 

plagioclase. Carlsbad twins are common. The feldspar and quartz 

are crossed by fractures which are filled with mineral matter.
GRANITES OF SOUTH CAROLINA. 201

A chemical analysis of a similar granite on Milton Prater's place 

on Clouds Creek, 4.7 miles north of Batesburg, taken from Sloan's 

report,0 is given below and serves to show the general composition 

of the rock.

Analysis of porphyritic granite from Prater''s place, north of Batesburg, S. C.

Silica (Si02 ).................................................. 68. 70

Alumina (A1 2 03 )............................................. 15. 49

Ferric oxide (Fe203 )............................................. 1.10

Ferrous oxide (FeO)........................................... 3. 73

Magnesia (MgO)............................................... .86

Lime(CaO)................................................... 1.70

Soda(Na2 0).................................................. 3.09

Potash (K20)................................................ 3. 36

Ignition...................................................... . 81

Manganese oxide (MnO)....................................... Trace.

Titanic oxide (Ti02 )......................................... -84

Phosphoric oxide (P2O5) ...- .................................. 1 Trace.

Sulphuric oxide (S0:t)-. -..................................... . 13

99.51

The specific gravity is 2.73.

The dark-gray, coarse-grained porphyritic granite occupies an 

extensive area, the width of which is not less than 3 miles. Large 

bowlder outcrops are abundant near Moores and Clouds creeks. 

Numerous small openings have been made in the vicinity of both 

streams and some of these date back many years. The product was 

formerly used for millstones.

SPARTANBURG COUNTY.

The quarries in Spartanburg County are near Pacolet, about 12 

miles southeast of the city of Spartanburg,

The- Pacolet Granite Company's (Jolmsori) quarry is located about 

0.75 mile northwest of Pacolet station. The dominant facies of the 

rock is a biotite granite of medium-gray color and fine grain. A second 

facies is a pronounced biotite granite gneiss of light-gray color and 

fine grain. The banding of the gneissic phase is in places highly 

contorted. Mineralogically there is no difference in the two facies. 

The minerals are potash feldspar (orthoclase and microcline), sodalime feldspar (oligoclase), quartz, biotite, and a little muscovite, 

together with accessory apatite, zircon, and iron oxide and secondary 

chlorite, much epidote, light mica, and kaolin.. The orthoclase is 

intergrown with plagioclase as microperthite. The feldspars are 

partly altered to kaolin and light mica. A partial granulation of 

the quartz and feldspar is apparent in small areas of fine-grained 

mosaics. Some of the larger feldspar individuals inclose irregular 

rounded grains of quartz and feldspar.

aSloan, Earle, op. cit., p. 192.
202 GKANITES OP SOUTHEASTEKN ATLANTIC STATES.

The quarry had not been worked for some time prior to the writer's 

visit in July, 1908. It is roughly circular in outline, about 250 by 

300 feet and 15 to 20 feet deep. The sheets range from 4 inches to

2 feet in thickness and are approximately horizontal. The vertical 

joints strike east and west and are spaced at intervals of 1 inch to

3 feet. The faces of some of the joints are slickensided. Pegmatite 

dikes up to 12.inches thick are abundant. Besides the usual minerals -feldspar, quartz, and mica (biotite and muscovite) some of 

the pegmatite dikes carry black tourmaline. There are some knots 

in the granite. Several feet of stripping is necessary.

The Keystone Granite Company's quarry, comprising two openings 

half a mile apart, is 2£ miles N. 20° W. from Pacolet station. The 

rock is a biotite granite of medium-gray color and fine grain. It is 

identical with the dominant facies of granite at the Pacolet Granite Company's quarry, described above. The minerals are potash 

feldspar (orthoclase and a little microclihe), soda-lime feldspar (oligoclase), quartz, biotite, and some muscovite, together with accessory 

apatite, zircon, and magnetite and secondary chlorite, epidote, 

kaolin, and much light-colored mica. The orthoclase is partly intergrown with plagioclase as microperthite. Twinning on the Carlsbad 

law occurs. Rutile is present as threadlike inclusions in the quartz. 

Some of the feldspar shows partial alteration into kaolin and lightcolored mica.

A chemical analysis of the granite made by the Pittsburg Testing 

Laboratory, Pittsburg, Pa., is given on page 175 (No. 12). Sloan0 

gives the compressive or crushing strength as 21,420 pounds to the 

square inch.

The largest opening is about 300 by 350 feet and 30 feet deep. The 

sheets average several feet in thickness. The vertical joints strike 

east and west and are widely spaced; their faces are locally slickensided. Pegmatite dikes up to 18 inches thick are observed. A large 

cutting and polishing plant was formerly operated at the quarry, but 

it has been almost dismantled. A spur track, now unused, runs between the quarry and Pacolet station.

The working qualities of this granite are very good. It is susceptible of a high degree of polish and of carved work, as shown in large 

pieces of the granite at the old dressing plant. It was extensively 

used for monumental stock.

UNION COUNTY.

Granite has been quarried at two localities in Union County in 

the extreme southeast corner, north west of Carlisle, and near the center, within several miles on the south and west sides of Union, the 

county seat. The product from the quarries near Union was used

a Sloan, Earle, op. cit., p. 198.
GBANITES OF SOUTH CAROLINA. 203

for macadamizing the streets of Union and the county highways. 

The granite formerly quarried northwest of Carlisle merits description.

Flatrock quarry is about 2£ miles north-northwest of Carlisle. It consists of one fairly large opening last worked about fourteen years ago. 

The rock is a biotite granite of medium-gray color and fine gram, both 

color and texture being very uniform. The feldspars are white and 

highly lustrous. The minerals are potash feldspar (orthoclase, partly 

microperthite, and naicrocline), soda-lime feldspar (oligoclase), quartz; 

biotite, and a few shreds of muscovite, together with accessory apatite, 

zircon, and magnetite and secondary chlorite, epidote, and light-colored mica. A part of the feldspar is considerably altered. Zonal and 

micropoikilitic structures and Carlsbad twinning are indicated in some 

of the feldspars. Micropegmatite (intergrowths of quartz and feldspar) occurs in small, irregularly rounded areas.

A chemical analysis of this granite is given on page 174 (No. 8). 

The specific gravity is 2.63.

There are several sets of vertical joints having directions of N. 30° 

E., N. 35° W., N. 60° W., N. 70° W., and east-west. Slickensides are 

developed on some of the joint faces. There are a few small knots 

and pegmatites.

The product from this quarry was used for bridge piers along the 

Seaboard Air Line Railway and to some extent in the neighborhood

for buildings.

YORK COUNTY.

The granites of York County which have thus far attracted attention and are of economic importance are limited to the north-central 

portion of the county. Beginning near Bowling Green, at the state 

line on the north, the area extends southward to Yorkville and probably beyond and is traversed in a nearly north-south direction by the 

Yorkville-Gastonia Railway. The granites are biotite granites, but 

vary in color and texture, as indicated in the individual descriptions of 

the two areas below. Systematic quarrying has not been attempted, 

but a little stone has been quarried from time to time in different 

places to meet the local demand.

 Clover area. The Clover area, containing a single type of biotite 

granite, extends southward from a point near Bowling Green to Yorkville. The granite is exposed at the surface in many places over the 

area in nearly flat-lying (locally called "flat-rock") and sloping surface masses of considerable areal extent. ' Exposures of this character 

are especially noted within a radius of 2 miles to the north, northwest, 

east, and southeast of Clover station. The exposures of the granite 

near Filbert station (west side) are in the form of huge isolated bowlders 10 to 15 feet high and proportionately large otherwise. A small
204 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

amount of the granite has been quarried from surface "raises" at a 

number of places in the vicinity of Clover.

The rock is a biotite granite of light-gray color and medium-coarse, 

even-granular to porphyritic texture. Both feldspar and biotite show 

some alteration in the surface portions of the granite, the former appearing white, opaque, and chalky from partial kaolinization, the latter showing irregular areas of reddish-brown staining frcm partial 

leaching of the iron oxide immediately adjacent. The minerals are 

potash feldspar (orthoclase and microcline), soda-limefeldspar (oligoclase), quartz, biotite, and occasional muscovite, together with accessory apatite, zircon, and iron oxide and secondary chlorite, epidote, 

colorless mica, and kaolin. Intergrowths of orthoclase with plagioclase feldspar, as microperthite, and of feldspar with quartz, as micropegmatite, are abundant. The larger feldspar individuals carry 

many inclosures of feldspar, chiefly quartz and feldspar-quartz intergrowths (micropegmatite). Microcline exceeds orthoclase in some 

sections and is much less in others. Plagioclase, likewise, may be 

greater or less in amount than potash feldspar. The feldspars are in 

part much altered and some of them show peripheral granulation from 

pressure effects.

In the porphyritic facies of this granite the feldspar phenocrysts 

are of both regular (idiomorphic) and irregular (allotriomorphic) outline and of white color and contain inclosures of groundmass biotite. 

In size they range up to 2 inches by half an inch. The ratio of phenocrysts to groundmass is very variable.

A chemical analysis of the granite from Jackson's quarry, half a 

mile north of Clover, reported by Sloan, a is given below and shows 

the general composition of the rock in the York County area. The 

specific gravity is 2.66.

Analysis of granite from the Jackson quarry, York County.

Silica (Si02 )................................................ 68. 90

Alumina (A1203 )............................................. 15. 75

Ferric oxide (Fe203 )......................................... 1.16

Ferrous oxide (FeO) ......................................... 1. 49

Magnesia (MgO)...........................................:. :74

Lime (CaO)................................................. 2. 66

Socla(Na20).................................................. 4.76

Potash (KjjO)................................................ 3. 49

Ignition...................................................... .18

Manganese oxide (MnO)....'................................... Trace.

Titanic oxide (Ti02).......................................... .36

Phosphoric oxide (P205)...................................... Trace.

Sulphuric oxide (S03 )........................................ Trace.

99.49

Sloan, Earle, op. citv p. 216.
GRANITES OF SOUTH CAROLINA. 205

Filbert area. The Filbert area lies several miles west of Filbert 

station. The granite quarried on the Whiteside place, on Buckhorn 

Creek, 2 miles west of Filbert, may be taken as the type. It is a 

biotite granite of medium-gray color and fine grain, with a pronounced 

porphyritic tendency in places. The scattered feldspar phenocrysts 

are usually of irregular (allotriomorphic) outline, locally flat-tabular 

(idiomorphic), measuring up to 1 inch by half an inch, and twinned 

on the Carlsbad law. They are of white color. The minerals composing the granite at the Whiteside quarry are potash feldspar (orthoclase and microcline), soda-lime feldspar (oligoclase), quartz, biotite, 

and scant muscovite, together with accessory apatite and zircon and 

secondary chlorite, epidote, and light mica. Feldspar intergrowths 

as microperthite and feldspar-quartz intergrowths as micropegmatite are abundant.

A chemical analysis of this granite is given on page 174 (No. 10). 

The specific gravity is 2.65.

The sheets are from 6 inches to 2 feet thick and the vertical joints 

recur at wide intervals. There are a few pegmatite dikes not exceeding 2 inches in thickness and some scattered small knots.

Quarrying operations were suspended in the spring of 1908. The 

product was used for building purposes in Yorkville.
CHAPTER VII.

THE GRANITES OF GEORGIA. 

THE GEORGIA PIEDMONT REGION." 

TOPOGRAPHY.

The Georgia Piedmont region occupies the middle northern portion of the State. It is a belt of undulating country having a northeast-southwest extension along the eastern base of the Appalachian 

Mountains and disappearing beneath the Coastal Plain sediments on 

the southeast. It has an altitude along its western edge of about 

1,000 feet and slopes gradually seaward, with an elevation along the 

fall line, its southeastern limit, of 250 to 300 feet. Residual masses 

of partly reduced areas, such as Kenesaw, Lost, and Stone mountains, rise several hundred feet above the general level of the upland 

surface.

The major streams preserve a general parallelism in' their courses 

across the Piedmont region. With the exception of the upper course 

of Chattahoochee River, the major streams trend in general to the 

southeast, approximately at right angles to the northeast-southwest 

course of the plateau. The streams have apparently maintained 

their courses across the plateau regardless of the structure and hardness of the rocks. They have cut through the deep mantle of decayed 

rock into the fresh, hard rock beneath. The resulting valleys are

deep and narrow, and the interstream areas are as a rule marked by 

low, rounded hills and ridges of slight and gentle curvature. 

. All the large streams except Savannah and Chattahoochee rivers 

head within the limits of the plateau. The Chattahoochee rises near 

the South Carolina line and flows across the plateau in a nearly southwest course, changes to a southward course near the middle southern 

portion of the plateau, at the Alabama line, and continues so to the 

Gulf. This stream presents an unsymmetrical aspect with reference 

to its tributaries.6 Since the establishment of the minor drainage 

ways on the plateau some of them, by means of more favorable conditions, have encroached on the northeast drainage area of the Chattaa Watson, T. L., Bull. Geol. Survey Georgia, No. 9-A, 1902, pp. 00-05.

6 Campbell, M. II., Drainage modifications and their interpretation: Jour. Geology, vol. 4, 1896, 

pp. 672-673.

206
GRANITES OF GEORGIA. 207

hoochee. A strong southeast slope has been acquired by the plateau 

since its elevation in middle Mesozoic time, which has enabled the 

minor drainage lines to establish straight and regular courses at right 

angles to that of the Chattahoochee, while forming in the basins of 

the other major streams a symmetrical drainage of dendritic pattern. 

The western portion of the plateau in the vicinity of Cartersville 

lies wholly within the drainage basin of the Etowah. The conditions 

in the Georgia Piedmont are similar to those in the same province 

through the Carolinas, Virginia, and Maryland; the streams are not 

navigable within the limits of the area, a fact which precludes the 

shipment of stone by water.

GEOLOGY.

ROCKS OF THE PLATEAU.

The Piedmont region is composed of crystalline rocks, which in 

places afford at present but little evidence of having been deposited 

as sediments. Whatever may have been their origin, they have been 

subjected to such profound metamorphism, mainly pressure and 

recrystallization, that proof of sedimentation is scant. This metamorphism has induced a secondary foliation in the rocks, by arranging 

the mineral constituents along parallel lines that evidently bear 

little or no relation to the possible original bedding planes in many of 

the sedimentary rocks.

The rocks consist principally of granites, gneisses, and schists, 

invaded by dikes of basic eruptive rocks belonging mainly to the 

gabbroic, dioritic, and diabasic types. Along the northwestern margin and in other parts of the plateau a belt of basic ferromagnesian 

silicate rocks, containing deposits of corundum, crosses the State in 

an approximately northeast-southwest direction. In the eastern, 

middle, northern, and southwestern parts of the plateau are belts of 

quartzite and in some places limestone. The rocks usually dip to 

the southeast at variable angles, and strike from 20° to 30° east of 

north. Local variations in both dip and strike are shown in all parts 

of the region.

AGE RELATIONS OF THE ROCKS.

Very little has yet been done toward deciphering the age and 

structural relations of the rocks of the Georgia Piedmont region. 

According to Hayes a the southeastern portion'of Bartow County in 

northwestern Georgia is about equally divided between the older 

crystalline and metamorphic rocks of the Piedmont Plateau and 

Appalachian Mountains on the east and the Paleozoic sediments of 

the Appalachian Valley on the west. The Paleozoic sediments are

<» Hayes, C. W., Geological relations of the iron ores in the Cartersville district, Georgia: Trans. Am. 

Inst. Min. Eng., vol. 30, 1901, pp. 403-408.

38971° Bull. 426 10 14
208 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

Cambrian to Silurian in age. To the south and east of them lie the 

metamorphic crystalline rocks of the Piedmont area, comprising slates, 

schists, conglomerates, gneiss, and granite. The oldest of these rocks 

is the granite at Corbin, Ga., which is mapped as pre-Cambrian. The 

conglomerate, slate, and schist were mapped asOcoee and provisionally 

assigned to the Algonkian because .no fossils were found in the rocks 

and because they have every appearance of extreme age.

The rocks of the Ocoee group generally show an increasing degree 

of metamorphism toward the southeast; within a few miles of this 

region they pass into schists and gneisses, the original form of which, 

whether igneous or sedimentary, can not be determined. This 

increased metamorphism toward the southeast is due in part to the 

greater compression which that region has suffered and in part to 

the intrusion of considerable bodies of igneous rocks into the sedimentary beds.

The intrusive rocks present a considerable variety in composition, 

varying from extremely basic diabase to acidic granite. Diorite is 

the most common type and was among the earlier intrusions. . It has 

been metamorphosed for the most part into amphibolite schist. An 

area near Acworth, Ga., is occupied by gneiss which, like the granite 

at Corbin, is probably Archean in age and formed the foundation on 

which the oldest sediments of the region were deposited.

Several thin bands of magnesian limestone and' larger areas of 

sandstone or quartzite occur in the Georgia Piedmont area, intimately 

associated with other probably older metamorphic crystalline rocks. 

It is not unlikely that careful study will reveal a post-Algonkian age 

for at least the limestones and the quartzite of this area.

In his study of the granites and gneisses of the Georgia Piedmont 

region,0 the present writer mapped and described most of them as 

pre-Cambrian. Several periods of intrusion of closely similar acidic 

material are represented, the earliest being schistose in structure, the 

later massive. The granite gneisses, regarded as belonging to the 

earlier intrusion, are pre-Cambrian, and the massive granites representing the later period of intrusion are very probably Paleozoic 

in age.

THE GRANITES.

FIELD RELATIONS.

The Piedmont region in Georgia is occupied chiefly by mica schists 

and gneisses, cut in places by dikes of basic eruptive rocks. The 

schist-gneiss complex is invaded by large masses of granite. From 

many of the larger granite masses well-defined granite dikes or tongues 

project and cut abruptly into the adjacent rocks. The line of contact between the granites and the contiguous fresh rocks can be

a Watson, T. L., Granites and gneisses of Georgia: Bull. Geol. Survey Georgia, No. 9--A, 1902, 367 pp.
GRANITES OF GEORGIA. 209

observed in few places, because of the extreme depth of residual 

decayed material, but here and there the contact is shown in the 

partial decay of the rocks and the relations of the granites to the 

surrounding schists are apparent.

Mica-quartz schist forms a considerable part of the crystalline 

complex. It is a thinly foliated rock with somewhat variable mineral 

composition, ranging from a rock containing dominant quartz to 

one containing dominant mica. Feldspar is in many places nearly 

or entirely absent, but locally it forms an important constituent. 

Fresh exposures of this rock are rare in the Georgia area.

The dikes of basic eruptive rocks are less common in the Georgia 

granites than in those of North Carolina. They vary from a few 

inches to a few hundred' feet in width and some of them can be traced 

for many miles on the surface. They present the usual characteristics of gabbros, diabases, and diorites, and range from gray to

almost black in color. In mineral composition they vary from olivinefree rocks to those in which olivine is an important constituent, and 

in texture from fine to coarse granular. The final product of weathering of the basic eruptive rocks is a stiff, highly ferruginous deep-red 

to yellow clay.

No definitely identified inclusions of foreign rocks have been 

observed in the exposed granite masses, but many of the granites 

contain areas of an irregular character, which can doubtless be 

ascribed to such origin. In some respects these bodies differ strongly 

from the inclosing granites and many of them probably represent 

inclusions of foreign rock. Basic segregations (schlieren) of various 

sizes and shapes, such as form so common a feature of slowly solidifying granite magmas, are present in many of the granite stocks. 

They are abundant in the porphyritic granite area of Fayette County 

and in the granite worked by the Greenville Granite Company in 

Meriwether County. The segregations are darker in color and finer 

grained in texture than the inclosing granites, are more or less rounded 

in outline, and in places display a decided porphyritic tendency. 

Irregular dark bodies of variable size, composed almost entirely of 

biotite, are common in some of the Lithonia quarries.

DISTRIBUTION.

The granites and granite gneisses of workable grade in Georgia 

are limited to the Piedmont region, described on pages 217-267. 

That the granitic rocks are very generally distributed over the 

Georgia crystalline area is indicated by the fact that of the sixty-one 

counties composing the area, few, if any, are without such rocks. 

The quarrying industry, however, is confined to ten of the sixty-one, 

and, in fact, the total output of quarried granite shipped beyond the
210 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

limits of the State comes from only four counties, of which Dekalb 

County is vastly the largest producer.

The map (PI. XXIV) shows the distribution of the granites and 

gneisses that are quarried in Georgia. They occur in five principal 

areas (1) the Elberton-Oglesby-Lexington area, (2) the LithoniaConyers-Lawrenceville area, (3) the Fairburn-Newnan-Greenville 

area, (4) the Stone Mountain area, and (5) the Sparta area. The 

most important of these at present, commercially, are the Lithonia 

and Stone Mountain areas, in Dekalb County, the stone from which 

is used principally for building and street purposes and is not desirable for monumental stock. For the latter purpose the stone from 

the Oglesby-Lexington area is the most desirable in the State. 

Besides the five principal areas named above, there are numerous 

minor ones in which more or less stone has been quarried at times 

for strictly local purposes.

GENERAL CHARACTER OF OUTCROPS.

The Georgia granites are exposed at the surface in the form of 

large horizontal masses, as dome-shaped areas of steep and gentle 

slopes, as large well-rounded bowlders scattered over the surface and 

partly buried in the residual clay, and as ledges exposed along the 

streams. The outcrops of the horizontal masses vary in extent 

from 1 acre to 50 acres or more; the dome-shaped areas contain from 

50 to many hundred acres of exposed rock.

The best illustrations of the horizontal masses occur in Hancock, 

Heard, Meriwether, and Pike counties. Stone Mountain, in Dekalb 

County, which rises to an elevation of 686 feet above the surrounding lowland plain and has a basal circumference of approximately 

7 miles, is the most extensive of the dome-shaped masses. Pine, 

Arabia, Collinsville, McDaniel, and Rock Chapel mountains, belonging

to the Lithonia-Conyers-Lawrenceville area of contorted granite 

gneiss, are some of the other dome-shaped areas which vary in elevation from 75 to 200 feet. Similar exposures of porphyritic granites 

include the Heggie (Cedar rock) area in Columbia County and the 

porphyritic area 10 miles south of Greensboro, in Greene County. 

Outcrops of the kinds described above are numerous throughout 

the Georgia Piedmont region.

The large exposures require no stripping prior to opening quarries, 

but in many of the smaller areas, if extensive quarrying is contemplated, it is necessar}^ to remove a variable depth, up to 12 feet or 

more, of loose residual material before hard rock can be reached. 

For a slight depth below the surface the bared and hard rock surfaces 

in the natural outcrops invariably show a partial decay and discoloration termed "sap,'' which must be removed before fresh rock can be 

quarried. The first or surface "raise" usually removes all the sap 

portion of the rock so that the second and succeeding raises include 

fresh granite.
U. 8. GEOLOGICAL SURVEY BULLETIN 426 PLATE XXIV

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A R. R I S(S TALB OT

LEGEND

MAP OF GEORGIA SHOWING DISTRIBUTION OF GRANITE AREAS AND LOCATION Op GRANITE QUARRIES.

 Based on map of Georgia Geological Survey, Bulletin g-A, 1902.

Fall line

. , QUARRIES

1 Adams

2 Brewer

3 Fortson (Swift &. Etheridge)

4 Carlton

5 Tate & Oliver

6 Swift &. Wilcox 

1 Heard

8 Etheridge (Long Blue Granite Co.)

9 Seabord Air Line Railway

10 Deadwyler, or Collins & Venable (Long Blue

Granite Co.) 

i i Coggins (Long Blue Granite Co.)

12 Hill (Long Blue Granite Co.)

13 Brown &. Deadwyler

14 David

15 Lexington Blue Granite Co.

16 Willingham &. Wllkins 

\1 Heath

18 Arnold

19 Diamond Blue Granite Co. 

20,21 Athens

22 Charley Rocker

23 Georgia Quincy Granite Co. (new)

24 Georgia Quincy Granite Co.

25 Mallally

26 Linch 

z-j Freeman

28 Powell

29 Whittaker

30 Redwine &. James

31 Paper Mill

32 Tilly

33 Pierce

34 Turner

35 Mary Reagin and Georgia Railroad

36 McDaniel Mountain 

37, 38 Arabia Mountain

39 Jenkins

40 Cooper

41 Johnson 

42, 43 No name

44 Walker

45 Collinsville Mountain

46 Pine (Little Stone) Mountain

47 Southern Granite Co

48 Chupp

49 Wilson, Whitley

50 Rock Chapel Mountain

51 Floyd

52 Nash &. McCurdy, Veal 

53, 54 Stone Mountain

O II

55 Sne "

56 Sawyer

57 Langley

58 Turner

59 Trip (Cates, Tribble & Bennett)

60 Lawrenceville

61 Carmichael

62 Turner

63 Overby

64 Sam Hill

65 Cole

66 Greenville Granite Co.

67 Odessa

68 Mountville

69 Wynn

70 Flat Rock

71 Saunders

Note. The Brand, Brantley, Chupp, J. L., 

Crossley, Goddard, Johnson, and Lee Bros, quarries are opened near to and may be considered 

parts of Arabia, Collinsville, Pine (Little Stone), 

and Rock Chapel mountains
GRANITES OF GEORGIA. 211

CHEMICAL COMPOSITION.

The Georgia granites show more or less variation in texture and 

structure and are grouped accordingly as even-granular granites, 

porphyritic granites, and granite gneisses. In chemical composition 

the three groups show remarkably close agreement and are similar to 

the granites from the other States described in this bulletin. The 

analyses of the Georgia granites show their most characteristic feature 

to be a high soda content, which is above the average for normal 

granites. The soda and potash show nearly equal percentages in 

most of the analyses, but in some the potash exceeds the soda and in 

others the soda is in considerable excess over the potash. The high 

soda content is due principally to the presence of large amounts of 

plagioclase feldspar, which places the rocks with the quartz monzonites. Analyses were made of the potash feldspar phenocrysts 

from two of the widely separated porphyritic areas, with the result 

that approximately one-third of the potassium was found to have 

been replaced by sodium in the orthoclase (analyses 4 and 5 below).

Analyses of Georgia granites. a

Constituents.

Silica (BlOt)................ ........ ...........................

Lime (CaO). . .................................................

Potash (K2O) .................................................

1.

09.07

16.63

1.28

.55

2.13

4.73

4.71

2.

69.28

16.73

1.75

.72

2.16

4.33

4 59

3.

73.76

14.52

1.03

.29

1.14

4.16

4.03

4.

64.64

19.64

.37

Trace.

.67

3.06

10.00

5.

64.40

18.97

.37

.59

3.60

a Watson, T. L., Granites and gneisses of Georgia: Bull. Geol. Survey Georgia No. 9-A, 1902, pp. 239, 241.

1. Average of 21 analyses of Georgia even-granular granites.

2. Average of 10 analyses of Georgia porphyritic granites.

3. Average of 12 analyses of Georgia granite gneisses.

4. Porphyritic feldspars (phenocrysts) from fleggie Rock, Columbia County, Ga.

5. Porphyritic feldspars (phenocrysts) from McCollum place, Coweta County, Ga.

Averages of 21, 10, and 12 analyses of the even-granular granites, 

porphyritic granites, and granite gneisses, respectively (1, 2, and 3 in 

the table), show remarkable uniformity in the soda and potash contents for these groups of granite rocks; but many of the individual 

analyses exhibit a greater variation. The high range in total alkalies (Na2O + K2O)is also a very noteworthy feature in these analyses. 

The general average for the total alkalies is from 8.79 per cent in the 

granite gneisses to 9.44 per cent in the granites.

The Georgia granites contain an average of approximately 70 per 

cent of silica, as shown in the table. The normal granites and their 

porphyritic facies show no appreciable difference in silica content, 

as would be expected; but the granite gneisses are slightly more acidic 

and range from 3 to 4 per cent higher in this constituent. This 

relationship in the silica content is almost equally well shown when 

a comparison of individual analyses of the several groups is made.
212 GEANTTES OF SOUTHEASTERN ATLANTIC STAGES..

MINERAL COMPOSITION.

The close similarity in mineral composition between the three 

types of granitic rocks here distinguished can not be emphasized 

too strongly. They are as nearly identical in mineral composition 

as different rocks could well be. The minerals found in one are 

invariably present in the others, and those most abundant in one 

also predominate in the others.

The granitic rocks of Georgia are made up of mixtures of the essential minerals feldspar, quartz, and biotite, with varying proportions 

of muscovite intimately associated with the biotite. Plagioclase is 

invariably present in large amount and in many rocks exceeds the 

orthoclase. Biotite is subordinated to muscovite in only two of the 

specimens examined. The absence of hornblende is a marked feature. Other minerals that are common to most granites occur as 

microscopic accessories, but do not exert any influence on the properties of the rock. A number of other minerals, such as calcite, garnet, 

tourmaline, hornblende, hyalite, molybdenite, and uranophane, occur 

sporadically in several localities, but are only of local interest.

PHYSICAL TESTS.

The following table gives some properties of the even-granular 

granites of Georgia:

Properties of Georgia, even-granular granites.

Qjiarry.

Lexington Blue Granite Co ........ .

Diamond Blue Granite Co......... ......... .................

Echols Mill..... ...............................................

Sam Hill. .....................................................

R.D. Cole... ..................................................

A. M.Hill..... ...............................................

T. B. Tigner. .................................................

Swift & Wilcox. ...............................................

Swift & Wilcox "flat rock" ....................................

Tate & Oliver. .................................................

Bisson .........................................................

Childs .........................................................

Specific 

gravity.

2.666

2.666

2.657

2.689

2.700

2.731

2.739

2.662

2.652

2.645

2.670

2.840

2.664

2.662

2.665

2.658

2.701

2.686

Ratio of 

absorption.

0.092

.088

.086

.090

.092

.093

.090

.092

.060

.067

Weight 

per cubic 

foot 

(pounds) .

166.25

160. 62

166.06

168. 06

168. 75

170. 68

171. 18

166.37

165.75

165.31

166. 87

177.50

166. 50

166.37

166. 56

166. 12

168. 81

167. 90

Cubic 

feet of 

stone in 

2,000 

pounds.

12.0

12.0

12.0

11 9

U o

11.7

11.6

12.0

12 0

12.0

11.9

10.7

12.0

12.0

12.0

12.0

11.8

11.9
GBANITES OF GEORGIA. 213

The following table shows the results of tests on specimens of granite from Stone Mountain and contorted granite gneiss from Lithonia, 

Ga.:

Crushing tesls of Georgia even-granular granite and granite gneiss.0-

AT WASHINGTON NAVY-YARD, 1887.

Locality.

Do.....................................................

Lithonia (No. 3). ...........................................

Do. ....................................................

Do. ....................................................

Do.. ........ ...........................................

Do. ....................................................

Dimensions 

(inches).

2.00x2.00x2.02 

2.00x2.01x2.00 

2.06x2.06x2.09 

2.01x2.01x2.01 

2.00x1.98x1.98 

2.05x2.00x2.01 

 1.99x1.99x2.00 

1.99x1.99x2.00 

2.02x2.02x2.03

Crushed at 

Pounds.

76, 000 

83, 400 

52, 650 

(o) 

(«) 

(°) 

50,325 

48, 760 

05,010

Pounds 

per square 

inch.

« 'Did not crush at 85,000 pounds pressure. 

AT PURDUE UNIVERSITY, LAFAYETTE, IND.

Do.....................................................

Do.....................................................

Do.....................................................

Do. ....................................................

Do. ....................................................

Do. ....................................................

Do. ....................................................

Do. ....................................................

Do. ....................................................

Do. ....................................................

Do. ....................................................

Do. ....................................................

Do. ....................................................

Do. ....................................................

Do. ....................................................

Do. ....................................................

2. 02 x 2. 04 x 2. 07

2. 02 x 2. 01 x 2. 06

2.01x2.01x2.01

2.01x2.00x2.00

2.02x2.08x2.02

2. 02 x 2. 05 x 2. 02

2. 06 x 2. 02 x 2. 02

2.04x2.04x2.06

2. 04 x 2. 03 x 2. 03

2.04x2.04x2.05

2.02x2.02x2.01

2.01x2.02x2.04

2.00x2.01x2.02

1.99x2.01x1.99

2. 04 x 2. 04 x 2. 05

2.04x2.07x2.05

2.01x2.03x2.02

2.02x2.05x2.01

80,000

80,000

80, 700

75, 700

64, 000

78, 700

71, 700

79, 700

79, 700

74, 700

70, 700

50, 000

57, 700

53, 700

55, 700

54, 700

52, 7flO

15, 024

IQ ftm

18,017

15, 455

18,913

17,229

19,246

18,307

17,413

12, 438

14, 425

12,904

13,190

13, 406

12, 726

a Granile pavements, compiled by Venable Brothers, Atlanta, Ga., 1893.

STRUCTURAL FEATURES OF THE GRANITES.

JOINTS.

The principal granite masses in Georgia are cut by joints, but as a 

rule these are by no means so conspicuously developed as in many 

granite areas elsewhere in the United States. The large residual 

masses of the granite gneiss of Lithonia and the granite of Stone 

Mountain are cut by joints that are in the main widely spaced and 

not very conspicuous. In most places there are two sets of joints 

which intersect each other approximately at right angles, the bestdeveloped ones having nearly due east-west and north-south courses. 

In many of the quarries the major set of joints approximates'a true 

northeast-southwest direction.
214 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

In the Oglesby-Lexington area of dark blue-gray granite many of 

the outcrops are in the form of large and small rounded bowlders 

strewn loosely over the surface or partly buried in the residual clay. 

These bowlders have been derived from weathering along the joint 

planes which intersect the granite. Decay progressed more rapidly 

on the edges and corners than along the flat sides of the blocks, thus 

giving them their present form. In these bowlder areas the surface 

rock is as a rule partly weathered for some distance down, and care 

should be used in selecting rock for dimension work. Beneath the 

weathered material the quarries exhibit soli.d rock of excellent quality 

and furnish highly satisfactory dimension stone. Jointing in the 

Oglesby-Lexington area is sufficiently developed to aid materially in 

quarrying the stone.

SLICKENSIDES.

Subsequent movement in many of the quarries is indicated in the 

slickensided surfaces of the joints. Slickensides are conspicuously 

developed in the Stone Mountain, Lithonia, and Hancock-Putnam 

counties granite areas, where the surfaces of the joints are coated with 

smooth yellowish damourite, in many places grooved and striated 

from the movement.

DIKES AND VEINS.

Two sets of intersecting material, differing in texture and origin 

and to some degree in mineral composition, are common to the granitic rocks. On the basis of texture and composition these are divisible into true dikes and veins. They are not so conspicuous in the 

Georgia granites as in areas of similar rocks over other parts of the 

continent, and only very rarely do they interfere with the quarrying 

of dimension stone.

GRANITE DIKES.

 Nearly vertical granite dikes, varying in width from a few inches 

to 40 feet, cut the rocks in places. They are dark blue-gray in 

color and of fine and even grain, and are composed of quartz, orthoclase, and plagioclase feldspars, and biotite as the principal minerals. 

Except for their finer-grained texture they can not be distinguished 

in hand specimens from granites of the Oglesby and other areas of 

blue-gray granite in the State. They are common to some of the 

porphyritic granites and gneisses, but have not been observed penetrating any of the even-granular granites. They cut the porphyritic 

granite of Hancock and Warren counties and the contorted granite 

gneiss of Meriwether County.

A chemical analysis of the specimens collected from a 40-foot dike 

cutting the porphyritic granite gneiss in Warren County gave the 

following results:
GRANITES OF GEORGIA. 215

Analysis of granite dike in Warren County, Ga.

[T. L. Watson, analyst.]

Si02 .......................................................... 68.76

A1 2 03 ........................................................ 16.80

Fe2 03 .......................................................... .99

CaO.. ........................................................ 2.72

MgO .......................................................... 1. 00

Na,0... ...................................................... 4.82

K2 6. .......................................................... 3.70

Ignition....................................................... .29

99. 08

This analysis should be compared with the analyses of the granites 

from the Elberton-Oglesby-Lexington and Fairburn-Newnan-Greenville areas (pp. 220, 225, 229).

APLITE DIKES.

Aplites have been observed in association with the granite masses 

only at Stone Mountain, on the northwest side of which several less 

than 6 inches in width are exposed in the quarries. The aplite is 

banded with pegmatite. Apart from its being more compact and of 

much finer grain, the aplite is readily distinguished-in the hand specimen from the inclosing granite by its lighter color and by its small 

content of mica. Biotite is entirely absent and muscovite is only 

sparingly distributed through the rock. Here and there small crystals of red garnet are present.

The aplite is composed chiefly of the potash and soda feldspars and 

quartz. Stout laths of striated acidic plagioclase are numerous. The 

small percentage of lime (less than 1 per cent) and the large percentage of soda shown in the analysis below indicate the preponderance 

of the soda molecule (albite).

Analysis of aplite from Stone Mountain, Georgia.

[T. L. Watson, analyst.]

Si02 ......................................................... 74. 30

Ti02 ......................................................... None.

A1 2 63 ...........................................'............ 14.73

Te^............................................ J........... .78

MnO.. ....................................................... Trace.

CaO......................................................... .90

BaO......................................................... None.

SrO............................... '........................... None.

MgO.................................................... Strong trace.

Na2 0........................................................ 4/61

K2 0.......................................................... 4.52

H2 0.......................................................... .21

P2 05 ......................................................... Trace.

100. 05
216 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

The mineral composition of the aplite computed from the above 

analysis is as follows:

Potash feldspar................................................. 26. 69

Soda molecules................................................. 38. 77

Lime molecules................................................ 4. 45

Quartz........................................................ 28. 30

From the above calculations the ratio of soda molecules to lime 

molecules is 9 to 1, which corresponds to a lime-bearing albite of the 

composition AbgAn^

PEGMATITE DIKES AND VEINS. .

The pegmatite dikes of this region differ from the true granite dikes 

described above principally in texture. Some of them are true pegmatite intrusions of aqueo-igneous origin; others are as certainly-true 

veins of segregation. They are common to the porphyritic and nonporphyritic granites and granite gneisses, and are characterized by 

the usual coarse-grained texture, being composed almost exclusively 

of large cleavable pink and white feldspar and quartz with some biotite and here and there a little muscovite. Some of the dikes are very 

extensive and are apparently deep seated; others are minute and are 

entirely inclosed by the granite. They are of irregular outline and 

cut the granite without regard to direction. Thin sections show the 

feldspar to be microcline, orthoclase, and plagioclase, with local microperthite. Nearly all degrees of variation in the proportion of feldspar 

to quartz are indicated.

ORIGIN OF PHENOCRYSTS IN THE PORPHYRITIC GRANITES.

The porphyritic feldspars in the Georgia granites are believed to 

have crystallized contemporaneously with that of the groundmass 

minerals after the magma had come to rest. The evidence favoring 

this belief consists in (1) the absence of definite arrangement among 

the phenocrysts; (2) the absence of phenocrysts from the border 

zones of the granite areas that is, gradation from an interior porphyritic facies peripherally into an even-granular granite of coarse 

texture and the same mineral and chemical composition; (3) the 

absence of evidence of magmatic resorption or corrosion of the 

phenocrysts; and (4) the presence of abundant inclusions of the 

groundmass constituents in the phenocrysts. These facts are 

regarded by the writer to indicate that the phenocrysts of these 

granites were developed in place and are not, according to the old 

belief, of intratelluric origin.
GRANITES OF GEORGIA. 217 

RELATIONS OF THE GRANITES AND THE GRANITE GNEISSES.

The granites and granite gneisses of the Georgia Piedmont are 

genetically very closely related. Both are light to dark gray in 

color and even granular to porphyritic in texture, and both have 

suffered more or less the effects of pressure. The granite gneisses 

differ from the granites only in the banded structure induced in 

them through pressure metamorphism. As has been pointed out 

elsewhere, the granite gneisses represent unquestionable foliated 

phases of massive granites similar to those of the present areas but 

of an earlier period of intrusion.

VARIETIES OF GRANITE.

Mineralogically the granites of Georgia are divisible into three 

leading .types (1) biotite granite or granitite, under which most of

the granites of the State are grouped; (2) muscovite-biotite granite; 

and (3). biotite-bearing muscovite granite, of which the granite of 

Stone Mountain is the best representative. Texturally and structurally the granites are grouped as even-granular massive granites, 

porphyritic granites, and granite gneisses. a The relationships of 

these three phases of the granitic rocks are established below.

EVEN-GRANULAR MASSIVE GRANITES. 

GENERAL STATEMENT.

Granites of superior quality and variety, well suited for general 

building and monumental work, have long been known in Georgia. 

For many years the famous light-gray muscovite granite from Stone 

Mountain was the only type of Georgia granite generally known 

beyond the limits of the State. Within the past few years, however, 

several areas yielding a high-grade monumental granite have come 

somewhat prominently into favor. Developments have recently 

been made in other areas of the Georgia Piedmont region, and the 

local granite industry has steadily grown until Georgia now ranks as 

the first granite producer among the Southern States.

With two exceptions all the granites are biotite granites. Muscovite is usually present in variable amount and is very prominent as an 

accessory in several localities. Hornblende is entirely lacking. In 

color the even-grained granites vary from light gray through intermediate gray to a dark blue gray, and in texture from fine to medium 

grained. Both color and texture are fairly uniform for each type.

There are four principal areas of even-granular granites in Georgia 

that are commercially important at present, or will become so in the 

near future. These are the Oglesby-Lexington blue-gray granite

oThe term granite gneiss is here used to denote those gneisses that .have been derived trom original 

granites by metamorphism and that are, therefore, of igneous origin.
218 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

area, comprising the counties of Elbert, Madison, and Oglethorpe; 

the Elberton-Echols Mill light-gray granite area, in Elbert and Oglethorpe counties; the Fairburn-Newnan-Greenville medium blue-gray 

granite area, comprising the counties of Campbell, Coweta, and Meriwether; and the Stone Mountain light-gray granite area in Dekalb 

County. Besides these there are numerous smaller areas widely distributed over the Piedmont region, the granite of which belongs .to 

one .or the other of the types of the four areas named above.

BLUE-GEAY GRANITE OF THE OGLESBY-LEXINGTON AREA. 

GENERAL DESCRIPTION.

The Oglesby-Lexington belt of dark blue-gray granite has a northeast-southwest direction through parts of Oglethorpe, Madison, and 

Elbert counties for about 30 miles, with an average width of 4 to 6 

miles. The accompanying map (fig. 18) shows the Oglesby-Lexington area of blue-gray granite and the Elberton-Echols Mill area of 

light-gray granite as a single area. A variable thickness of residual 

decayed granite mantles the fresh rock, but outcrops of the granite 

are rather common, as flat-surfaced areas along the stream courses 

and as large bowlder outcrops on the interstream areas. Both forms 

of outcrops usually afford good quarry sites, and numerous quarries 

have been opened, grouped chiefly about two principal centers 

Lexington and Huching, in Oglethorpe County, and Oglesby, in 

Elbert County. A list of the principal quarries opened in this belt 

is given below.

The rock is a biotite granite of dark blue-gray color and fine, even 

grain. It is fairly uniform in texture and color throughout the area; 

local variation in color is noted here and there, but not to such an 

extent as to injure the stone. The granite works well under the hammer and takes an excellent polish, with a striking contrast between the 

cut and polished surfaces. Its uniformity in color and texture, 

fineness of grain, freedom from imperfections and blemishes, and 

great strength and durability give it first rank as a monumental stone. 

It is used almost entirely for monumental stock, and for this purpose 

is commercially the most important in Georgia. The area is traversed by several lines of railroad, which afford abundant transportation facilities.

The large number of openings made over the area from which the 

granite has been quarried show the vertical joints to be widely 

spaced, thus affording abundant opportunity for the quarrying of 

dimension stone. Only in one opening the Hill quarry, near 

Oglesby are the joints so closely spaced as to prevent the quarrying 

of dimension stone, and here in only a single zone of about 10 feet in 

width. Small pegmatite veins from a fraction of an inch to several 

inches wide intersect the granite in nearly every opening, but only in
GRANITES OF GEORGIA. 219

one quarry are they so abundant as to interfere seriously with quarrying. These veins consist of coarse crystallizations of quartz and feldspar with scant muscovite and biotite.

MICROSCOPIC CHARACTERS.

This granite consists of anhedra of an average size of 0.5 to 1:5 

millimeters. The principal minerals are orthoclase, microcliner plagioclase near oligoclase, quartz, biotite, some muscovite, a little

Schists and gneisses 

(probably pre-Cambrian)

Granite

FIGURE 18. Map of Oglesby-Lexington and Elberton-Echols Mill granite areas, Georgia.

included apatite and zircon, and occasional grains of .magnetite and 

pyrite. The secondary constituents are chlorite, epidote, muscovite, 

and kaolin. Much of the quartz occurs as droplike inclusions in the 

large feldspar individuals; and locally it is intergrown with a part of 

the feldspar in the form of ovals or rounded disks of granophyric 

structure. Orthoclase is the dominant feldspar and exhibits in places 

microperthitic intergrowths with a triclinic feldspar. Microcline 

.varies in quantity, but may equal the orthoclase. Twinning on the
220 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

Carlsbad law is common to the potash feldspars. Plagioclase is 

present in large amount and in most sections equals or exceeds 

orthoclase. As a rule, low extinction angles in basal sections characterize the plagioclase a fact which, with the percentage of lime given 

in the analyses/indicates oligoclase. Biotite is regularly distributed 

through the rock in single shreds of deep-brown color and strong 

pleochroism. It is intimately associated with muscovite, which is 

usually present in smaller amount but here and there may equal, the 

biotite. The biotite is partly altered to chlorite.

CHEMICAL COMPOSITION.

The following chemical analyses of the dark blue-gray granite from 

the Oglesby-Lexington area were made by the writer in the chemical 

laboratory of the Georgia Survey:

Analyses of dark blue-gray granite from the Oglesby-Lexington area, Georgia.

Silica (Si02 ) .................................

Lime-(CaO) . .................................

Potash (KS 0). ................................

Specific gravity. ..............................

1.

70.30

16.17

1.19

.31

2.61

4.72.

4.88

.63

2.666

2.

70.18

17.30

1.20

.64

2.03

4.36

4.77

.35

3.

70.03

15.62

1 "U

.52

2.45

4.82

.77

2.666

4.

69.53

16.46

1.15

.85

2.10

5.00

4.91

01

5.

69.36

17.23

i 4^

.59

2.14

5.17

4

C7

.33

2.665

6.

69.64

17 91

1 ^9

.66

2.14

4.53

4 95

.35

7.

70.38

16.47

1.17

.31

1 79

d QS

^ R9

.31

1. Diamond Blue Granite Company's quarry, near Huching, Oglethorpe County.

2. Brown & Deadwyler quarry, Madison County.

3. Lexington Blue Granite Company's quarry, Lexington, Oglethorpe County.

4. Huching quarry, Oglethorpe County.

5. Childs quarry, near Oglesby. Elbert County.

6. Hill quarry, near Oglesby, Elbert County.

7. Etheridge quarry,'3 miles east of Oglesby, Elbert County.

According to the definition given by Brogger the above analyses 

show the rock of this belt to be quartz monzonite.

PHYSICAL TESTS.

The ratio of absorption of these granites was determined by the 

writer in the Georgia Survey laboratory on carefully selected specimens from a number of quarries in this belt, with the following 

results:

Absorption of granite from Oglesby-Lexington area, Georgia.

Percentage 

of absorption.

Lexington blue-granite quarry, Oglethorpe County............... 0. 092

Diamond blue-granite quarry, Oglethorpe County................ . 088

Coggins quarry, Elbert County................................. . 090

Childs quarry, Elbert County................................... .092

The above figures indicate a compact, close-grained rock that will 

not be appreciably affected by frost action.
GRANITES OF GEORGIA. 221

Tests made on specimens of the Diamond Blue Granite Company's 

granite at the Watertown Arsenal January 17, 1894, illustrate the 

compressive crushing strength of the dark blue-gray granite of the 

Oglesby-Lexington granite area.

Compressive strength of granite from Diamond Blue Granite Company's quarry, 

Oglethorpe County, Ga.

Test No.

7304 

7307

How tested.

On bed...... 

On grain....

Size (inches):

3.07 x 3.00 x 3.04 

3.10x2.99x3.10

Pressure 

(pounds 

per sq uare 

inch).

20,340 

23,860

DESCRIPTIONS OF QUARRIES.

INTRODUCTORY STATEMENT. %

A list of the quarries, both large and small, opened in the belt of 

dark blue-gray granite follows. Some of the openings listed are small 

and the production from them has been very meager. Only two were 

operating during the summer of 1908, namely, the Deadwyler (Collins 

& Venable) and the Etheridge.

Quarries in the Oglesby-Lexington belt of dark blue-gray granite.

Oglethorpe County:

Arnold.................................1$ miles west of Huching.

Diamond Blue Granite Company.... .2 miles southwest of Huching.

Heath....................................2 miles west of Huching.

Lexington Blue Granite Company... One-half mile west of Lexington. 

Willingham.. ......................1^ miles north west of Crawford.

Madison County:

Brown & Deadwyler.....................2^ miles south of Carlton.

David..................................... 2 miles west of Carlton.

Elbert County:

Long Granite Company's quarries 

Coggins........................ 1^ miles southwest of Oglesby.

Deadwyler (Colliiis & Venable)... 1^ miles southwest of Oglesby.

Hill.............................1 mile southwest of Oglesby.

Etheridge............................3 miles east of Oglesby.

Bisson.......................... 1^ miles southwest of Oglesby.

Childs............................... 1 mile southwest of Oglesby.

Seaboard...................... One-half mile northeast of Oglesby.

ELBERT COUNTY.

The Coggins quarry, opened in 1882 in a bowldery outcrop of the 

granite, is about 1£ miles southwest of Oglesby. It has been operated 

at intervals since its opening. The rock is a biotite granite of dark 

blue-gray color and fine, even grain. Its minerals are potash feld-
222 GBANITES OF SOUTHEASTERN ATLANTIC STATES.

spar (orthoclase and microcline), soda-lime feldspar (oligoclase), 

quartz, black mica (biotite), and a little white mica (muscovite), 

together with accessory apatite and zircon and secondary chlorite.

Chemical analyses of the fresh and decayed granite gave the following results:

Analyses of granite from Coggins quarry, near Oglesby, Ga. 

[T. L. Watson, analyst.]

-

Silica (Si02 ) .........................................................................

Soda ( Na2 0) ........................................................................

Potash (K2 0) .......................................................................

^

Fresh.

69 74

16. 72

1.45

1 01

.36

4.84

A '}'2

.47

Decayed.

fin Q4

23.29

9 44

.04

.43

2.18

3 <V7

8.03

The specific gravity is 2.84 and the percentage of absorption is 0.090.

This granite does not contain any blemishes; it takes a high polish, 

works well under the hammer, and shows strong contrast between the 

hammered and polished surfaces.

The Deadwyler (Collins & Venable) quarry is near the Coggins 

quarry, about 1,900 feet north of the Seaboard Air Line Railway. It 

is opened in a bowldery outcrop, and in some places decayed material 

is visible along the joint surfaces to the entire depth of 40 feet. 

(See PI. V, B.) The stone is identical in mineral composition, color, 

and texture with the granite of the Coggins quarry. About 568 

cubic yards of it was quarried in 1891 for bridge piers along the 

Seaboard Air Line. The quarry was operating during 1908 to supply 

monumental stock exclusively.

The Hill quarry is a mile southwest of Oglesby, directly south of

the Seaboard Air Line Railway. It has been worked to a depth of 

40 feet and during its period of activity it was probably the most 

extensive quarry in the Oglesby portion of the area. It has been 

idle for some years. The rock is a biotite granite of the same color, 

texture, and mineralogy as the granite of the Coggins quarry. Magnetite is sparingly present in some of the thin sections. Vertical 

joints strike east-west and north-south, and except in a 10-foot 

zone at the south end of the quarry, the joints are sufficiently far 

apart to permit the quarrying of dimension stone. Weathering along 

some of the joints, extends to the depth of working 40 feet. A 

chemical analysis of the granite, made by the writer, is given on 

page 220 (No. 6).

The Elberidge quarry is about 3 miles east of Oglesby, directly 

southeast of the Seaboard Air Line Railway. It was opened in 1893,
GRANITES OF GEORGIA. ' 223

in a sloping surface exposure of the granite, and in places is worked 

to a depth of 20 feet or more. It was one of the two quarries in 

the Oglesby area operating during the summer of 1908. The rock 

is biotite granite of medium-gray color and fine, even grain. It is 

somewhat lighter in color than the granite quarried in the immediate 

vicinity of Oglesb}71 . On account of this difference the company 

designates the two granites "Oglesby dark-blue" and "Oglesby 

light-blue" granite. It differs in mineral composition from the 

granite nearer Oglesby only in possessing slightly more muscovite. 

A chemical analysis of the granite is given on page 220 (No. 7).

The Childs quarry, 800 yards east of the Hill quarry, is in an excellent body of the fine even-grained dark blue-gray granite. Quarrying 

was discontinued many years ago because of the large waste occasioned by the numerous dikes of pegmatite. These vary in thickness 

from a fraction of an inch to many inches and cut the granite indiscriminately. A chemical analysis of the granite is given on page 220.

The Seaboard quarry is immediately south of the Seaboard Air Line 

Railway about half a mile northeast of Oglesby. The rock is a 

biotite granite of dark blue-gray color and fine grain, similar in all 

respects to the granite quarried by the Long Granite Company near 

by. The quarry is operated at intervals by the Seaboard Air Line 

Railway to supply crushed stone for ballast. It was idle at the time 

of the writer's visit in July, 1908, and was reported to have suspended 

work in September, 1907.

MADISON COUNTY.

The Brown cfc Deadwyler quarry is near the confluence of the north 

and south forks of Broad River, about 2£ miles south of Carlton. 

The opening, made about fifteen years ago, is a small one in large 

bowlder outcrops. In mineral content, color, and texture the granite 

is-identical with that quarried near Oglesby. A chemical analysis of 

it is given on page 220 (No. 2).

OGLETHORPE COUNTY.

The Diamond Blue Granite Company's quarry comprises four openings some distance apart, about 2 miles southwest of Huching. The 

openings are on both sides of a small stream, and the principal one is 

in a 20° to 30° slope of exposed granite. The product, which was 

used almost exclusively for monuments, was shipped to various points 

outside of the State.

The rock is a biotite-muscovite granite of dark blue-gray color and 

fine, even grain. The feldspars have a decided bluish-gray tone and 

in descending order of abundance, comprise microperthitic orthoclase, 

microcline, and a soda-lime feldspar near oligoclase. Muscovite

38971° Bull. 426 10 15
224 ' GRANITES OF SOUTHEASTERN" ATLANTIC STATES.

nearly equals the biotite in amount. A few pegmatite dikes of slight 

thickness cut the granite. Two chemical analyses made by the writer 

from specimens collected from the four openings averaged as follows:

Average analysis of granite from Diamond Blue Granite Company's quarry, near

Huching, Ga.

Silica (Si02).................................................. 69.915

Alumina (A1203).............................................. 16. 315

Iron oxide (Fe2 03)............................................. 1.170

Lime (CaO)................................................. 2. 355

Magnesia (MgO)............................................. .580

Soda (Na20).................................................. 4.860

Potash (K20)................................................ 4. 895

Ignition...:..............................'..........-.......:.. . 770

Results of tests of the compressive crushing strength and the percentage of absorption of the granite ar,e given on pages 220, 221.

The Lexington Blue Granite Company's quarry is half a mile west of 

the court-house at Lexington. The granite outcrops as flat masses 

and bowlders over a considerable area over the south slope of Town 

Creek. Half a dozen openings have been made. The rock is a biotite 

granite of dark blue-gray color and fine, even grain. The minerals 

are potash feldspar (orthoclase and microcline), soda-lime feldspar 

(oligoclase), quartz, and black mica (biotite), with considerable white 

mica (muscovite) arid the usual accessory and secondary minerals. 

Micrographic intergrowths .of quartz and feldspar are abundant. 

Pegmatite dikes varying from a fraction to several inches in thickness 

cut the granite in many places. A chemical analysis of the granite is 

given on page 220 (No. 3). The ratio of absorption is 0.092.

LIGHT-GRAY GRANITE OF THE ELBERTON-ECHOLS MILL AREA. 

GENERAL DESCRIPTION.

The light-gray granite of the Elberton-Echols Mill area is represented 

by a belt of approximately the same dimensions and general direction as the dark blue-gray granite of the Oglesby-Lexington area, 

which lies immediately adjacent on the southeast. The two areas 

are well differentiated as to color, and in a less degree as to texture, 

in their extreme portions, but they undoubtedly form parts of the 

same general area, as the gradation is well shown near Elberton and 

Carlton. The two areas are mapped together in figure 18.

The rock is a biotite granite of light-gray color and medium evengrained texture. Slight local variation in color and texture is 

noted. The granite is well suited to all grades of constructional 

work. Dimension stone is readily obtained and the rock works well 

under the hammer. Pegmatite veins and dark segregations, chiefly 

of biotite, are observed here and there in some of the openings, but
GRANITES OF GEORGIA. 225

these can readily be avoided without waste in working. The principal openings in this belt of granite are grouped about Elberton, 

in Elbert County. The rock has been used chiefly for building 

purposes to supply the local market.

The light-gray granite of the Elberton-Echols Mill area does not 

differ essentially i-n mineral composition from the dark blue-gray granite of the Oglesby-Lexington area, although the two contrast strongly 

in hand specimens. The difference is essentially one of color, the 

biotite being distributed at greater intervals and in somewhat shorter 

aggregated shreds in the light-gray granite. As a rule, the light-gray 

rock is a little more coarsely crystalline in texture than the dark 

blue-gray rock. The same minerals are present in nearly the same 

proportions and they show the same characteristics in the two types. 

Orthoclase, microcline, acidic plagioclase (oligoclase), quartz, biotite,

a little muscovite, apatite, and zircon are the primary minerals.

CHEMICAL COMPOSITION.

The following analyses, made in the Georgia Survey laboratory by 

the writer, serve to illustrate the composition of the light-gray granite 

of the Elberton-Echols Mil area. Analyses 1, 2, and 3 represent the 

typical light-gray granite; analysis 4, the rock intermediate between 

the Oglesby dark blue-gray and the Elberton light-gray types.

Analyses of granite from Elberton-Echols Mill area.

Silica (SiOj).. ..........................................................

Lime (CaO). ................:..........................................

Soda (NajO) . .......................................................:..

Potash (K2 0) ..........................................................

1

1.

68.81

17.67

1.13

.50

2.17

4.97

3.90

.30

99.45

2.657

2.

69.45

15.93

1.31

.55

1 91

4.33

5.16

.50

99.14

2.652

3.

69.25

16.04

1.72

.31

1.89

4.52

4.4940

99. 10

2.670

4.

71.00

16.33

1.12

.35

1.83

4.80

4.65

.87

100. 95

a Contains traces of Ps06 , TiOs, and ZrO2 when present. & All iron estimated as FesO3 .

1. Echols Mill, Oglethorpe County.

2. Swift & Wilcox, Elbert County.

3. Tate & Oliver, Elbert County.

4. Fortson, Elbert County.

ABSORPTION TESTS.

The percentage of absorption of the light-gray granite of the 

Elberton-Echols Mill area is from 0.090 to 0.092 at the Swift & Wilcox quarry, near Elberton, and 0.093 at the Tate & Oliver quarry at 

Elberton.
226 GRANITES OF SOUTHEASTERN ATLANTIC STATES. 

DESCRIPTIONS OF QUARRIES. 

INTRODUCTORY STATEMENT.

The principal openings made in the light-gray granite are in the 

vicinity of Elberton, Elbert County. Most of these are very small. 

About half of them are in granite intermediate in color and texture 

between the dark blue-gray of Oglesby and the light-gray of Elberton, 

and mark the passage of one type into the other. In the Echols Mill 

portion of the area, in Oglethorpe County, extensive exposures of the 

light-gray granite are numerous and good quarry sites are readily 

obtained, but the distance from transportation lines is a barrier to 

development. No openings of sufficient size to be called quarries 

have been made in the Echols Mill area. The quarries and openings 

worked in the light-gray granite are listed below:

Quarries and openings in the light-gray granite of the Elberton-Echols Mill area.

Elbert County:

Adams a ........................... 4£ miles northeast of Elberton.

Carlton a......................... 1^ miles northeast of Elberton. «

Fambrough............................. f mile south of Elberton.

Fortson «............................... $ mile northeast of Goss.

Heard............................. 1 mile southwest of Elberton.

Hester «.......................... 1£ miles northwest of Elberton.

Swift & Wilcox........................ 1 mile south of Elberton.

Tate & Oliver...................... $ mile northeast of Elberton.

Oglethorpe County:

Andrew............................. 2 miles southeast of Carlton. 

Arnold.......................... 10 miles northeast of Lexington.

Echols Mill...................... 11 miles northeast of Lexington.

ELBERT COUNTY.

The Adams quarry, comprising two openings 150 feet apart, is 

4£ miles northeast of Elberton. The granite outcrops as large 

bowlders over approximately 5 acres of surface. Several bowlders 

were worked up in 1885 and 1886 for local purposes. In 1890 a large 

quantity of stone was quarried for bridge piers in the construction of 

the Seaboard Air Line Railway bridge over Savannah River. The rock 

is a biotite granite of medium blue-gray color and medium-fine grain. 

It is intermediate in color and texture between the Oglesby dark 

blue-gray and the Elberton-Echols Mill light-gray types. The minerals are potash feldspar (orthoclase and microclme), soda-lime feldspar (oligoclase), quartz, and black mica (biotite), with a little white 

mica (muscovite), and the accessories apatite, zircon, and magnetite. 

Secondary chlorite and epidote occur. A chemical determination of 

silica gave 69.41 per cent. The sap (partly weathered granite) is

a Granite intermediate in color and texture between the dark blue-gray of Oglesby and the Hght-gray ol 

Elberton, and marking the transition of one type into the other.
GRANITES OF GEORGIA. 227

very thin. The granite takes a good polish, works well under the 

hammer, and is desirable for either monumental or general architectural purposes.

The Swift & Wilcox quarry, opened in 1888 and worked at intervals since, comprises two openings close together, a mile south of 

Elberton. A stripping of 3 to 6 feet is necessary in the larger opening. 

Flat-surfaced and bowlder exposures of the granite are abundant 

in the vicinity of the quarry. The rock is a biotite granite of lightgray color and even, medium grain. It is entirely massive and uniform in color and texture. It has been regarded by the writer as 

the typical light-gray granite of the Elberton-Echols Mill area. Its 

minerals are potash feldspar (orthoclase and microcline), soda-lime 

feldspar (oligoclase), quartz, and black mica (biotite), with a little 

white mica (muscovite); accessory apatite and zircon are sparingly 

present. The biotite is partly altered to chlorite. The potash

feldspar exceeds plagioclase. Micropegmatitic intergrowths of quartz 

and feldspar are common. Chemical analyses of the fresh and partly 

decayed granite from this quarry gave the following results:

Analyses of granite from Swift & Wilcox quarry, near Elberton, Ga. 

[T. L. Watson, analyst.]

Silica (SiOs)............... .........................................................

A lumtna ( AljOs) ....................................................................

Lime (CaO) . .......................................................................

Soda (NasO) ..............................................:.........................

Potash (KS0) . ......................................................................

Fresh.

15. 93

1.91

.55

4.33

5.16

.50

Partly 

decayed.

'69. 00

17.31

1 O1

1.18

.42

4.00

1 79

Small dikes of pegmatite, and a few small dark areas (knots) occur 

here and there. Results of physical tests made on specimens of 

the granite are given on page 225.

The Tale & Oliver quarry is located in Pinetown, a district of 

Elberton, about half a mile northeast of the court-house. The 

larger part of a 2-acre flat-surfaced exposure has been worked to a 

depth of less than 15 feet. The rock is a biotite granite of the same 

color, texture, and mineral composition as the light-gray type from 

the Swift & Wilcox quarry, described above. A chemical analysis 

of this granite made by the writer is given on page 225. The percentage of absorption is 0.093.

OGLETHORPE COUNTY.

The light-gray granite is abundantly exposed in the north-central 

portion of Oglethorpe County at and near Echols Mill, 12 miles 

northeast of Lexington. Extensive outcrops occur at Echols Mill
228 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

and are in every respect identical in color, texture, and mineral 

composition with the granite of the Swift & Wilcox quarry, near 

Elberton, in Elbert County. The light-gray type has not been 

quarried in Oglethorpe County.

Thin sections of the Echols Mill light-gray granite show the minerals 

to be potash feldspars (orthoclase and microcline), soda-lime feldspar 

(oligoclase), quartz, black mica (biotite), and a little white mica 

(muscovite), together with accessory apatite, zircon, and magnetite 

The biotite is partly altered to chlorite. A chemical analysis of 

this granite is given on page 225 (No. 1).

MEDIUM-GRAY GRANITE OF THE FAIRBURN-NEWNAN-GREENVILLE AREA.

GENERAL DESCRIPTION.

i

The medium-gray type of the Fairburn-Newnan-Greenville area 

traverses Campbell, Coweta, and Meriwether counties in a nearly 

north-south course, quarries being opened near Fairburn, Newnan, 

and Greenville, the respective county seats. A similar granite has 

been quarried in the vicinity of Griffin, Spaulding County, for strictly 

local use. Coarsely crystalline porphyritic granites and gneisses of 

essentially the same mineral and chemical composition as the evengranular type are found in intimate association with it over parts 

of Campbell, Coweta, and Meriwether counties.

The even-granular massive biotite granite of this area comprises 

two varieties. One, a medium-gray, is. an average fine-textured 

rock; the other, a dark blue-gray granite occurring in the southwest 

part of Meriwether County, is more coarsely crystalline and darker 

in color and contains a larger proportion of biotite than the mediumgray type. Variation in color and texture of the even-grained 

granites in general is very slight over the area.. In the northern

part of the area, near Fairburn, the granite is somewhat lighter in 

color, and in the middle and southern parts, near Newnan and 

Greenville, it is correspondingly darker. This type is closely similar 

in mineral and chemical composition to the dark blue-gray of the 

Oglesby-Lexington area and the light gray of the Elberton-Echols 

Mill area described above, and is intermediate between the two in 

color and texture.

MICROSCOPIC CHARACTERS.

The primary constituents are orthoclase, microcline, plagioclase 

near oligoclase, quartz, biotite, a little muscovite, apatite, and zircon. 

Secondary epidote and chlorite from the alteration of feldspars 

and biotite are usually present. A few garnets have been noted 

in several places in the northern part of the area. The orthoclase
GEANITES OF GEORGIA. 229

is intergrown in part \vith a second feldspar, acidic plagioclase, as 

microperthite. Microcline is nearly absent in some places and is 

very abundant in others. Acidic plagioclase is a constant constituent 

and in some thin sections it equals or exceeds in amount the potash 

feldspars. Biotite is variable in amount and is everywhere the 

principal accessory. Muscovite, usually present in small quantity, 

is intimately associated with the biotite. Epidote occurs in irregular 

grains and is rather common as large idiomorphic crystals in thin 

sections of the granite from the Cole quarry, near Newnan.

CHEMICAL COMPOSITION.

The chemical composition of the granite from the FairburnNewnan-Greenville area is shown in the analyses below, which 

were made by the writer in the laboratory of the Georgia Survey:

Analysis of granite from the Fairburn-Newnan-Greenmlle area, Georgia.

Silica (SiOa) ...........................................

Alumina ( A12 03 ) ......................................

Lime (CaO) . ..........................................

Soda (Na2O) ..........................................

Potash (KS 0) . ........................................

Carraichael.

69.55

10.72

.99

.27

1.69

5.88

3.94

.27

99.31 

2.C58

Greenville 

Granite 

Co.

69. 88

16. 42

1.96

.36

1.78

5.63

.36

100.85 

2.662

Cole.

69.08

17.67

1.41

.64

3 97

4.56

3 29

.56

100. 48 

2.700

Overby.

69.07

10.56

1 ^7

1.83

4.65

5.02

Q9

100. 18

Hill.

68.38

17. 79

1.21

.72

1.76

4.36

3.57

.78

99.66 

2.689

Considered singly, three of the analyses (Carmichael, Cole, and 

Hill quarries) show an excess of soda over potash, and the rock from 

these quarries is more properly designated quartz monzonite. In the 

two remaining analyses (Greenville Granite Company and Overby 

quarries) the soda content is quite large, but is inferior in amount 

to the potash. An average of the alkalies for the five analyses shows 

an excess of soda over potash of about 0.5 per cent, a fact which 

would group the even-granular acidic plutonic rocks of this area with 

the quartz monzonites. The high soda content in each of the analyses 

is a noteworthy feature.

ABSORPTION TEST.

The percentage of absorption of the granite of this area corresponds 

closely with that of the dark blue-gray and light-gray belt of Oglethorpe and Elbert counties described above. The percentage of 

absorption of the granite from the Greenville Granite Company's 

quarry in Meriwether County was found to be 0.086.
230 GSlANlTfiS OF SOUTHEASTERN ATLANTIC STATES. 

DESCRIPTIONS OF QUARRIES.

INTRODUCTORY STATEMENT.

Practically no systematic quarrying has been carried on in any part 

of the area. Five quarries have been worked as follows:

Quarries in the Fairburn-Newnan-Greenville area, Georgia.

Meriwether County:

Greenville Granite Company.........1 mile northeast of Greenville.

Coweta County:

Hill....................................3£ miles east of Newnan.

Cole ................................. One-half mile east of Newnan.

Overby................................... 10 miles east of Newnan.

Campbell County:

Carmichael.........................21 miles N. 25° E. of Fairburn.

Practically none of the stone from this area has been marketed 

outside of the State. The granite is of homogenous color and texture; 

and is admirably adapted for general building and constructional 

work, and in places for monumental stock. - It has been used locally 

for nearly all grades of work, such as buildings, monuments, cemetery 

coping and retaining walls, and railroad construction.

The openings are in bowlder, and. flat-surfaced exposures, the common form of outcrops. Most of the outcrops are of large dimensions and practically free from soil covering. The quarries are well 

located with reference to transportation by rail and admit of easy 

working. The most extensive areas of the granite and the largest 

quarries are mainly in Coweta and Meriwether counties. Jointing 

is not very conspicuously developed and the planes are always 

widely spaced, permitting the quarrying of dimension stone. Dikes 

of pegmatite and fine granite are rare, and the rock is generally free 

from deleterious minerals.

CAMPBELL COUNTY.

The Carmichael quarry, opened in an area of bowlder outcrops 

covering 10 to 15 acres, lies on the east side of the Altanta and West 

Point Railroad, about 2J miles N. 25° E. of Fairburn. It was 

opened in 1898 to supply stone for coping and monuments for the 

cemetery in Jacksonville, Fla. Thirty-five cars of the stone were 

shipped by June, 1899. The rock is a biotite granite of mediumgray color and even, fine grain,. Its minerals are potash feldspar 

(orthoclase and microcline), soda-lime feldspar (oligoclase), quartz, 

black mica (biotite), and a little white mica (muscovite), with secondary chlorite, epidote, and a light-colored mica. A chemical analysis 

of this granite is given on page 229. A few pegmatite dikes of slight 

thickness cut the rock. The vertical j oints strike northwest-southeast 

and their surfaces are slickensided, indicating some movement in the 

mass. The rock is susceptible of a high polish.
GRANITES OF GEORGIA. 231

COWETA COUNTY.

The Cole quarry is opened in a flat-surfaced exposure of granite less 

than 1 acre in extent half a mile east of Newnan. It was opened 

about eighteen years ago and is worked to a depth of about 30 feet. 

The product has been used mostly for building purposes in the town 

of Newnan. The rock is a biotite granite of dark-gray color and 

medium-fine, even grain. Scattered folia of muscovite are visible to 

the naked eye. In the hand specimens the rocks resemble somewhat closely the dark-gray granite of Oglesby. The minerals are 

potash feldspar (orthoclase and microcline), soda-lime feldspar 

(oligoclase), quartz, black mica (biotite), and a little white mica 

(muscovite), with accessory apatite and zircon. The secondary minerals are chlorite, epidote, and a light-colored mica. Epidote occurs 

both in irregular grains and in platy form with partial crystal outline.

Chemical analyses of the fresh and decayed granite gave the following 

results:

Analyses of granite from Cole quarry, Coweta County, Ga. 

[T. L. Watson, analyst.]

Constituents.

Silica (SiOj) ........................................................................

Lime (CaO) . ........................................................................

Soda (NajO) ........................................................................

Potash (KaO) .......................................................................

Fresh.

69.08 

17.67 

1.41 

.64 

3.27 

4.56 

3.29 

.56

Decayed.

56.99 

26.02 

1.91 

.17 

.75 

1.91 

2.40 

9.76

The decayed rock extends to a depth of 15 feet below the surface. 

Within this zone the granite is sheeted, the sheets being thinnest 

near the surface and merging below into perfectly massive rock. 

The vertical joints strike east-west and north-south, the two sets 

having about equal development. There are numerous dikes of 

pegmatite, most of which strike north and south. Small areas of 

biotite chiefly (knots) occur.

The Hill quarry, opened in a ledge on tHe east side of White Oak 

Creek, is 3J miles nearly east of Newnan. It was first opened about 

1888 to supply stone for the Central of Georgia Railway. The 

opening is only a few feet above stream level. The rock is a biotite 

granite of medium dark-gray color and medium-fine, even grain. 

Scattered shreds of muscovite are visible to the unaided eye. The 

minerals are potash feldspar (orthoclase and microcline), soda-lime 

feldspar (oligoclase), quartz, black mica (biotite), and a little white 

mica (muscovite), with accessory apatite and zircon. Chlorite and 

epidote occur as secondary minerals. A chemical analysis of this 

granite is given on page 229.
232 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

The vertical joints strike S. 35° E. Numerous thin dikes of a 

fine-grained biotite granite, striking approximately northwest to 

southeast, cut the main mass. The stone takes a good polish.

The Overby quarry is opened in a 2-acre flat-surfaced exposure 

10 miles east of Newnan. Its long distance from the railroad has 

hindered its development. The small quantity of stone quarried 

was used for monument basies, sills to windows and doors, and retaining walls in cemeteries. The rock is a biotite granite of mediumgray color and medium-fine, even grain. It resembles very closely 

that from the Carmichael quarry in Campbell County (p. 230). It 

is a shade coarser in texture and lighter in color than that from the 

Cole and Hill quarries, described above. In mineral composition 

it is identical with these granites. A chemical analysis, made by 

the writer, is given on page 229.

MERIWETHER COUNTY.

The Greenville Granite Company's quarry, 1 mile northeast of the 

court-house at Greenville, is opened in a bowlder outcrop of granite. 

Similar outcrops extend over a considerable area. The product 

was used chiefly for cemetery and building purposes in Columbus, 

Ga. The rock is a biotite granite of dark blue-gray color and mediumfine, even grain. Scattered shreds of muscovite and Carlsbad twins 

of orthoclase are visible in the hand specimens. The minerals are 

potash feldspar (orthoclase and microcline), soda-lime feldspar 

(oligoclase), quartz, black mica (biotite), and a little white mica 

(muscovite), with accessory apatite, zircon, and rutile. The biotite 

is partly altered to chlorite. The orthoclase is intergrown with a 

second feldspar. Rounded areas of quartz and feldspar are inclosed 

in the larger grains of the two minerals. Chemical analyses of the 

fresh and decayed granite from this quarry gave the following

results:

Analyses of granite from Greenville Granite Company's quarry, near Greenville, Ga.

[T. L. Watson, analyst.]

Constituents.

Silica (Si02 ) ........................................................................

Lime (CaO). ........................................................................

Soda (NasO). . ......................................................................

Potash (K8 0)................................. \............. .......................

\

Fresh.

69. 88

16.42

1.96

.36

1.78

4.46

5.63

.36

Decayed.

51.29

29.69

6.33

.14

.07

1.12

1.50

10.36

The specific gravity is 2.662 and the percentage of absorption is 

0.086. This granite resembles very closely that quarried in the 

Oglesby area in Elbert County, described on pages 221-223, except 

that the latter is a shade darker in color and slightly finer grained. 

Both are susceptible of a high polish.
GRANITES OP GEORGIA. 233

LIGHT-GRAY GRANITE OF STONE MOUNTAIN. 

GENERAL DESCRIPTION.

The light-gray granite of Stone Mountain (map, fig. 19) is strongly 

contrasted with all other types of granite in Georgia. It differs 

from them in mineral composition in its large preponderance of 

muscovite over biotite, which, though invariably present, occurs in

Schists and gneisses Granite and granite gneiss 

(probably pre-Cambrian)

FIGURE 19. Map of Stone Mountain and Lithonia-Conyers-Lawrenceville granite and gneiss area,

Georgia.

very small quantity. The rock is therefore a biotite-bearing muscovite granite: It is uniformly light gray in color over the entire 

area, but in places shows slight variation in texture. It is intermediate between the other types of even-granular granites 6n the 

one hand and the coarsely crystalline matrix of the porphyritic 

granites on the other. The potash feldspars predominate, with 

orthoclase usually in excess of microcline. The orthoclase is locally 

intergrown with a second feldspar in micropeithitic structure.
234 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

The microcline is subject to considerable variation in amount, 

equaling orthoclase in some sections and sinking to a minimum in 

others. Plagioelase is present in large amount as stout laths twinned 

on the albite law; the lamellae usually give low extinction angles 

in basal sections. Micropoikilitic structure is developed in the 

larger feldspar individuals. The small quantity of biotite is intimately associated with the muscovite. Accessory apatite and 

zircon and some secondary chlorite occur.

Several minerals not usually seen in the sections of the granite from 

Stone Mountain are common constituents of the rock. The most 

abundant of these is black tourmaline, which is present in nearly 

every large block of the stone quarried. The tourmaline occurs 

rarely as single crystals distributed through the granite, but mostly 

as radiating and roughly parallel groups that occupy white areas of 

quartz and feldspar from which the two micas, muscovite and biotite, 

have been excluded. These quartz-feldspar areas vary from a fraction 

of an inch to several inches in diameter and from oblong to circular 

outlines. The tourmaline individuals are of slender prismatic form, 

varying from a fraction of a millimeter to several millimeters in cross 

section without terminal faces; they are jet black in color and are as 

a rule considerably fractured. These tourmaline areas are not sufficiently numerous in the granite nor large enough to affect the color 

of the rock, and, though clearly visible, they do not in any measure 

detract from the good qualities of the stone for general building purposes. Small crystals of red garnet are not uncommon. The surfaces 

of some of the joints are thinly incrusted with a mixture of uranophane and hyalite.

At Constitution, about 6 miles southeast of Atlanta and about 12 

miles southwest of Stone Mountain, is a second exposure of a biotitebearing muscovite granite of light-gray color and fine grain. A 

small quantity of the rock has been quarried and used chiefly for 

monuments. It consists of the same minerals in the same proportions as at Stone Mountain. Intergrowths of quartz and feldspar are 

common. The prismatic inclusions of apatite are in places bent and 

broken, indicating pressure effects on the granite mass.

CHEMICAL COMPOSITION.

The composition of the granite of Stone Mountain is shown in 

analyses 1 and 2, below; analysis 3 is that of an aplite which intersects the granite.
GKANITES OF GEOKGIA. 

Analyses of granite from Stone Mountain, Georgia.

235

Constituents.

Silica (Si02).. ............................................................

L'me(CaO).... ..........................................................

Potash (K2 0). . ..........................................................

1.

72. 50

14.81

.94

.20

1.19

4.94

5.30

.70

Not det.

100. 64

2.

71.66

10.05

.86

.17

1.07

4.66

4.92

1.00

Not det.

100. 39

3.

74.30

14. 73

.78

.90

4.61

4.52

.21

100.05

1. Fresh granite, Stone Mountain, Georgia. R. L. Packard, analyst.

2'. Granite spall exposed for three or four years, Stone Mountain, Georgia. R. L. Packard, analyst.

3. Aplite, Stone Mountain, Georgia. T. L. Watson, analyst.

PHYSICAL TESTS.

Four crushing-strength tests of 2-inch cubes of granite from Stone 

Mountain gave 85,000, 50,325, 48,760, and 65,610 pounds, equivalent 

to 21,250, 12,581, 12,190, and 16,402 pounds per square inch. A 

similar series of strength tests made in 1890 at Purdue University, 

Lafayette, Ind., gave 12,438, 14,425, 12,904, 13,190, 13,406, and 

12,726 pounds per square inch. Another series of tests made at the 

Watertown Arsenal gave 25,630 and 28,130 pounds per square inch, 

on bed.

DESCRIPTION OF QUARRIES.

In addition to the Stone Mountain quarries, which are the most 

extensive in the State, about half a dozen small quarries have been 

worked nearby in the adjacent lowland belt of the same granite. 

All the quarries opened in the Stone Mountain type of granite are 

located in Dekalb County. The quarries in this area are listed below.

Dekalb County, Ga., quarries in the light-gray granite near Stone Mountain.

Constitution a. ................................6 miles south of Atlanta.

Nash & McCurdy.......................3 miles east of Stone Mountain.

Shepard ............................2^ miles south of Stone Mountain.

Stone Mountain........................ 1 mile east of Stone Mountain.

Thomas..........................6 miles southeast of Stone Mountain.

Thompson........................ 2 miles northeast of Stone Mountain.

Veal..................................3 miles east of Stone Mountain.

Wiggins........................................ 1 mile north of Redan.

Stone Mountain, which is a huge doming ridge of granite (PI. XXV, 

A), is situated about 16 miles east of Atlanta in Dekalb County. 

It is an elliptical boss, with its longer axis trending northeast and 

southwest and its steepest side facing northward. It rises 686 feet 

above the adjacent lowland plain of crystalline rocks, and measures 

7 miles in circumference around its base. The present ridge is the

oThe Constitution granite quarry is not in the Stone Mountain area, but is listed here because it is 

located in Dekalb County.
236 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

unreduced remnant of a much larger granite mass. The evidence 

favoring this conclusion is the fact that a belt of the same granite 

reduced to the general level of the surrounding Tertiary Piedmont 

plain skirts the north, west, and south sides of the ridge with a width 

varying from a quarter of a mile to more than a miJo.

The granite of Stone Mountain and the granite gneiss of the adjacent Lithonia area in the same county have had the widest distribution and are the best known of the Georgia granites outside of the 

State. From the time of their first opening, prior to the civil war, 

to within the last few years the quarrying of stone in these two areas 

formed practically the whole granite industry in Georgia. These 

are the largest granite quarries in Georgia and they yield a much 

larger output than any other areas in the State.

Numerous quarries yielding an excellent light-gray granite are 

worked along the western and southern flanks of the ridge. (See 

PI. XXV, B.) The stone has been used most extensively for general 

building purposes, and almost as largely for street material in the 

form of blocks and curbing. Its very light color makes it undesirable for monument stock. It has been marketed in the principal 

towns and cities in the South and West.

The doming mass is apparently formed of sheets of varying thicknesses, with no visible lines of separation except at the surface, where 

the granite has been subjected to weathering. The sheets conform 

in general to the present surface of the boss. They are cut by two 

sets of vertical joints, which, in connection with the slope, afford 

superior facilities for easy quarrying. The vertical joints are widely 

spaced and intersect at approximately right angles, but jointing is 

not a conspicuous feature. Slickensides on the joint surfaces indicate subsequent movement. The rock is further cut by pegmatite 

dikes, which vary in width from a fraction of an inch to 18 inches. 

In addition to the coarsely crystallized feldspar and quartz composing these dikes, mica, tourmaline, and garnet occur, in places concentrated along the central portion of the dike rather than distributed through the light-colored quartz-feldspar portions. Several 

aplite dikes less than 6 inches in width, banded with pegmatite, are 

exposed in the quarries on the northwest side of the mountain. The 

table of analyses (p. 235) shows that the aplite of the Stone Mountain 

boss contains equal potash and soda.

Every facility in the way of modern equipment for work, such as 

engines, boilers, steam drills, and other appliances and machinery, 

is in use at Stone Mountain. About 8 miles of railway are operated 

from the main line of the Georgia Railroad at Stone Mountain station 

to and around the base of the ridge. The equipment is probably 

equal in all essentials to that of the larger quarries in the East, and 

renders the company abundantly able to handle stone of any desired
U. S. GEOLOGICAL SURVE

A. STONE MOUNTAIN, A GRANITE DOME, DEKALB COUNTY, GA.

li. STONE MOUNTAIN QUARRIES, STONE MOUNTAIN, DEKALB COUNTY, GA.
GRANITES OF GEORGIA. 237

dimensions and shape. As opened in 1893, the Stone Mountain 

quarries were capable of yielding 25,000 paving blocks a day. At 

present this can be increased to any desired output.

ISOLATED AREAS OF EVEN-GRAINED GRANITE.

Putnam, Spaulding, Warren, and Wilkes counties contain evengranular granites which belong to one or the other type of biotite 

granites described above. These are of future commercial importance 

and should therefore be noted. In each place a little of the stone 

has been quarried for local purposes. The granites are closely 

similar in mineral and chemical composition and range from light to 

dark blue-gray in color and from medium-coarse to fine grained in 

texture. Muscovite is sparingly present in the granite of Spaulding 

and Putnam counties. The location and general properties of these

granites may be briefly summarized as followS:

Just beyond the northern limits of Griffin, Spaulding County, 

several very small openings are made in a biotite granite of lightgray color and medium-coarse grain. A little muscovite occurs in 

the rock, a chemical analysis of which is given below.

The Linch quarry, 4 miles west of Eatonton, Putnam'County, 

is opened in a biotite granite of dark blue-gray color and even, fine 

grain. Scant muscovite is associated with the biotite. The granite 

is susceptible of a high polish and is entirely suited for monumental 

stock. It resembles the dark blue-gray granite of the OglesbyLexington area. ' A chemical analysis of the stone is given below.

Analyses of granite from Putnam and Spaulding counties, Ga.

Constituents.

Silica (SIOs)..- - ....................................................................

Iron oxide (Fe2 03 ) .................................................................

Lime (CaO). . ......................................................................

Soda (Na2 0) ............................................................ ; ..........

Potash (K2 0) ......................................................................

Putnam 

County.

69.34

17.01

1.74

.61

2.77

4.69

4.54

.26

Spaulding 

County.

69.07

16.56

1.37

.76

1.83

4.66

5.02

.92

The specific gravity is 2.701 and the percentage of absorption is 

0.060.

In Warren County, 2 miles southeast and 7£ miles east of Warrenton, are large areas of biotite granite of light-gray to dark blue-gray 

color and fine grain. This area extends eastward into McDuffie 

County.

Two miles south of Washington, Wilkes County, a biotite granite 

of medium-gray color and medium-coarse grain has been opened. 

A schistose structure is indicated in places,
238 GEANITES OF SOUTHEASTERN ATLANTIC STATES. 

PORPHYRITIC GRANITES. 

GENERAL STATEMENT.

Associated with the even-granular granites within the Georgia 

Piedmont region are a number of coarse-textured porphyritic granites. 

The distribution of the principal areas of porphyritic granite is shown 

on the accompanying map (fig. 20.) These are (A) the area in Campbell, Co weta, and Fayette counties; (B)the Pike County area; (C) the 

Fulton County area; (D) the Brinkley Place-Holders Mill area; (E) 

the Sparta area; (F) the Milledgeville area; (G) the Greene County 

area; and (H) the Columbia County area.

Except in the Sparta area, the porphyritic granite has been only 

sparingly quarried, and then to supply a strictly local demand. The

0 10 20 30 40 50 60 Miles

FIGURE 20. Map of Piedmont Georgia, showing areas of porphyritic granite.

areas in Greene and Columbia counties are too remote from lines of 

transportation to be of commercial importance. The granite exposures are in the nature of bowlders and flat-surfaced or low doming 

masses, usually of large size.

Certain general features are common to all the porphyritic granites, 

Although the rocks are strongly contrasted in some of the areas. 

With one exception they are massive, without, as a rule, visible evidence of primary or secondary foliated structure. The exception is in 

the Brinkley Place-Holders Mill area, where the rock has a pronounced schistose structure, induced by pressure metamorphism. 

The porphyritic granites are prevailingly of light to dark gray color, 

according to the amount of biotite present, and of coarse grain.
GRANITES OF GEORGIA. 239

The same textural and structural characteristics and relationships 

are generally developed in each of the areas of porphyritic granite. 

Gradation from one rock facies (porphyritic) into the other (even 

granular) was not sharply defined in every area, owing, perhaps, to a 

lack of sufficient exposures, but it could be easily traced in many of 

them.

MICROSCOPIC CHARACTERS.

Microscopically, the rocks are as nearly identical as it is possible 

for rocks of separate areas to be. They all contain the same minerals, 

both essential and accessory, in nearly the same proportions. They 

are composed of admixtures of the feldspars and quartz, in which lie 

stout plates of biotite.

The groundmass is a coarse-grained biotite granite, the essential 

constituents of which measure 3 to 8 millimeters. Microcline is subject to more variation in amount than in the even-granular granites 

described above, and plagioclase is slightly increased. The plagioclase shows roughly lath-shaped outlines and as a rule the extinction 

angles indicate an acidic feldspar near oligoclase. The ratio of lime to 

soda in the analyses given on page 240 corroborates the inference. 

Orthoclase shows microperthitic intergrowths with a second feldspar, 

probably albite. Intergrowths of quartz and feldspar, present in all 

the thin sections, afford evidence of simultaneous crystallization of a 

part of the feldspar and quartz. Micropoikilitic feldspars, from inclusions of quartz principally, are abundant. Biotite, intergrown 

with occasional foils of muscovite, is the chief accessory and varies 

somewhat in quantity for the individual areas. Apatite, zircon, and 

magnetite occur as accessories. A little chlorite, epidote, and lightcolored mica are present as constant secondary products from the 

alteration of the biotite and feldspars. Many of the thin sections 

show the effects of pressure metamorphism in the nature of crushing, 

lines of fracture, and undulatory extinction common to some of the 

larger quartz-feldspar individuals.

The potash feldspars are the only porphyritically developed minerals. They are usually opaque and white in color, but pink tints 

are common. They vary from 10 to 15 millimeters in length and 

from 5 to 10 millimeters in width, and show further variation from 

allotriomorphic (without crystal faces) to idiomorphic (with crystal 

faces) individuals. The idiomorphic type prevails and is flat tabular, 

parallel to the clinopinacoid, with (001) and (101) cleavages well 

developed. The feldspars display the usual habit of simple Carlsbad 

twins. As a rule the phenocrysts are very conspicuous and are 

readily differentiated from the groundmass feldspar; although in 

Campbell, Coweta, and Fayette counties the phenocrysts and a portion of the groundmass feldspars seemingly grade into each other. 

The phenocrysts invariably contain inclusions of all the ground,- 

38971° Bull. 426 10 16
240 GEANITES OF SOUTHEASTERN ATLANTIC STATES.

mass minerals, and this, with other evidence, indicates simultaneous 

growth with the interstitial components. The included biotite 

plates are macroscopic in size and in many places the included mica 

is as large as -the same groundmass mineral. The inclusions are 

distributed through the phenocrysts without regard to definite 

arrangement. Analyses of feldspar phenocrysts from two of the 

.Georgia areas are given below (Nos. 9 and 10).

CHEMICAL COMPOSITION.

The marked uniformity in the mineral composition of the various 

porphyritic granites from the widely separated areas suggests similar 

uniformity in chemical composition. The usual amount of free 

quartz common to this class of rocks and the abundance of potash 

feldspar, with increased amounts of plagioclase and proportionally 

small amounts of accessory minerals, indicate a normal percentage 

of silica and lime, an increased percentage of alkalies, and comparatively small amounts of iron and magnesium oxides. These inferences are well shown in the analyses given below. Attention is 

called to the prevailingly high percentage of soda shown. In nearly 

half of the analyses the soda is slightly in excess of the potash and in 

the remainder it nearly equals or is but slightly less than the potash; 

a proportion which allies these rocks, like the even-granular granites, 

with quartz monzonites. This high range in soda is traceable 

primarily to the large amount of acidic plagioclase; second, to the 

microperthitic intergrowths of acidic plagioclase with the potash 

feldspars present in the rocks; and last, to the partial replacement 

of potash by soda in the straight potash feldspar (analyses 9 and 10). 

A comparison of these analyses with those of the even-granular 

granites (pp. 220, 225, 229, 235, 237) shows very close agreement.

Analyses of the Georgia porphyritic granites.

SiOi.. ..............

FesO8&...... ........

MgO.... ............

CaO. ...............

KjO. ...............

Na2O ...............

 1.

70.90

15.86

1.37

.02

2.15

4.62

5.05

.50

100.47

2.

70.88

15.86

1.77

.93

1.79

4.64

3.94

.49

100. 30

3.

70.24

16.78

1.46

.76

2.00

5.03

. 3.70

.50

100. 47

4.

69.77

17.05

l.GO

.99

2.21

4. OS

3.97'

.44

100. 11

5.

69.48

16.64

1.84

.29

2.32

4.49

4.74

.46

100. 26

6.

69.37

16.99

1.99

.84

2.93

4.54

3.44

.55

99.75

7.

69 17

16.47

1.23

.61

2.02

4.41

4.89

 1.06

99.85

S.

69.13

17.14

1.52

.79

1.85

5.49

4.06

.52

100.50

9.

64.64

19.64

.37

Tr.

.67

10.00

3.06

.22

98.60

10.

18.97

.37

Tr.

.59

11.40

3.60

.19

99.52

a Contains traces of 1'sOs and /rOj. All iron was determined

1. Georgia Quincy Granite Company's quarry, near Sparta, Hancock County.

2. McElwaney place, near Line Creek, Favette County.

3. Flat (Cedar) Rock, 9 miles west of Zebulon, Pike County.

4. Heggie Rock, 3 miles east of Appling, Columbia County.

5. Sparta quarry, Hancock County.

6. Calloway place, 3 miles southeast of Milledgeville, Baldwin County.

7. Moseley quarry. 6 miles south of Atlanta, Fulton County.

8. Porphyritic granite area, 10 miles south of Greensboro, Greene County.

9. Feldspar phenocrysts from Heggie Rock, Columbia County.

10. Feldspar phenocrysts from McCollurn place, Coweta County.
GRANITES OF GEORGIA. 

PHYSICAL TESTS.

241

Tests to determine specific gravity, ratio of absorption, weight per 

cubic foot, and number of cubic feet of stone contained in 2,000 

pounds were made on the porphyritic granites as follows:

Physical tests of porphyritic granites.

Quarry. Specific 

gravity.

2.687

2.664

2.674

2.659

Ratio of 

absorption.

0.037

.049

Weight per 

cubic foot 

(pounds).

167. 93

166. 50

166.87

166. 18

Cubic feet 

of stone in 

2,000 

pounds.

11 9

12.0

11.9

12.0

DESCRIPTION OF INDIVIDUAL AREAS. 

CAMPBELL, COWETA, AND FAYETTE COTJNTIES.

The area occupying contiguous portions of Campbell, Coweta, and 

Fayette counties, marked A on the accompanying map (fig. 20), lies 

30 miles southwest of Atlanta. The outcrops are usually small and 

in the nature of bowlder and flat-surfaced masses. The exposures 

are most numerous in the vicinity of Palmetto and Coweta, stations 

on the Atlanta and West Point Railroad, and near Line Creek, in 

Fayette County. Specimens of the porphyritic granite collected 

from the outcrop near Line Creek are somewhat lighter in color than 

similar ones from the Palmetto and Coweta areas. The ratio of 

quartz to biotite in the Line Creek outcrop is visibly greater than in 

the exposures in Campbell and Coweta counties. The rock, however, 

is generally rather uniform over the entire area. Several good contacts of the partly decayed porphyritic granite and mica schist are 

exposed along the wagon roads and in the cuts of the railroad traversing the area. The field relations of the two rocks indicate that the 

porphyritic granite is the younger rock, intruded into the overlying 

schist and exposed subsequently by erosion.

The granite is a porphyritic granite of medium-light to dark gray 

color and coarse grain. Its extreme coarseness renders the porphyritic 

texture less pronounced in this than in the finer-grained porphyritic 

granites. The porphyritically developed mineral (feldspar) grades 

imperceptibly from very large, irregular, locally stout, tabular phenocrysts into the smaller feldspars of the groundmass, making it difficult 

usually to distinguish between groundmass and phenocryst feldspar.

The feldspar phenocrysts vary from extremely irregular cleavable 

grains, anhedra 30 by 30 millimeters in size, to roughly idiomorphic 

crystals, tabular, parallel to the clinopinacoid (010), and twinned
242 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

on the Carlsbad law. Abundant inclusions of large irregular plates 

of biotite are readily visible to the unaided eye, in all the phenocrysts. 

The phenocrysts are prevailingly allotriomorphic and differ in this 

respect from those of the other areas described below. The feldspars 

are white in color, as a rule partly cloudy or opaque rather than 

limpid in appearance. The porphyritically developed minerals are 

composed of both orthoclase, with microperthitic structure, and microcline usually inclosing inequidimensional grains of quartz, feldspar, 

and biotite, without orientation. The more basic inclusions, accessory apatite and zircon, are also contained in the phenocrysts.

A thin section of one of the feldspar phenocrysts from the Coweta 

portion of the area shows the characteristic microcline structure and 

contains abundant inclusions of irregularly bounded crystals of feldspar, quartz, and biotite; several rounded disks or ovals of intergrowths of quartz and feldspar; and prismatic needle-like inclusions" 

of apatite and zircon. A chemical analysis of fragments of carefully 

selected phenocrysts from hand specimens of the Coweta outcrops of 

the rock is given on page 240 (No. 10).

The porphyritic granites from Anson and Richmond counties and 

those from Mount Monroe, Iredell County, N. C., closely resemble 

in color and texture the porphyritic granite of Campbell, Coweta, 

and Fayette counties in Georgia. The phenocrysts in the North 

Carolina granite are usually without crystal boundaries (allotriomorphic) and as a rule are large and contain numerous plates of 

included biotite. A similar rock, though darker colored because of 

the larger amount of biotite present, occurs in Aiken County, S. C. 

The porphyritic feldspars in the Aiken County granite present the 

same characteristics as the phenocrysts of the Georgia and North 

Carolina porphyritic granites.

The granite of the Georgia locality has been opened in a number of 

places where a little stone has been quarried to supply a purely local 

demand.

PIKE COTTNTY.

The Pike County granite area, marked B on the map (fig. 20), 

includes 50 acres or more of exposed flat-surfaced rock in the northwestern part of the county. The porphyritic facies of the rock gradually passes into the even-textured granite. Only a small proportion 

of this area, however, shows the porphyritic texture. The rock is a 

biotite granite of medium-gray color and medium grain. It varies 

from even granular to porphyritic in texture, and shows in places a 

partial gneissoid structure. The phenocrysts consist of the potash 

feldspars, orthoclase and microcline, measuring 10 to.30 millimeters 

long and 5 to 10 millimeters broad, flat tabular, and parallel to the 

clinopinacoid (010). Carlsbad twinning is common. Inclusions of 

biotite as large as that occurring in the groundmass are very abundant
GRANITES OF GEORGIA. 243

in the phenocrysts, which contain, in addition to the biotite, microscopic inclusions of irregularly bounded crystals of the interstitial 

quartz and feldspar.

The granite has not been quarried, except that now and then a 

surface "raise" is made, and some stone is obtained for chimneys and 

foundations for houses in the immediate neighborhood. The stone 

can be easily quarried, and is of good quality.

FULTON COUNTY.

The porphyritic granite of the Fulton County area, marked C on 

the map (fig. 20), is exposed in bowlder form over a large territory 

6 miles south of Atlanta, in the extreme southern part of the county. 

The gradation from the interior porphyritic facies, peripherally, into 

an even-textured granite of the same color and texture and having 

the same mineral and chemical composition is more gradual and more

strikingly shown in this than in any of the areas previously described.

Near the center of the granite mass the phenocrysts compose more 

than 50 per cent of the rock and near the center the phenocrysts 

usually show crystal outline (idiomorphic), but in the transition zone 

of the granite mass they are allotriomorphic (without crystal outline).

The granite consists of a medium-coarse groundmass of quartz, 

the potash feldspars (orthoclase and microcline), numerous laths of 

twinned plagioclase, biotite, and some muscovite, in which are 

embedded large potash-feldspar phenocrysts. Accessory apatite, 

magnetite, and zircon and the alteration products chlorite, kaolin, and 

light-colored mica are noted. Some of the feldspars and biotite are 

considerably altered. Microcline and orthoclase are porphyritically 

developed and measure 15 to 50 millimeters in length. The phenocrysts possessing idiomorphism (crystal outline) usually display the 

Carlsbad twinning and are elongated in the clinopinacoidal direction.

A thin section of one of the phenocrysts showed the characteristic 

microcline structure and numerous inclusions of quartz, biotite, and 

the groundmass feldspars, which measure as much as 1 millimeter. 

Prismatic crystals of apatite and zircon, as inclusions in both the 

phenocrysts and the included groundmass feldspars of the porphyritic crystals, are numerous. The zircon crystals are in places grouped 

in threes, much after the manner of penetration twins.

Quarrying in this area has been confined to the working up of a few 

large bowlders, but the accessibility and good qualities of the stone 

should give it future importance.

WARREN COUNTY.

Two somewhat extensive outcrops of foliated porphyritic biotite 

granite occur in the middle portion of Warren County, approximately 

10 miles from each other in an almost east-west direction. These are
244 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

known as the Holders Mill and Brinkley Place granite masses, and 

are marked D on the map (fig. 20).

The rock has a pronounced secondary foliated structure. The 

quartz and feldspar crystals are drawn out and inclosed between the 

biotite layers, forming in places distinct augen of the two lightcolored minerals. The rock contains abundant black biotite plates 

arranged along somewhat parallel lines. The quartz and feldspar 

grains are greatly squeezed and mashed, and are more or less drawn 

out in directions parallel with the biotite layers, as a result of pressure 

metamorphism. The foliated structure is derived or secondary and 

not primary.

The feldspar phenocrysts are composed principally of microperthitic orthoclase, with some microcline 15 to 20 millimeters long, are 

opaque white to pink in color, contain numerous inclusions of bio'tite 

plates, and exhibit the usual habit of Carlsbad twins. They are prevailingly irregular in crystal outline and badly fractured from subsequent intense metamorphism. They are embedded in a coarsegrained groundmass of quartz, feldspar, and biotite. The groundmass feldspathic constituent consists of the potash feldspars, with 

microperthitic structure, and some laths of plagioclase near oligoclase. The large feldspar individuals (phenocrysts) contain inclusions of irregularly bounded crystals of quartz, biotite, and other 

feldspar species. These inclusions are usually round or oval in outline. Peripheral shattering from pressure effects of the larger feldspar 

and quartz crystals is pronounced. Intergrowths of quartz and 

feldspar are common. Biotite occurs as grouped shreds and plates 

altered to chlorite and here and there to epidote. A few scattered 

grains of magnetite are observed.

Still a third exposure of granitoid rock showing a pronounced porphyritic texture in places lies 6 to 8 miles south of the Brinkley 

Place-Holders Mill area. It differs greatly from the granite of that 

area in having a less strongly marked and finer-grained porphyritic 

texture, in containing less biotite, and in being massive instead of 

foliated in structure; it also contains a larger proportion of plagioclase and a smaller percentage of microcline. This area is entirely 

undeveloped.

HANCOCK COUNTY.

A coarse-grained porphyritic granite outcrops a quarter of a mile 

east of Sparta depot, Hancock County, and the exposures are more or 

less continuous from this point for 11 miles in a northeast direction 

along the Georgia Railroad, extending from Sparta to Mayfield station. This area, marked E on the map (fig. 20), lies near the passage 

of the crystalline rocks beneath the Coastal Plain sands and clays 

(the "fall line") and is the only producing area of porphyritic granite
GRANITES OF GEORGIA. 245

in Georgia. It is elliptical in shape, with its longer diameter trending 

northeast and southwest for 11 miles. The granite outcrops as 

bowlder and flat-surfaced masses, covering as much as 4 to 5 acres in 

a single exposure. The area is traversed by the Macon branch of the 

Georgia Railroad, which affords ample facilities for shipping.

The rock is generally porphyritic, grading in many localities into a 

non porphyritic, even-grained granite of the same mineral and chemical composition. In several places the porphyritic texture almost 

wholly disappears and the rock grades into a coarse-grained biotite 

granite. In a number of quarries the rock shows in places a somewhat pronounced gneissoid structure. Joints are not conspicuous 

in any of the quarries and are everywhere widely spaced. Pegmatites cut the granite in several of the quarries.

The rock is prevailingly a coarse-grained, medium-gray porphyritic biotite granite. The phenocrysts are composed of the potash

feldspars, having a pronounced pinkish cast, which appears in the 

thin sections. They are flat tabular in crystal form, averaging 20 

millimeters in length parallel to the clinopinacoid (010). Carlsbad 

twins are common. The phenocrysts are further characterized by 

numerous inclusions of the principal groundmass minerals.

The porphyritic feldspars are embedded in a coarse-grained groundmass of quartz, potash and soda-lime feldspars, and biotite, with 

some accessory muscovite, chlorite, apatite, zircon, epidote, and 

scattered grains of magnetite. Microperthitic structures are common to the potash feldspars. Intergrowths of quartz and feldspar 

are less frequently observed than in some other areas. The rock of 

the Hancock County area differs from that of Campbell, Coweta, 

and Fayette counties in containing less biotite and hence being lighter 

in color, and'in that the phenocrysts are idiomorphic instead of allotriomorphic and are usually of a pinkish cast rather than white. 

Microcline is likewise variable for the two areas in thin sections of 

the rock examined from various places.

Like the rock in the Campbell-Fayette area, the porphyritic granite 

of Sparta is surrounded on all sides by mica schist; but the great 

depth of residual decay of the granite and schist prevents exposures 

of the contact between the two. The field relations indicate, as in the 

other area, that the granite is the younger rock, intrusive into the 

then overlying schist.

The chemical composition, of the- granite from this area is shown in 

analyses 1 and 5, page 240. The percentage of absorption is small, 

as indicated on page 241. The granite has had an extensive use in 

Georgia and several of, the adjoining States, principally for street 

purposes, as in Belgian blocks and curbing. It has been used to some 

extent as a building stone and occasionally for monuments.
246 GKANITES OF SOUTHEASTERN ATLANTIC STATES.

A number of quarries have been worked somewhat extensively 

within several miles northeast of Sparta. These are listed below.

Quarries in the Sparta area, Hancock County, Ga.

Miles northeast of Sparta.

Charley Rocker................................................... 3£

Georgia Quincy Granite Company................................. 2

Mackin.......................................................... If

Mallally......................................................... |

Old Rocker....................................................... 3£

The Charley Rocker quarry, about 3£ miles northeast of Sparta 

and three-quarters of a mile north of the Georgia Railroad, is opened 

in a flat-surfaced exposure of the granite. It has been worked to a 

depth of less than 20 feet. The product is used principally in the 

form of blocks for street paving. The rock is a porphyritic biotite 

granite of light gray color and coarse grain. A chemical analysis of 

the granite is here given for reference:

Analysis of granite from Charley Rocker quarry, near Sparta, Ga.

Silica (Si02)................................................... 67. 62

Alumina (A1203 ).............................................. 16. 29

Iron oxide (Fe2 03 )............................................. 2. 31

Magnesia (MgO).............................................. .78

Lime (CaO). .........................................f ....... 2. 37

Soda(Na20)................................................... 5.42

Potash (K20)................................................. 4. 58

Ignition....................................................... .32

The specific gravity is 2.687, and the percentage of absorption is 

0.037.

The Georgia Quincy Granite Company's quarry is half a mile south

of the Georgia Railroad and about 2 miles northeast of Sparta, in a

large flat-surfaced exposure of granite. Three acres or more have 

been stripped. The product is used principally for street work in 

the form of blocks and curbing and to a minor extent in buildings. 

The rock is a porphyritic biotite granite of medium-gray color and 

coarse grain. A gneissoid structure is discernible in places. Vertical 

joints of wide spacing and a few pegmatite dikes several inches 

wide intersect the granite. The joint surfaces are slickensided from 

subsequent movement in the granite mass. A chemical analysis 

of the granite is given on page 240 (No. 1); and the results of physical 

tests on page 241.

The Mackin (Sparta) quarry, a quarter of a mile north of the 

Georgia Railroad and about If miles northeast of Sparta, is a small 

opening. The rock is a porphyritic biotite granite of medium-gray 

color and coarse grain. The opening exposes a 9-foot dike of darkgray, fine, even-grained granite penetrating the porphyritic granite..
GRANITES OF GEOEGIA. 247

The Medially (Sparta) quarry, a quarter of a mile north of the 

Georgia Railroad and about three-quarters of a mile northeast 

of Sparta, is opened in a flat-surfaced outcrop. It has been worked 

to a depth of 25 feet in places. The rock is a porphyritic biotite 

granite of medium-gray color and coarse grain. It is difficult to 

distinguish in hand specimens from the Georgia Quincy Granite 

Company's rock. A chemical analysis of the granite is given on 

page 240 (No. 5); and the results of physical tests on page 241. The 

rock is cut by an east-west set of vertical joints, and by a dike several 

feet wide of very fine textured, dark blue-gray biotite granite. It 

contains a few dark-colored segregations (knots).

The Old Rocker quarry, one of the first quarries opened in the 

area, is about a quarter of a mile northwest of the'Charley Rocker 

quarry, described above. The granite is exposed in ledge form over 

several acres of ground. Considerable quarrying has been done 

and the product was used as blocks and curbing for street WOI'k. 

The rock is a biotite granite of light-gray color and even, coarse 

grain. It differs in texture from the granite of the other quarries 

in the area in being even granular instead of porphyritic and in 

containing less of the black mica (biotite).

BALDWIN COUNTY.

Large bowlder outcrops of coarse-grained porphyritic granite occur 

3 miles southeast of Milledgeville, the county seat of Baldwin County. 

Like the rock of the Hancock County area, the Baldwin County 

porphyritic granite mass is located near the line of contact between 

the Piedmont crystalline rocks and the Coastal Plain sediments 

(area marked F on the map, fig. 20).

A part of the granite used in the construction of the old state 

capitol at Milledgeville, now the State Normal and Industrial College, was quarried from this area. No regular quarries have been 

opened and no recent quarrying has been done.

Hand specimens of the granite from Baldwin County are indistinguishable from similar specimens of the Columbia County porphyritic mass, described below. The rock is a very coarse grained 

porphyritic granite, composed of an aggregate of interlocking quartz 

and feldspar orthoclase with microperthitic structure, microcline, 

and plagioclase with intergrown shreds of biotite. It varies in color 

from medium to dark gray. Both microcline and orthoclase occur 

in the groundmass and as porphyritically developed minerals. The 

larger phenocrysts are 30 to 40 millimeters long and 5 to 10 millimeters broad. They are prevailingly idiomorphic (with crystal 

faces) in form, flat tabular parallel to the clinopinacoid (010), and 

commonly twinned on the Carlsbad law. Abundant inclusions of 

black biotite folia are plainly visible to the unaided eye in the feld-
248 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

spar phenocrysts, and numerous additional irregularly bounded 

quartz and feldspar grains without definite orientation are shown 

by the microscope.

The groundinass is composed of an abundance of white, opaque 

feldspars, dark-colored smoky quartz, and biotite plates measuring 

2 to 5 millimeters in diameter. The accessories are apatite, zircon, 

and scattered grains of magnetite, with some secondary light-colored 

mica, chlorite, and epidote derived from the alteration of the feldspars and biotite. Bent and curved filaments of rutile are abundant 

in the larger quartz grains. The effects of slight pressure metamorphism are evident in the lines of fracture and undulous extinction 

common to the larger quartz and feldspar individuals.

GREENE COUNTY.

The Greene County porphyritic granite area, marked G in figure 20, 

includes at least 100 acres in the main outcrop, located 10 miles 

south of Greensboro, in the southern part of the county. The main 

central exposure is in the form of a low, flat-doming mass with a 

roughened and irregular surface, partly covered with a thick growth 

of cedars.

An even-granular granite of medium-coarse grain outcrops in 

bowlder form 3 miles south of Greensboro, and is continuous along 

the public highway from this point to the main porphyritic mass. 

The even-granular texture grades interiorly into the typical porphyritic texture. The even-granular granite apparently varies in 

mineral composition from place to place along the north-south section. 

A zone 2£ miles north of the porphyritic area shows absence of all 

trace of porphyritic texture, but is a medium-grained biotite granite 

agreeing, microscopically, in mineral and in chemical composition 

with the porphyritic granite. Five miles north of the central porphyritic mass are outcrops of a coarse but close, compact-grained 

granite, containing only a very small amount of biotite. The feldspars show pronounced pink and greenish tints. About 4 miles south 

of Greensboro, on the north side of Beaver Dam Creek, is an outcrop 

of practically the same granite. The quartz is decidedly dark in 

color and of the smoky variety; the feldspars are flesh colored, and 

the rock contains but little mica.

The porphyritic facies of the rock consists of a coarse-grained 

light-gray groundmass of quartz, feldspar, and biotite, in which are 

embedded large, flat-tabular feldspar phenocrysts. The porphyritic 

feldspars average 30 to 50 millimeters in length and 10 to 15 millimeters in breadth, and indicate the usual elongation parallel to the 

clinopinacoid (010) and Carlsbad twinning. The phenocrysts are 

deep pink to perfectly white in color and are mostly cloudy and opaque 

in appearance.
GRANITES OF GEOEGIA. 249

A thin section of one of the phenocrysts under the microscope 

showed the feldspar/variety microperthitic orthoclase. The microscope further revealed abundant inclusions of fairly large grains of 

feldspar, twinned in several places after the albite and Carlsbad laws, 

and of quartz and biotite having partial orientation with the (010) 

cleavage. As a rule, however, the inclusions are not oriented. The 

biotite inclusions are sufficiently large to- be visible to the unaided 

eye.

The ratio of phenocrysts to groundmass is variable, the probable 

extremes being 1 to 1 and 2. to 1, with all gradations between. The 

individual mineral grains range from a few millimeters to 5 or 6 

millimeters in size. The arrangement of phenocrysts in some small 

portions of the mass is suggestive of fluxion structure.

The potash feldspars, orthoclase, and microcline are the porphyritically developed minerals. The orthoclase contains numerous micro- 

 perthitic structures. Plagioclase is abundant. Small rounded disks 

or ovals of intergrown quartz and feldspar are common. The larger 

feldspar and quartz crystals indicate slight peripheral shattering in 

some of the thin sections.

The biotite is considerably altered to chlorite and some epidote, 

and some of it carries inclusions. Scattered grains of magnetite, and 

prismatic inclusions of apatite and zircon are present.

Remoteness from lines of transportation has precluded development of this area. A few stones have been stripped from time to 

time from several of the surface ledges and used in the construction 

of some of the county homes.

COLUMBIA COUNTY.

The Columbia County area, marked H on figure 20, lies near the 

fall line (the contact between the Piedmont crystalline rocks and the 

Coastal Plain sediments), a short distance west of the South Carolina 

boundary. ,

About If miles east of Appling, the county seat of Columbia County 

is an outcrop of coarse-grained porphyritic granite. The feldspars are 

slightly pink in color, with a somewhat greenish cast in places. The 

phenocrysts measure 20 to 35 millimeters in length and 5 to 15 millimeters in breadth, and commonly show the contact type of Carlsbad 

twins. The rock is composed of a coarse-grained groundmass of potash and plagioclase feldspars (orthoclase predominating) and quartz, 

with biotite and scattered large plates of muscovite. The phenocrysts 

consist of large tabular microperthitic orthoclase. The quartz grains 

are badly fractured. Plagioclase feldspar is more abundant in this 

than in many of the other granite areas. Intergrowths of quartz and 

feldspar are sparingly present. The large feldspar phenocrysts con-
250 GRANITES OP SOUTHEASTERN ATLANTIC STATES.

tain abundant inclusions of the groundmass minerals, especially biotite and plagioclase.

The main porphyritic granite body is l'£ miles farther east, outcropping as a large doming mass. The porphyritic facies is readily 

traceable peripherally into an even-granular granite of medium-coarse 

texture. The even-granular facies of the rock is best exposed "along 

the public highway 3 miles slightly east of south from Appling. 

Hand specimens of the rock from the two exposures can not be distinguished from each other. The porphyritic feldspars in the principal exposure show the same microscopic tendencies as in the other 

areas.

A thin section of one of the phenocrysts from the main outcrop 

showed the characteristic microcline structure, with numerous inclusions of irregular grains of all the groundmass minerals. A chemical 

analysis of carefully selected fragments of phenocrysts from this rock 

yielded the results given on page 240 (No. 10).

The phenocrysts are embedded in a coarse-grained groundmass of 

flesh-colored feldspars having a slight greenish cast, somewhat dark, 

smoky quartz, and biotite. The porphyritic feldspar crystals make 

up nearly half of the rock. The feldspars are white and opaque rather 

than pink in color over the greater part of the exposure. In the hand 

specimens this rock very closely resembles that from Greene County. 

Here, as in the areas described above, the feldspathic constituent 

consists of potash and plagioclase feldspars in nearly equal amounts. 

The porphyritic feldspars are chiefly orthoclase with some microcline, 

carrying inclusions of all the groundmass minerals. The included 

biotite shreds are visible microscopically. Some of the largest plagioclase inclusions in the orthoclase phenocrysts carry, in turn, microscopic inclusions of quartz and other groundmass minerals. Twinning according to the Carlsbad and albite laws among the included 

feldspar species is commonly observed. The biotite is partly altered 

to chlorite and epidote. Muscovite is sparingly present, intergrown 

with biotite. Accessory magnetite and apatite occur.

Like that of Greene County, the Columbia County area is entirely 

undeveloped, because of its remoteness from lines of railroad.

GRANITE GNEISSES. 

INTRODUCTORY STATEMENT.

A major part of the granitic rocks in the Piedmont region of Georgia 

are gneisses, both light-colored (acidic) and dark-colored (basic) 

rocks. The light-colored or acidic gneisses closely resemble the 

massive granites; the dark-colored or basic gneisses usually carry 

much hornblende in place of biotite and a preponderance of plagioclase 

over the potash feldspars. These features suggest that the basic
GRANITES OF GEORGIA. 251

gneisses are the banded equivalents of the eruptive basic rocks, gabbro 

and diorite, from which they have probably been derived. They 

assume a porphyritic facies in some localities.

Extensive areas of light-colored gneiss of granitic composition occur 

in the Georgia Piedmont region, this type being one of the most 

important in the plateau complex. The granitic gneisses vary from 

medium to coarse textured rocks, having a pronounced banded or 

schistose structure. The planes of schistosity vary from moderately 

irregular to highly contorted lines and the banding is exceedingly 

irregular, ranging from very thin to relatively thick layers.

The granite gneisses are closely related, genetically, to the massive 

granites, from which they differ only in the banded structure, secondarily induced by pressure metamorphism. The two types are essentially alike in mineral and chemical composition. The minerals

occurring in.one are invariably present in the other. Moreover, the

minerals most abundant in one are predominant in the other. Like 

the massive granites the acidic gneisses are biotite-bearing rocks. 

Muscovite is a general associate of the biotite but is subordinate in 

amount. Hornblende does not occur. For these reasons the acidic 

gneisses are believed to have been derived from the massive granites, 

and are therefore designated granite gneisses. Probably there are 

gneisses of sedimentary origin in the Georgia Piedmont region, but 

the areas of gneiss studied and described in this report afford no evidence of such rocks.

There are in Georgia two principal areas of granite gneiss, which, 

though widely separated, are essentially identical in all respects. 

These are the Lithonia-Conyers-Lawrenceville area (fig. 19) and the 

Odessa-Mountville area. Of these only the first has been extensively developed. The stone from it has been extensively quarried 

and shipped beyond the limits of the State and is probably as well 

known both in and out of the State as the famous granite of Stone 

Mountain.

Among the larger and more important areas of undeveloped 

granite gneiss are Flat Rock, in Heard County; Flat Shoals, in 

Meriwether County; Flat Rock, in Coweta County; the Covington 

area, in Newton County; and the Athens area, in Clarke County.

CHEMICAL COMPOSITION.

The chemical composition of the granite gneisses is well brought 

out in the analyses below, which were made by the writer in the 

Georgia Survey laboratory. A comparison of these analyses with 

those of the massive even-granular granites on page 211 will indicate 

strikingly close similarity. The gneisses average slightly higher in 

silica and somewhat lower in alumina and lime than the granites.
252 GRANITES OF SOUTHEASTERN ATLANTIC STATES. 

Analyses of granite gneisses from Georgia.

Silica (SiOs). ........................

Lime (CaO). .........................

Soda (Na2O) .........................

Potash (K2O) ........................

1.

76.37

13.31

1.21

.10

1.13

4.02

3.68

.20

2.642

2.

76. 00

13.11

.92

.27

1.06

3.88

4.69

.31

2. 686

3.

75.89

14.02

.71

.12

.70

3.64

5.56

.28

2.642

4.

75.45

13.71

.92

.18

.94

3.87

4.30

.40

2.643

5.

74.06

14.22

1.09

.12

1.09

3.97

4.89

.27

6.

71.20

15.46

1.17

.38

1.36

4.96

5.30

.52

7.

69.51

16.32

2.38

1.28

1.84

3.82

3.47

1.11

8.

68.89

16.47

9 Id.

40

1.63

4.38

4.15

OO

1. Contorted biotite granite gneiss, Odessa quarry, Meriwether County.

2. Contorted biotite granite gneiss, Crossley quarry, near Lithonia, Dekalb County.

3. Contorted biotite granite gneiss, Snell quarry, Snellville, Gwinnett County.

4. Contorted biotite granite gneiss, Tilly quarry, Rockdale County.

5. Contorted biotite granite gneiss, average of quarries near Lithonia, Dekalb County.

6. Biotite granite gneiss, Freeman quarry, near Covington, Newton County.

7. Biotite granite gneiss, Athens, Clarke County.

8. Biotite granite gneiss, McElvaney Shoals, Gwinnett County.

PHYSICAL TESTS.

The results of tests made on the Georgia gneisses to determine 

specific gravity, ratio of absorption, weight per cubic foot, and 

number of cubic feet of stone in 2,000 pounds are tabulated below:

Physical tests of granite gneisses from Georgia.

Quarry. Specific 

gravity.

2. 642

2.642

2.643

2.686

2.648

Ratio of 

absorption.

0.056

.075

.052

' .050

Weight per 

cubic foot 

(pounds).

165. 12

165. 12

165. 18

167. 90

165.50

Cubic feet 

of stone in 

2,000 

pounds.

12.1

12.1

12.1

11.9

12.0

i

The following crushing tests were made on specimens of Lithonia

contorted granite gneiss.

Crushing tests of granite gneiss from Lithonia, 

AT WASHINGTON NAVY-YARD, 1887.

Dimensions (inches).

2. 00 X 2. 00 x 2. 02 

2. 00 x 2. 01 x 2. 00 

2. 06 X 2. 06 x 2. 09 

2. 01 x 2. 01 x 2. 01 

2. 00 x 1. 98 x 1. 98 

2. 02 X 2. 04 x 2. 07 

2.02x2.01x2.06 

2. 01 x 2. 01 x 2. 01 

2. 01 x 2. 00 x 2. 00 

2. 02 x 2. 08 x 2. 02 

2. 02 x 2. 05 x 2. 02

Crushed at 

Pounds.

76, 000 

83, 400 

52,650 

(ft ) 

(") 

80, 000 

61,000 

80, 000 

80, 700 

75, 700 

. 64.000

Pounds per 

square inch.

15, 024 

19,801

18,017 

15, 455

a Granite pavements, compiled by Veaable Brothers, Atlanta, Ga., 1893. 

i> Did not crush at 85,000 pounds.
U. S. GEOLOGICAL SURVEY

SURFACE OF GRANITE GNEISS, LITHONIA, DEKALB 
GRANITES OF GEORGIA. 253

Crushing tests of granite gneiss from Lithonia, Ga. Continued. 

AT PURDUE UNIVERSITY, LAFAYETTE, IND.

Dimensions (inches).

2. 00 x 2. 02 x 2. 02

2. 04 x 2. 04 x 2. 00

2. 04 x 2. 03 x 2. 03

2. 04 X 2. 04 x 2. 05

2. 02 x 2. 02 x 2. 01

2. 01 x 2. 02 x 2. 04

Crushed at 

Founds.

78, 700

71,700

79,700

79,700

74, 700

70, 700

Founds per 

square inch.

18,913'

17,229

19, 240

19,151

18,307

17,413

LITHONIA-CONYEKS-LAWKENCEVILLE AREA. 

GENERAL DESCRIPTION.

The Lithonia-Conyers-Lawrenceville area covers parts of five counties and lies immediately adjacent on its north and west sides to the 

famous Stone Mountain. (See map, fig. 19.) The area includes the 

extreme eastern part of Dekalb County and extends in a northeasterly direction through the northern and middle portions of Rockdale County, the western part of Walton County, and the southern 

half of Gwinnett County, into Jackson County, in the vicinity of 

Winder. The principal quarrying center is Lithonia, a station on 

the Georgia Railroad, in Dekalb County. Quarries have been worked 

in the vicinity of Conyers, Rockdale County, and a few scattered 

small openings have been operated near Snellville and Lawrenceville, 

Gwinnett County.

In the immediate vicinity of Lithonia and to the north and east 

the granite gneiss is exposed as fiat-surfaced masses and in residual 

domelike bosses (PL XXVI), some of the latter rising several hundred feet above the surrounding plain. Pine (Little Stone), Arabia, 

Collinsville, and Rock Chapel mountains, in Dekalb County, and 

McDaniel Mountain, in Rockdale County, are the most conspicuous 

of the dome-shaped masses of granite gneiss in this area. Pine 

Mountain is the largest, and is second in size and importance as a 

producer of stone only to Stone Mountain, about 8 miles distant.

The readiness with which sheets of the stone of large size and of any 

desirable thickness can be raised over the slopes of the doming masses 

makes them important quarrying areas. The most extensive quarries in the Lithonia portion of the area are to be found on some of 

the domes of granite gneiss.

LITHOLOGIC CHARACTERS.

The rock is a hard, firm, close-textured, fine-grained biotite granite 

gneiss of medium-gray color. It is in the main highly contorted and 

usually thin banded, the black biotite and light-colored feldspars and 

quartz being more or less differentiated into layers. As compared
254 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

with the bands of light-colored minerals those of biotite are very thin. 

In addition to forming distinct bands, the biotite is more sparingly 

distributed through the quartz-feldspar layers.

The principal minerals are orthoclase, microcline, plagioclase (oligoclase), quartz, biotite, a little muscovite, apatite, zircon, and magnetite. Some secondary chlorite, epidote, kaolin, and a light mica 

occur. Crystals of red garnet are very common in some of the quarries. The garnet forms in places thick lenses of considerable length, 

alternating with bands of the principal minerals, and is distributed 

through the rock as single crystals. Small bunches of black tourmaline, similar to those in the granite of Stone Mountain, in well-rounded 

areas of quartz and feldspar, are distributed through the gneiss, but 

are by no means so abundant as at Stone Mountain.

Orthoclase is the dominant feldspar and in part is intergrown 

with a plagioclase feldspar as microperthite. Microcline is subject 

to much variation, its general average being probably somewhat 

larger for the gneiss than for the even-grained granites. This 

increase in microcline in the gneiss can probably be accounted 

for as a result of pressure metamorphism, for numerous pieces of 

the mineral show some indications of a possible induced structure, 

such as might result from excessive strain. Plagioclase is likewise 

variable in amount, but, as indicated in the analyses on page 252, its 

general average is high, as shown by the N2O being approximately 

equal to or greater molecularly than K20. Some muscovite is associated with the biotite. Rounded inclusions of quartz and feldspar 

are common to the larger feldspar individuals. Intergrowths of 

quartz with feldspar occur, but are less common than in the massive 

granites.

Pegmatite dikes in which black tourmaline is one of the minerals

are present. Vertical j oints are by no means conspicuously developed. 

They are widely spaced and their surfaces are in many plaqes coated 

with damourite, which is slickensided, grooved, and striated, affording 

evidence of subsequent movement.

DESCRIPTIONS OF QUARRIES.

GENERAL STATEMENT.

Forty-six quarries have been worked in the Lithonia-ConyersLawrenceville granite gneiss area. These are distributed among five 

counties Dekalb, Rockdale, Gwinnett, Jackson, and Walton. 

Dekalb County contains most of the quarries and all the larger ones; 

they are grouped about and near Lithonia, 20 miles east of Atlanta, 

as the quarrying center and shipping point on the Georgia Railroad.

All quarries within the area, both large and small, that are now 

operating or have been operated are listed below. Numerous small
GEANITES OF GEORGIA. 255

openings are not included in the list. Of the 46 quarries listed only 

a few were operating during the summer of 1908.

The description of the quarries will be limited to some of the larger 

and more important ones in each county. The stone from the numerous quarries over the area shows only slight if any variation in color, 

texture, and structure, so that description of each quarry would entail 

a useless amount of repetition. Moreover, the fresh rock from the 

several quarries, both large and small, seems equally well adapted to 

the uses made of it. Joints and pegmatite dikes are not so pronounced 

as in many granite areas, and in none of the quarries do they involve 

waste in operating.

Quarries in the Lithonia-Conyers-Lawrenceville granite gneiss area.

Quarry.

Almond.... ...........

Arabia Mountain. . ....

Bush..................

Gates.. ................

Chupp, J. .El..........

Floyd.................

Goddard..............

PierCe

Pine (Little Stone) Mo

Reagin and Georgia Ra 

Keel wine & James. .... 

Rock Chapel Mountain

Snell........ ..........

Southern Granite Com 

Tilly..................

Wade.................

Walker...............

Whitley.. .............

\Vilson

Location.

Post-office.

.....do................

.....do................

.....do................

.....do................

.....do................

.....do................

.....do................

.....do................

.....do................

.....do................

.....do................

.....do................

.....do................

.....do................

.....do................

Conyers............... 

Lithonia. .............

.....do................

.....do................

.....do................

.....do................

County.

Rockdale. 

Dekalb. 

Do. 

Do. 

Do. 

Do. 

Gwinnett and Walton. 

Gwinnett. 

Dekalb. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

G winnctt. 

Dekalb. 

Do. 

Do. 

Do. 

Do. 

Do. 

Gwinnett. 

Do. 

Dekalb. 

Rockdale. 

Do. 

Dekalb. 

Rockdale. 

Dekalb. 

Rockdale. 

Dekalb. 

Walton. 

Jackson. 

Gwinnett. 

Do. 

Dekalb. 

Rockdale. 

Gwinnett. 

Do. 

Dekalb. 

Do. 

Do. 

Do. 

Rockdale. 

Dekalb.

DEKALB COUNTY.

The Arabia Mountain quarries are opened on Arabia Mountain, 

which consists of two large dome-shaped granite gneiss masses, 3. 

miles south of Lithonia. The peaks are close together, having a

38971° Bull. 426 10 17
256 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

northeast-southwest alignment and averaging about 85 feet high. 

The southwest peak is the higher and larger of the two. Quarries 

of large dimensions have been worked over the basal slopes and 

edges of the northeast peak, and less extensively on the east side. 

(See PL XXVII, B.) Development has not been so extensive on 

the southwest peak, but the stone has been " raised" over approximately half of its slope, preparatory to opening quarries. The south 

and southwest sides of the peak have not been touched. The rock 

is a contorted biotite granite gneiss of light-gray color, medium 

grain, and irregular banding. Garnet and magnetite are visible in 

the rock. Segregation veins of pegmatite and small dark areas of 

black tourmaline occur. The joint surfaces are mostly slickensided 

and are coated in some places with damo.urite, indicating movement 

in the rock mass. A chemical analysis of the rock from these quarries 

is given on page 252 (No. 5). The percentage of absorption for the 

rock is 0.050. A spur track is operated between the Georgia Railroad 

at Lithonia and the northeast peak.

The J. L. CJiupp quarries comprise six large openings in a 10-acre 

flat-surfaced exposure about a mile from/ Lithonia. Work was first 

begun in 1882 and has been more or less continuous to the present 

time. An approximate estimate showed that about 50,000 feet of 

stone had been quarried annually for the ten years prior to 1900. 

The product was shipped to various cities in and outside of the State, 

and used principally for street purposes and to some extent in building. The rock is a contorted biotite granite gneiss of light-gray 

color and medium grain. It carries local thin bands of red garnet 

and is cut in places by thin pegmatite dikes.

The CollinsviTle Mountain quarries are about a mile east of south 

from Lithonia, on Collinsville Mountain, one of the smaller domeshaped masses. The peak lies south of and adjacent to Little Pine 

Mountain. Its greatest elevation is less than 100 feet and its slopes 

are gentle, with partly rough and uneven surfaces. The main line of 

the Georgia Railroad passes directly over the south slope of the 

dome. Quarries have been worked over nearly the entire rock mass. 

The rock is a contorted biotite granite gneiss of light-gray color and 

irregular banding and is in places highly garnetiferous. Many of the 

garnets are of large size and are partly altered to brownish epidote. 

Crystals of magnetite and black tourmaline are distributed through 

the rock in the usual quantity. The product was shipped to different 

parts of the South for paving and general street work. During the 

summer of 1901 work was resumed on rather an extensive scale to 

supply orders from Washington, D. C., and St. Louis, Mo., for curbing. A crusher was operated on the property in order to work up 

the quarry waste.
 ULLETIN 426 PLATE XXVII

A. EAST SLOPE OF PINE MOUNTAIN, A GRANITE GNEISS DOME, LITHONIA, DEKALB COUNTY, GA.

v«V2.fs&.

QUARRY FACE OF GRANITE GNEISS, ARABIA MOUNTAIN QUARRIES, NEAR LITHONIA, DEKALB

COUNTY, GA.
GRANITES OF GEOEGIA. 257

The Cooper quarry, 2£ miles south of Lithonia, comprises several 

openings in an 8-acre flat-surfaced outcrop. The rock is a contorted 

biotite granite gneiss of excellent grade and of somewhat darker color 

than is common because of the slightly increased amount of the dark 

mineral biotite. Segregation veins of pegmatite and dark areas of 

black tourmaline are exhibited in places in the rock. The production 

has been large.

The Crossley quarry, comprising six openings, is 3^ miles southeast 

of Lithonia. The openings are in a 40-acre tract of exposed rock forming a part of the extended basal slope of Arabia Mountain, cut off by 

stream erosion. The first quarrying was clone more than twenty 

years ago. The rock is a contorted biotite granite gneiss of light-gray 

color and irregular banding. Many small segregation veins of pegmatite penetrate the gneiss. Garnets of red color, in the form of thin 

bands and as single individuals disseminated through the rock, are

common. Scattered small groups of black tourmaline also occur.

The following analyses of the fresh and partly decayed rock were 

made by the writer:

Analyses of fresh and decayed granite gneiss from Crossley quarry, Dekalb County, Ga.

Silica (SiOj)............. .................-......................'...................

Alumina (A12 03 ) . .....................................................................

Lime (CaO). ........................................................................

Soda (Na2 0) . .......................................................................

Potash (K2 0) . ......................................................................

Fresh.

76.00

13.11

.92

.27

1.00

3.88

4.G9

.31

Decayed.

71.07

10.14

1.22

.10

.29

2.80

4.52

4.03

The product from this quarry has been used almost entirely for 

street work and has had a good market in St. Louis, Birmingham, and 

Montgomery, and in the principal towns in Georgia.

The Georgia Railroad quarry is located near the southeast limits of 

the town of Lithonia. The rock is exposed as flat-surfaced masses and 

most of the exposed surface has been worked to considerable depth. 

Much stone has been quarried, worked into blocks for curbing for 

street paving, and shipped to various points in Alabama, Florida, 

Georgia, and Tennessee, with smaller shipments to Chicago and 

Washington. The rock is a contorted biotite granite gneiss of lightgray color, medium grain, and irregular banding. It is of good grade.

The Johnson quarry, half a mile north of Little Pine Mountain, was 

first opened in 1886. It is very extensive and a large amount of stone 

has been quarried. The rock, which is of excellent grade, is a contorted biotite granite gneiss carrying in places large quantities of 

small red garnets in bands and also irregularly distributed through the
258 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

rock as single grains and crystals. Some magnetite and black tourmaline crystals are disseminated through the rock. The-product 

was worked into blocks, curbing, and nagging, and used for street purposes.

The Pine Mountain quarries, on Pine Mountain (Little Stone 

Mountain) 1 mile east of Lithonia, are the most extensive quarries in 

the granite gneiss area. Pine Mountain is the largest of the doming 

masses of granite gneiss in the area and is se'cond in size only to Stone 

Mountain. Its height is about 150 feet. Its slopes are rounded and 

have easy gradients and for the most part are bare of plant growth. 

The worked quarries are limited to the north and southwest slopes 

of the mountain, which have been "raised" and worked from the base 

nearly to the top. The southwest slope has been worked to a greater 

depth than the north slope. (See PL XXVII, A.}

The rock is the typical contorted biotite granite gneiss, of lightgray color, medium grain, and irregular banding. Scattered folia of 

muscovite are visible in the hand specimens. Here and there small 

segregation veins of pegmatite and dark areas of'biotite occur. Scattered grains of magnetite and garnet and rarely areas of tourmaline 

have been noted in places. The general absence of visible jointing in 

this mass is a very noticeable feature.

The chemical composition of the rock is shown in an analysis on 

page 252, and the results'of strength tests on 2-inch cubes are given on 

page 252. A test to determine the capacity of the rock to absorb 

water, made by F. W. Clarke, showed a gain in weight of 0.2 gram 

(from 381.5 to 381.7 grams) after soaking for forty-eight hours.

The Pine Mountain quarries were the first to be opened and worked 

in the Lithonia area. They are among the largest and most productive in the area°; the product being shipped to many of the principal 

towns and cities in the South and West. The ease with which the 

stone can be quarried is of considerable economic importance. Beginning at the bottom of the slope, one raise, ranging from 7 to 11 feet in 

thickness, is readily effected, extending nearly or quite to the top. 

This method of quarrying the stone is equally available for each of the 

doming masses in the area. It is very similar to that in use in the 

Mount Airy quarries in North Carolina, described on pages 150-151.

The shipments from these quarries have amounted to as much as 

30 carloads of stone a day in some years. The product is extensively 

used in the form of blocks and curbing for street work.

The Southern Granite Company's guarry, three-quarters of a mile 

north of Lithonia, includes about 5 acres of a flat-surfaced exposure 

worked to a depth of 20 feet. The product, worked into blocks and 

curbing, is shipped to the principal towns in the South. The rock is 

a contorted biotite granite gneiss of good grade. A considerable
GSANTTES OF GEOBGIA. , 259

sprinkling of magnetite grains and several small areas of molybdenite 

occur. The following analyses of the fresh and partly decayed rock 

were made by the writer:

Analyses of granite from Southern Granite Company's quarry, near Lithonia, Ga.

Silica (Si02 ). .. . .....................................................................

Soda (Na20) ........................................................................

Potash (K2 0) . ......................................................................

Fresh.

72.90

14.70

1.28

.07

1.28

4.18

4.73

.23

Partly 

decayed.

74.53

13.70

1.15

Trace

.95

4.41

5.20

.81

The Rock Chapel Mountain quarries are opened on the doming mass 

known as-Rock Chapel Mountain, 3 miles northeast of Lithonia.

This is one of the smaller domes in the Lithonia area. Fourteen 

quarries have been raised over the peak, but no stone has been 

removed except from the west-side quarry. The raised quarries 

extend from the top down to the base of the north and northwest 

sides. The rock is a contorted biotite granite gneiss of light-gray 

color and medium grain. The sap (partly decayed rock) is very thin 

and consists of the usual hard, firm, reddish material.

The Wilson quarry, 2£ miles northeast of Lithonia, consists of five 

large openings close together in flat-surfaced outcrops. Systematic 

quarrying was first begun in 1891. In 1898, between January and 

August, 150 carloads of the stone were shipped. The rock is the 

contorted biotite granite gneiss, containing a goodly sprinkle of large 

magnetite grains. The partly decayed rock (sap) is very thin and 

usually of a reddish color, due to the iron stain derived from the 

partial decay of the biotite.

The Whitley quarry, a quarter mile southwest of the Wilson quarry, 

includes six openings almost joining one another. The product is 

used for paving and curbing in street work. The rock is a contorted 

biotite granite gneiss of excellent grade, containing the usual sprinkle 

of magnetite grains. There are a few thin veins of pegmatite in it.

GWINNETT COUNTY.

The Bush quarry, a quarter of a mile south of Winder, includes a 

number of openings in flat-surfaced exposures of the rock. The 

Gwinnett-Walton county line divides the property, placing the 

openings partly in one county and partly in the other. The rock is 

a contorted biotite granite gneiss of variable color and texture, cut 

by many pegmatite dikes. It is not so highly contorted as the gneiss 

in the vicinity of Lithonia, described above. When broken across
260 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

the schis.tosity the fractured, surf ace presents roughly an augen-gneiss 

appearance, the quartz-feldspar grains being partly lens-shaped and 

irregularly wrapped by the layers of biotite.

The LawrenceviTLe quarry lies near the limits of the town of Lawrenceville, 460 yards from the Seaboard Air Line Railway. The 

opening is made in a 3-acre flat-surfaced exposure of the rock and has 

been worked to a depth of 10 feet. The rock is a contorted biotite 

granite gneiss of light-gray color and medium grain. Its minerals 

are orthoclase, microcline, plagioclase, quartz, and biotite, with 

accessory zircon and secondary chlorite, epidote, and a light-colored 

mica. The larger feldspar and quartz individuals inclose smaller 

grains of the two minerals, of irregular outline.

The Snell quarry includes four large openings in a flat-doming mass 

2 miles south of Snellville. Quarrying was begun here in 1883. The 

rock is a contorted biotite granite gneiss of light-gray color and 

medium grain, cut by numerous pegmatite dikes several inches thick. 

The minerals are orthoclase, microcline, plagioclase near oligoclase, 

quartz, biotite, and a little muscovite, with secondary chlorite, garnet, 

epidote, and a light-colored mica. Microcline and orthoclase are 

about equal in amount. The large feldspar individuals contain 

rounded grains of quartz and feldspar. A chemical analysis of this 

rock (No. 3) and an absorption test are given on page 252.

The Turner quarry comprises three large openings in a 6-acre 

exposure of gneiss 5 miles southeast of Lawrenceville. The product 

has been used principally in railroad construction. The rock is a 

biotite granite gneiss of light-gray color and medium grain. The 

bands are less contorted than in the rock near Lithonia. There are 

very few pegmatite dikes. The principal minerals are orthoclase, 

microcline, plagioclase near oligoclase, quartz, and biotite. Slender

foils of muscovite are developed along the roughly parallel lines of 

fracture.

JACKSON COUNTY.

For several miles on the north and west sides of Winder, in the 

southeastern part of Jackson County, the Lithonia belt of contorted 

biotite granite gneiss outcrops as flat-surfaced masses. So far as the 

writer has been able to trace it, the Jackson County outcrops mark 

the northernmost extension of the Lithonia-Conyers-Lawrenceville 

granite gneiss area. Several openings have been made just beyond 

the north and west limits of the town of Winder, and some of the 

stone has been quarried for local purposes.

The rock exposed in the openings is fairly uniform and somewhat 

highly contorted and is composed of an admixture of feldspar, quartz, 

and biotite. It can hardly be distinguished in the hand specimens 

from the similar rock quarried at Lithonia, although on close inspection slight differences are discernible between the rocks of the two
GEANITES OF GEORGIA. 261

localities. The Jackson County rock contains an increased amount 

of biotite in larger flecks and perhaps a little less quartz and more 

feldspar than that at Lithonia. It is also somewhat coarser in grain 

and as a rule less highly contorted than the typical granite gneiss at 

Lithonia. The variations are regarded as very slight indeed, for the 

extreme portions of so extensive a granite area.

ROCKDALE COUNTY.

The McDaniel Mountain quarries are opened on McDaniel Mountain, a doming mass of granite gneiss located near the DeKalb County 

line, about three-fourths of a mile east of the north peak of Arabia 

Mountain. Its height will not exceed 100 feet and its slopes are 

gentle. The quarries are confined to the west and southwest slopes 

of the peak. On the south and northwest slopes surface raises have 

been made but the stone has not been worked up. The rock is a

contorted biotite granite gneiss of light-gray color, medium grain, 

and irregular banding. It is cut in places by a few veins of pegmatite 

and locally contains a sprinkle of magnetite grains.

The Pierce quarry, on Yellow River, 3 miles north of Conyers, is a 

large one and much stone has been taken from it, but it has been idle 

for more than twelve years. The rock is a contorted biotite granite 

gneiss of light-gray color and medium grain, containing many magnetite grains distributed through it. The principal minerals are 

orthoclase, microcline, plagioclase near oligoclase, quartz, and biotite, 

with some secondary chlorite and epidote.

The Powell quarry comprises four openings in a 4-acre exposure 

about 2 miles east of Conyers. It was last worked in 1896. The 

rock is a highly contorted biotite granite gneiss of the usual color and 

texture,- containing numerous garnets in places. The principal minerals are orthoclase, microcline, plagioclase near oligoclase, quartz, 

biotite, and a little muscovite, with secondary chlorite, epidote, 

and a light-colored mica. Roughly rounded grains of quartz and 

feldspar are common as inclosures in the larger individuals of these 

two minerals. Intergrowths of the quartz and feldspar occur.

The Tilly quarry includes three large openings close together in a 

5-acre flat-surfaced exposure of the rock, 2 miles northwest of Conyers. 

The rock is of the same grade of contorted biotite granite gneiss as 

that of the Powell quarry, described above, and consists of the same 

minerals in the same order of abundance. A chemical analysis of this 

rock is given on page 252 (No. 4).

The Turner quarry, in a 6-acre exposure near Conyers, about a mile 

from the Georgia Railroad, was opened in 1890. A large quantity 

of the stone has been quarried and used principally for Belgian blocks. 

The rock is a highly contorted biotite granite gneiss of light-gray
262 GKANITES OP SOUTHEASTERN ATLANTIC STATES.

color, containing considerable magnetite grains in places. Some 

bands of garnet occur and the rock is cut by a few thin veins of pegmatite. The principal minerals are the same as for the similar rock 

described above.

WALTON COUNTY.

The Lithonia-Conyers-Lawrenceville granite gneiss area includes a 

portion of eastern Walton County. Less than half a dozen small 

openings, from which granite gneiss has been quarried, have been made 

in the county, most of them near the village of Loganville. No stone 

has been shipped. Some variation in the color and texture of the rock 

is observed, although many of the hand specimens can not be distinguished from those of the typical granite gneiss of the Lithonia area.

ODESSA-MOUNTVILLE AREA. 

INTRODUCTORY STATEMENT.

The Odessa-Mountville area extends in a general east-west direction 

through parts of Troup and Meriwether counties, in middle southwestern Georgia, near the Alabama line. Hand specimens of the rock 

from this area are indistinguishable from those of the LithoniaConyers-Lawrenceville area, and the two rocks are identical in mineral 

and chemical composition. The results of physical tests and chemical 

analysis of specimens of the Odessa rock are given on page. 252. 

The granite gneiss is exposed along the streams and on the interstream areas as flat-surfaced masses, some of which are of considerable 

extent. Only a few quarries are opened in the area.

LITHOLOGIC CHARACTERS.

The gneiss is an irregularly banded, highly contorted biotite granite 

gneiss of medium light-gray color and fine to medium grain. Its 

minerals are orthoclase, .microcline, plagioclase near oligoclase, 

quartz, and biotite, with accessory magnetite, zircon, and apatite. 

Secondary chlorite and epidote occur. The potash feldspar is inter: 

grown with a second feldspar in microperthitic fashion. Microcline 

and plagioclase usually average high in quantity but are rather variable. The larger feldspar and quartz individuals contain rounded 

inclosures of the same minerals. Magnetite crystals, mostly visible 

to the naked eye, are disseminated through the gneiss of this area, as 

through that of the Lithonia-Conyers-Lawrenceville area.

The granite gneiss is intersected in places by dikes of pegmatite and 

of biotite granite of dark-gray color and fine grain. Dark segregated 

areas (knots) of black mica (biotite) occur to a minor extent.
GSAMfES OF GEORGIA. 263 

DESCRIPTIONS OF QUARRIES.

Although large outcrops of biotite granite gneiss are numerous 

over the Odessa-Mountville area, very few quarries have been opened. 

The two principal ones are the Odessa quarry, in Meriwether County, 

and the Mountville quarry, in Troup County:

The Odessa quarry, 6 miles west of Greenville and half a mile north 

of Odessadale, in Meriwether County, lies in a 15-acre exposure of 

the rock and comprises about 2 acres worked to a depth of 10 feet. 

It was worked for a period of three years after being first opened 

about fourteen years ago, the product being used principally for 

river work by the United States Government on St. Johns River in 

Florida.

The rock is a highly contorted biotite granite gneiss of light-gray 

color, medium grain, and irregular banding. It is entirely similar 

to the granite gneiss quarried near Lithonia, Dekalb County, and 

hand specimens of the rock from the two localities can not be distinguished. Its principal minerals are orthoclase, microclme, plagioclase near oligoclase, quartz, and biotite. Rounded inclusions of 

quartz and feldspar are contained in the larger feldspar individuals. 

The biotite is partly altered to chlorite. Pressure effects are indicated in peripheral shattering, wavy extinction, and lines of fracture 

in the larger grams of quartz and feldspar. Dikes of pegmatite and 

of biotite granite of dark-gray color and fine grain cut the granite 

gneiss and in places the rock contains segregated areas (knots) of 

black mica (biotite) and scattered grains of magnetite.

A chemical analysis of this rock is given on page 252 (No. 1); the 

results of physical tests are given On page 252.

The Mountville quarry, 8 miles east of Lagrange and 1 mile west 

of Mountville, is opened in a 4-acre flat-surfaced outcrop. The small 

quantity of stone quarried here has been used for street purposes.

The rock is a highly contorted biotite granite gneiss of light-gray 

color, medium grain, and irregular banding, carrying a few scattered 

grains of magnetite in places. Its minerals are orthoclase, microcline, plagioclase (oligoclase), quartz, and biotite, with accessory 

zircon, apatite, and magnetite. The secondary minerals are chlorite 

and epidote. Orthoclase is intergrown with a second feldspar and 

is largely microperthitic. Inclosures of quartz and feldspar are contained in the larger feldspar grains. The thin sections exhibit evidences of pressure effects similar to those in the Odessa quarry 

described above. A comparative study of the thin sections of the 

rock with those of the granite gneiss from Lithonia reveals their 

practical identity.
264 GKANITES OP SOUTHEASTERN ATLANTIC STATES. 

MERIWETHER COUNTY.

The Flat Shoals area of foliated granite is 12 miles east of Greenville and about the same distance west of Zebulon. Extensive 

exposures of the rock can be traced along Flint River for some distance in Meriwether and Pike counties. The outcrops extend back 

from the river for some distance on the Meriwether County side. 

The area is somewhat remote from the railroad, and except for a 

small opening made some years ago at Freeman's mill it is wholly 

undeveloped.

The rock is a foliated biotite granite of light-gray color and medium 

grain. Its minerals are microperthitic orthoclase, microcline, plagioclase (albite), quartz, and biotite, .with accessory apatite and zir-. 

con. The secondary minerals are chlorite, epidote, and a lightcolored mica. Finely crushed grains of the quartz and feldspar are 

abundant about the borders of the larger individuals of the two 

minerals. The following chemical analysis was made by the writer:

Analysis of foliated granite from Flat Shoals, - Meriwether County, Ga.

Silica (Si02 )................................................. 74. 80

Alumina (A120;H )- -............................................ 15. 46

Iron oxide (Fe2 03 ).......................:................... 1. 04

Magnesia (MgO)............................................... .11

Lime (CaO).................................................. .82

. Soda (Na2 0)............................................... 4. 80

Potash (K,0)................................................. 2.52

Ignition..................................................... .31

COWETA COUNTY.

About 11 miles northwest of Newnan, the county seat of Coweta 

County, are large areas of foliated granite (granite gneiss) bordering 

Chattahoochee River and extending across the river into Carroll and

Heard counties on the north and west, respectively. The rock outcrops as flat-surfaced and low dome-shaped masses, forming the 

prominent hills and ridges in the area. The topography is less subdued here than in other portions of the county. The most extensive 

outcrop of the gneiss is that known as Flat Rock, which derives its 

name from the character of the exposure at the surface. No quarries have been opened in it. The main body of the rock in Coweta 

County is 6 miles from Sargent, the nearest railroad station.

The rock is a thinly banded biotite granite gneiss of light-gray 

color and medium grain. Its minerals are microperthitic orthoclase 

and microcline in nearly equal amounts, plagioclase, quartz, biotite, 

and muscovite, with accessory zircon and apatite and secondary epidote, garnet, chlorite, and light-colored mica. Pressure effects are 

-manifested in the peripheral shattering of the larger quartz and feldspar individuals. Inclusions are common.to the quartz, feldspar, 

and biotite. Pegmatite dikes an inch or more in thickness cut the
GRANITES OF GEORGIA. 265

rock in places. A comparison of the following chemical analysis, 

made by the writer, with that of the Flat Shoals rock, in Meriwether 

County (p. 264), and that of Flat Rock, in Heard County (p. 265), 

establishes their practical chemical identity.

Analysis of granite gneiss from Flat Rock, Coweta County, Ga.

Silica (Si02 ).................................................. 73. 95

 Alumina (A12 08 )..........................:................... 14. 23

Iron oxide (Fe2 03 )....................."........................ 1. 29

Magnesia (Mgd). ............................................... .23

Lime (CaO) .................................................. 1. 07

Soda (Na20).................................................... 4. 61

Potash (KaO)................................................. 5. 29

Ignition....................................................... .25

HEARD COUNTY.

An extensive body of foliated granite occurs 3 miles southwest of 

Franklin, the county seat of Heard County. There are at least 400 

acres of the rock exposed in one continuous flat-surfaced outcrop, 

broken here and there by knolls of slight elevation. Parts of the 

exposure are timbered. Small amounts of the stone have been quarried from time to time during the last fifty years for strictly local 

use. Seven openings have been made in all.

The rock is a thinly foliated biotite granite, of light-gray color and 

fine grain. Biotite is distributed along roughly parallel lines through 

the rock in flattened areas of grouped shreds, which vary from 2 to 

20 millimeters in diameter. When the rock is broken at angles to 

the foliation the parallel arrangement of the mica (biotite) is very 

noticeable. The rock is composed of orthoclase, microcline, and 

plagioclase (oligoclase) in about equal amounts, quartz, biotite, and 

scattered intergrown shreds of muscovite. Here and there grains of 

reddish garnet occur. The biotite is partly altered to chlorite. 

Rounded areas of quartz are inclosed in the larger feldspar grains. 

The orthoclase is partly intergrown with a second feldspar as microperthite. Partial peripheral shattering of the quartz and feldspar is 

shown in the thin sections.

The following chemical analysis of the rock, made by the writer in 

the Georgia Survey laboratory, will show its composition: ' 

Analysis of foliated granite from Flat Rock, Heard County, Ga.

Silica (Si02)................................................... 74.96

Alumina (A12 03 ).............................................. 13. 71

Iron oxide (Fe203 )............................................. .90

Magnesia (MgO).............................................. .24

Lime (CaO).................................................. 1. 02

Soda (Na2 0)................................................... 4. 68

Potash (KjjO)................................................. 4.79

Ignition....................................................... .44

The specific gravity is 2.648.
266 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

NEWTON COUNTY.

Newton County contains a number of areas of irregularly banded 

biotite gneiss of coarse grain and medium to dark gray color. Among 

these are two rather large flat-surfaced exposures, which may be of 

commercial importance one 2 miles northwest and the other 1£ 

miles southeast of Covington, the county seat. Considerable stone 

has been quarried from the mass exposed 2 miles northwest of Covington.

The rock is a biotite granite gneiss of dark-gray color and coarse 

grain, and is very irregularly banded. When compared with the 

granite gneiss of the Lithonia area in Dekalb ^County, it shows a 

striking contrast in color and texture. In addition to its coarser 

grain and darker color, it lacks the hardness, compactness, and 

lively appearance of grain so characteristic of the Lithonia rock. 

Thin sections of the gneiss show the principal minerals to be microciine, orthoclase, plagioclase, quartz, and biotite, and the secondary 

minerals chlorite, kaolin, and a light-colored mica. Intergrowths 

of the feldspar with quartz are somewhat common. The larger 

grains of microcline contain rounded inclosures of both quartz and 

feldspar.

A chemical analysis of the gneiss, made by the writer, shows the 

following composition:

Analysis of gneiss from Newton County, Ga.

Silica (Si02 )................................................... 71. 20

Alumina (A12 03 ).............................................. 15. 46

Iron oxide (Fe203 )............................................. 1.17

Magnesia (MgO).............................................. .33

Lime (CaO).................................................. 1.36

Soda(Na20)................................................... 4.96

Potash (K2O)................................................. 5. 30

Ignition....................................................... .52

CLARKE COUNTY.

An irregularly banded gneiss of dark-gray color and coarse grain 

is extensively exposed along Oconee River within and beyond the 

limits of Athens, and considerable of the stone has been quarried and 

used in that city.

The rock is a biotite gneiss of dark-gray color and 'coarse grain. It 

is of porphyritic texture in places, the feldspar phenocrysts measuring 

from 30 to 40 millimeters in length. Thin sections of the gneiss show 

the principal minerals to be orthoclase, microcline, plagioclase, quartz, 

and biotite, with some muscovite. The biotite is partly altered to 

chlorite and the feldspars to kaolin and a light-colored mica. The 

plagioclase is more altered than the potash feldspars. Intergrowths 

of quartz with feldspar are noted here and there.
GRANITES OF GEOEGIA. 267

A chemical analysis of the gneiss, made by the writer, is given

below:

Analysis of gneiss from Clarice County, Ga.

Silica (Si02 )................................................... 69. 51

Alumina (A1203 ).............................................. 16. 32

Iron oxide (Fe203 )............................................. 2. 38

Magnesia (MgO).............................................. 1. 28

Lime(CaO).................................................. 1.84

Soda (Na20)................................................... 3.82

Potash (K2 0)................................................. 3. 47

Ignition........................................................ 1.11
CHAPTER VIII. 

THE GRANITES OF ALABAMA.

THE CRYSTALLINE AREA.

The crystalline area in Alabama, representing the extreme southwestern extension of the Piedmont Plateau in the southeastern 

Atlantic States, is roughly triangular in shape and has an estimated 

area of less than 5,000 square miles. Its greatest dimension is along 

the Georgia-Alabama boundary, where it extends from Columbus, 

Ga., northward for an approximate distance of 100 miles. From this 

boundary it narrows toward the west, and near the central portion of 

Alabama it passes beneath and is concealed by the cover of younger 

sediments. On. the south and southwest the rocks of the crystalline 

area pass beneath the coastal plain sediments and on the northwest 

they are covered by the Paleozoic sediments.

The crystalline area occupies the eastern north-central portion of 

the State, and comprises the whole or a part of Chambers, Chilton, 

Clay, Cleburne, Coosa, Elmore, Lee, Macon, Randolph, Talladega, 

and Tallapoosa counties. Both granites and gneisses occur within 

this area, and not, so far as known, elsewhere in the State, but no 

quarrying industry has been established and these rocks are commercially almost wholly undeveloped.

According to the geologic map of the State and the accompanying 

chart, published by the State survey in 1894, the rocks of the area are 

grouped into those "fully crystalline" (Archean) and those "imperfectly crystalline," which are of uncertain age, but are referred 

partly to the Algonkian and partly to the Cambrian or later. Of the 

"fully crystalline" rocks, mica-schist is the prevailing type, with 

some gneiss and granite. Hornblendic, pyroxenic, and chry soli tic 

rocks are reported. The "imperfectly crystalline" rocks comprise 

an unknown thickness of quartzites, conglomerates, and clayey and

sandy shales.

THE GRANITES.

«. Granite in considerable quantity, and of good quality occurs in a 

few localities in the crystalline area of Alabama, but no regular quarries have been opened. It is reported in a position favorable for quarrying at different points in Lee, Tallapoosa, Chambers, Randolph, 

Elmore, Chilton, Coosa, Cleburne, and Clay counties.

268 .' 
GRANITES OF ALABAMA. 269

The granite outcrops in low.domelike masses of naked rock, some 

of them 200 acres or more in extent, locally called "flat rocks." 

According to Smith and McCalley,0 the largest of these flat-rock 

areas lie near Almond, Blakes Ferry, Kock Mills, and Wedowee, in 

Randolph County; near Mill town, in Chambers County; and southwest of Roxana and along Sougahatchee Creek, in Lee County. 

Smaller exposures of granite are reported from each of the other 

counties hi the crystalline area.

Gneisses are associated with the massive granites and in places 

both rocks yield desirable stone for building and other purposes. 

The^factories, dams, and bridge piers at Tallassee and vicinity were 

constructed of the gneissoid granite, which is exposed along Tallapoosa River in this locality. Smith and McCalley 6 say that some 

granite has been quarried and used locally about Wedowee, in Randolph County, and at Kockford and other places in Coosa County.

Rough stone was quarried in many of the counties in the crystalline 

area traversed by the Central of Georgia Railroad, and used in the 

construction of the culverts and bridge foundations along the road. 

The small amount of granite and gneiss thus far quarried in Alabama has been consumed entirely by the local trade, which has been 

very slight. Should a demand arise for this kind of stone favorable 

quarry sites could be obtained and the stone developed. The most 

promising areas of granite in Alabama are remote from lines of transportation, a fact which, taken in connection with the meager demand 

for granite, which is readily supplied from Georgia, is unfavorable to 

development of the areas.

a Smith, E. A., and McCalley, Henry, Index to Uio Mineral Resources of Alabama: Alabama Gool. 

Survey, 1904, p. C7-. 

6 Idem, p. 67.
APPENDIX.

STATISTICS OF PRODUCTION.

The following tables show the production of granite in the -area 

covered by this report, by States and uses, for the years 1905, 1906, 

1907, and 1908:°

Production of granite in southeastern Atlantic States, 1905-1908.

1905.

State.

North Carolina. .... 

South Carolina. ....

Building stone.

Rough.

$89,350 

233,716 

75, 125 

18,989 

31,224

448, 404

Dressed.

$101,375 

125, 177 

228, 726 

40, 670 

28, 950

524, 898

Monumental stone.

Rough.

$50,038 

38,860 

5,969 

29, 740 

10, 415

135,022

Dressed.

$25 

4,600 

3,142 

14, 250 

37, 180

59, 197

Paving blocks.

Number.

7,946,000 

869,000 

1, 139, 675 

348, 500 

913, 440

11,216,615

Value.

$296, 750 

38, 900 

48, 234 

9,604 

19,220

412, 708

Curbing.

$246,543 

21,742 

70, 535 

14, 197 

8,948

361,965

Flagging.

$2, 310 

7,419 

3,773 

1,178 

. 2, 550

17, 230

State.

North Carolina..... 

South Carolina..... 

Virginia............

Crushed stone.

Road making.

$7,300 

133, 599 

27, 736 

900 

21, 175

190, 710

Railway 

ballast.

877,717 

8,046 

56,574 

28,876 

69,360

240, 573

Concrete.

$62, 723 

212,592 

34, 161 

70,392 

166, 364

546, 232

Rubble.

$29,314 

102, 733 

6,311 

10, C30 

28,961

177, 949

Riprap.

82,996 

2,842 

1,901 

27, 236

34, 975

Other.

$7,722 

26, 668 

1,450 

55,957 

807

92,604

Total.

$971,207 

957, 048 

564,578 

297, 284 

452, 390

3,242,507

1906.

State.

North Carolina. .... 

South Carolina. ....

Building stone.

Rough.

S109, 215 

211,524 

62, 059 

26,910 

18, 158

427,866

Dressed.

$26, 350 

113, 693 

289, 705 

8,564

438, 312

Monumental stone.

Rough.

$56,010 

80, 780 

17,477 

35, 690 

15, 804

205,761

Dressed.

$1,730 

5,733

16, 936

24, 399

Paving blocks.

Number.

3,927,500 

1,126,082 

974,330 

348,615 

1,385,000

7,761,527

Value.

$123,211 

51,539 

33,428 

11,340 

29,536

249, 154

Curbing.

$189,524 

27, 745 

124,499 

45,605 

14, 339

401,712

Flagging.

$750 

3,788 

3,762 

10,700 

1,216

20,216

a Mineral Resources U. S. for 1905 to 1908, U. S. Geol. Survey.

270
APPENDIX. 271

Production of granite in southeastern Atlantic States, 1905-1908 Continued.

1906.

State.

North Carolina. 

South Carolina.

Crushed stone.

Road making.

$19,400 

125, 055 

18,091 

0,825 

34,981

205,552

Railway 

ballast.

$150, 090 

5,803 

134, 800 

11,790 

04,380

307,475

Concrete.

$81,400 

171,809 

00, 702 

50, 890 

85,077

456, 004

Rubble.

§27,515 

52,503 

5,088 

0,065 

28, 477

120,908

Riprap.

$7,000 

4,290 

4,140 

750 

31, 790

47, 970

Other.

$1,250 

32, 902 

18, .103 

20, 257 

200

78,712

Total.

8792, 315 

883,881 

778,847 

247,998 

340, 900

3,043,941

1907.

State.

Georgia........

Maryland......

North Carolina. 

South Carolina. 

Virginia........

Building stone.

Rough. Dressed.

SS9,075 

107,094

50,062 

9,425

19,350

276,206

$76,252 

55,781

319.821

900

13,275

400,029

Monumental stone.

Rough. Dressed.

$31,100

13,057

16,010

50,515

8,039

119,321

$1,000

8,928

41,120

9,787

60,835

Paving blocks.

Number. Value.

5,410,000

901,225

1,115,859

239,086

085,100

8,351,270

$151,181

50,585

05,379

5,253

18,072

290,470

Curbing.

$215,758

23,279

03,001

18,491

6,000

326,589

Flagging.

$5,515

13,400

4,236

25

23,182

State.

Crushed stone.

Road makingRailway 

ballast. Concrete.

Rubble. Riprap. Other. Total.

Georgia.........

Maryland.......

North Carolina. 

South Carolina. 

Virginia........

$25,000

282,310

53,939

25,887

59,937

$152,297

41,266

175,847

17

50,804

$60,896 

490,378 

106,497 

4,500 

167,960

820,954

77,901

6,823

13,939

16,350

$925

7,266

2,941

25

28,852

$22,050

5,302

740

400

$858,003

1,183,753

900,470

129,377

398,426

447,073 420,231 830,231 141,907 40,009 28,492 3,476,635

1908.

State.

Building stone.

Rough. Dressed.

Monumental stone.

Rough. Dressed.

Paving blocks.

Number. Value.

Curbing. Flagging.

Georgia........

Maryland......

North Carolina. 

South Carolina. 

Virginia........

$60,850 

119,094 

109,919 

12,699 

20,709

$125,350 

48,407 

144,201 

12,012 

11,500

$27,450

0,824

29,822

52,565

12,664

$9,500 

3,273 

46,834 

18,697 

22,303

4,735,770

092,538

3,079,745

351,250

358,004

$135,510 

71,316 

122,488 

12,277 

10,173

$346,383

20,003

99,070

11,070

0,130

$36,000

3,869

8,258

100

329,331 341,530 129,325 100,007 351,764 489,250 48,227

State.

Georgia.........

Maryland.......

North Carolina. 

South Carolina. 

Virginia........

Crushed stone.

Road making.

$2,500 

206,505 

114,474 

30,300 

21,670

Railway 

ballast.

$9,543 

32,923 

33,612 

27,500 

71,704

Concrete.

$50,518 

143,838 

27,333 

35,000 

102,930

Rubble.

$119,516

60,359

4,933

9,475

18,270

375,449 175,282 359,025 212,553 134,801 09,200 3,110,950

Riprap.

$36,000

7,751

730

73,984

16,336

Other.

$11,712

32,280

22,538

1,595

1,075

Total.

$970,832 

762,442 

764,272 

297,874 

321,530

38971° Bull. 426 10 18
BIBLIOGRAPHY.

The following list comprises only'the papers and reports that have 

special bearing on the granites of the region treated in this bulletin. 

Papers and reports treating of some purely geologic aspect of the 

whole or a part of the region, or of granites in other areas, are referred 

to in their proper places in the text.

BASCOM, F. The geology of the crystalline rocks of Cecil County (Maryland). Maryland Geol. Survey, Cecil County, 1902, pp. 83-148. 

BRADLEY, F. H. On unakyte, an epidotic rock from the Unaka Range. Am. Jour.

Sci., 3d ser., vol. 7, 1874, pp. 519-520. 

CLARK, W. B., and MATHEWS, E. B., with the collaboration of others. Report on the

physical features of Maryland'. Maryland Geol. Survey, 1906, pt. 1, pp. 93-118,

171-176. 

DARTON, N. H., and KEITH, ARTHUR. Washington folio (No. 70), Geol. Atlas U. S.,

U. S. Geol. Survey, 1901. 

GILLMORE, Q. A. Report on the compressive strength, specific gravity, and ratio of

absorption of the building stones in the United States. Rept. Chief Eng., U. S.

Army, pt. 2, pp. 819-850; New York, Van Nostrand, 1876, 37 pp. 

GRATON, L. C., and LINDGREN, W. Reconnaissance of some gold and tin deposits

of the southern Appalachians. Bull. No. 293, U. S. Geol. Survey, 1906, 134 pp. 

GRIMSLEY, G. P. The granites of Cecil County, in northeastern Maryland. Jour.

Cincinnati Soc. Nat. Hist., vol. 17, 1894, pp. 59-67, 78-114. 

HOBBS, W. H. On the rocks occurring in the neighborhood of Ilchester, Howard

County, Maryland; being a detailed study of the area comprised in sheet No. 16

of the Johns Hopkins University maps. Johns Hopkins Univ. Circ. No. 65) 1888,

pp. 69-70. 

 On the paragenesis of allanite and epidote as rock-forming minerals. Am.

Jour. Sci., 3d ser., vol. 38, 1889, pp. 223-228.,

New occurrence of parallel intergrowths of the minerals allanite and epidote.

Am. Geologist, vol. 12, 1893, pp. 218-219.

HUNTINGTON, J. H., MoNROE, C. E., and SINGLETON, H. K. Descriptions of quarries 

and of quarry regions. Tenth Census, Washington, 1884, vol. 10, pp. 175-179.

KEITH, ARTHUR. Geology of the Catoctin belt. Fourteenth Ann. Rept. U. S. Geol. 

, Survey, pt. 2, 1894, pp. 285-395.

 Harpers Ferry folio (No ; 10.), 1894; Greeneville folio (No. 118), 1895; Cranberry folio (No. 90), 1903; Asheville folio (No. 116), 1904; Mount Mitchell folio 

(No. 124), 1905; Nantahala folio (No. 143), 1907; Pisgah folio (No. 147), 1907; 

Roan Mountain folio (No. 152), 1907; Geol. Atlas U. S.

KEMP, J. F. Granites of southern Rhode Island and Connecticut, with observations 

on Atlantic Coast granites in general. Bull. Geol. Soc. America, vol. 10, 1899, 

pp. 378-382.

KERR, W. C. The geology of North Carolina, vol. 1, 1875, 325 + 120 pp. For building 

stones see especially pp. 302 et seq.

272 .
BIBLIOGEAPHY. 273

KERK, W. C. and W. H. Description of quarries and quarry regions, North Carolina.

Tenth Census, vol. 10, 1884, pp. 181-186; especially pp. 182-185. 

KEYES, C. E. Some American eruptive granites. Proc. Iowa Acad. Sci., vol. 1,

pt. 3, 1893, pp. 24-26.

 Surface disintegration of granitic masses. Proc. Iowa Acad. Sci., vol. 1, 

pt. 3,-1893, pp. 22-24.

 Some Maryland granites and their origin. Bull. Geol. Soc. America, vol. 4, 

1893, pp. 299-304.

 Epidote as a primary component of eruptive rocks. Bull. Geol. Soc. America, vol. 4, 1893, pp. 305-312.

 Secular decay of granitic rocks. Proc. Iowa Acad. Sci., vol. 2,1895, pp. 27-31.

 Acidic eruptives of northeastern Maryland. Am. Geologist, vol. 15, 1895,

pp. 39-46.

 The origin and relations of central Maryland granites, with an introduction 

by G. H. Williams. Fifteenth Ann. Bept. U. S. Geol. Survey, 1895, pp. 685-740.

 Central Maryland granites. Stone, vol. 13, 1896, pp. 421-428, 527-531;

vol. 14, 1897, pp. 20-24, 126-129, 226-228. 

LEWIS, J. V. Notes on building and ornamental stones. First Bienn. Rept. State

Geologist, North Carolina Geol. Survey, 1893, pp. 57-107. For granites and

gneisses see especially pp. 75-95. 

MATHEWS, E. B. An account of the character and distribution of Maryland building

stones, together with a history of the quarrying industry. Maryland Geol. Survey,

vol. 2, 1898, pp. 125-241. 

MERRILL, G. P. Report on the building stones of the United States, and statistics of

the quarry industry for 1880. Tenth Census, vol. 10, 1884.

 The collection of building and ornamental stones in the United States 

National Museum; a handbook and catalogue. Ann. Rept. Smithsonian Inst. 

for 1886, pt. 2, 1889, pp. 277-648.

 Disintegration of the granite rocks of the District of Columbia. Bull. Geol. 

Soc. America, vol. 6, 1895, pp. 321-332.

 Weathering of micaceous gneiss in Albemarle County, Virginia. Bull. Geol. 

Soc. America, vol. 8, 1897, pp. 157-168.

 The physical, chemical, and economic properties of building stones. Maryland Geol. Survey, vol. 2, 1898, pp. 47-123.'

 Stones for building and decoration, 3d ed., New York, 1903, xi + 551 pages. 

Granites of Georgia, pp. 55-56; of Maryland, pp. 66-68; of North Carolina, pp. 

79-81; of South Carolina, p. 82; of Tennessee, pp. 82-83; of Virginia, pp. 85-86.

 Stone (granite). Twelfth Census Spec. Repts. on Mines and Quarries, 1905. 

Rocks, rock weathering, and soils, 2d ed., New York, 1906, ix -}- 400 pages.

OWEN, D. D. Report on the Baltimore County (Maryland) quarries. S. Doc. No. 23,

30th Gong., 1st sess., pp. 25-32. 

PHALEN, W. C. A new occurrence of unakite. Smithsonian Misc. Coll., vol. 45,1904,

pp. 306-316.' 

PRATT, J. H. The mining industry in North Carolina for 1901, 1902, 1903, 1904, and

1905. Econ. Papers, Geol. Survey, North Carolina. 

PURINGTON, C. W. Geological and topographical features of the region about Atlanta,

Ga. Am. Geologist, vol. 14,1894, pp. 105-108. 

SLOAN, EARLE. A catalogue of the mineral localities of South Carolina. Bull. Geol.

Survey, South Carolina, ser. 4, No. 2, 1908, 505 pp. Granites, pp. 167-225. 

SMITH, E. A., and assistants. Geological map of Alabama; chart to accompany geological map of Alabama. Geol. Survey, Alabama, 1894. 

SMITH, E. A., and MCCALLEY, HENRY. Index to the mineral resources of Alabama,

with map and illustrations. Geol. Survey, Alabama, 1904, p. 67.
274 GRANITES OF SOUTHEASTERN ATLANTIC STATES.

WATSON, T. L. On the origin of phenocrysts in the porphyritic granites of Georgia. 

Jour. Geology, vol. 9, 1901, pp. 97-122.

 The granitic rocks of Georgia and their relationships. Am. Geologist, vol. 27, 

1901, p-j9. 199-225.

 Weathering of granitic rocks of Georgia. Bull. Geol. Soc. America, vol. 12,

1901. pp. 93-108.

 A preliminary report on the granites and gneisses of Georgia. Bull. Geol. 

Survey, Georgia, No. 9-A, 1902, 367 pp.

 On the occurrence of aplite, pegmatite, and tourmaline bunches in the Stone 

Mountain granite of Georgia. Jour. Geol., vol. 10, 1902, pp. 186-193.

 On the occurrence of uranophane in Georgia. Am. Jour. Sci., 4th ser., vol. 13,

1902. pp. 464-466.

 Granites of North Carolina. Jour. Geol., vol. 12, 1904, pp. 373-407.

 .Lithological characters of the Virginia granites. Bull. Geol. Soc. America, 

vol. 17, 1906, pp. 523-540.

 Occurrence of unakite in a new locality in Virginia. Am. Jour. Sci., 4th ser., 

vol. 22, 1906. p. 248.

 Mineral resources of Virginia. Virginia Jamestown Expo. Comrn., 1907, 

xxxii + 618 pp. Granites and gneisses, pp. 17-35.

 Petrology of the South Carolina granites. Jour. Geology, vol. 17, 1909, pp.

' 730-751. 

WATSON, T. L., and LANEY F. B., in collaboration with MERRILL, G. P. Building

and ornamental stones of North Carolina. Bull. North Carolina Geol. Survey

No. 2, 1906, 283 pp. Granites and gneisses, pp. 11-187. 

WILLIAMS, G. H. Petrography and structure of the Piedmont Plateau in Maryland.

Bull. Geol. Soc. America, vol. .2, 1891, pp. 301-318. 

 The general relations of the granitic rocks in the middle Atlantic Piedmont

Plateau (introduction to Origin of central Maryland granites), by C. R. Keyes,

Fifteenth Ann. Kept. TJ. S. Geol. Survey, 1895, pp. 657-684. 

WOLFF, J. E. Details regarding quarries (granite). Tenth Census, vol. 10, 1884.
INDEX.

Absorption tests of granites, results of. 

Accessory minerals, names of..........

Acknowledgments to those aiding.....

Acworth, Ga., granite near............

Page.

48 

17 

15

. 208 

Adams quarry, Ga., description of......... 226-227

Akerite, analysis of.......................... 78

Alabama, crystalline area of, description of.. 268 

Alabama granites, occurrence of........... 268-209

Anderson quarry, S. C., description of..... 187-188

dikes at................................. 179

granite at, analyses of................... 187

sections in, figures showing.............. 188

Annandale, Va., granite near.............. 109-110

quarry near............................. 110

Appalachians, description of................. 37-38

granites of............................... 38

Appling, Ga., granite near................. 249-250

granite near, analysis of.................. 240

Arabia Mountain quarries, Ga., description

of.............................. 255-256

view in.................................. 256

Asheville quadrangle, rocks of............... 154

Athens area, Ga., granite of................ 260-267

granite of, analyses of................. 252j 267

Atherton quarry, Md., description of........ 59

Atkinson quarry, Md., location of........... 67

Atlanta, Ga., granite near. ................ . .if 235

granite near, analysis of.................. 240

B.

Baldwin, Md., granite of................... 65

Balfour Quarry Co.'s quarries, N. C., description of........................... 141

Basic dikes, occurrence and character of..... 28-29

Batesburg, S. C., granite near................ _ 201

granite near, analyses of........... 174, .175,201

Bates quarry, S. C., description of........... 200

Baxter quarry, S. C., description of.......... 196

Beech granite, occurrence and character of. 154,150 

Belmont, N. C., granite at................... 134

Belmont Springs, N. C., granite at......... 135-136

Benjamin quarry, S. C., granite at........... 190

Benson, Md., granite of...................... 05

Beverly station, S. C., granite at and near... 178

granite at and near, analysis of.......... 175

view of............................. 192

Beverly quarry, description of............ 197-198

granite of, analysis of.................... 197

view in................................. 192

Biddell quarry, N. C., description of........ 144

Page.

Black granites, exclusion of................. 15

Blair, S. C., granite near, analysis of......... 175

Blair quarry, S. C., description of......... 188-189

Blowing Rock gneiss, occurrence and character of.......................... 154,156

Blue Ridge region, Va., granites of........ 110-112

granites of. Sec also Unakite. 

Bordeaux quarry, S. C., description of...... 184

Breed quarry, N. C., description of.... 143-144,167

Brinkley Place-Holders Mill area, Ga., granite of..................... 238,243-244

Broad Branch area, D. C., granite of........ 44

granite of, analysis of.................... 42

Sec also Garrett Park. 

Brookville area, Md., granite of............. 65

granite of, analysis of.................... 42

Sec also Garrett Park. Brown and Deadwyler quarry, Ga., description of.......................... 223

Brown Summit area, N. C., granite of....... 146

Bryson, N. C., granite near, view of......... 118

Burlington area, N. C., granites of......... 147-148

Bush quarry, Ga., description of.......... 259-260

Cabin John Bridge, Md., granite near....... 65

granite near, analysis of................. 42

See also Garrett Park.

Camak, Ga., granite dike near, analysis of.... 28 

Carlisle, S. C., granite near............... 202-203

granite near, analysis of................. 174

. Carlton, Ga., granite near................. 221,226

Carmichael quarry, Ga., description of...... 230

granite of, analysis of.................... 229

Carolina gneiss, occurrence and character of. 154-155 

Cartwright & Davis quarry, description of. 107-108

granite of.............................. 83,107

section in, figure showing............... 107

Casparis Stone Co.'s quarry, S. C., description of........................ 199-195

dikes at................................. 179

Chain Bridge, D. C., granite near, analysis of. 42 

Chapel Hill, N. C., granite near........... 132-133

Charley Rocker quarry, Ga., description of.. 246 

Charlotte area, N. C., leopardite near, views of. 136

quarries in............................ 135-136

Charlotte City quarry, N. C., description of.. 135 

Childs quarry, Ga., description of........... 223

Chupp (J. L.) quarries, Ga, description of... 256 

Clark, W. B., and Mathews, E. B., on Maryland gneiss...................... 06-67

275
276 INDEX.

Page. 

Cleyburn, S. C., granite near................ 191

Clouds Creek, S. C., granite on, analysis of. 174,201 

Clover area, N. C., granite of............... 203-204

granite of, analysis of.................... 174

Coastal Plain, description.of................. 34-35

granites of............................... 35

Coggins quarry, Ga., description of........ 221-222

granite of, analysis of.................... 222

Cold Point, S. C., granite at, analysis of..... 174

Cold Point Granite Co.'s quarry, S. C., description of.................... 193-194

Cole quarry, description of.................. 231

granite of, analyses of.................. 229,231

Collins & Venable quarry, Ga., description of. 222 

Collinsville Mountain quarries, Ga., description of........................... 250

Columbia, S. C., granite near.......... 194,198-199

granite near, analysis of................. 175

Composition of granite, nature of............ 16-19

Compressed air, use of, in quarrying......... 151

Concord, N. C., granite at and near. 137,105,107-108

granite at and near, view of.............. 140

Consolidated Granite Co.'s quarries, N. C.,

description of.................. 141-142

Contentnea Creek area, N. C., granites of..... 122

Conyers, Ga., granite near............. 253,255,261

See also Lithonia-Conyers-Lawrenceville. 

Cook quarry, Va., description of..:.-......... 89-90

view of.................................. 80

Cooper quarry, Ga., granite of............... 257

Covington area, Ga., granite of............... 206

granite of, analyses of.................. 252,206

Coweta, Ga., granite near.................... 241

Cowherd quarries, Va., description of...... 112-113

section in, figure showing............... 113

Cranberry granite, occurrence and character

of......................... 154,155-150

Cranberry quadrangle, N. C., rocks of....... 154

Crawford, Ga., granite near.................. 221

Crossley quarry, Ga., description of.......... 257

granite of, analyses of.................... 257

Curley-Schwind quarry, Md., location of.... 67

D. 

Dale, T. N., on granites..................... 13

on rift and grain......................... 22-23

Davidson, N. C., granite of.................. 116

Davidson area, N. C., granite of............ 136-137

Deadwyler quarry, Ga., description of....... 222

Definition of granite......................... 15,16

Diamond Blue Granite Co.'s quarry, Ga., description of..................... 223-224

granite from, analysis of................. 224

Dikes, occurrence and character of........... 25-29

See also particular States. 

District of Columbia granites, analyses of.... 42

weathering of............................ 33

Donald quarry, Va., description of.......... 96-97

section in, figure showing................ 86

views in................................. 80

Dorsey Run area, Md., description of........ 02

granite dike in, analysis of.............. 28

granite of................. 41,42,44,40,47,62-63

analyses of........................ 42,44,47

quarries of............................... .63

Dunns Mountain area, N. C., description

of. ............................ 137-138

Page.

Dunns Mountain area, N. C., granite of...... 116,

121,138-139 

granite of, analysis of.................... 117

quarries of.............................. 138-143

DunnsMountain Granite Co.'s quarries, N. C.,

description of.................. 139-140

E.

Eatonton, Ga., granite near................. 237

Echols Mill, Ga., granite near ............ 227-228

granite near, analysis of................. 225

Echols Mill, Ga. See Elberton-Echols Mill. 

Edgefield quarry, S. C., description of....... 185

Elberton-Echols Mill area, Ga., description

Of............................. 224-225

granite of................................ 225

map of.................................. 219

quarries of............................. 225-228

Ellicott City area, Md., description of....... 51

granite of....................... 41,45,47,50,51

quarries of............................... 51-53

view of.............................. 52

Elm City area, N. C., granite of........... 116,123

Entrekin quarry, S. C., description of........ 194

Etheridge quarry, Ga., description of...... 222-223

European granites, analyses of............... 18

Excelsior quarry, S. C., description of..... 191-192

granite of and near.................... 192-193

analysis of........................... 192

F. '

Fairburn-Newnan-Greenville area, Ga., description of...................... 228

granite of.............................. 228-229

map of.................................. 233

quarries of............................. 230-232

Faith, N. C., quarry near, view in........... 142

Falls Church area, Va., granite of. 73,77,84,108-109 

quarry near............................. 109

Feldspar, occurrence of, in granite........... 16,18

Field work, extent of........................ 13

Filbert area, S. C., granite near.............. 205

granite near, analysis of................. 174

Flatrock, S. C., granite near, analysis of..... 174

Flatrock quarry, S. C., description of........ 203

Flat Rock area, Ga., granite of............ 264-265

granite of, analysis of.................... 265

Flat Shoals-area, Ga., granite of............. 264

granite of, analysis of.................... 264

Fortson, Ga., granite of, analysis of.......... 225

Fox Rock quarry, Md., description of....... 58

Franklin, Ga., granite near.................. 265

Franklinton, N. C., granite near............. 164

Franklinville area, Md., granite of........... 65

Fredericksburg area, Va., description of..... 106

granite of........................ 71,76-77,106

quarries of........................... 106-108

See also Richmond; Fredericksburg. 

Frenchtown area, Md., description of........ 01

granite of................... 41,43,46,47,51,61

quarries of............................. 61-62

Friendship area, N. C., granite of.......... 146,169

Gaither quarry, Md., description of......... 51-53

view of.................................. 52
INDEX. 277

Page. 

Garrett Park area, Md., description of....... 04

granite of...................... 41, 40, 47, G4-G5

quarries of............................. 65

Gastonia, N. C., granite at and near. 134,164,165-160 

Georgia, aplite in.......................... 215

aplite in, analysis of................... 215-210

Campbell, Coweta, Fayette counties,

granite of..................... 241-242

granite of, analyses of................ 240

Fulton County, granite of............... 243

Greene County, granite of............. 248-249

Jackson County, granite of............ 260-201

map of, showing granite................. 210

pegmatite of ......................'...... 215

Pike County, granite of.............. 242-243

piedmont region of, geology of........ 207-239

map of.............................. 238

topography of.................... 200-207

Putnam County, granite of.............. 237

granite of, analysis of................ 237

Spanieling County, granite of............ 237

granite of, analysis of................ 237

Warren County, granite of............ 243-244

Georgia granites,absorption by....212,220,225,229

analyses of............. 19,211,220,225,229,235

chemical composition of................. 211,

220,225,229,230-235 

dikes in........... 25,20,27,28,208-209,214-210

analyses of........................ 215-210

distribution of......................... 209-210

map showing........................ 210

even-grained type of................... 217-218

occurrence of...................... 218-237

field relations of....................... 208-210

inclusions in............................. 31

joints in............................ 24,213-214

minerals in............................. 31,212

porphyritic type of, absorption by....... 241

analyses of.......................... 240

chemical composition of........... 240-241

occurrence of...................... 241-250

phenocrysts in....................... 210

strength of.......................... 241

weight of............................ 241

quarries of............................. 221-224

quarrying of...:......................... 210

slickensides in........................... 214

specific gravity of........................ 212

Strength of........................ 213,221,235

structure of............................ 213-210

varieties of.............................. 217

veins in..'............................... 210

views of................................. 230

weathering of............................ 33-34

view of.............................. 58

weight of................................ 212

Georgia granite gneiss, absorption by........ 252

analyses of.............................. 252

chemical composition of............... 251-252

description of.......................... 250-251

distribution of........................... 251

specific gravity of........................ 252

Strength of............................. 252-253

views of............................... 252,250

weight of................................ 252

Georgia Quincy Granite Co's. quarry, Ga.,

description of.................... 240

Page.

Georgia Railroad quarry, Ga., description of. 257 

Gillmore,Q. A., on Maryland granites....... 49

Glen Echo,Md., quarries near, view in...... 42

Gneiss, inclusion of, view of................. 98

Gneiss, views of........................ 80,252,250

See also particular States. 

Goss, Ga., granite near...................... 220

Grain,nature of............................. 22-23

Granite, analyses of......................... 18-19

bibliography of........................ 272-274

chemical composition of................. 18-19

classification of.......................... 22

color of.................................. 20

composition of........................... 10-19

decay of................................. 32-34

views of............................. 58

definition of............................. 15,10

distribution of........................... 34-38

map showing ....................... 14

See also particular States. 

hardness of.............................. 2.1

inclusions in............................. 30-31

view of.............................. 98

joints in. See Joints.

knots in................................. 30

literature on........................... 272-274

mineral composition of.................. 10-18

physical properties of.................... 20-21

production of....................... 13.270-271

sheeting in. See Sheets.

strength of............................... 21

variations in............................. 25-32

varieties of............................... 22

weathering of............................ 32-34

views of............................. 58

weight of................................ 20-21

See also particular States. 

Granite-aplite dikes, occurrence and character

Of................................ 25

Granite Development Company's quarries,

Va., description of............... 97

Granite dikes, analyses of.................... 28

occurrence and character of.............. 27-28

Grayson, Ga., granite near................... 255

Great Falls, Md., granite near............... 49

granite near, analysis of.................. 42

Greensboro, Ga., granite near................ 248

granite near, analysis of.................. 240

Greensboro, N. C., granite of and near..... 147,169

Greenville, Ga., granite near................. 230

See also Fairburn - Newnan - Greenville

area. 

Greenville, S. C., granite near................ 189

Greenwood, S. C.,granite near............... 190

granite near, analysis of.................. 174

Greystone area, N. C., granite of............. 110,

125,12C-128,164

Greystone Granite and Construction Company's quarry, description of.... 127

Griffin, Ga., granite near..................... 237

Guilford, Md., granite at, view of............ 60

Guilford and Waltcrsville Granite Company's quarries, Md"., description 

of............................ 55,57-58

views of................................. 52, CO
INDEX.

Page. 

Guilford area, Md., description of. ........... 54

granite of .................... 41, 43, 44, 47, 50, 54

analysis of. .......................... 42

quarries of. .............................. 54-56

Guilford Granite and Stone Co.'s quarry,

description of ................... 56

G wynns Falls area, Md. , gneiss of ........... 51

quarries of. .............................. 68-69

H.

Hanckel quarry, S. C., description of ...... 184-185

Harris mine, Ga., pegmatite in, view of.. .... 118

Hawkins quarry, Va., description of. ........ 97

Hayes, C. W., on Georgia Piedmont. ........ 207

Hazel Run area, Va., description of. ......... 106

granite of. .................... 71, 73, 70, 106-107

Heath Springs, S. C., granite near.... 160-191,193

granite near, analyses of. .......... 174, 175,191

view of .............................. 192

Heggie Rock, Ga., granite of.. ............... 210

granite of, analyses of.. ................ 211, 240

Henderson, N. C., granite at. ................ 125

Henderson granite, occurrence and character

of................-.."......-..... 154,159

Herring Run, Md., gneiss quarries on.. . ..... 69

Hillebrand, W. F., analyses by. ............. 28, 47

Hill quarry, Ga., description of ............ 222, 231

granite of, analysis of .................... 229

Hoffman & Miller quarry, Va., description of 110 

Hornblende, occurrence of, in granite. ....... 17

Hornsboro, S. C., rocks at. .................. 173

Huching, Ga., granite near. ................. 221

granite near, analysis of.... ........'...... 220

Hyalite, occurrence and character of. ........ 31

I.

Ilchester, Md., granite of. ............ 1 ... 41, 42, 52

pegmatite at, view of .................... 44

Inclusions in granite, occurrence and character of............................ 30-31

See also particular States.

204 

146-147

J.

Jackson quarry, S. C., granite of, analysis of 

Jamestown area, N. C., granite of..........

Jenkins quarry, N. C., description of....... 165-1(16

Johnson quarry, Ga., description of........ 257-258

Johnson quarry, S. C., granite of........... 201-202

Joint faces, minerals on...................... 31-32

Joints, nature and cause of................... 23-25

views of.............................. 42,94,96

See also particular Stztes. 

Jones Falls area, Md., gneiss of.............. 50,51

quarries of............................... 67-C8

K.

Keith, Arthur, on Appalachians............. .38

on Blue Ridge granites................ 110-111

on Max Patch granite................... 157

Kenbridge quarry, Va., description of....... 113

Keyes, C. R., on Maryland granites.... 44,46,47,59

Keystone Granite Co.'s quarry, S. C., description of...................... 202

Knots, occurrence and character of........... 30

See also particular Sta'es. 

Krimm quarry, Va., description of.......... 98

L. Page.

Landers area, N. C., granite of............ 107-168

Lassiter quarries, Va., description of..........90-91

Lawrenceville, Ga., granite near....... 253,255,260

See also Lithonia-Conyers-Lawrenceville. 

Lawrenceville quarry, Ga., description of.... 260

'Lays'Mill, S. C., granite near.............. 196-197

Leiper-Davis quarry, S. C., description of.... 189

J^eitzsey quarry, S. C., description of....... 195-196

Leonard quarry, Md., location of............. C8

Leopardite, definition of...................... 15

occurrence of.......................... 135-136

views of................................. 136

Level quarry, S. C., description of........... 196

Lexington, Ga., granite near................. 226

granite near, analysis of................. 220

Lexington, N. C., granite near. 144-145,1C8-169,194 

Lexington area, Ga. See Ogleby-Lexington

area.

Lexington Blue Granite Co.'s quarry, description of...................... 224

Liberty Hill, S. C., granite near........... 190-191

Linch quarry, Ga., description of............ 237

Line Creek, Ga., granite of................... 241

granite of, analysis of.................... 240

Lipscomb quarry, S. C., description of........ 198

Lithonia, Ga., granite near............ 253,254-259

granite near, analysis of................. 252

views of........................... 252,256

Lithonia-Conyers-Lawrenceville area, Ga.... 253

granite of.......................... 251,253-254

quarries of............................. 254-262

rocks of.................................. 210

Loganville, Ga., granite near.............. 255,262

Long Granite Co.'s quarry, Ga., view in..... 58

Louisburg, N. C., granite near............... 125

Luray, Va., granite near.............. 71,73,78,111

Lynchburg area, Va., gneiss of............... 81

'gneiss of, view of........................ 80

M. 

McCalley, H., and Smith, E. A., on Alabama

granites......................... 269

McClenahan Granite Co.'s quarry, Md., description Of...................... 60

view of.................................. 60

McCloy quarry, Va., description of.......... 105

McDaniel quarries, Ga., description of....... 261

McElvaney Shoals, Ga., granite at, analysisof. 252 

McGowan quarry, description of............ 99-100

gneiss of.....................:........... SO, 83

sections in, figures showing.............. SO, 84

views in................................. 96,98

McGranigan quarry, Va., description of...... 97

Mclntosh quarry, Va., description of........ 98-99

Mackin' quarry, Ga., description of.......... 246

McNeely quarry, N. C., description of....... 143

Mallally quarry, Ga., description of.......... 247

Manchester, Va.; granite near, analysis of.... 72

granite near, section of, figure showing... 86 

views of............................. 96,98

Map of South Atlantic States................. 14

Maryland, Baltimore Co., quarries of...... 48,51-53

Howard County, quarries of............. 51,53

pegmatites in............................ 45-46

dikes of, view of...........'.......... 44

feldspar of, analyses of.............. 46

piedmont region in, geology of.......... 39-40
INDEX. 279

Page. 

Maryland gneiss, distribution of.......... 41,00-07

distribution of, map showing............ 40

quarries of........................ 50-51,07-09

tests of.................................. 48

Maryland Granite Co.'s quarry, description of. 54-55 

Maryland granites, absorption of......... 48,49-50

analyses of.............................. 19,42

composition of.......................... 42-43

dikes in........................... 27,28,44-40

distribution of........................... 40-41

map showing........................ 40

freezing tests of......................... 49-50

inclusions in......................... 20,40-47

analysis of........................... 47

joints in................................. 43

knots in................................. 47

minerals in........................:.. 32,41-42

physical tests of......................... 48-50

quarries of.............................. 50-00

distribution of, map showing........ 40

quartz veins in........................... 29,40

schistosity in............................ 44

strength of.............................. 49-50

structure of............................. 43-48

varieties of.............................. 41

views of........................... 44.52,58, CO

weathering of........................... 58

view of.............................. 58

Mathews, E. B., on Maryland granites. 48,50,03,09 

Mathews, E. B., and Clark, W. B., on Maryland gneiss..............'........ 06-07

Max Patch granite, occurrence and character

of.......................... 154,156-157

Merrill, G. P., on Maryland granites......... 48

on Tennessee granites.................... 171

Mica, occurrence of, in granite....... 17,18,175-170

Middendorf quarry, Va., description of..... 97-98,

100,101-102 

section in, figure showing................ 80

Middleburg area, N. C., granite of............ 125

quarries of............................. 128-129

Midlothian, Va., granite near................ 79,85

Milams Gap, Va., granite near........ 73,77-78, 111

granite near, analysis of.................. 78

Milledgeville, Ga., granite near............. 247-248

granite near, analysis of.................. 240

Minerals in granite, nature of................ 10-17

percentage of............................ 17-18

See also particular States. 

Mooresville area, N. C., granite of............ 119,

143-144,104,100-107 

granite of, analysis of.............'....... 117

Morning G lade Church area, N. C., granite of. 130 

Morris & Co. quarry, S. C., description of.. 198-199 

Mount Airy, N. C........................... 150

granite of.............................. 110,148

absorption of........................ 150

analysis of........................... 117

strength of........................... 149

monolith at, view of..................... 150

quarries of............................. 148-151

view of.............................. 148

quarrying at........................... 150-151

Mount Mitchcll quadraugle, rocks of......... 154

Mount Mourne, N. C., granite near.... 164,100-107

Mountville area, Ga. See Odessa-Mountville.

Page. 

Mountville quarry, Ga., description of....... 263

Murdock Mill, Md. See Garrett Park.

N.

Nantahahl quadrangle, rocks of.............. 154

Netherwood quarry, Va., description of...... 95

granite of............................. 75,95-90

sections in, figures showing.............. 83,85

views in................................. 94

Newberry, S. C., granite near.............. 195-196

granite near, analysis of.................. 174

New Greystone quarry, N. C., description

of.............................. 126-127

Newnan, Ga., granite near ................ 230,264

See also Fairburn-Newnan-Greenville 

area.

North Carolina, Allegheny County, granite of. 152 

aplite of................................. 120

Appalachians, granite of............... 153-161

Davidson County, granite of... 144-145,168-109 

Davie County, granite of....... 145,1G4,1C8-1G9

Franklin County, granite of.............. 125

Gaston County, granite of............... 134

Granville County, granite of............. 125

Guilford County, granite of.... 145-147,109-170

leopardite in, view of.................... 136

map of, showing granite................. 116

pegmatite in.............................. 119

feldspars of, analyses of.............. 170

Vance County, granite of.............. 125-129

Wilkes County, granite of............... .152

North Carolina gneiss, occurrence and character of.......................... 152-153

North Carolina granif.;s, analyses of......... 117

belts of..............1................... 124

descriptions of............. 124,132-134,148

composition of......................... 110-117

dikes in................... 25,20,27,28,118-121

distribution of........................... 115

map showing........................ 116

even-grained type of................... 121-161

inclusions in............................. 31

joints in........................ 24,117,120-121

knote in................................ 30,117

minerals of.............................. 110

porphyritic type of.................... 161-170

quarries in............................. 121-170

quartz veins in......................... 29,1^0

structure of............................ 117-121

variaties of ............................. 115-110

distribution of....................... 121

views of........... 118,130,140,142,144,148,150

North Carolina Granite Corporation's quarries, N. C., description of...... 148-151

0.

Oders quarry, N. C., description of.......... 135

Odessa-Mountville area, Ga., description of.. 262

granite of................................ 202

quarries of............................. 203-267

Odessa quarry, Ga., description of........... 263

Oglesby, Ga., granite near................... 221

granite near, analysis of.................. 220

view of.............................. 58
280 INDEX.

Page.

Oglesby-Lexington area, Ga., description of.. 218 

granite of.............................. 218-221

map of.................................. 219

1 quarries of............................. 221-224

Old Dominion Granite Co.'s quarries, Va.,

description of............ 97-98,101-102

Old Dominion Iron and Nail Works quarry,

Va., description of............... 102

Old Greystone quarry, N. C., description of.. 120 

Old Rocker quarry, Ga., description of...... 247

Orange Grove, Md., pegmatite at, view of... 44 

Orbicular granite, definition of............... 15

occurrence of............................ 145

view of............... \................. 144

Oro quarry,' S. C., description of............. 185

Overby quarry, Ga., description of.......... 232

granite of, analyses of.................. 229,232

Oxford, N. C., granite near.................. 125

Pacolet, S. C., granite near, analysis of....... 175

Pacolet Granite Co.'s quarry, S. C., granite

of............................. 201-202

Palmetto, Ga., granite near................. 241

Peddicord quarry, Md., location of.......... 07

Pegmatite dikes, occurrence and character of.. 20-27

views of................................ 80,118

See also particular States. 

Pendleton, S. C., granite near, analysis of.... 175

Penny quarry, Md., quarry of............... 55-50

Petersburg area, Va., description of......... 88

granite of................................. 89-92

See also Richmond-Petersburg.

quarries of........................... 88,89-92

view of.............................. 80

Petersburg Granite Co.'s quarries, Va., description of...................... 91-92

section in, figure showing................ 91

Petersburg Passenger Co.'s quarry, location of. 92 

Phalen,W.C.,on unakite................... 77

Philadelphia quarries, Va., description of.. 104-105

section at, figure showing................ 104

Phillips Mountain quarries, N. C., description

of............................... 142

view at.................................. 142

Piedmont Plateau, description of............ 35-30

granites of............................... 30-37

section of, figure showing................ 35

Pierce quarry, Ga., description of........... 201

Pine Mountain, Ga., granite of............... 253

view of.................................. 250

Pine Mountain quarries, Ga., description of.. 258 

Piney Mountain, S. C., granite at............ 190

Piney Run, Md., granite of.................. 44

See also Garrett Park. 

Pisgah quadrangle, rocks of................. 154

Porosity, data on............................ 21

Port Deposit area, Md., description of....... 59-C1

granite of............................. 41-52,59

analysis of........................... 42

view of.............................. CO

quarries of.............................. GO

Powell quarry, Ga., description of........... 201

Powlers Mountain quarries, N. C., description

of............................. 142-143

Production, statistics of..................... 13

Q. Page.

Quartz, occurrence of, in granite.......... 1G-17,18

veins of, occurrence and character of...... 29

See also particular States. 

R.

Raleigh area, N. C., granite of, and near... 119,122 

granite of and near, analysis of............ 117

quarries of............................ 129-131

Redan, Ga., granite near.................... 255

Relay area, Md., granite of.................. 50,00

Rice, Va., granite near...................... 112

Richmond area, Va., description of.......... 92

granite of................................ 93

minerals of.......................... 94-95

See also Riehmond-Fredericksburg. 

quarries of......................:. 92-93,95-100

views of.......................... 86,94,90

Riehmond-Fredericksburg area, aplite in..... 85

apophyses in............................ 83

contacts in.............................. 82-83

section showing..................... 83,85

dikes in................................. 8.5-88

section of, figure showing............ 84

gneiss of................................. 80-81

section of, figure showing............ 80

granites of............................... 70

analyses o!.......................... 72

inclusions in......................... 84

joints in............................. 84-85

knots in............................. 84

structure of.......................... 82-88

pegmatite in............................ S0-8s

feldspar in, analyses of. .............. 88

sections of, figures showing..... 84,85,80,87

Richmond Granite Quarrying Co.'s quarry,

Va., description of............... 103

granite of................................ 85

section in, figure showing................ 87

Richmond-Petersburg area, Va.,granites of.. 71,

74-75,84 

granites of, analyses of................... 72

Ridge Summit, N. C., granite near.......... 119

Rift, nature of............................... 22-23

Rion, S. C., granite near................... 180-187

granite near, analysis of........... 174,175,180

Rion quarry, S. C., description of.......... 180-187

views of............................... ISO, 192

Roan gneiss, occurrence and character of... 154,155 

Roaring Fork, N. C., unakite on............. 158

Rock Chapel Mountain quarries, Ga., descrip-

. tion of........................... 259

Rock Creek area, Md. See Garrett Park. 

Rockingham-Wadesboro area, N. C., granite

of............................. 102-104

Rocky Mount area, granite of................ 123

Rolesville-Wyatt area, N. C., granite of...... 131

Ross quarry, S. C., description of............ 194

Rowan Granite Company's quarries, N. C.,

description of..............'.... 140-141

view of.................................. 140

Rowlandsville, Md., granite of............... 41,44

granite of, analysis of...;................ 42

S.

Salisbury, N.C., granite near...... 137-142,104,168

granite near, view of.................. I.. 140
INDEX., 281

Page. 

Sargent, Ga., granite near................... 264

Schwind quarry, Md., location of............ 68

Saxe, Va., granite of......................... 73

Schulenberger Branch, N. C., granite on..... 167

Seaboard Air Line Railway quarry, description of......................... 127-128

Seaboard quarry, Ga., description of........ 223

Sheets, description of........................ 24

view of.................................. 96

Slickensides, description of.................. 25

Sligo Branch, Md. Sec Garrett Park.

Sloan, Earl, on South Carolina............ 172,175

Smith, E. A., and McCalley, H.,on Alabama

granites......................... 269

Smith Branch quarry, S. C., description of.... 199

dikes at................................. 178

Smith quarry, Va., description of.......... 103-104

Snell quarry, Ga., description of............. 260

Snellville, Ga., granite near............ 253,255,260

granite near, analysis of................. 252

South Carolina, analyses of................ 174-175

aplite of............................... 178-179

chemical composition of............... 174-175

crystalline region, description of....... 172-173

Fairfield County, granite of............ 18.5-189

Greenville County, granite of.......... 189-190

Kershaw County, granite of........... 190-191

Lancaster County, granite of........... 191-193

Laurens County, granite of............ 193-194

map of, showing granite............... 172

Oconee County, granite of............. 196-197

pegmatite of............................. 179

feldspar of, analyses of............... 180

Saluda County, granite of................ 200

Union County, granite of.............. 202-203

York County, granite of............... 203-205

South Carolina granites, absorption of....... 182

analyses of.............................. 19

dikes in................... 25,26,27,28,178-183

distribution of........................... 173

map showing........................ 172

inclusions in........................ 31,181-182

joints in............................... 180-181

knots in................................. 181

minerals of............................ 173-174

quartz veins in................ 1......... 180

quarries of............................. 183-205

slickensides in........................... 181

specific gravity of........................ 182

strength of............................ 182-183

varieties of............................ 175-178

views in............................... 186,192

Southern Granite Co.'s quarry, Ga., description of........................ 258-259

granite from, analyses of................ 259

Sparta area, Ga., granite of............ 238,244-247

granite of, analysis of.................... 240

quarries of............................ 246-247

Sparta quarry, Ga., description of......... 246,247

Spears quarry, S. C., description of.......... 196

Specific gravity, data on.................... 20-21

Springhope area, N. C., granite of........... 123

State Test Farm quarry, Va., description of. 112 

Stewart quarry, S. C., description of........ 189

Stone Mountain, Ga., description of......... 210

granite of............................. 210-235

map of.................................. 210

Page. 

Stone Mountain, Ga., minerals at........... 31,211

quarries of............................ 235-237

uranophane from, analysis of............ 31

. views of................................. 236

Stone Mountain, N. C., granite of........... 152

view of................................... 142

Stone Mountain quarries, Ga., view in....... 236

Strother quarry, S. C., description of........ 188

Structure of granite, description of.......... 22-25

See,also particular States.

Summerfleld area, N. C., granite of.....'... 146,169 

Swift & Wilcox quarry, Ga., description of.. 227

granite of, analysis of.................... 227

Sykesville area, Md., granite of........... 44,46,63

granite of, analysis of.................... 42

quarries of.............................. 63

Tarr, R. S., on rift.......................... 22

Tar River, N. C., granite on............... 123,125

Tate & Oliver quarry, Ga., description of.... 227

Tennessee granites, occurrence and character

of............................... 171

Texas area, Md., description of.............. 66

granite of......................... 41,44,50, CO

Texture, description of...................... 19-20

Thornton, W. M., jr., analyses by........... 72

Tidewater Quarry Co.'s quarry, Va., description of.................... 100-101

Tilly quarry, Ga., description of............. 261

Toisnot area, N. C., granite of............. 11C, 123

Trip quarry, Va., description of............. 109

Troutdale, Va., granite near.......... 71,73,78, 111

Tunnel Hill, S. C., granite near............ 196-197

Turner quarry, Ga., description of..... 260,261-262

U.

Unaka Mountains, granite of............ 77-78, 111

Unakite, analysis of......................... 78

definition of............................ 22, 111

occurrence and character of............... 71,

73,77-78,111-112,157-159

See also Virginia. 

Union, S. C., granite near................. 202-203

United States granites, analyses of........... 19

Uranophane, analysis of..................... 31

occurrence of............................ 31

V.

Veins, quartz, occurrence and character of... 29 

Virginia, Alexandria County, gneiss of....... 81-82

aplite in................................. 73

Charlotte County, granite of............. 112

Chesterfield County, quarries of......... 95-102

 Fairfax County, gneiss of............ 81-82,108

quarries of......................... 108-110

Fluvanna County, granite of........... 112-113

Goochland County, granite of.......... 112-113

Henrico County, quarries of........... 103-105

Lunenburg County, quarry in........... 113

map of, showing granites................. 70

Nottoway County, granite in............ 112

Piedmont region, description of......... 70

Prince Edward County, granite in....... 112

Prince William County, quarries in...... 113

unakite in............................... 78

Virginia gneiss, description of................ 79-80
282 INDEX.

Page. 

Virginia granites, analyses of................ 72

composition of........................... 72

distribution of........................... 70-71

map showing........................ 70

dikes in.............................. 25,26,27

inclusions in............................. 31

knots in................................. 30

minerals of.............................. 71

outcrops of.............................. 73

porphyritic type of...................... 78-79

quarries of, descriptions of.............. 88-114

maps showing....................... 70

quartz veins in.......................... 29

structure in. See Richmoncl-Fredericksburg area, 

varieties of.............................. 72-73

views of........................ 80,86,94,96,98

See also particular areas.

W.

Wadesboro-Rockingham area, N. C., granite of.......................... 162-104

Ware Shoals, S. C., granite at, analysis of..... 175

Ware Shoals Manufacturing Co.'s quarry,

S. C., description of.............. 184

Warren Plains, N. C., granite of............. 116

quarry near............................. 132

Warrenton, Ga., granite near................ 237

Warrenton area, N. C., granite of.......... 131-132

Washington, Ga., granite near......'........ 237

Water pressure, use of, in quarrying......... 151

Watson, T. L., analyses by ................ 28,215

Weathering, effects of....................... 32-34

views of................................. 58

Weber quarry, Md., description of.....:.... £3

Page. 

Weller quarry, Md., description of.......... 59

view in................................. 58

Westham quarries, Va., description of....... 99

Whiteside granite, occurrence and character

of............................. 154,160

Whiteside Mountain, N. C., view of......... 118

Whitley quarry, Ga., description of......... 259

Whittle, C. L., on rift and grain............. 22

Whittle quarry, S. C., description of........ 200

Williams, G. H., on Maryland minerals..... 32,

43,44,45,47,64 

Wilson quarry, Ga., description of ......... 259

Winder, Ga., granite near............. 255,259,260

Wingo quarry, Va., description of........... 112

Winnsboro Granite Corporation quarries,

S. C., description of........... 185-188

view of.................................. 186

Winston area, N. C., granite of........ 145,164,169

Winston & Co.'s quarry, Va., description of.. 104 

Wise, N. C., granite near.................. 131-132

Woodleaf area, N. C., granite of...........'.. 143

Woodstock area, Md., description of......... 56-57

granite of................... 41-48,50,52,56-57

analysis of.......................... 42

quarries of............................. 57-59

view of.............................. 52,58

Wray quarry, Va., description of............ 96

view in.................................. 96

Wyatt-Rolesville area, N. C., granite of..... 131

Z.

Zebulon, Ga., granite near.................. 264

analysis of.............................. 240

'O