DEPARTMENT OF THE INTERIOR

UNITED STATES GEOLOGICAL SURVEY

GEORGE OTIS SMITH, DIRECTOR

BULLETIN 420

ECONOMIC GEOLOGY

OF THE

FELDSPAR DEPOSITS OF THE 

UNITED STATES

BY

EDSON S. BASTIN

WASHINGTON

GOVERNMENT PRINTING OFFICE 

1910

CONTENTS.

Page.

Introduction............................................................... 5

Chemical and physical characters......................................... 5

Potash-soda feldspars................................................. 5

Lime-soda feldspars, or plagioclases.................................... 7

Origin and geologic occurrence..................... *...................... 10

Minerals of the feldspar deposits............."............................... 11

Methods of mining ....................................................... 15

Commercial availability of deposits............................... ........ 16

Methods of milling........................................................ 18

Uses..................................................................... 19

Grades and prices ........................................................ 21

Production ............................................................... 22

Localities by States....................................................... 23

Maine............................................................... 23

Androscoggin County............................................. 23

Auburn.............;........................................ 23

Minot ....................................................... 26

Poland ...................................................... 26

Lincoln County .................................................. 27

Edgecomb .......................-...:.....-................. 27

Oxford County........................;.......................... 28

Hebron...................................................... 28

Sagadahoc County.. '...... ........................................ 31

Georgetown.................................................. 31

Topsham .................................................... 33

Massachusetts........................................................ 41

Connecticut, i........................................................ 41

General statement................................................ 41

Hartford County ..... ....................:............ ........... 42

Glastonbury ................................................. 42

Middlesex County................................................ 47

Chatham ....................I............................... 47

Haddam..................................................... 48

, Middletown.................................................. 49

Portland............................................;........ 50

New Haven County............................................... 53

New York ........................................................... 54

Essex County.................................................... 54

Crown Point................................................. 54

Ticonderoga ................................................. 55

Fulton County .......:............................................ 56

Saratoga County.................................................. 57

Corinth.......... 1....,...............................'....... 57

Edinburg.................................................... 58 /

3
4 CONTENTS.

Localities by States Continued. Page. 

New York Continued.

Westchester County........^..................................... 60

General statement............................................ 60

Bedford ..................................................... 60

North Castle................................................. 63

Pennsylvania ........................................................ 63

General statement................................................ 63

Chester County .................................................. 64

London Grove ............................................... 64

New Garden................................................. 66

Newlin ...................................................... 67

West Cain................................................... 67

West Nottingham ............................................ 68

Delaware County................................................. 70

Concord .............................. ..... .................. 70

Middletown ....................'........-.................... 72

Maryland............................................................ 72

Baltimore County ................................................ 72

Howard County.................................................. 75

Cecil County..................................................... 76

Virginia............................................................. 77

Wisconsin ........................................................... 78

Minnesota...........................................:............... 78

Texas ............................................................... 79

Index ............................................................... 83

ILLUSTRATIONS.

PLATE I. Microphotograph of thin section of feldspar from quarry of Goldings

Sons Company, Georgetown, Maine............................ 6

II. A, Highly inclined dike of pegmatite in schists at Pemaquid Point, 

Maine; B, Flat-lying or sill-like dike in pegmatite in bed of 

Androscoggin River,-Auburn-Lewiston, Maine..................' 10

III. Intergrowths of feldspar and quartz.............................. 12

IV. Preliminary geologic map of portions of Maine, showing location of

feldspar quarries and mills..................................... 24

V. A, Crystal of microcline feldspar in Roaring Creek feldspar quarry, 

Connecticut; B, Portion of G. D. Willes feldspar quarry, Topsham, Maine................................................... 38

VI. Preliminary geologic map of a portion of Connecticut, showing location of feldspar quarries and mills.............................. 40

VII. A, Vertical pegmatite dike intruded along fracture plane in granite 

gneiss, East Glastonbury, Conn.; B, Quartz dike cutting pegmatite at Howe quarry, South Glastonbury, Conn.................. 42

VIII. Preliminary geologic map of southeastern Pennsylvania and adjacent 

parts of Delaware and Maryland, showing locations of feldspar 

quarries and mills............................................. 64
ECONOMIC GEOLOGY OF THE FELDSPAR DEPOSITS OF 

THE UNITED STATES.

By EDSON S. BASTIN.

INTRODUCTION.

The present bulletin brings together in a single volume all available 

practical information concerning the commercial feldspar deposits of 

the United States. Scientific problems are discussed only so far as 

they are of commercial importance or so far as the discussion may 

contribute to a general understanding of the deposits.

The feldspar localities of Maine were visited by the writer in the 

summer of 1906, the work being authorized by the United States Geological Survey in cooperation with the Maine State Survey Commission. 

Those of New York, Connecticut, Pennsylvania, and Maryland were 

visited at various times from 1906 to 1909 under the auspices of the 

United States Geological Survey.

CHEMICAL AND PHYSICAL CHARACTERS.

The feldspars are compounds of alumrna and silica with one or more 

of the bases potash, soda, and lime; rarely barium is present. They 

fall into two principal groups, the potash-soda feldspars and the limesoda feldspars, both of which may be present in the same deposit or 

even intergrown in the same crystal.

POTASH-SODA FELDSPARS.

The principal representatives of the potash-soda feldspar group are 

orthoclase and microcline, both of which have the composition 

KAlSi3O8 or K.jO.Al2 03.6Si02 . These two varieties have also the same 

crystal form and are similar in most of their physical properties. For 

commercial purposes they may be regarded as identical, since they 

can not be distinguished from each other with the unaided eye and 

are often associated in the same crystal. The theoretical percentage 

composition of pure orthoclase or microcline is as' follows: Silica 

(Si02 ), 64.7 per cent; alumina (A12 03 ), 18.4 per cent, and potash 

(K2O), 16.9 per cent. Soda may partly or completely replace potash 

in these feldspars. If it is more abundant than the potash the 

feldspar is called anorthoclase.

5
6 FELDSPAR DEPOSITS -OP THE UNITED STATES.

The feldspars of the potash-soda group mined in the United States 

are mostly pale flesh colored to nearly white, though the rock from 

Bedford, N. Y., is reddish and that from near Batchellerville, N. Y., 

is a pearl gray. The potash spars from Norway and from Bedford, 

Ontario, are reddish in color. The cause of the reddish color is not 

definitely known, but in some feldspars it seems to be due to the 

presence of small quantities of finely divided iron oxide. The percentage of iron oxide is smaller, however, in many pink feldspars than 

in those of lighter color. All the pink spars burn perfectly white, and 

if the color is due to the iron, the content is too small to be in the least 

detrimental in pottery manufacture. Fresh feldspar is so hard that 

only with difficulty can it be scratched with a knife blade.

As found in the quarries, the potash-soda feldspars seldom show 

true crystal faces, but when undecomposed break readily into angular 

pieces, bounded in part by smooth cleavage faces. There are three 

directions of cleavage, intersecting at definite angles, which are practically identical for orthoclase and microcline, and change only slightly 

with an increase in the soda content. Only two of the cleavages are 

well defined, arid these invariably intersect approximately at right 

angles. Both of these principal cleavage surfaces show a high luster, 

comparable to that exhibited by a plate of glass, though one cleavage 

face is a trifle less brilliant than the other. The hardness and the two 

lustrous cleavage planes intersecting at an angle of 90° are usually 

sufficient to identify the mineral as belonging to the group of potashsoda feldspars.

Recent experiments have shown that the potash-rich feldspars do 

not have a definite melting point as do metals, for example. Fusion 

tests made on finely powdered microcline in the geological laboratory 

of the Carnegie Institutiona showed that at 1,000° C. traces of sintering were evident; at 1,075° the powder had formed a solid cake; at 

1,150° this cake had softened somewhat, and at 1,300° C. it had 

become a viscous liquid, which could be drawn out into glassy threads. 

In most of the determinations complete fusion has taken place in the 

dry state at temperatures below Seger cone No. 9, which fuses at 

about 1,310° C., or 2,390° F.

The great bulk of the feldspar quarried in the eastern United States 

and in Canada belongs to the class described above, being orthoclase 

or microcline or an intergrowth of these two. In most quarries this 

is associated with minor quantities of soda feldspar albite or oligoclase (see below) occurring either in separate crystals or delicately 

intergrown with the potash feldspar, as shown in Plate I. The presence of the soda spar renders the ground product slightly more fusible. 

The specific gravity of orthoclase and microcline varies from 2.54 

to 2.56.

a Day,-A. L., and Alien, E. T., The isomorphism and thermal properties of the feldspars: Publ. No. 31, 

Carnegie Inst. of Washington, 1905, pp. 13-75; also Am. Jour. Sci., 4th ser., vol. 19, pp. 93-142, 1905.
U. S. GEOLOGICAL SURVEY lULLETIN 420 PLATE t

MICROPHOTOGRAPH OF THIN SECTION OF FELDSPAR FROM QUARRY OF GOLDING SONS 

COMPANY, GEORGETOWN, MAINE, MAGNIFIED ABOUT 40 DIAMETERS.

Showing perthitic intergrowth of potash and soda feldspar characteristic of many commercial feldspars. The 

lighter portions with striae crossing at right angles are potash feldspar (microcline). The datker portions 

with striations in only one direction are soda feldspar (albite).
CHEMICAL AKD PHYSICAL CHABACTEBS.

LIME-SODA FELDSPARS, OR PLAGIOCLASES.

The lime-soda group of feldspars, the plagioclases, as they are called, 

form a continuous series ranging from pure soda feldspar, albite, at 

one end to pure lime feldspar, anorthite, at the other end. The chemical composition of albite is represented by the formula NaAlSi 3O8 

(designated Ab) or Na2O.Al203 .6Si02 , being similar to that of orthoclase, except that soda is present in place of potash. The composition 

of anorthite is represented by the formula CaAl2Si2 08 (designated An) 

or CaO.Al2O3 .2SiO2 . The intermediate members of this feldspar series 

are mixtures in varying proportions of the two molecules Ab and An 

and have been divided arbitrarily, as shown in the following table:

Lime-soda scries of feldspars.

Albite................ AbjAn,) to Ab0Ani

Oligoclase ............ Ab6An, to Ab3An1

Andesine............. Ab3 An, to AbjAn,

Labradorite. 

Bytownite. AbAn

Anorthite. ............ AbjAn6 to

The following table shows the percentages of the various oxides 

corresponding to each feldspar variety:

Percentage weights of the oxides in the feldspars in the lime-soda scries.

SiO2 .

08. 7

64.0

62. 0

55.6

49.3

46.6

43.2

A1 2 03 .

19.5

22.1

24.0

28.3

32.6

34.4

36.7

NasO.

11.8

10.0

8.7

5.7

2.8

1.0

.0

CaO.

0.0

3.0

^ i

10.4

1 r, 1

17.4

20.1

The field and microscopic studies made by the writer and .the few 

analyses available indicate that most of the plagioclase present in 

feldspar deposits worked for pottery purposes belongs to the sodic 

varieties albite or oligoclase, though, the more calcic varieties are 

probably also present in minor amounts in a few localities. The albite 

and oligockse vary from pure white to pale green in color. In their 

commonest forms they show, as do the feldspars of the potash-soda 

group, two principal cleavage faces with brilliant luster, but these 

intersect not at 90°, as in orthoclase and microcline, but at about 86°. 

This difference in angle is not readily recognizable without careful 

measurements, and in the field albite and other lime-soda feldspars 

are most readily distinguished from the potash-soda feldspars by the 

presence in them of faint, perfectly straight striations on the most 

brilliant of the cleavage faces. These are the result of repeated 

twinning of the crystal, and are best seen by holding the crystal in 

the sunlight, so as to catch the reflection from the principal cleavage 

face. By turning the crystal slightly one way or another the striations, if present, are readily recognized.
FELDSPAR DEPOSITS OF THE UNITED STATES,

Pure soda feldspar, or albite (NaAlSi308 , designated Ab), like 

potash feldspar, has no definite melting point, but, as shown by 

Day and Allen,a melts at temperatures having a range of 150° C. or 

more, certain portions of a crystal persisting solid while other portions are fluid. Melting in a piece of natural albite was observed 

to begin below 1,200° C. and was not complete at 1,250°. Complete 

fusion takes place in albite at a somewhat lower temperature than in 

orthoclase and microcline. Hence, in the manufacture of pottery, a 

glaze prepared with albite will become fluid and will run at a kiln 

temperature at which a^potash-feldspar glaze remains more viscous 

and yields good results.

The feldspars of this class that contain notable amounts of calcium have fairly well-defined melting points. These melting points, 

as determined by Day and Alien,0 are given below, with the determinatiohs of their specific gravity.

Melting temperature and specific gravity of lime-soda feldspars.

Melting 

temperature in 

degrees 

centigrade.

1,340

1,367

1,419

1,463

1,500

1,532

Specific 

gravity of 

crystalline 

form.

2. 005

2. 660

2. 679

2.710

2.733

2.765

As shown in this table the melting points become progressively 

higher and the minerals become heavier with increase in the percentage of calcium.

If a melt composed solely of the constituents of pure potash

feldspar or pure soda feldspar is allowed to cool, the result is invariably 

a glass; a crystalline product has not yet been obtained in this way. 

If, however, melts of the lime-rich feldspars are cooled, partial or 

complete crystallization usually takes place. It is this property of 

cooling to a glass that renders the potash- and soda-rich feldspars 

serviceable for use in making glazes for pottery and enamel ware: 

The crystallization that takes place in the lime-rich feldspars under 

similar conditions makes them worthless, or at least much less desirable, for these uses. ; . The following analyses show the chemical characters of typical 

feldspars that are -used commercially. Most of the specimens of 

crude material analyzed were especially selected for their purity and 

are not typical of the material in commercial use. Nos. 5 and 6, on 

the contrary, are analyses of specimens of ground "spar" collected

a Day, A. L., and Alien, E. T., loc. cit.
CHEMICAL AND PHYSICAL CHARACTERS. 9

by the writer personally from the bins at feldspar mills and represent 

materials in actual0 commercial use.

Analyses of feldspars.

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

Ferric oxide (Fe203 ).--..... ...............

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

Magnesia (MgO). . ........................

Potash (K2O) .............................

Soda (Na2O) ..............................

Water (I12O). . ............................

1.

64.7 

18.4

16.9

100.0

Selected specimens of crude 

feldspar.

2.

64.98 

19. 18 

.33 

Trace. 

.25 

12.79 

2.32

.48

100. 33

3.

66. 23 

18. 77 

Trace. 

.31 

None. 

12.09 

3.11

100. 51

4.

65.95 

18.00 

.12 

1.05 

Trace. 

12.13 

2.11

99.36

Commercial specimens of ground 

feldspar.

5.

76. 37 

a]3.87

.26 

None. 

5.24 

3.74 

.30

99.78

6.

65.87 

a 19. 10

.20 

None. 

12.24 

2.56 

.64

100. 61

a Includes trace of iron and any TiOs and PaOs that may be present.

1. Theoretical composition of pure orthoclase or microcline.

2. Specimen of crude Norwegian potash feldspar, probably with some intergrown soda feldspar (albite). 

Used at the Royal Porcelain Works at Charlottenburg, Sweden.

3. Crude pink orthoclase-microcline feldspar, evidently intergrown with some soda feldspar (albite). 

From feldspar quarry of Richardson & Sons, Bedford, Ontario. Analysis by J. B. Cochrane, Royal Military College, Kingston, Ontario.

4. Crude pink potash feldspar (microcline), intergrown with small amounts of soda feldspar (albite). 

From feldspar quarry of P. H. Kinkles's Sons, Bedford, Westchester County, N. Y. Analyses made for 

John C. Wiarda & Co.

5. Ground commercial feldspar from Kinkles's quarry, Bedford, N. Y., so-called No. 3 grade; used in 

glass manufacture, but not for pottery. Sample taken by writer from bins at-mill of P. H. Kinkles's Sons. 

Analysis by George Steiger, in laboratory of U. S. Geological Survey.

6. Ground commercial feldspar from quarry of J. B. Richardson & Sons, Bedford, Ontario. No. 1 grade. 

Sample taken by writer from bins at mill of Eureka Flint and Spar Company, Trenton, N. J. Analysis 

by George Steiger, in laboratory of U. S. Geological Survey.

The approximate mineral composition of the samples of the commercial ground feldspars Nos. 5 and 6 above, as computed from the 

analyses, is as follows:

Approximate mineral composition of feldspars Nos. 5 and 6, above.

Quartz (SiOt). .................

Potash feldspar (microcline or orthoclase) (KAlSi3 68 )

Soda feldspar (albite), containing some lime (NaAlSi3 08 and CaAl 2Si208 ) ... ......

Moisture (HS 0) ................

Other constituents. .............

5.

34.37

30.58

32.83

Ofi

1.63

99.71

6.

3.84

72.28

22.59

KA

1 99

100. 57

Samples Nos. 5 and 6 may be taken to represent, as far as the percentage of quartz is concerned, the two extremes among potash 

"spars" in commercial use. No. 5 is much richer in quartz and in 

soda feldspar than the higher grades from this same quarry and is 

suitable only for use in glass making, for enamel ware, and for like 

uses. No. 6 is the best grade of Canadian "spar," which is almost 

free from quartz and brings as high a price as any spar on the market. 

The bulk of the No. 2 or "standard" spar that is on the market is 

intermediate in its percentage of quartz between Nos. 5 and 6, the 

percentage in most of it being between 15 and 25 per cent.
10 FELDSPAR DEPOSITS OF THE UKtTED STATES. 

ORIGIN AND GEOLOGIC OCCURRENCE.

The feldspars are among the most widely distributed minerals and 

occur as constituents of nearly all rocks. In most rocks, however, 

the feldspar is in too small grains and is too intimately associated with 

other minerals to be of commercial importance. Commercially 

valuable feldspar usually occurs as a constituent of pegmatites 

rocks of extremely coarse and irregular texture. In mineral composition these rocks may vary greatly, but those of present commercial 

importance belong chiefly to two types: (1) The granite pegmatites, 

which are essentially giant granites, their minerals being the same as 

those most abundant in ordinary granites, and (2) the soda pegmatites, which contain no quartz, no tourmaline, and little or no 

mica, but consist mainly of soda feldspar (albite) with small quantities of hornblende. By far the larger number of the feldspar 

quarries of the. United States are in deposits of granite-pegmatite; 

only a few, in southeastern Pennsylvania and adjacent parts of Maryland, belong to the soda pegmatite type.

It is not possible here to discuss in detail the origin of pegmatite. 

Nearly all the granite pegmatites are more or less closely associated 

with areas of granite and appear to be connected with th« granites 

in their origin, probably representing simply one phase of the granitic 

intrusions. Geologists are now well agreed that^hose granite pegmatites which are exploited for their feldspar have been~"forced into 

the inclosing rocks in a fluid condition and that their coarse and 

irregular texture as compared with typical granites is due, in part 

at least, to the larger amounts of water vapor which they contained 

before solidification.

The origin of the soda feldspar -pegmatites worked in southeastern 

Pennsylvania is not so well known and will be discussed later.

In size the pegmatite masses vary from bands a few inches across 

to great masses half a mile in width and traceable for a length of 

over a mile. The form of some of these masses is very irregular 

but most of them are more or less lens-shaped and were intruded 

along the planes of easiest fracture in the surrounding rocks. In a 

region where the bedding or foliation of the surrounding rocks is 

steeply inclined, the pegmatite masses are usually dikelike in form, 

as shown in Plate II, A. When the bedding or foliation of the inclosing rocks is flat-lying the pegmatite masses are as a rule sill-like, 

as shown in Plate II, B. Because of this tendency of pegmatite to 

follow, the planes of easiest parting in the bordering rocks it is possible 

in some areas to predict its occurrence beyond the visible outcrops, 

but all such predictions must be made with reservation, since the 

pegmatite is liable to pinch out at intervals or to cut irregularly across 

the trend of the inclosing rocks. Pegmatite bodies in massive rocks,
U. S, GEOLOGICAL SURVEY BULLETIN 420 PLATE I

A. HIGHLY INCLINED DIKE OF PEGMATITE IN SCHISTS AT PEMAQUID POINT, MAINE. 

Showing characteristic swelling and pinching of such dikes. . :

B. FLAT-LYING OR SILL-LIKE DIKE IN PEGMATITE INTRUDING GENTLY INCLINED 

SEDIMENTARY SCHISTS. BED OF ANDROSCOGGIN RIVER, BETWEEN RAILWAY 

AND HIGHWAY BRIDGES, AUBURN-LEWISTON, MAINE.

Showing lenslike form characteristic of many of these pegmatite masses.
MINERALS OF THE FELDSPAR DEPOSITS. 11

such as granite, may be very irregular but usually follow more or 

less parallel-walled fracture planes in the rocks, as shown in Plate 

VII, A.

MINERALS OF THE FELDSPAR DEPOSITS.

General composition of pegmatites. The feldspar deposits of the 

granitic type in all parts of the country are very similar in essential 

constitution, but they differ notably with respect to the proportions 

in which the most abundant minerals are present and with respect to 

the presence or absence of certain minor constituents. In composition the pegmatites are essentially coarse granites, the principal lightcolored minerals being potash and soda feldspars, quartz, and muscovite (white mica), while the principal dark-colored constituents 

are biotite (black mica) and black tourmaline. In pegmatite in 

which biotite is abundant black tourmaline is almost always rare or

absent, and vice versa. Accessory constituents that are almost always 

present rare garnet, magnetite, and green opaque beryl.

The most distinctive characters of the principal pegmatite minerals 

other than the feldspars are summarized below.

Quartz. As a rule the quartz (silicon dioxide, Si02 ) is white to gray 

in color, though some of it is pale pink (rose quartz) or, more rarely, 

purplish (amethyst). It is transparent to opaque, of hardness 7, 

not scratched by steel, without regular cleavage faces, and of conchoid al fracture. In the pegmatites it occurs in irregular masses, 

some of them several feet across, and also in intergrowth with feldspar and other minerals. In pockets in the pegmatites it occurs as 

transparent to translucent crystals which are six-sided prisms terminated by six-sided or three-sided pyramids. Crude crystalline 

quartz free from iron-bearing impurities has a value of $2 to $3 a ton 

at the mines when not too far from the markets. It is ground for 

use in the manufacture of pottery, paint, wood filler, etc. Rose 

quartz and amethyst, if of good quality, have gem values.

Muscovite. Muscovite (white mica), a silicate of aluminum and 

potassium, of hardness 2 to 2£ (easily scratched with the finger nail), 

is transparent and colorless to pale yellowish or brownish, and is 

readily recognized by the ease with which it may be split into thin 

flexible and elastic plates. This is the mineral commonly called 

isinglass. Most of the- muscovite found in deposits of commercial 

feldspar is - of little value, being affected by imperfections due to fracture planes, by magnetite inclusions, etc. In the pegmatites, besides 

occurring in large crystals it is found in aggregates of small plates 

and in intergrowth with quartz. When obtainable in clear, imflawed 

plates it brings good prices for electrical purposes, stove fronts, etc.

Biotite. Biotite (black or brown mica), a silicate of potash, iron, 

and magnesia, is similar to muscovite (white mica) in most of its
12 FELDSPAR DEPOSITS OF THE UNITED STATES.

physical properties but is dark brown to nearly black in color. In 

the pegmatite deposits it usually occurs in long, thin, lath-shaped 

crystals, some of them several feet long, which in places form more or 

less radiate groups. Biotite has no commercial value; on the contrary, because of its iron content, it must be carefully separated 

from feldspar in mining that mineral.

Tourmaline. Tourmaline is a complex silicate of boron and 

aluminum, containing also either iron, magnesia, or the alkalies. It 

is without prominent cleavage, is of uneven and subconchoidal 

fracture, is not scratched by steel (hardness 7'to 7.5), and in luster 

is vitreous to resinous. Much of the tourmaline of pegmatite deposits is black and opaque and looks much like shiny anthracite 

coal, though it is much harder. This variety contains iron, is without commercial value, and must be carefully separated from feldspar 

in mining. Opaque to semitransparent colored varieties are also 

found embedded in the solid pegmatite, and transparent colored 

tourmalines that bring good prices as gem stones are occasionally 

found in pockets.

Beryl. Beryl is a silicate of beryllium and alumina, without welldefined cleavage, with fracture subconchoidal to uneven. It is 

slightly translucent to transparent and ranges in color from emeraldgreen or blue-green to pink and colorless. In the pegmatites beryl 

usually occurs in hexagonal prisms, the largest several feet in length 

and a foot or more in diameter. If not transparent it is of no commercial importance, but if clear and free from flaws it has value as a 

gem. The pale blue-green varieties are termed aquamarine; the 

deeper green varieties are known as emerald.

Garnet. A number of mineral varieties are included under the 

name garnet. Chemically they are silicates of aluminum with

lime, iron, or manganese. The varieties most commonly found in 

commercial feldspar deposits are dark wine-red in color, semitransparent to opaque. These contain iron and must therefore be carefully separated from feldspar used for pottery. The crystals are 

usually more or less equidimensional, though they may be very 

irregular. In diameter not many of them exceed an inch, though a 

few reach 4 or 5 inches. The fracture of garnet is uneven to subconchoidal. Clear specimens have a small value as gems, but few 

such are found in feldspar quarries.

Accessory minerals that are present only in certain pegmatites 

number more than fifty species, but perhaps the most important are 

lepidolite, or lithium mica; amblygonite; spodumene; blue, green, 

and pink tourmaline; transparent green, pale-blue, or golden beryl; 

colorless to amber-colored topaz; and rose and amethystine quartz.
U. S. GEOLOGICAL SURVEY

INTERGROWTHS OF FELDSPAR AND QUARTZ SHOWING CHARACTERISTIC GRAPHIC 

GRANITE STRUCTURE. NATURAL SIZE.

d, Graphic granite from Bedford, N. Y.; 7^, fine graphic granite from Topsham, Maine.; C, coarse 

graphic granite from Topsham, Maine.
MINEBALS OF THE FELDSPAR DEPOSITS. 13

For more detailed descriptions.of these minerals and for descriptions of other pegmatite minerals the reader is referred to. the textbooks on mineralogy.

Crystals. Pegmatites vary greatly in coarseness. Some, especially 

the narrower masses, are little coarser than coarse-grained granites, 

though differing strikingly from those rocks in texture; in others, 

single crystals of nearly pure feldspar are 20 feet across, and single 

crystals of beryl reach the diameter of a hogshead. Most of the 

deposits are nearer the lower limit of coarseness than the higher. 

Only the coarser deposits are commercially valuable for their feldspar, quartz, mica, or gem minerals, and these constitute a relatively 

small percentage of the total mass of pegmatitic material present in 

any district. In most of the pegmatites worked commercially the 

feldspar and quartz crystals will not average more than 4 or 5-feet in 

diameter.

The most striking characteristic of the texture of the pegmatites 

is its irregularity. In a mass of typical granite there is considerable 

uniformity in size among grains of the same mineral species,- .but in 

the pegmatites there is no such regularity; a feldspar crystal, for 

example, is as likely to be two or three or even ten times as large as 

an adjacent crystal as to be of similar size.

Graphic granite. In most pegmatites there is much intergrowth 

of large single crystals of quartz and feldspar. . On certain faces of 

the feldspar crystals of these intergrowths the quprtz forms a pattern 

somewhat resembling the cuneiform inscriptions of the ancients. 

To such intergrowths the name "graphic granite" has been given 

from the Greek verb Ypcefacv, to write. The characteristic structure 

of graphic granite is shown in Plate III. Fine-grained phases may 

pass into coarser graphic granite and this, by decrease in the percentage of quartz, may pass into masses of pure feldspar or, by 

decrease in the percentage of feldspar, into masses' of pure quartz. 

Much of the material mined for commercial use is graphic granite 

and numerous analyses have shown that the intergrowths in this 

rock are characterized by a very nearly constant proportion between 

the feldspar and the quartz, the feldspar forming from 70" to 80 per 

cent of the rock and the quartz from 20 to 30 per cent.

Analyses of four specimens of graphic granite are given below. 

These analyses were made by George Steiger in the laboratory of 

the United States Geological Survey.
14 FELDSPAB DEPOSITS OF THE UNITED STATES. 

Analyses of graphic granite.

SiOj.......... :................................................

Alj08 . .........................................................

Fe,08 ...... ....................................................

FeO........... ................................................

MgO..... ......................................................

CaO....... ................................................ ..

NasO..... .....................................................

KjO......... ..................................................

H,0......... ..................................................

1.

73.89

13.75

\ .20

2.10

9.00

.24

99.24

2.

73.92

14.26

.30

2.06

8-. 99

.11

99.64

3.

72.76

a. 15. 47

.19

2.35

9.28

.15

100. 20

4.

71.00

a 16. 31

.22

3.44

8.66

.12

99.75

a Includes trace of iron and any TiO2 and P2O5 that may be present.

1. Coarse graphic granite from Fisher's feldspar quarry (abandoned), Topsham, Me. Trace of P2O5 . 

The quartz layers in this specimen average about 0.1 inch and the feldspar layers 0.4 inch across. The 

feldspar is cream-colored potash feldspar (microcline), finely (perthitically) intergrown with smaller 

amounts of soda feldspar (albite).

2. Moderately coarse graphic granite from Fisher's feldspar quarry (abandoned), Topsham, Me. Grades 

into No. 1. Trace of PjOs. The quartz layers in this specimen average about 0.05 inch across and the 

feldspar layers about 0.15 inch across. The feldspars are of the same character as in No. 1. t

3. Fine-grained graphic granite from Kinkle's feldspar quarry, Bedford, Westchester County, N. Y. 

The quartz layers in this specimen average about 0.03 inch across and the feldspar layers about Q.08 inch 

across. The feldspars are pale-pink microcline finely intergrown with smaller amounts of soda feldspar 

(albite), containing a little lime.

4. Graphic granite from Andrew's quarry, Portland, Conn., varying in coarseness but all extremely fine 

grained. The quartz layers in this specimen average not more than 0.02 of an inch across and the feldspar 

layers not more than 0.05 inch across. Some small areas of pure feldspar were associated with the graphic 

granite in this specimen, so that the silica percentage shown in the analysis is lower than it would be-for 

graphic granite alone of this fineness. The feldspars are white potash feldspar (microcline), intergrown 

with smaller amounts of soda feldspar (albite), containing a little lime.

If allowance is made for the water present and the proportion 

of quartz to feldspars calculated from the above analyses, the results 

are as follows 1

Proportions of quartz and feldspar in graphic granites Nos. 1 to 4, above.

Q.uartz (Si02 ) ..................................................

Potash feldspar (microcline) (KAlSi 3 08 ) .......................

Soda feldspar (albite), with small amounts of lime feldspar in 

Nos. 3 and 4(NaAlSiACaAl2Si 2 04 ) ... . .

1.

27.13

54.42

.18. 45

100. 00

2.

26. 26

55.22

18.52

Trace.

100. 00

3.

22.94

u o<;

~ 20. 99

1.12

100.00

4.

17.65

K1 07

30.05

.92

99.99

Nos. 1 and 2 in the above tables represent graphic granite from 

Fisher's quarry in Topsham, Me., and show practically identical proportions between the quartz and the feldspar, although No. 1 is more 

than twice as coarse as No. 2. In No. 3, from Bedford, N. Y., sodalime feldspar is more abundant than in Nos. 1 and 2 and the proportion of quartz is slightly less. In No. 4 some pure feldspar is associated with the graphic intergrowth of feldspar. and quartz, so that 

the proportion of quartz in the whole specimen is lower than in any 

of the other samples. A graphic intergrowth of potash feldspar 

and quartz from Elfkarleo, Sweden, which was so fine grained that 

the graphic structure could be seen only under the microscope, 

showed on analysis about 79.2 per cent of feldspar and 20.8 per cent 

of quartz. From the analyses given above and from numerous
METHODS OF MINING. 15

others which have been published the conclusion seems justified that 

the proportion of feldspar to quartz in graphic granites, though varying somewhat according to the composition of the feldspars, is nevertheless fairly constant and is not dependent on coarseness of grain. 

This fact is of practical importance, since a large proportion of the 

commercial "spar" produced is graphic granite, and it has been the 

practice at some quarries to discard the finer-grained varieties on 

the supposition that they contained a larger percentage of quartz 

than the coarser kinds. Such mining practice is unwarranted, the 

fine graphic granite being as desirable as the coarse, though both 

should be mixed with a certain amount of pure feldspar in order to 

reduce the percentage of quartz in the ground product to between 

15 and 20 per cent for the standard grade.

In most pegmatite bodies there is no regularity whatsoever in the 

distribution of the different minerals. The mica plates here and 

there show a tendency to group themselves along certain planes, but 

these planes seem to have no definite orientation with respect to the 

general outline of the deposit. A deposit that is of excellent commercial quality as regards feldspar may grade within a short distance 

and in a wholly irregular manner into pegmatite that is worthless 

because of its large percentage of quartz or its abundance of biotite, 

black tourmaline, or garnet.

METHODS OF MINING.

The methods of mining feldspar are very simple. The excavations 

are nearly all open pits, most of them of rather irregular form, the 

valueless portions of the pegmatite being avoided wherever possible 

in mining. In a few Pennsylvania quarries where the pegmatite 

masses are rather flat-lying and are overlain by a roof of worthless 

rock short tunnels have been driven from the open pits.

In Maine, Connecticut, and New York the pegmatite is usually 

firm and undecomposed, even in the surface outcrops, and it is necessary to sink drill holes and blast out most of the material. In 

Pennsylvania and Maryland, however, most of the pegmatite is 

much decayed at the surface .and can be readily excavated with 

picks, shovels, and crowbars. In a few of these quarries kaolin 

produced by the -decay of the feldspar has been found in the past in 

sufficient quantities to be of commercial importance, though none is 

now produced. This difference in the character of the pegmatite 

deposits in the two regions is due to the fact that the PennsylvaniaMaryland region is unglaciated, while in the more northerly region 

glacial ice planed off most of the products of rock decay.

In some of the smaller quarries where the rock is firm drilling is done 

by hand, but in most of the larger quarries steam drills are used. The 

large masses are then broken with sledges into pieces 6 inches or less
16 FELDSPAK DEPOSITS OF THE UNITED STATES.

in size. If the material is to be used as poultry grit or for the manufacture of roofing materials no sorting is necessary, but material used 

for making pottery is hand picked at the quarry to remove the more 

micaceous and quartzose parts and the portions carrying iron-bearing 

minerals.. In most of the Pennsylvania and Maryland quarries, 

where the weathered materials near the surface can be excavated 

with the aid only of the pick and shovel, screening or even washing 

may be necessary to free the spar from dirt. In some of the larger 

and deeper quarries derricks and drags are used in hoisting the spar to 

the surface, the material being then loaded into wagons and hauled 

either to the railroad for shipment or to the mills for grinding. In 

some quarries the wagons descend into the pit along an inclined 

roadway. At two important quarries wire tramways connect quarry 

with mill.

The cost of actual mining at most of the quarries producing feldspar 

of pottery grade is reported at from $2 to $2.50 per long ton. At 

certain quarries where pegmatite is quarried for ready roofing, poultry 

grit, etc., where cobbing and hand sorting is unnecessary and where 

the work is conducted on a large scale, the cost may be as low as 50 

cents person. Hauling by team from mine to mill or shipping point 

in most of the feldspar districts may under ordinary conditions be 

estimated at a contract price of 35 to 40 cents per long ton per mile.

COMMERCIAL AVAILABILITY OF DEPOSITS.

Whether it will pay to work a given feldspar deposit depends upon 

a number of factors, chief among which are (1) the distance from the 

railroad or navigable water; (2) the freight rates to principal markets; 

(3) the quantity and quality of the material available; (4) the cheapness with which the feldspar can be mined; and (5) the market conditions. Favorable conditions with respect to some of these factors 

may offset unfavorable conditions with respect to. others. The 

principal markets for the better grades of feldspar are the great 

pottery centers Trenton, N. J., and East Liverpool, Ohio so that 

the mines of Connecticut, Pennsylvania, and Maryland have the 

advantage over those in Maine and northern New York of being much 

closer to these.markets. This superiority in position makes wagon 

hauls from mine to shipping point of 6 or 8 miles permissible in these 

Middle Atlantic States, whereas in Maine or in the Adirondack region 

a deposit must be much closer to the shipping point to be worked 

with a fair degree of profit. Pegmatite sold for roofing or poultry 

grit commands prices so small that hauls of more than 1 or 2 miles 

from mine to shipping point would in most places be prohibitive. 

The tariffs or hauling rates on feldspar from a number of the quarrying districts to the principal feldspar milling centers or markets are 

given below.
COMMERCIAL AVAILABILITY OF DEPOSITS. 17

Tariff rates per hundredweight on feldspar for carloads having a minimum weight of 40,000

pounds, May, 1909.

Maine:

Bath to Trenton, N. J................................................ $0.15

Cathance to Trenton, N. J...................................;........ .17

Auburn to Trenton, N. J.......................... ; ........;.......... .16

New York:

Crown Point to Trenton, N. J.......................................... .17

Crown Point to New York City (commodity rate on crushed pegmatite).. . 10 

Northville to Trenton, N. J............................................ .17

Pennsylvania:

Avondale to Trenton, N. J............................................. .08

.Avondale to Wilmington, Del.....................................:... .06

Maryland:

Woodstock to Trenton, N. J. (commodity rate)......................... .07

Woodstock to Wilmington, Del......................................... . 04^

The requirements of the potter's trade demand that in general the

percentage of free quartz associated with the feldspar used for this 

purpose shall not exceed 20 per cent in the ground product, and certain potters demand a spar which is nearly pure, containing probably 

less than 5 per cent of free quartz. In order to be profitably worked, 

in most feldspar mines between one-fourth and one-half of the total 

material that must be excavated should contain less than 20 per cent 

of free quartz. Freshness of the feldspar, though desirable, is not 

essential.

A factor of the utmost importance in the mining of pottery spar 

is the quantity of iron-bearing minerals (black mica, hornblende, 

garnet, black tourmaline, etc.) which is present and the manner in 

which these minerals "are associated with the feldspar. The requirements of the pottery trade demand that the spar be nearly free from 

these minerals, which if present produce upon firing brown discolorations in white wares. In order that a deposit may be worked profitably these minerals, if present in any appreciable quantity, must be 

so segregated in certain portions of the deposit that they can be 

separated from the spar without much more hand sorting and cobbing 

than is necessary anyway in the separation of the highly feldspathic 

material from that which is highly quartzose or rich in muscovite. 

A number of pegmatite deposits of coarse grain are rendered worthless 

for pottery purposes by the abundance of one or more of these ironbearing minerals. The presence here and there of minute flakes of 

white mica (muscovite) is characteristic even of the highest grades of 

commercial feldspar, and chemically this mineral is not injurious. It 

is, however, exceedingly difficult to pulverize the thin, flexible mica 

plates to a fineness equal to that required in the feldspar, and it is 

therefore necessary in mining to separate carefully as much of the 

muscovite as possible from the spar. 

16779-Bull. 420 10 2
18 FELDSPAR DEPOSITS OF THE UNITED STATES.

Almost any coarse, undecomposed granite pegmatite is adapted 

to the manufacture of roofing materials and poultry grit.

Operation on a large scale with the aid of modern machinery 

reduces the mining cost. Favorable topographic position a situation, for instance, that will permit the material to be excavated 

from a hillside opening instead of being hoisted from a pit also 

reduces the cost of mining.

METHODS OF MILLING.

The methods used for grinding feldspar 'for pottery, enamel ware, 

etc., are similar in a general way in all of the Eastern States 'and 

are very simple. The soda spar quarried in southeastern Pennsylvania is first burned in kilns, which serves to fracture it and thus 

to facilitate grinding. Most feldspar, however, is fed just as it 

comes from the quarry into a chaser mill consisting of two buhrstone 

wheels, 3 to 5 feet in diameter and 1 to 1-|- feet thick, attached to 

each other by a horizontal axle, as are the wheels of a cart. The 

horizontal axle is attached at its center to a rotating vertical shaft, 

which causes the buhrstone wheels to travel over a buhrstone bed, 

the feldspar being crushed between the wheels and the bed. In a 

few mills the spar before going to the chaser mills is crushed in a 

jaw crusher. *

The material as it comes from the chasers is screened, the tailings 

being returned to the chaser mills for recrushing; the fines go to 

tube mills for final grinding. The tube mills consist of steel cylinders 

revolving on a horizontal axis. The cylinders are generally lined 

either with hard-wood blocks or with blocks made of natural or 

artificial siliceous brick, and are charged with Norway or French 

flint pebbles 2 to 3 inches across. The type of tube mill used by

most feldspar grinders is 6 to 7 feet long and grinds from 2 to 3 tons 

of spar at one charging. Certain millers, however, claim to effect a 

considerable saving in-power by the use of larger mills, which grind 

from 4 to 6 tons at one charge.

Feldspar for pottery purposes is usually ground four to six hours, 

and in that time most of it is reduced to a fineness of more than 200 

mesh. Screen tests made by the writer on 4 samples of commercial 

ground pottery spar collected personally from the bins at 3 feldspar 

mills showed that from 99.3 to 99.8 per cent of the material would 

pass through a 100-mesh screen and from 96.7 to 98.2 per cent 

would pass through a 200-mesh screen. A sample of No. 3 spar, 

used only in making glass and enamel ware, was notably coarser, 

94 per cent passing through a 100-mesh screen and 74 per cent 

through a 200-mesh screen. This grade is ground only for two to 

three hours. Some feldspar prepared for use in abrasive soaps is 

ground for ten hours.
USES. 19

After grinding, the spar is ready for shipment either in bulk or in 

bags. The red spars from Bedford, N. Y., and Bedford, Ontario, 

have a faint pinkish tint when ground, but the cream-colored and 

white spars grind to a pure white. In a few mills the ground spar 

is allowed to settle slowly in water, so as to separate the finer from 

the coarser material, but this method is now rarely used.

In mills for grinding feldspar for poultry grit and roofing purposes 

the spar is first crushed in jaw or rotary crushers and then between 

steel rolls. It is then screened over vibrating screens, usually of 

the Newago or Jeffrey type, to the various sizes desired.

USES.

The principal consumers of feldspar are the pottery, enamel ware, 

enamel brick, and electrical ware manufacturers, its most important 

use being as a constituent part of both body and glaze in true pOICelain, white ware, and vitrified sanitary ware, and as a constituent of 

the slip (underglaze) and glaze in so-called "porcelain" sanitary 

wares and enameled brick. The proportion of feldspar in the body 

of vitrified wares usually falls between 10 and 35 per cent. Its 

melting point being lower than that of the other constituents, it 

serves as a flux to bind the particles of clay and quartz together. 

In glazes the percentage of feldspar usually lies between 30 and 50. 

The trade demands that feldspar for pottery purposes be nearly free 

from, iron-bearing minerals (biotite, garnet, hornblende, tourmaline, 

etc.) and that it contain little if any muscovite. The requirements 

in regard to the percentage of free quartz vary with different potters. 

A few manufacturers of the finer grades of pottery demand less than 

5 per cent of free quartz, and may even grind the spar themselves 

so as to be sure of its quality, preferring to insure a constant product 

even at higher cost by themselves mixing the requisite quantity of 

quartz with the spar. Most potters get satisfactory results with 

"Standard" ground spar carrying 15 to 20 per cent of free quartz, 

and in some acceptable spars the percentage runs even higher. In 

the finely ground mixture as it comes from the mills it is difficult 

to separate the quartz from the feldspar by physical methods on 

account of the extreme fineness of the material. Chemical analysis 

seems to be the readiest means of determining whether its percentage 

is high or low.

Feldspar is also used in the manufacture of emery and carborundum wheels as a flux to bind the abrading particles together.

Small quantities of feldspar are used in the manufacture of opalescent glass. The feldspar used for this purpose is ranked as No. 3 by 

the miners. This generally contains more free quartz and muscovite 

than that used for pottery, and most of it contains also fragments of 

iron-bearing minerals. Most of the spars known to the writer which
20 FELDSPAK DEPOSITS OF -THE UNITED STATES.

are used for opalescent glass are rich in soda. As shown by the tests 

cited on page 18, they are not ground so fine as pottery spars.

Small quantities of carefully selected pure feldspar are used in the 

manufacture of artificial teeth. Some is used in the manufacture of 

scouring soaps and window washes, the fact that feldspar is slightly 

softer than glass rendering these soaps less liable to scratch windows 

or glassware than the soaps in which quartz is the abrasive substance. Two firms in "New York State and one in Connecticut 

crush feldspar for poultry grit and for the manufacture of ready 

roofing.

Much interest has recently been aroused in the use of potash feldspar as a fertilizer. Potash is an important plant food, which, in 

fertilizers, has usually been supplied in the form of wood ashes or of 

easily soluble potash salts (sulphate, carbonate, or chloride) imported 

from Germany. The Department of Agriculture has recently made 

preliminary experiments to determine the availability of finely 

ground potash feldspar as a substitute for the more soluble potash 

salts. The following statement is quoted from the report on these 

tests: 0

The evidence so far obtained appears to indicate that under certain conditions and 

with certain crops feldspar can be made useful if it is ground sufficiently fine." On the 

other hand, it is highly probable that under other conditions the addition of ground 

feldspar to the land would be a useless waste of money. At the present stage of the 

investigation it would be extremely unwise for anyone to attempt to use ground rock, 

except on an experimental scale that would not entail great financial loss.

If further experimentation shows that ground feldspar has a wide 

efficiency as a fertilizer, it will undoubtedly lead to the utilization of 

many of the pegmatite deposits which, because of insufficient coarseness, too large a percentage of quartz, or too great an abundance of 

iron-bearing minerals, are not valuable as a source of pottery material. 

Deposits of this kind, favorably situated with respect to the railroads, 

are numerous, especially in the vicinity of the active feldspar quarries. 

An equally important result will be the utilization of much material 

that is now discarded at feldspar quarries.

A number of processes have been patented in this country for the 

dissociation of potash feldspar to obtain the more readily soluble 

potash salts, but none of these have yet been successfully applied on 

a commercial scale. What is perhaps the most promising method 

effects the decomposition through electrolytic methods. b

a Cushman, Allerton S., The use of feldspathic rocks as fertilizers: Bull. No. 104, Bureau of Plant Industry, U. S. Dept. Agriculture, 1907, p. 31.

6 Cushman, A. S., Extracting potash from feldspar: Min. World, June 22, 1907; also U. S. Patent No. 

772612, October 18,1904.
GBADES AND PRICES. 21

GRADES AND PRICES,

Most dealers recognize three grades of commercial feldspar: No. 1, 

No. 2 (sometimes called "Standard"), and No. 3. From quarries 

in granite pegmatite, where most of the spar is of the potash variety, 

these are usually graded as follows: No. 1 is carefully selected, free 

from iron-bearing minerals, largely free from muscovite, and contains 

little or no quartz, usually less -than 5 per cent. Analysis 6 of the 

table on page 9 shows the character of niaterial of this grade, the 

feldspar analyzed having been imported from Canada. No. 2 is 

largely free from iron-bearing minerals and muscovite, but usually 

contains when ground from 15 to 20 per cent of quartz. No. 3 is 

not carefully selected and contains somewhat higher percentages of 

quartz, muscovite, and iron-bearing minerals. Spar from the soda 

pegmatites of southeastern Pennsylvania and adjacent parts of

Maryland, being wholly free from quartz, is graded entirely on the 

basis of its freedom from iron-bearing minerals, principally hornblende. No. 1 is carefully selected and is practically free from 

such impurities; No. 2, though less carefully selected, is still fairly 

free from them; No. 3 is not carefully selected and carries hornblende 

in quantities large enough to render it unfit for use in the manufacture of pottery. It is utilized principally in making glass. Crushed 

pegmatite from New York State, used for poultry grit and for coverings for surfaces to give them the appearance of granite, and feldspar 

from Minnesota, used mainly for abrasive purposes, are graded 

.according to coarseness.

The prices of feldspar fluctuate with general market conditions 

and local conditions of competition but in general are about as follows:

.Prices of feldspar f. o. b. mills.

'

Maine: 

No. 2, or "Standard ".......................................................

Northern New York:

Southern New Yorlj: 

No. 1. ...................................... '.................................

Connecticut:

Pennsylvania:

Maryland:

Trenton, N. J.:

Crude, 

per long 

ton.

32. 50-3. 00

4. 25-4. 50

3.50-4.00

3. 50-4. 00

3. 50-4. 00

5.50

5.00-5.25

Ground, 

per short 

ton.

$3.00-3.50

8. 50-9. 00

6.00-C.50

5.50-6.50

7.50-9.00

10.50

9. 00-9. 50

Crude No. 1 feldspar usually brings from 50 cents to $1.50 more 

per ton than No. 2, and crude No. 3 brings about the same amount 

less. Ground No. 1 brings from $2 to $4 more per ton than. No. 2.
22 FELDSPAR DEPOSITS OF THE UNITED STATES.

With finer grinding, such as is demanded by some scouring soap 

manufacturers, the prices are proportionally higher. Very pure 

carefully selected potash feldspar, for use in the manufacture of 

artificial teeth, usually sells at from $6 to ,$8 per barrel of 350 pounds.

PRODUCTION.

The tables below show the recent production of feldspar in the 

United States. x

Production of feldspar (exclusive of abrasive feldspar) in 1907 and 1908, by States, in

short tons.

State.

1907.

Pennsylvania

Total .........................

1908.

Total.........................

Crude.

Quantity.

45 

3,909 

10, 663 

7,367 

7,169 

1,927

31,080

168 

504 

7,775 

3,616 

6,217 

560

18,840

Value.

$110 

15, 825 

28, 433 

28, 169 

23, 672 

5,607

101,816

375 

1,350 

27, 753 

13, 226 

21,076 

2,000

65, 780

Ground.

Quantity.

16,428 

11, 500 

8,380 

12, 266 

3,895 

1,000

53, 469

13, 751 

14, 109 

6,425 

10, 473 

3,517 

125

48, 400

Value.

$157, 224 

40, 500 

51, 770 

108, 678 

34, 081 

5,000

397, 253

123, 034 

51, 798 

38, 506 

90, 276 

30, 774 

750

335, 138

Total.

Quantity.

16, 473 

15, 409 

19, 043 

19,633 

11,064 

2,927

84, 549

13, 919 

14, 613 

14, 200 

14,089 

9,734 

685

67, 240

Value.

$157, 334 

56, 325 

80, 203 

136,847 

57, 753 

10, 607

499, 069

123, 409 

53, 148 

66, 259 

103, 502 

51, 850 

2,750

400, 918

Total production of feldspar in 1907 and 1908, in short tons.

Production of feldspar (exclusive of

Production of abrasive feldspar in 

1908...............................

Total production of feldspar in 

1908.........................

Total production of feldspar in 1907. .

Crude.

Quantity.

18,840

18,840 

31,080

Value.

$65, 780

65,780 

101,816

Ground.

Quantity.

48,400 

3,234

51,634 

60, 719

Value.

$335, 138 

27,635

362, 773 

457, 128

Total.

Quantity.

67,240

»

3,234

70, 474 

91, 799

Value.

$400, 918 

27, 635

428, 553 

558,944
The production of feldspar (exclusive of abrasive feldspar) from 

1903 to 1908 is given in the following table:

Production of feldspar (exclusive of abrasi re feldspar), 1903-1908, in short tons.

Year.

1903.................................

1904.................................

1905.................................

1900

1907.................................

1908.................................

Crude.

Quantity.

13, 432 

19,413 

14, 517 

39, 976 

31,080 

18,840

Value.

$51,036 

66, 714 

57, 976 

132, 643 

101, 816 

65, 780

Ground.

Quantity.

28, 459 

25, 775 

20, 902 

32, 680 

53, 469 

48, 400

Value.

$205, 697 

199,612 

168, 181 

268,888 

397, 253 

335, 138

Total.

Quantity.

41,891 

45, 188 

35,419 

72, 656 

 84,549 

67, 240

Value.

8256, 733 

266, 326 

226, 157 

401,531 

499, 069 

400, 918

LOCALITIES BY STATES.

MAINE.

The feldspar quarries of Maine are all in the south-central and 

southwestern part of the State, as shown in Plate IV. These portions of Maine are occupied by large areas of granite bordered by 

areas of highly metamorphic slates and argillaceous schists, which are 

intruded by granite, granite-pegmatite, and granite gneiss. It is 

very evident that the pegmatites are related to the granites in origin. 

The granites of eastern Maine are known to be late Silurian or Devonian in age and those of southwestern Maine, with their associated, 

pegmatites, are believed to be of the same age. The bordering slates 

and argillaceous schists are probably Cambrian or pre-Cambrian.

In 1908 six feldspar quarries were operated in Maine by four companies, nearly all of the product being ground at feldspar mills at 

Cathance, Sagadahoc County, and at Littlefields, Androscoggin 

County. The value of the product in Maine for 1908 exceeded that 

in any other State, though in number of tons the production was 

surpassed by Connecticut and Pennsylvania. The feldspar mined at 

all the Maine quarries is very similar in character and is a buff-colored 

potash spar.

ANDROSCOGGIN COUNTY. 

AUBURN.

Pegmatite deposits at Mount Apatite, in the northern part of the 

town of Auburn, are worked extensively for feldspar and to some 

extent for other minerals valuable as gems or for cabinet specimens. 

Mount Apatite is a low prominence 6 miles west of the city of Auburn, 

near the road to Minot and about 2 miles from Littlefield, the nearest railroad station, on the Lewiston branch of the Grand TrUnk 

Railroad. The locality was visited by the writer in August, 1906, 

and again in October, 1907.
24 FELDSPAR DEPOSITS OF THE UNITED STATES.

This locality was first worked for its semiprecious gem minerals 

and later for its quartz, but in recent years almost exclusively for 

feldspar. The largest producer is the Maine Feldspar Company, 

which has operated continuously from 1902 to the present time. 

The workings of this company consist of a number of small pits 75 

to 150 feet long, 50 feet in average width, and 10 to 20 feet in depth. 

These are either close together or partly connected, and are located 

in a single mass of pegmatite, which constitutes the summit of the 

hill. Much of the hilltop is bare, but in a few places as much as 6 

feet of soil must be stripped in working.

The most abundant minerals are those commonly found in granite 

pegmatites that are worked for feldspar, but in addition there are 

many minerals that are characteristic only of gem-bearing pegmatites.

The quartz varies from white to dark gray in color and from 

opaque to beautifully transparent. It commonly occurs in'graphic 

intergrowth with feldspar, but occasionally in large pure masses, arid 

also in pockets as clusters of transparent crystals. The quartz 

obtained in feldspar mining is white and very pure, and is therefore 

well suited for any purpose for which crystalline quartz is now used. 

It is saved in stock piles, where it is allowed to accumulate until a 

sufficient amount is obtained for shipment, The profit in handling 

quartz located so far from the markets is very small, so that the 

mineral can be profitably quarried only as an accessory product.

The feldspar is mostly buff to cream color, but contains here and 

there bluish-gray spots and streaks due to minute inclusions. On 

microscopic study it is found to be of the potash varieties (orthoclase 

and microcline), finely (perthitically) intergrown with small amounts 

of soda feldspar (albite). The variety of albite known as clevelandite is abundant in aggregates of thin radiating plates in certain 

parts of the. deposit. The "Standard" or No. 2 grade obtained at 

this quarry consists principally of graphic granite, with a subordinate 

amount of pure feldspar. Some No. 1 grade, nearly free from quartz, 

is also obtained, and an analysis of a sample of this made in the 

laboratory of the United States Geological Survey is given below.

Analysis of No. 1 ground feldspar from Auburn, Me.

Silica (Si02 ).................................................. 65. 73

Alumina (A1203)............................................ «19.28

Magnesia (MgO)............................................... None.

Lime (CaO)................................................... .22

Potash (K20)................................................ 10.26

Soda (Na^O).................................................. 4.08

. Water(H20).................................................. .48

100.05

Includes trace of iron and any Ti02 and I'zOs that may be present.
U.S..GEOLOGICAL SURVEY BULLETIN 1-20 PLATE IV

PRELIMINARY GEOLOGIC MAP OF A PORTION OF MAINE

SHOWING LOCATIONS OF FELDSPAR QUARRIES AND MILLS

O 1O £O Miles

SEDIMENTARY ROCKS 

CAMBRIAN?

IGNEOUS ROCKS 

LATE SILURIAN OR EARLY DEVONIAN

Slate and argillaceous 

(clayey)schist

Quartzose schist Slate and schist injected Mainly granite and 

by various amounts of granite gneiss 

granite, granite gneiss, 

and pegmatite

Active feldspar quarry Inactive feldspar quarry Feldspar mill
MAINE. 25

The mineral composition of this sample, as calculated from the 

analysis, is as follows:

Mineral composition of No. 1 ground feldspar from Auburn, Me.

Quartz....................................................... 2. 22

Orthoclase and microcline..................................... 6Q. 60

Albite....................................................... 35. 69

Water........................................................ .48

Other substances.............................................. 1. 02

100. 01

Muscovite is moderately abundant in bladelike " books, v some of 

which are as much as a foot in length. None of it is of commercial 

value except as ground mica.

Biotite is only locally abundant and as a rule can be easily separated in mining.

Small garnets occur occasionally in all parts of the pegmatite, but 

are most abundant in the more quartzose and micaceous parts and 

are not present in injurious amounts in the more highly feldspathic 

portions.

Black tourmaline is only locally abundant and can be easily 

avoided in quarrying.

Bluish-green beryl is moderately abundant, and gem tourmalines 

are occasionally found. Many other minerals are present in subordinate amounts.

Neither the exact form nor the area of this pegmatite body could 

be determined, but it occupies practically the whole top of Mount 

Apatite, and it is probable that further stripping of the soil in the 

neighborhood of the present workings will disclose a considerable 

amount of commercial feldspar and possibly portions valuable enough 

to be worked'for their gem minerals. There are some indications 

that in general this pegmatite mass is rather flat lying. Several dikes 

of fine-grained dark-green diabase intrude the pegmatite.

The topographic situation of this deposit, on the crest of the hill, 

favors the ready disposition of the waste from the quarries and also 

provides a downhill haul most of the way from the quarry to the 

mill. The excavating is accomplished by steam drilling and blasting, 

the material then being broken up with sledges and picked over by 

hand. It is hauled 2 miles by teams- to the mill at Littlefield station. 

The force usually employed at the quarry consists of a foreman and 

ten laborers.

Three small pits on the southern part of the summit of Mount 

Apatite have been worked intermittently during the last ten years 

by E. Y. Turner, of Auburn, the product being ground at the mill of 

the Maine Feldspar Company. The quarries were idle at the time of 

the writer's visit in 1906-7. The amount of material that has been
26 FELDSPAR DEPOSITS OF THE UNITED STATES.

taken out is small. The excavations consist of three pits, none of 

which is over 10 feet deep. The largest is 75 feet long and 30 feet 

wide. The pegmatite at this quarry appears to form a part of the 

same large pegmatite mass that is worked by the Maine Feldspar 

Company, but the material is of much poorer quality and there seems 

little prospect that the quarries will yield much feldspar of pottery 

grade. The excavating has been done in part by hand drilling and 

blasting and in part by steam drilling. The equipment includes a 

small derrick.

The feldspar quarried at Mount Apatite, as well as that from the 

Berry quarry, in Poland, is ground at a mill beside the Grand Trunk 

Kailway at Littlefield station. The ground spar is loaded directly 

into cars at the mill and shipped in bulk mainly to potters at Trenton, 

N. J., and East Liverpool, Ohio. The equipment consists of a chaser 

mill, each stone of which weighs about 3^ tons, and a ball mill, larger 

than that used at most feldspar mills, grinding 3 tons at a load. The 

capacity of the plant is about 15 tons in twenty-four hours, and eight 

men and a foreman are employed. The power is supplied by a 75- 

horsepower Westjnghouse motor, the current coming from a power 

plant on Androscoggin River.

MINOT.

In the southeastern part of the town of Minot, near the Auburn 

line, some pegmatite which appears to be of commercial grade with 

respect to feldspar was observed on the farm of Mr. Edward Hackett. 

Here masses of practically pure feldspar 2£ to 3 feet across are associated with masses of pure quartz of about the same dimensions. 

Almost no biotite, garnet, or black tourmaline was seen. The pegmatite here seems to underlie a mass of fine-grained pegmatitic 

granite. There is no doubt of its commercial quality, but the present 

outcrops cover an area only a-bout 100 feet square, so that it is uncertain whether the quantity would warrant mining. The locality is 

worth prospecting, however.

POLAND.

A quarry in the town of Poland, just across Androscoggin River 

from Mount Apatite, is operated for feldspar and occasional gem 

minerals by A. R. Berry, of Auburn, Me. This quarry is about 3 

miles from Littlefield station on the Lewiston branch of the Grand 

Trunk Railway.

The quarry was opened in 1900 and has been worked intermittently on a small scale ever since. It was visited by the writer in 

August, 1906. The openings are very irregular, shallow, open pits, 

none more than 18 or 20 feet in maximum depth, and cover an area 

of about 2 acres.
MAINE. 27

The general character of the pegmatite is similar to that at the 

Maine Feldspar Company's quarries at Mount Apatite. The rock is 

mainly a graphic intergrowth of quartz with buff microcline and 

some orthoclase. Albite in irregular crystals a few inches across is 

occasionally encountered.

Muscovite occurs in brush-like and rosette-like intergrowths with 

quartz. No plate mica occurs and no attempt has been made to 

market the muscovite as scrap mica.

Biotite, which is locally very abundant, occurs in irregularly disposed blades or bundle-like masses, with thin layers of feldspar or 

quartz between the blades. Such biotitic bundles occur in association with the coarser phases of the pegmatite and render valueless 

for pottery purposes much feldspar that could otherwise be used.

Black tourmaline is abundant in certain parts of the pegmatite, 

usually in intergrowth with quartz, one mass of intergrown quartz 

and black tourmaline being 10 to 12 inches across. One black tourmaline crystal observed was 5 by 12 inches in size. Colored tourmalines 

of gem quality are occasionally found in pockets. Other minerals are 

beryl, lepidolite, and herderite.

The feldspar is excavated by hand drilling and blasting, and after 

hand sorting is hauled by wagons 3 miles to the mill of the Maine 

Feldspar Company at Littlefield station. All the spar is sold to this 

company and ground at this mill. Gem tourmalines and minerals 

of value as cabinet specimens are not found so frequently that it 

would pay to work the deposit for them alone. In 1906 the quarry 

force consisted of three men. The gems and other valuable minerals 

obtained are marketed irregularly through local collectors, and no 

estimate of their value is obtainable. The feldspar output is a few 

hundred tons a year. A considerable amount of commercial feldspar 

of pottery grade is still available at this locality.

LINCOLN COUNTY. 

EDGECOMB.

A feldspar quarry that has been abandoned for many years is in 

the town of Edgecomb, 2£ miles south of the village of Newcastle and 

about one-half mile south of the road extending from North Edgecomb to Briar Cove, on Damariscotta River. The locality is shown 

on the Boothbay topographic sheet of the United States Geological 

Survey. ;

The locality was visited by the writer in August, 1906. The 

excavations consist of two open pits, one 150 feet long and 50 feet 

wide, filled with water at the time of the writer's visit; the other 50 

feet long, 25 feet wide, and 15 feet deep. There is only a slight overburden of soil. The pegmatite resembles in mineral character that
28 FELDSPAR DEPOSITS OF THE UNITED STATES.

quarried at Topsham, in Sagadahoc County (see p. 38), but contains 

less feldspar of commercial grade.

The largest masses of pure quartz observed, which were between 

the two pits, were 3 feet across. In color the quartz varies from 

white to dark gray. It is not abundant enough to be of commercial 

importance.

The feldspar is buff. to cream-colored orthoclase and microcline, 

occurring principally in graphic intergrowth with quartz. At the 

northwest end of the larger pit are some masses of nearly pure feldspar 3 feet across, but these are exceptional.

 Biotite in the usual lath-shaped crystals, some attaining a length 

of 3 feet, is very abundant and is the most injurious of the mineral 

constituents, black tourmaline being wholly absent so far as observed.

Pink opaque garnets occur here and there, but are not abundant. 

Many of these are inclosed by muscovite.

As far as could be observed the quantity of feldspar suitable for 

the manufacture of pottery still remaining at this locality is very 

small, the prevalence of biotite rendering most of the material worthless for t^e potter's use. The water in the larger pit prevented it's 

thorough examination. An exploration of the region near this quarry 

yielded no information as to the trend or extent of this deposit and 

showed no other masses of commercially valuable feldspar. Gem 

minerals have not been reported from this locality and there are no' 

indications, such as the occurrence of pockets, lepidolite, black tourmaline, etc., that any are likely to be found. Under present commercial conditions the deposit may be regarded as worked out. It 

may be of value in the future if some commercially practically method 

of separating the mica can be devised, or the feldspar may be used 

for purposes where the presence of black mica (biotite) is npt detrimental, as for fertilizing or for*poultry grit.

OXFORD COUNTY. 

HEBRON.

Hibls quarry. A small feldspar and mica mine was opened in 

1906 about 1| miles north of the village of Hebron, near the Buckfield road. It is on the farm of Alton Hibbs and was operated in 

1906 by J. A. Gerry, of Mechanic Falls, and W. Scott Robinson. 

It was abandoned in 1<007. The property was visited by the writer 

in August, 1906, after considerable stripping and prospecting had 

been done. The ledge was exposed for a distance of 300 to 350 feet 

along the southwest side of the valley of a small creek, the outcrop 

averaging in width about 30 feet, though it increased to 50 feet at 

one point at least. Only shallow excavations had been made at the 

time of the writer's visit. The expqsures show numerous masses of
MAINE. ' 29

pure orthoclase-microcline feldspar, 2 to 3 feet across, associated with 

much graphic granite. In color the spar ranges from mottled buff 

to blue-gray. Small amounts of the soda feldspar, albite, are occasionally found. It was estimated that the feldspar of commercial 

grade.for pottery purposes formed about 60 per cent of the rock 

mined\ The principal iron-bearing impurity is black tourmaline, but 

this is so aggregated that it can be readily separated in the mining. 

Biotite is present in the usual lath-shaped crystals up to 1 foot wide 

and 3 feet long, but is not at all abundant.

Muscovite is found in most parts of the pegmatite in small "books" 

up to 2 to 3 inches across, but occurs abundantly and in larger plates 

only at the southwest border of the pegmatite mass. Here, in a 

;,;.zone averaging 3 or 4 feet in width, the mica " books" average 5 

pinches in diameter' and one observed was 30 inches, though imperfect. 

It is estimated that in this zone muscovite constitutes on the average 

at least 10 per cent of the rock and in some places 20 per cent. Of 

this mica it was estimated that fully 60 per cent could be trimme.d 

into plates, the remainder being usable only as scrap mica. Wedge 

structure and ruling are the common defects. Plates as large as 

5 by 6 inches could be trimmed from a few of the mica books.

Exposures are not numerous enough to reveal the full form or extent of the pegmatite mass. On its southwest side it is bounded by 

quartz-mica schists whose trend varies from N. 30° W. to N. '50° W., 

averaging about N. 45° W. and apparently dipping to the northeast 

at an angle of about 45°. The northeast border of the deposit is 

wholly obscured by drift. The mica-rich band which follows the 

southwest margin of the pegmatite mass can be traced for nearly the 

whole distance that the pegmatite mass itself is exposed that is, 

300 to 350 feet.

From the exposures made at the time of the writer's visit this 

property was regarded as a promising one for both feldspar and mica 

mining. It seems probable that further stripping will show that the 

deposit extends northwest and southeast of the present exposures, 

and since the deposit seems to be steeply inclined there is no reason 

why it should not persist in good quality to a considerable depth. 

The development work was suspended for reasons wholly aside from 

the quality of the deposit. All the product must be hauled by teams 

3 miles to Hebron station, on the Rangeley division of the Maine 

Central Railroad.

Mills feldspar quarry. A small abandoned feldspar quarry on 

Number Four Hill, near the Paris-Hebron line, was visited by the 

writer in August, 1906. The quarry was worked by the Mount Marie 

Mining Company in 1901 but was soon abandoned.
30 FELDSPAR DEPOSITS OF THE UNITED STATES.

The principal pit here is about 75 feet long by 30 feet wide and 

10 feet in maximum depth. A second pit close by is about 30 by 30 

feet and 10 feet deep.

The bulk of the feldspar belongs to the potash varieties, orthoclase 

and microcline, though some albite of the clevelandite variety-occurs 

in the coarser-grained portions. In the northwest part of the'.larger 

pit some masses of pure spar are 3 to 4 feet across. The bare ledge 

to the north of the smaller pit for a length of 40 or 50 feet and a 

width of about 30 feet shows feldspar in crystals 2 to 4 feet across 

but containing numerous small crystals of black tourmaline. In 

the northwest end of the larger pit there is a small amount of feldspar 

of commercial grade, but in the smaller pit and in the unopened ledge 

near the pits black tourmaline is so intimately and abundantly associated with the feldspar as to render most of it valueless for pottery 

purposes under present .commercial conditions. The coarsest and 

most highly feldspathic portion of the deposit exposed in the larger 

pit contains some clevelandite and granular lepidolite and a few 

colored tourmalines, of pink and green tints, which are translucent 

to opaque. Several small pockets less than a foot in diameter were 

exposed at the time of the writer's visit. In some of the pockets a 

few transparent tourmalines of gem quality were found in the course 

of the mining operations. South of the workings the ledge shows 

very little feldspar of pottery grade, and within 200 feet there begins 

to be some admixture of schist with the pegmatite.

Muscovite has been saved in the mining, but most of it is what is 

known as wedge mica and would be valueless except as a source of 

ground mica. Biotite or black mica is very rare, black tourmaline 

being the principal iron-bearing impurity.

The trend and exact limits of this deposit could not be determined,

but it is evident that the supply of feldspar here that is suitable for 

use in the pottery trades is very small, most of the material showing 

too great an abundance of black tourmaline. An examination of 

the whole crest of the hill south of the pits showed no spar or other 

minerals of commercial grade. Even if the mica and tourmalines 

were marketed as accessories it is probable the deposit could not be 

made to pay.

No mining machinery was installed at this locality. The feldspar 

was hauled 5 miles, mostly down grade, to South Paris, on the Grand 

Trunk Railroad. Only a few tons were shipped, and much spar now 

lies in stock piles at the quarry.
MAINE. 31 

SAGADAIIOC COUNTY.

GEORGETOWN.

Golding's feldspar quarry. One of the most productive feldspar 

quarries in Maine, and one which has been worked intermittently for 

over thirty years, is located near the east shore of Todds Bay, near 

the mouth of Kennebe6. River, and is now owned and operated by 

Golding's Sons Company, of Trenton, N. J. It may be reached by 

a drive of 11 miles from Woolwich or by steamer from Bath to Bay 

Point Landing, which is only about 1$ miles from the quarry. The 

Bath topographic sheet of the United States Geological Survey covers 

this area. The property was visited by the writer in July, 1906, 

and again in November, 1908.

The excavations consist of three open pits covering an area of about 

3 acres. The southernmost pit, which is the oldest and largest, had

been abandoned for many years at the time of the writer's visit in 

1906, but in 1908 quarry waste that had been dumped in it was being 

removed and new excavating had revealed considerable amounts of: 

excellent feldspar. It is significant that much of the waste material 

dumped into this pit in the early mining is of good commercial grade, 

according to present standards, and is being saved. In the early days 

graphic granite was mostly discarded and only practically pure feldspar utilized. This pit is now about 100 feet in depth. The northernmost pit, from which large amounts of spar, have recently been 

taken, is 200 feet long in a direction N. 25° E., 40 to 75 feet wide, 

and 20 to 30 feet deep.

The rock from this quarry that is used commercially is mainly 

a coarse graphic intergrowth of feldspar and quartz, and it is estimated that commercial rock forms about One-half of the total material excavated, the other half being waste, which is highly quartzose 

or contains muscovite or iron-bearing minerals.

Most of the feldspar is orthoclase or microcline, but there are small 

amounts of albite. The following analysis by the Pittsburg Testing 

Laboratory of the best grade of buff-colored feldspar from this quarry 

was furnished by the company:

Analysis of feldspar from Golding's quarry, Georgetown, Me.

Silica (Si02 ).................................................. 65. 23

Alumina (A1 2 03 )..........'................................... 20. 09

Iron oxide (Fe203)............................................ .71

Lime (CaO)................................................. None.

Magnesia (MgO).............................................. None.

Potash (K2 0)-................................................ 11. GO

Soda (Na20).................................................. 2. 00

Loss on ignition............................................... .36

99. 99
32 FELDSPAR DEPOSITS OP THE UNITED STATES.

Very few large masses of pure feldspar are exposed in the present 

quarry openings, but it is said that in the past some single blasts have 

loosened 100 tons of almost pure feldspar. In the southern pit a 

number of masses of pure feldspar several feet across were exposed 

in 1908, but most of the rock here and practically all that is exposed 

at the middle and northern pits is an intergrowth of quartz and 

feldspar. Most of this intergrowth, however, is of excellent quality 

for pottery uses, for as a rule injurious minerals, such as muscovite 

and black tourmaline, are confined to certain portions of the mass 

and can thus be readily separated from the rest of the rock in mining.

The quartz of this quarry is mostly gray and semiopaque, and 

much of it has a granular appearance. In a few places it is slightly 

pinkish in hue. Most of the masses of pure quartz are small, the 

largest observed by the writer, a mass in the northernmost pit, being 

6 feet across. It is not utilized commercially.

Muscovite is not present in sufficient amounts and is not of the 

proper quality to be of commercial importance. Graphic intergrowths of quartz and muscovite are found locally, as-are rounded 

aggregates that are made up almost entirely of small muscovite crystals and are similar to those at the G. D. Willes. quarry in Topsham.

Biotite is almost entirely absent. In its stead occurs black tourmaline, which is locally very abundant in prismatic crystals, some of 

them 2-| to 3 inches in diameter and a foot or more in length. The 

tourmaline is not evenly distributed through the pegmatite, but is confined almost entirely to certain irregular zones which may be avoided 

or discarded in the quarrying process. It is more abundantly associated with the quartz than with the feldspar.

Garnet occurs in deep flesh-colored crystals, most of them small 

and associated with quartz and muscovite.

Light-green opaque beryl is found occasionally, one mass penetrating quartz being 14 inches long and 4 inches in diameter.

The contact of the pegmatite with other rocks is not exposed in any 

of the quarry openings, but is fairly well shown a few rods northeast 

of the quarry, near the highest part of the hill on which the quarry is 

located. Here the bordering rocks are schists with strike .slightly 

east of north and dip almost vertical. The contact nearly parallels 

the trend of the schists and the pegmatite is plainly intrusive, locally 

cutting across the foliation of the schists and sending off broad 

tongues into them.

The excavations at the Golding quarry cover almost the whole 

outcrop of the pegmatite body there mined. Future quarrying will 

probably consist largely in deepening the present pit, but there is 

reason to expect that the deposit will continue of good quality and of 

about the same dimensions to a considerable depth. A number of 

other pegmatite dikes of similar size and shape occur in this vicinity ?
MAINE. 33

and some of them have been worked to a slight extent. None of 

these, as far as seen, showed any large amount of feldspar of commercial grade.

The rock is excavated by steam drilling and dynamite blasting, 

and that in the largest pit is hoisted by derrick and hoisting engine. 

It is broken up and sorted by hand and then loaded onto wagons 

which haul it a quarter of a mile to the shore, where it is transferred to 

small sailing barges, which convey it either to vessels for shipment to 

Trenton by water, or up Kennebec River 10 miles to Bath, for shipment by rail. About fifteen men are usually employed in this quarry.

Abandoned feldspar quarry. A small feldspar quarry, now abandoned and partly filled with water, is located one-half mile east of the 

Goldings quarry, near the head of Sagadahoc Bay and east of the 

highway. It is a single pit about 75 feet long, 35 feet wide, and probably 30 to 40 feet deep, though only 25 feet of wall shows above the 

water level. The rock is similar in nearly every respect to that quarried at the Goldings quarry, but the area of the deposit seems to be 

very small, schist occurring within a hundred feet to the north, west,

and south of the pit.

TOPSHAM.

General character and relations of the deposits. The feldspar quarries 

in the town of Topsham all lie within a belt about a mile wide, which 

extends northeastward from Mount Ararat, near Topsham village, 

nearly to the Topsham-Bowdoinham line. Within this belt are eight 

quarries, only three of which are now active, and, in addition, a number of prospect pits. It is significant that the line of distribution of 

these quarries corresponds closely with the trend of the metamorphosed sedimentary schists into which the pegmatites were intruded. 

Because of the depth of the soil it is impossible to determine exactly the 

limits of the coarse pegmatite bodies exposed at each of these eight quarries, but a study of the rocks between the various quarries shows that 

the pegmatite bodies which are worked are not parts of a single mass, 

but are more or less detached masses of pegmatite in a region where 

the rocks are mainly schists. Within this belt, however, the pegmatitic 

intrusions are more numerous and some of them are of coarser texture than in the surrounding country. If the form of the smaller and 

finer-grained pegmatite masses may be taken as an index to the form 

of the larger and coarser ones that are commercially valuable most of 

the latter are probably somewhat elongate in a direction slightly east 

of north, parallel to the general trend of the inclosing schists and 

gneisses.

Feldspar is the only mineral of much commercial importance at 

any of these quarries. Quartz of excellent quality is present in considerable amounts, and much of it is saved in quarrying, though at 

16779 Bull. 420 10 3
34 FELDSPAR DEPOSITS OF THE UNITED STATES.

present it finds but slight market. At some of the quarries tourmalines and aquamarines of gem quality are now and then obtained. 

A description of the quarries in the order of their distribution from 

southwest to northeast is given below.

Mount Ararat feldspar quarries. Feldspar and quartz have been 

obtained from a quarry on the eastern slope of Mount Ararat, about 

a mile north of Topsham village. The deeper part of the hillside 

excavation here is about 40 feet long from east to west, 10 feet wide, 

and 12 feet in maximum depth. A shallow excavation adj acent to the 

northwest part of the deeper pit covers an area about 20 by 30 feet in 

size. The quarry has not been operated for several years.

The lower pit exposes considerable amounts of clear white, gray, 

and nearly black semiopaque quartz, but shows few masses of pure 

feldspar more than 3 to 4 inches in diameter. Several tons of quartz 

that have been saved in the quarrying process are now piled near the 

pit, though feldspar was the principal mineral sought. The feldspar is 

cream colored to nearly white and is shown by microscopic examination to be principally microcline with occasional very small amounts 

of the white soda feldspar, albite. In the upper and shallower portion 

of the quarry the amount of pure quartz is less and the amount of pure 

feldspar is greater than in the lower portion. Some of the masses of 

pure feldspar there are 3 to 4 feet across. They grade into a coarse 

graphic intergrowth of quartz and .feldspar, which in turn grades into 

extremely fine graphic granite. Only the pure feldspar and the coarse 

graphic granite were used commercially. Among the iron-bearing 

minerals that would injure the quality of the feldspar for pottery 

purposes black tourmaline is almost entirely absent and black mica 

(biotite) is rare. Garnet is a rather abundant constituent, but is 

associated mainly with the muscovite and with the finer-grained 

portions of the pegmatite and only rarely with the more feldspathic 

parts that are commercially available. Magnetite occurs rarely, in 

small irregular octahedra.

Muscovite, or white mica, is also an abundant constituent of the 

pegmatite exposed in the upper pit. It is pale green to nearly colorless and occurs in " books," some of which are 8 to 10 inches in 

diameter. The great bulk of the muscovite is of the wedge variety 

and shows twinning, and could be utilized commercially only as scrap 

mica. A small amount is plate mica and splits readily into sheets 

which, when trimmed, may measure 4 by 5 inches, though most of 

them are smaller. As a rule, however, this plate mica incloses between its lamellsB thin, branching crystals of magnetite, and would 

therefore be useless for electrical and most other purposes to which 

plate mica is usually applied.

Occasionally small masses of columbite, most of them exhibiting 

very imperfect crystal forms, are found in the quartz-feldspar masses.
MAINE. 35

The wall rock of schist or gneiss is nowhere exposed at this quarry, 

and the depth of the soil makes it impossible to trace exactly the 

limits of the deposit. If we may judge from neighboring masses of 

pegmatite whose boundaries are exposed, this mass is probably more or 

less irregular in outline and somewhat elongate in a direction parallel 

to the trend of the neighboring schists that is, somewhat east of 

north. The deposit appears to be not very extensive but the quality 

of the product is good, and there seems to be warrant for further 

development work on a small scale.

A second small feldspar quarry is on the northern slope of Mount 

Ararat. It consists of a single hillside pit about 150 feet long, 30 feet 

in average width, and 20 feet in greatest depth. It is not now worked, 

but was -worked as recently as 1905. The rock at this quarry is a 

wholly irregular association of quartz, feldspar, muscovite, biotite, and 

garnet, with smaller amounts of rarer minerals. The quartz is prevailingly dark gray in color and semiopaque, though here and there 

it is white and in a few places nearly black. Some of the pure quartz 

masses are 3 to 4 feet across. One flat-lying irregular mass exposed 

at the base of one of the quarry walls is 5 feet in maximum width 

and 25 feet in length.

Most of the feldspar is pale pink, but certain portions are cream 

colored, while other parts are decidedly red. Microscopic examination shows that the feldspar belongs mainly to the potash varieties, 

orthoclase and microcline, the former greatly predominating. With 

these are associated small amounts of the soda feldspar, albite, which 

is here and there intergrown microscopically with the orthoclase or 

microcline. Throughout the greater part of the quarry the masses 

of pure feldspar are. not more than 4 to 5 inches across, though a few 

crystals 2 to 3 feet across are found. The bulk of the material 

quarried for pottery use is a graphic intergrowth of feldspar and 

quartz, most of it coarser than that found at the quarry on the eastern 

slope of Mount Ararat. Some of the quartz thus intergrown with the 

feldspar assumes branching or dendritic forms, a characteristic not 

generally observed in pegmatite deposits.

Muscovite of the wedge variety occurs sparingly in "books" up to 

6 inches in greatest diameter and also in intergrowth with quartz and 

feldspar. No clear plate mica was observed.

Biotite is much more abundant here than at the quarry on the 

east side of Mount Ararat and predominates over muscovite. It 

occurs in the characteristic lath-shaped crystals, many of them 2 

feet long, 4 to 5 inches wide, and one-half an inch to 1 inch thick.. 

The largest biotite crystal observed was 3£ feet long, 2£ feet wide, 

and 1 to 2 inches thick. These crystals penetrate the pegmatite 

mass in every conceivable direction.
36 FELDSPAR DEPOSITS OF THE UNITED STATES.

Garnet is rather abundant and as a rule is dark red and submetallic 

in appearance. It is here and there intergrown with quartz or with 

quartz and muscovite. One garnet crystal was 2£ inches across. 

Garnet is most abundant in the finer-grained portion of the pegmatite 

and in those portions that are rich in muscovite. It is rare in the 

parts that .are used commercially. Magnetite occurs only rarely, in 

imperfect octahedra showing step structure.

Schists and gneisses are nowhere exposed in this quarry and outcrops near the quarry are not numerous, so that it is impossible to 

determine the form or area of this body of pegmatite. On the north 

wall of the quarry a small mass of fine-grained granite showing 

locally a somewhat gneissic structure is exposed and is intruded by the 

pegmatite, which cuts across the banding of the granite gneiss.

The amount of feldspar of commercial quality now exposed is not 

large and the abundance of biotite and garnet render much of the 

material valueless for pottery uses. The extent of the deposit can 

not be determined, but it is probably not very great. Further development on a small scale could perhaps be profitably undertaken 

and might reveal some good spar not now exposed. The deposit is 

2 miles from the Maine Central Railroad station at Topsham. The 

nearest point on the railroad is only three-fourths of a mile southeast 

of this quarry and the one previously described, but no wagon road 

is available for transportation in this direction.

Fisher's feldspar quarry. A small quarry not now worked is situated \\ miles west-northwest of Cathance station on a southern 

hill slope in the valley of Cathance River. This quarry, which was 

formerly operated for feldspar by J. A. Fisher, consists of a single pit 

about 150 feet long from north to south, 20 feet or so in average width, 

and about 18 feet in maximum depth.

Here, as in most other feldspar quarries, there is no regularity in 

the arrangement of the constituent minerals with the single exception 

of muscovite, which occurs principally along certain zones whose 

trends, however, have no definite relation to the general outlines of 

the deposit.

The quartz is white to gray in color, but no very large masses are 

exposed.

The feldspar is cream colored and is shown by microscopic examination to be microcline with some orthoclase finely intergrown with 

small amounts of soda feldspar (albite). One mass of pure feldspar 

exposed on the west wall of the quarry was 3 to 4 feet wide and 10 feet 

high. This passes by perfect gradations into a coarse graphic intergrowth with quartz, and this in turn into a much finer graphic intergrowth. Here, as in most other feldspar quarries, the coarse graphic 

granite forms the bulk of the material mined for pottery purposes.
MAINE. 37

The chemical and mineralogical composition of graphic granites from 

this quarry are shown on page 14.

The muscovite, so far as the present exposures show, is all of the 

wedge variety. It is confined mainly to certain zones which penetrate the pegmatite irregularly. None is of commercial value except 

for grinding. Being localized in this manner it does not seriously 

interfere with the feldspar mining. Graphic intergrowths of quartz 

and muscovite are common. In' some parts of the pegmatite, biotite 

dominates over muscovite, but is usually most abundant in the finergrained portions of the pegmatite.

Outcrops are not numerous enough in the immediate vicinity to 

determine the extent or form of the pegmatite body. The materials 

exposed in the present excavation indicate that a considerable supply 

of spar is still available and seem to warrant further development.

William Willes feldspar quarry. A small quarry opened early in 

1906, at a point 1£ miles northwest of Cathance station, is operated by 

William Willes for the Trenton Flint and Spar Company. It occupies an area of a little more than 1 acre, and the average depth of 

excavation is about 10 feet. Natural drainage is possible at present 

depth, but further excavation will necessitate pumping. The rock 

is a wholly irregular association of quartz, feldspar, mica, and-rarer 

minerals.

The quartz is mainly light gray in color and occurs locally in pure 

masses 5 or 6 feet in diameter. Many of even the larger quartz 

masses exhibit crystal faces along their contact with other minerals. 

Quartz is saved in the quarrying process, though it finds only a very 

irregular market.

The feldspar is buff colored and is mainly orthoclase and microcline. The soda variety, albite, also occurs, but forms only a small 

percentage of the total mass of feldspar. A few crystals of albite are 

4 to 5 inches across. The great bulk of the material quarried for 

pottery purposes here, as at most of the Maine feldspar quarries, is a 

coarse graphic intergrowth of quartz with potash feldspar. In the 

northern part of the quarry a mass of pure feldspar 10 feet across is 

exposed on a glaciated surface.

Muscovite occurs in graphic intergrowth with quartz and also in 

"books," most of which are of the variety known as wedge mica. 

Some of these "books" are 10 inches across. The total amount of 

muscovite present is not sufficient to make it worth while to save it 

in the quarrying process.

Biotite is about as abundant as muscovite and occurs in the characteristic lath-shaped crystals. One of these was 4 feet long, 8 

inches wide, and 1 inch thick. Much of the biotite is decomposed to 

what appears to be chlorite colored with hematite.
38 FELDSPAR DEPOSITS OF THE UNITED STATES.

Garnet is moderately abundant, usually occurring in compound 

crystals of dark-red color with submetallic luster.

Beryl is moderately abundant, some hexagonal crystals being 

10 inches in diameter. Some of the smaller crystals are partly 

transparent and have been sold to mineral collectors.

Columbite is found occasionally in small, imperfectly developed 

crystals, but is not sufficiently abundant' to be of commercial importance.

In one place in the quarry a small amount of hornblendic granite 

gneiss occurs. The pegmatite boundary cuts across the foliation of 

the granite gneiss and is plainly somewhat later. The exact attitude and boundaries of the pegmatite mass could not be determined 

because of the scarcity of outcrops in the vicinity of the quarry, but 

it is probable that further stripping near the present workings will 

reveal considerable amounts of commercially valuable spar.

At-the time of the writer's visit seven laborers were employed in 

the quarry besides the foreman and the superintendent. The rock 

is hauled by two-horse teams a distance of 1^ miles to the feldspar 

mill near Cathance station. ^

Maine Feldspar Company's feldspar quarry. A small feldspar 

quarry a few rods southeast of that operated by William Willes was 

opened in 1906 by the Maine Feldspar Company of Auburn, Me. 

The rock is similar in every way to that at the William Willes quarry. 

The rock is hauled by team about 1| miles to Cathance station and 

from there shipped by rail to the Maine Feldspar Company's mill at 

Littlefield, 3 miles southwest of Auburn.

G. D. Willes feldspar quarry. The oldest and by far the largest of 

the Topsham quarries is about 2 miles northwest of Cathance station 

and is operated for the Trenton Flint and Spar Company by G. D. 

Willes. It is an irregular opening covering several acres and the 

material is excavated from several levels, the greatest depth being 

about 50 feet. (See PL V, A.)

Although the great bulk of the commercial spar now taken from 

this quarry is a coarse graphic intergrowth of feldspar and quartz, it 

has yielded masses of pure quartz and of pure feldspar that are larger 

than those seen at any other quarry in the State. A single mass of 

pure white quartz in the northern part of the quarry is 50 feet long 

and is exposed for a height of 10 feet. The pegmatite is in general 

coarser at the north end than at the south end of this quarry.

The feldspar also occurs occasionally in crystals of large size, one 

in the northern part of the quarry being 15 feet across. The bulk of 

the feldspar, as shown by microscopic study, is of the potash varieties 

orthoclase and microcline, finely intergrown with soda feldspar 

(albite), and there are small masses, most of them only a few inches 

across, of pure white albite.
U. S. GEOLOGICAL SURVEY IULLETIN 420 PLATE V

A. CRYSTAL OF MICROCLINE FELDSPAR IN ROARING CREEK 

FELDSPAR QUARRY, CONNECTICUT.

Crystal faces painted for photograph ing. Front face is the fr-pinacoid. Hammer 

rests on the c-pinacoid. The crystal was originally entirely inclosed by 

pegmatite.

P**>''~ I %.- -". W

B. PORTION OF G. D. WILLES FELDSPAR QUARRY, TOPSHAM, MAINE 

- Photograph by Prof. Leslie A, Lee. - . .., : . - 
MAINE. 39

Muscovite is concentrated principally along certain belts that 

traverse the pegmatite mass in various directions, but in the southern 

part of the quarry it occurs in rounded aggregates, some of them 5 

feet across, of small, heterogeneously arranged plates averaging 

about one-fourth inch across. Some graphic intergrowths of quartz 

and muscovite occur, but they are not abundant. Under present 

conditions it would probably not pay to save as scrap mica the muscovite obtained in mining the feldspar. No plate mica occurs.

Biotite is moderately abundant in certain parts of the pegmatite, 

penetrating the feldspar -and quartz as long, lath-shaped masses, the 

largest of them 2 yards long by 3 inches wide and one-fourth of an 

inch thick.

Small garnets here, as in most other feldspar quarries, are abundant 

only in certain portions of the deposit, the coarser graphic granite 

and the pure feldspar being almost entirely free from them, and they 

can be readily separated in mining.

Many cavities up to 1 foot in diameter and of various forms are 

found in the coarser portions of the pegmatite in the northern part 

of the quarry. Most of these cavities contain groups of somewhat 

smoky semitransparent quartz crystals, some of which make handsome cabinet specimens. In a few of these cavities transparent 

green tourmalines and aquamarines (beryl) of gem quality have been 

found.

The schists and gneisses that border the pegmatite are exposed at 

the southern end of the quarry, where they show evidence of some 

softening as a result of the pegmatite intrusion. In general they lie 

rather flat. Probably the pegmatite mass is also in general somewhat 

flat lying, though very irregular. It is probable that the workable 

pegmatite does not extend southward much beyond the limits of the 

present pit, but it is known to extend north of the Willes quarry into 

property that is said to be controlled by the Maine Feldspar Company. 

Here it has been worked in the past from a number of small openings 

and very considerable amounts of commercial spar are still available.

The methods of operation at this quarry are somewhat antiquated 

for a working of this size, the drilling all being done by hand and the 

blasting by black powder. A tramway carries the waste to dump 

piles and the good rock to stock sheds, from which it is loaded into 

wagons and hauled If miles to the mill described below, near Cathance station.

Feldspar mill of the Trenton Flint and Spar Company. The feldspar 

mill of the Trenton Flint and Spar Company is on Cathance River 

about one-half mile north of Cathance station. During high water 

it utilizes the water power of this small river, but it is also provided 

with steam power. The equipment consists of three chaser mills 

and four ball mills of the types usually used in feldspar mills. The
40 FELDSPAR DEPOSITS OF THE UNITED STATES.

grinding process is that described on page 18. The capacity of the 

mill is about 16 tolls in twenty-four hours, the ground spar being 

hauled by wagon for one-half mile from the mill to Cathance station, 

on the Maine Central Railroad, where it is loaded for shipment.

Feldspar quarry in northern part of the town of Topsham. A feldspar quarry one-half mile west of Cathance River, and 1 mile south of 

the Topsham-Bowdoinham line was formerly operated by the Trenton 

Flint and Spar Company, the rock being hauled by team 2 miles to 

the mill near Cathance station. This quarry, which is on the western 

slope of the river valley, is an irregular opening extending north and 

south along the hill slope for about 200 feet and running into the hill 

for about 40 feet. There is no regularity in the arrangement of the 

pegmatite constituents.

The quartz is prevailingly white or light gray, though some of it is 

smoky.

The feldspar is white to cream-colored and is shown by microscopic examination to be mainly orthoclase, though it includes small 

amounts of albite and microcline. The albite in places forms a fine 

microscopic intergrowth (microperthite) with the orthoclase; some 

masses of pure feldspar here have a diameter of 4 to 5 feet, but the 

bulk of the material quarried for the manufacture of pottery was a 

graphic intergrowth of quartz and feldspar.

Muscovite, mostly pale green in color, is as a rule graphically 

intergrown with quartz, though there are a few '' books'' of clean mica, 

the largest 5 or 6 inches in diameter. All of those observed are of the 

wedge variety and the quantity is so small that it would be hardly 

worth while to save them for scrap mica.

Biotite, which is not very abundant in any part of the quarry and 

is in some parts wholly absent, forms thin lath-shaped .crystals 

averaging about 6 inches long, 1 inch wide, and a quarter of an inch 

thick.

Garnet is absent from much of the pegmatite, but is locally abundant in the finer-grained portions, occurring in crystals from onesixteenth to one-quarter of an inch in diameter. Very rarely crystals 

as much as 3 inches in diameter are found, and in these the garnet is, 

as a rule, graphically intergrown with quartz. The color varies from 

pink to deep red and opaque submetallic.

The area and form of this pegmatite body could not be determined because of the scarcity of outcrops in the vicinity of the quarry, 

but the occurrence of small masses of pegmatite of commercial grade 

short distances east and west of the quarry indicates that the 

deposit may have a considerable extension beyond the area now 

exposed.

The abundance of material now in sight and the freedom of most 

of it from iron-bearing minerals would favor further development.
U.S.GEOLOGICAL SURVE1

PRELIMINARY GEOLOGIC MAP OF A PORTION OF CONNECTICUT

Hist. Survey

SHOWING LOCATIONS OF FELDSPAR QUARRIES AND MILLS 

' ° * ' ~~ * » Miles

LEGEND 

GRANITE GNEISSES

Glastonbury Monson

GNEISSES OF COMPLEX ORIGIN

Maromas Had dam

TRIASSIC

Bolton

__I Hebron Middletown Diabase (dikes) Sandstone and shale Basalt

Active feldspar Inactive feldspar Feldspar mill 

quarry quarry
FELDSPAR DEPOSITS OF THE UNITED STATES. 41 

MASSACHUSETTS.

Small quantities of feldspar have recently been quarried by the 

Blandford Quarries Company, of Boston, near Blandford, in Hampden County, and shipped for grinding to Trenton, N. J. This property has not been visited by the writer.

CONNECTICUT. 

GENERAL STATEMENT.

For many years Connecticut has ranked among the most important 

of the feldspar-producing States, and in 1908 it stood first in the value 

of the feldspar produced. In that year feldspar was obtained from 

eight quarries, all of them near Connecticut River in Middlesex 

County and in the southern part of Hartford County. There are 

three feldspar mills in the State, two at South Glastonbury and one at 

White Rocks, near Middletown. (See PL VI.) Much of the feldspar, 

however, is ground outside of the State, at Trenton and other pottery 

centers. All the active quarries and some that are now idle were 

visited by the writer in November, 1907, and are described below.

The geologic relations of the deposits are not fully known, but all 

are typical granite pegmatites and are believed to be intrusive in the 

bordering rocks. The Connecticut Valley pegmatites that are worked 

occur near the borders of large areas of granite gneiss mapped by 

the Connecticut Geological and Natural History Survey as Glastonbury granite gneiss and Haddam granite gneiss. It is highly probable that they are connected with one or both of these in origin. In 

Connecticut, as in other States, most of the pegmatite masses are 

more or less lens-shaped and their longest diameter is, as a rule, 

parallel or nearly parallel with the trend of the bordering rocks. In 

at least one place, however, the pegmatite is a vertical dikelike mass 

cutting sharply across the foliation of the inclosing granite gneiss.

The form and size of the quarries vary greatly. All are open 

pits, and the largest one, the Howe quarry, 2 miles south of South 

Glastonbury, has a length of about 500 feet, an average width of 

100 feet, and a maximum depth of 50 feet. From these dimensions 

the openings range downward in size to mere prospect pits. The 

feldspar from all these deposits is white to cream-colored potash 

feldspar (microcline or orthoclase) delicately intergrown with varying but minor amounts of soda feldspar (albite). Masses of pure feldspar more than 2 to 3 feet across seldom occur, and most of the material quarried is either a graphic or an irregular intergrowth of quartz 

and feldspar. From most of the quarries only one grade is shipped, 

which ranks commercially as No. 2, or "Standard." Quartz does 

not occur in commercial quantities at most of the feldspar quarries,
42 FELDSPAR DEPOSITS OF THE UNITED STATES.

and none is shipped. The quarrying processes are those commonly 

employed elsewhere.

Feldspar has been quarried at a number of places in the western 

part of the State in Litchfield, New Haven, and Fail-field counties 

and a feldspar mill was operated at Glenville, in Fairfield County. 

Microcline feldspar of good quality for pottery manufacture occurs 

associated with quartz in the quartz quarry of the Bridgeport Wood 

Finishing Company, near Southford, New Haven County, but is not 

saved in the mining.

HARTFORD COUNTY. 

GLASTONBURY.

Roaring Broolc quarry. A small quarry one-half mile east of South 

Glastonbury, on the south side of the valley of Roaring Brook, was 

formerly worked by the Eureka Mining and Operating Company. 

It was visited by the writer in November, 1907. A small hillside 

opening shows granite-pegmatite intrusive in a gray to purplish 

mica schist, probably the Bolton schist of the Connecticut Geological 

Survey. The schist is rather flat-lying and the attitude of the pegmatite body is probably similar. The line between the pegmatite and 

schist is very sharp, and there is no noticeable change in texture in 

either as the contact is approached. The constituents of the pegmatite show a slight tendency to lie in very uneven and not very 

noticeable bands, approximately parallel to the banding of the schists, 

this feature being most apparent in the quartz layers.

The quartz is opaque and milky white. The feldspar is buff 

microcline, finely intergrown with albite. It occurs in pure masses 

up to 3 feet across, some of which are characterized by very perfect 

crystal faces, though they were originally entirely inclosed by finergrained portions of the pegmatite. One of these feldspar crystals 

which has been partly uncovered during quarrying is shown in Plate 

V, A, the crystal faces having been painted for photographing, so as 

to show up more clearly. The side or & pinacoid is toward the front. 

The hammer rests on the third or c pinacoid. This crystal shows 

strikingly the tendency of feldspar crystals in many pegmatites to 

develop perfect faces, even when they are entirely inclosed by other 

constituents. The pure feldspar of the crystal grades below into 

arborescent intergrowths of feldspar and quartz containing small 

muscovite plates. The crystal is bordered above by light-gray 

quartz and by muscovite "books," many of them 3 or 4 inches in 

diameter. Some of the muscovite plates lie perpendicular to the 

border of the feldspar crystal; others lie nearly parallel to it and 

curve around the crystal angles in a manner suggesting that they 

may have been somewhat deformed by the forces of crystal growth 

in the feldspar. Some of the muscovite "books" at this quarry
U. S. GEOLOGICAL SURVEY BULLETIN 420 PLATE VII

PEGMATITE DIKE INTRUDED ALONG FRACTURE PLANE IN GRANITE GNEISS 

AT FELDSPAR QUARRY NEAR EAST GLASTONBURY, CONN.

It. QUARTZ DIKE CUTTING PEGMATITE AT HOWE QUARRY, SOUTH GLASTONBURY, CONN.

Showing light-colored feldspar crystals with well-developed crystal faces projecting into the quartz of the 

dike. The quartz appears dark colored in the photograph.
CONNECTICUT. 43

are 6 inches thick and 4 to 6 inches wide. Nearly all are characterized by close ruling and crumpling and are not of commercial value 

except for ground mica. The fracture planes known as ruling are so 

closely spaced in some places that the mica near them is reduced to 

an aggregate of long fibers. Small folds in the mica pass at many 

places into planes of ruling. These therefore some of them at 

least represent a yielding to deformation. Biotite is present only 

rarely and in small plates or aggregates. Garnet is abundant in 

the finer-grained portions of the pegmatite and renders much of the 

material valueless for pottery purposes.

The amount of feldspar of pottery grade at this locality appears 

to be small and the quarry was very properly abandoned.

East Glastonbury quarry. A feldspar quarry 2£ miles northeast of 

South Glastonbury, near the road to East Glastonbury, is worked

by a firm that uses the product entirely in the manufacture of abrasive 

soaps. This quarry is on the farm of Frank G. Curtis and. consists 

of a single pit about 250 feet long, trending northeast and southwest. It is about 30 feet wide at the northeast end and narrows to 

15 feet at the southwest end, having an average depth of about 20 

feet.

The bordering rock, a biotite granite gneiss, is well exposed at the 

quarry. The pegmatite forms a nearly vertical dike which cuts 

across the trend of the gneiss. (See PI. VII, A.) The metarnorphic 

effects of the pegmatite on the gneiss have been so slight that the 

contacts are of knife-edge sharpness, the delicate foliation of the 

gneiss being perfectly preserved quite to the contact with the pegmatite. At the small granite quarry about one-fourth mile from 

the feldspar quarry pegmatite dikes up to a foot in diameter cut 

sharply across the folia of the granite gneiss without evidence of 

contact metamorphism. The main pegmatite mass at the feldspar 

quarry shows absolutely no change in texture near the walls. It 

sends off into the bordering granite gneiss a number of small branches, 

which also show little change in texture near their walls, though in 

some there is a slight increase in the amount of quartz next the walls 

and near the ends of the branches.

The rock at this quarry is typical granite pegmatite showing 

some masses of pure feldspar 2$ to 3 feet across. Most of the feldspar 

is cream-colored microcline finely intergrown with small amounts of 

albite. Graphic granite is almost entirely absent, but the microcline 

and also white albite are irregularly intergrown with quartz. Quartz 

is not present in pure large masses and is not of commercial importance.

Muscovite is next to quartz in abundance. A few of the "books" 

are 5 to 6 inches across, but most of them are under 3 inches. All
44 FELDSPAR DEPOSITS OF THE XJNITED STATES.

show wedge structure, ruling, or twinning, and are therefore of value 

only for ground mica.

Red garnets are abundant in certain of the finer portions of the 

rock, and as a rule occur in streaks or zones. Few of the crystals are 

over one-eighth inch in diameter.

Surface outcrops show that the pegmatite dike extends northeastward somewhat beyond the wagon road. Its width at the wagon road 

is over 80 feet, and some of the pegmatite exposed at the roadside is of 

excellent quality. The dike can be traced for over 100 yards northeast of the road, and feldspar of commercial grade outcrops beyond, 

the house of James H. Cox. It is therefore probable that the vein 

can be worked for some distance along its trend beyond the present 

workings, and it is also practically certain that it continues downward 

to considerable depths.

The material is quarried by steam drilling and blasting and is 

hauled by two-horse and four-horse teams 9 miles to the mill at North 

Manchester. Here it is crushed, first in a rotary crusher, then in a 

chaser, and is ground to requisite fineness in tube mills. Only the 

purest portions of the pegmatite are used, and the amount of quartz 

in the ground product will probably not exceed 10 per cent.

John C. Wiarda quarry. John C. Wiarda & Co. operate a small 

feldspar quarry about 1J miles south of South Glastoribury, in the 

same belt with the Howe quarry and the quarries formerly operated 

by the Eureka Mining and Operating Company. The largest pit 

is about 40 by 60 feet and is 15 feet in maximum depth. The 

rock is granite pegmatite, not very coarse, and seldom showing 

feldspar crystals more than 6 to 10 inches across. The quartz is 

light gray to dark gray in color and is not present in commercial 

quantities. Most of the material shipped is an irregular intergrowth

of feldspar and quartz, though small amounts of graphic granite also 

occur. The feldspar is white to cream-colored microcline intergrown 

with small amounts of albite. No plates of muscovite larger than 3 

inches across were observed, and all the muscovite is much affected 

by ruling and crumpling. Some is graphically intergrown with 

quartz. Some parts of this pegmatite are very fine grained, and 

these contain abundant biotite, most of it in radially arranged 

crystals.

A new pit about 100 feet northeast of the one described above 

is just being opened, and exposes a small mass of gray granite 

gneiss in which the pegmatite is plainly intrusive. In both pits a 

vague banding is produced by an alternation of finer and coarser 

portions. In the southern pit this banding trends about N. 30° E. 

and dips about 40° to the northwest. In the northern pit it has a 

similar trend, but dips about 60° to the northwest. It is probable 

that this banding indicates in a general way the trend of the deposit.
CONNECTICUT. 45

The pegmatite can be traced N. 25° E. for some distance beyond the 

present workings, but its quality is rather uncertain. The material is 

worked by steam drilling and blasting and is hauled by teams 1£ 

miles to the mill of the company at South Glastonbury.

John C. Wiarda feldspar mill. This mill, at South Glastonbury, is 

equipped with one chaser for crushing the feldspar and three smallsized tube mills. The capacity of the mill is said to be about 15 tons 

in twelve hours. A considerable amount of the material produced by 

this firm is used in glass manufacture and enamel ware. From the 

mill the material is hauled 1 mile to Connecticut River, then ferried 

across to Rocky Hill and shipped by rail.

' Two quarries formerly worked by the Eureka Mining and Operating 

Company but not operated at the time of the writer's visit, in November, 1907, are located in the town of Glastonbury, about one-half 

mile north of the Howe quarry, described below. These consist of 

two pits on a western hill slope lying about 100 feet apart on a northsouth line. The southernmost one is 100 feet by 40 feet in, horizontal 

dimensions and 30 feet in maximum depth. The rock is granite 

pegmatite, similar to that quarried at the Howe quarry. A considerable amount of feldspar was piled in stock piles at these quarries 

at the,time of the writer's visit, and there still appears to be an 

important amount of material of pottery grade available.

Howe quarry. This quarry is about 2 miles south of South Glastonbury, a short distance east of the Portland road and close to the 

Hartford-Middlesex County line. It is operated by Lewis W. Howe, 

of South Glastonbury, and is the largest feldspar quarry in Connecticut 

as well as the oldest, having been worked for over forty years. The 

principal pit trends in general about N. 5° E. and is 500 feet long, 

100 feet in average width, and has an average depth of about 50 feet, 

though the eastern wall is considerably higher than the western. 

The rock is typical granite-pegmatite, which is cut by a number of 

small quartz veins, one of them traceable continuously for 100 feet. 

The largest vein becomes locally 2 feet wide, and from this tapers 

in width to 3 inches. These veins are plainly contemporaneous with 

the pegmatite, for feldspar crystals continuous with the bordering 

pegmatite project into the quartz of the veins with well-developed 

crystal faces, as shown in Plate VII, B. The particular dike here 

figured was traceable from the bottom of the quarry upward for 

about 30 feet to a point where it pinched out. Its width varies 

from 3 to 8 inches.

The feldspar of this quarry is white microcline intergrown with 

small amounts of albite. It seldom occurs in pure masses more than 

3 feet across, the bulk of the material shipped being an irregular or 

graphic intergrowth of quartz and feldspar.
46 FELDSPAR DEPOSITS OF THE UNITED STATES.

In the highly feldspathic parts of the pegmatite muscovite is only 

rarely present and is usually in small plates, often graphically intergrown with the quartz. The largest mica "books" seen were not 

more than 5 inches across and showed wedge structure, crumpling, 

or ruling. None of the mica is of commercial quality. Biotite is 

present only here and there. It occurs in small crystals in the finergrained portions of the pegmatite, its mode of occurrence being in 

every way similar to that at the Wiarda quarry. In a few places there 

are red garnets up to an inch in diameter, but muscovite, garnet, 

and dark quartz occur principally in certain irregular areas, and 

can readily be separated from the better material in mining.

Black tourmaline is present, but none of the crystals observed 

were more than one-half inch in diameter. Occasionally it is present 

in granular masses of minute crystals that form veins, one-sixteenth to 

one-fourth of an inch wide, traversing the pegmatite. These are 

probably the result of pneumatolytic action subsequent to the 

solidification of most of the deposit.

The wall rock is exposed at the south end of the pit, where the 

pegmatite is seen to be intrusive in a purplish to grayish quartzmica schist, probably the Bolton schist of the Connecticut Geological 

Survey. The schist strikes about north and south and dips about 

30° to the west. The pegmatite cuts across the folia of the schist 

at a low angle. The east wall of the quarry is of pegmatite, most 

of it too quartzose or too garnetiferous to be of commercial value. 

All the best feldspar has been found in the western part of the mass 

and there appears still to be a considerable amount of commercial 

material in the west wall. The deposit can be traced for 100 feet 

north of the present workings and probably extends much farther. 

To the south it probably continues for at least 150 feet beyond the 

present pit, to a point where the hill slope descends abruptly. Much 

spar of excellent grade is exposed also on the floor of the quarry, so 

there is every reason to believe that this quarry will not be exhausted 

for many years to come.

The hillside position of the quarry permits wagons to be driven 

directly into the pit for loading. The excavating is done by steam 

drilling and blasting, and the spar is hauled 2£ miles to the mill 

of Mr. Howe, at South Glastonbury.

Howe mill. The Howe mill, at South Glastonbury, is operated 

during part of the year by water power of Koaring Brook and during 

the remainder of the year by steam power. Its capacity is said to 

average about 27 tons in twelve hours. The equipment includes 

2 chaser mills and 5 tube mills, each 7 feet in diameter and 5 feet 

long. The ground spar is shipped in bulk or in bags and is hauled 

from the mill 1 mile to Connecticut River and ferried across to 

Rocky Hill, where it is shipped by rail.
CONNECTICUT. 47

MIDDLESEX COUNTY. 

CHATHAM.

Eureka Mining and Operating Company's quarry. A small quarry 

operated by this company is located about 1£ miles southeast of 

Middle Haddam. The quarry had been worked only a short time 

when the writer visited it, in November, 1907. It consisted of a 

single pit on a northeast hillside. The breast opened here is about 

50 feet high and 40 feet wide. The rock is a typical granite pegmatite. 

Quartz does not occur in masses large enough to be commercially 

valuable. The feldspar is cream-colored orthoclase and microcline, 

finely intergrown with small amounts of albite. It seldom occurs 

in pure masses more than 2 feet across, the commercial product being 

principally graphic granite.

Muscovite occurs in "books," most of them 4 to 5 inches, but 

some of them 8 inches across, and shows wedge structure and ruling, 

none of it being of commercial grade except for grinding. It also 

occurs in flat intergrowths with quartz, some of which are one-fourth 

inch to one-half inch thick and 2 feet across.

Biotite occurs in crystals, some of them 3 to 4 inches across, and 

is frequently inclosed by muscovite in parallel intergrowth. Black 

tourmaline is also moderately abundant, the largest crystal observed 

being 3 inches in diameter. Some is in graphic intergrowth with 

quartz.

Pockets or cavities are irregularly distributed through this pegmatite. The largest are 7 or 8 inches in diameter, and some of 

them, especially the smaller ones, contain tourmalines of gem quality. 

In color these are usually grass to olive green, and many show veiy 

perfect terminations. Some are of the variety achroite, being colorless or very pale green or- pink. Near the pockets opaque or translucent green tourmalines, granular aggregates of lepidolite, and muscovite bordered by lepidolite or in parallel intergrowth with it, are 

common. The gem tourmalines are, as a rule, found lying in sandlike matrices at the bottoms of the pockets.

The rocks bordering this pegmatite are mica schists, probably the 

Bolton schist of the Connecticut Geological Survey, which strikes 

N. 25° W. The pegmatite, which constitutes practically the whole 

of the ridge in which the quarry is located, appears to be a clikelike 

mass whose greatest length is about parallel to the trend of the 

schist. The natural exposures on the summit of this ridge and on 

the western slope show considerable amounts of feldspar of pottery 

grade, some pure feldspar crystals being 3 feet. across. The width 

of the ridge appears to be about 150 feet. Quarrying is done in the 

usual manner, and the spar is hauled by teams about 1£ miles to 

Connecticut River, where it is shipped to Trenton, N, J., in barges.
48 FELDSPAR DEPOSITS OF THE UNITED STATES.

HADDAM.

Haddam Neck quarry. One of the oldest feldspar quarries in 

Connecticut,, and one which is well known for the gem tourmalines 

and fine mineral specimens it has yielded, is located on the east 

bank of Connecticut River about opposite Haddam village. A ferry 

.crosses at this point. The property was visited by the writer in 

November. 1907.

The quarry consists of two pits located about 100 yards east of 

the river bank. The western one was worked mainly for its tourmalines and mineral specimens and is now abandoned. It is 50 to 

60 feet in length from north to south and about 40 feet in width, 

and is partly filled with water. According to Mr. John C. Wilkes, 

the superintendent of the quarry, some of the cavities that yielded 

gem tourmalines in this pit were as large as a bushel basket. The 

opening now being worked lies just east of the old pit and is separated from it by a 20-foot wall of. schist and pegmatite. It is 300 

feet long from north to south, 100 feet in maximum width, and 40 

feet in average depth.

The rock at the pit now worked is a granite pegmatite, but in 

addition to the minerals usually present in such deposits contains 

many others that are characteristic of gem-bearing pegmatites, and 

also contains numerous cavities or pockets in which occur tourmalines of the best quality. Most of these minerals have been described by H. L. Bowman. a

Quartz is not present in pure masses large enough to be commercially important. The feldspar is buff orthoclase and microcline, 

finely intergrown with small amounts of albite. No masses of pure 

feldspar more than 3 feet across were observed, and masses of this 

size are said to be rare. Most of the material shipped is a graphic 

or irregular intergrowth of feldspar and quartz. The feldspar near 

some of the pockets is very pale green albite. Muscovite occurs in 

"books," some of which are a foot in diameter and 5 to 8 inches 

thick. Some "books" 2 feet across, have been reported. Nearly all 

are affected by ruling and wedge structure, though a few would cut 

good clear pieces 2 by 3 inches in size. The mica here and there 

becomes more abundant within 2 or 3 feet of some of the schist 

walls. Several tons of mica are piled at the quarry but none has 

been marketed.

Crystals of dark red fluorite under an inch in size are occasionally 

found, as is also columbite.

The principal iron-bearing mineral is black tourmaline, which is 

very abundant in certain parts of the pegmatite. Its distribution 

is usually irregular, but in one place it is particularly abundant in a

a Min. Mag. and Jour. Min. Soc. London, vol. 13, pp. 97-121,4 figs. Reviewed in Mineral Resources U. S. 

for J.902, U. S. Geol. Survey, pp. 841-842.
CONNECTICUT, 49

band 1 to 2 inches thick and 5 feet long. In many places it penetrates mica " books."

The pockets or cavities which occur in the eastern pit and which 

carry the gem tourmalines average 8 or 10 inches in diameter, though 

there are many smaller ones only 2 to 3 inches across. They are distributed with great irregularity through the pegmatite mass. Lepidolite in finely granular masses, pale green albite, and small green 

tourmalines are abundant near many of the pockets. Muscovite 

surrounded by a border of lepidolite, or in parallel growth with 

lepidolite, is also of common occurrence near the pockets. As in 

most of the gem-bearing pegmatites the tourmalines are seldom in 

their original positions on the walls of the cavities, but he embedded 

in a sand-like mass of quartz fragments, cookeite, and other decomposition products at the bottom of the pockets. They are mainly 

grass green to olive green in color, becoming nearly colorless toward 

the tip. The exact apex of some of the crystals is pink and many of 

them show very perfect terminations. Gem tourmalines are not so 

abundant that it would pay to work the mine for these alone. Those 

encountered in the feldspar mining are marketed irregularly through 

local collectors.

The schists bordering the pegmatite at this locality are nearly 

vertical and trend north and south. Their contact with the pegmatite is absolutely sharp. They are gray to purplish muscovitebiotite schists, probably of sedimentary origin and belonging to the 

Bolton schist of the Connecticut Geological Survey. They are lithologically similar to those at the Roaring Brook quarry of this company. The pegmatite mass for the most part is elongate parallel to 

the trend of the schists, though locally cutting across them. Considerable amounts of commercial material seem still to be available. 

There is an overburden of sands and gravels, which in places attains 

a thickness of 10 feet. The feldspar is quarried in the usual way, 

by simple drilling and blasting, and is loaded into barges for shipment by water to the mill of this company at Trenton, N. J.

MIDDLETOWN.

Consolidated Feldspar Company. This company has a quarry at 

White Rocks, 3 miles east of Middletown, at an elevation of nearly 

500 feet. At the time of the writer's visit, in November, 1908, the 

quarry consisted of a single open pit on a north hillside and had not 

be'en extensively worked. The rock is typical granite-pegmatite 

and contains no masses of pure quartz that are large enough to be 

of commercial value. The feldspar is cream-colored microcline, in 

most places finely intergrown with small amounts of albite. Muscovite occurs in crystals 3 to 5 inches across and from 2 to 3 inches 

16779 Bull. 420 10 i
50 FELDSPAR DEPOSITS OF THE UNITED STATES.

thick, but is rendered worthless by the presence of ruling and wedge 

structure. The principal iron-bearing mineral is biotite, which 

occurs in lath-shaped crystals 1 to 2 inches wide, and is very abundant in some parts of the pegmatite. Black tourmaline is rare. 

The ledge that is now being worked and a number of others on this 

property contain considerable amounts of feldspar of pottery grade.

The material is taken by tramway downhill for about half a mile to 

the mill, which is at the side of the railroad and also within a few 

rods of Connecticut River, so that shipments may be made by water 

if desired. The mill is equipped with a gyratory crusher, crushing 

rolls, rotary drier, and two tube mills, 18 by 6 feet, whose capacity 

is stated to be 30 tons in ten hours. It is the purpose of this company to use the better grade of material for pottery purposes and 

to crush the remainder for use as poultry grit and in the manufacture of ready roofing. Power is furnished by a gas engine and gas 

producer.

Riverside quarry. A small quarry about a mile northeast of the 

one just described was operated in 1907 by L'. T. Snow, of New 

Haven, but work was suspended in 1908. The quarry consists of a 

single open pit on a northwest hill slope. Trie pegmatite is similar 

to that at the quarry above described and much of it appears to be 

of excellent quality for .pottery purposes. Some masses of pure 

feldspar are 2 to 3 feet across, and pegmatite of good quality is 

traceable for at least 300 feet southeastward from the present quarry. 

Both biotite and black tourmaline are present but are not abundant. Other minerals are light-green translucent beryls (in one 

specimen the beryl crystal was penetrated by a crystal of black 

tourmaline) and pink to deep salmon-colored fluorite.

The White Rocks region is in general one of the most promising

known to the writer for quarrying the best grades of feldspar. 

Aside from that at the two quarries described, feldspar of good 

quality was observed at several localities near the wagon road north 

of White Rocks. The situation is also favorable for cheap quarrying 

and shipment.

PORTLAND.

Andrews quarry. This quarry is about 2£ miles south of South 

Glastonbury, near the road to Portland, and is about one-half mile 

south of the Middlesex-Hartford county line. It consists of two 

open pits at the north end of a ridge trending nearly north and 

south, a lower northern pit 150 feet long, 30 to 50 feet wide, and 

50 feet deep, and an upper pit immediately to the south and 50 feet 

above the floor of the lower one. The breast at the upper pit is 

about 70 feet wide and 25 feet in maximum height, and from this 

breast feldspar that appears to be of good grade for pottery was
CONNECTICUT. 51

traced southward along the sides of the ridge for more than 600 

feet to a place where the slope descends sharply to the south.

The rock is a typical granite-pegmatite. The quartz is light gray to 

white and is not present in masses large enough to be commercially valuable. The feldspar is principally of the potash variety (microcline), 

finely intergrown with small amounts of albite, and seldom occurs in 

pure crystals more than 2 to 3 feet across. The bulk of the material 

quarried is graphic granite, most of it rather coarse, containing here 

and there small crystals of pale-green microcline. Locally the 

graphic granite becomes very fine grained. An analysis of this 

material is given in the table on page 14 (analysis No. 4). In some 

places the very fine grained pegmatite is banded, the darker bands 

being rich in muscovite and containing some garnet and black tourmaline, and the lighter bands consisting mainly of quartz, microcline,

and albite.

Muscovite is the mineral next in abundance to the quartz and 

feldspar. Most of the crystals are under 3 inches in diameter and 

are not of commercial quality except for ground mica. The muscovite is in places intergrown graphically with quartz.

The garnets present are all very small, few of them more than 

one-sixteenth of an inch in diameter. They are abundant in some 

of the fine-grained portions of the pegmatite, but rare in the coarser, 

commercial portions. On decomposing, they produce brown stains.

Black tourmaline is entirely absent from most of the deposit, 

though it occurs in curved bands of small crystals at the north end 

of the lower pit and at a small test pit one-fourth of a mile south 

of the present workings.

Biotite occurs only scantily and in very small plates.

The rocks bordering the pegmatite are nowhere exposed in the 

vicinity of this quarry, but the pegmatite mass seems to have a northand-south trend, the same as that-of the ridge on which it occurs. 

The deposit differs from all others with which the writer is familiar in 

the unusual scarcity of all iron-bearing minerals, and for this reason 

is of uncommonly good quality for the manufacture of pottery, the 

amount of waste material in the quarrying process being smaller 

than at most quarries. A large amount of commercial feldspar is 

still available at this place.

The situation of the quarry on a steep hill slope is favorable for 

economical working. Steam drills are employed. Some of the 

spar is hauled 2 miles to Connecticut River for shipment by water; 

some is hauled 3 miles and ferried across the river to Rock Hill, 

where it is shipped by rail, and some is hauled 2£ miles to the mill 

of John C. Wiarda & Co., at South Glastonbury.

Eureka feldspar quarry. A feldspar quarry operated by the Eureka 

Mining and Operating Company of Trenton, N. J., is located about
52 FELDSPAR DEPOSITS OF THE UNITED STATES.

2£ miles northwest of Portland, on the west slope of Collins Hill. 

The quarry was visited by the writer in November, 1907, and at 

that time the working extended along the hillside for about 100 feet, 

but was not excavated to any considerable depth. The rock is a 

granite pegmatite. The quartz is mostly white or light gray, but 

occurs occasionally in transparent, pale amber-colored masses several 

feet across. It would probably be profitable to save it in the mining. 

The feldspar is white to cream colored, and is an intergrowth of 

microcline with a small amount of albite. Most of the masses of 

clear feldspar are less than 3 feet across. The principal commercial 

product is a graphic or irregular intergrowth of quartz and feldspar.

Some of the muscovite plates are 8 or 9 inches in diameter, but 

nearly all show ruling and wedge structure.

Biotite is almost entirely absent.

Black tourmaline is moderately abundant, and one crystal 4 inches 

in diameter was seen. Some of the tourmaline crystals show almost 

perfect terminations. Smaller crystals are frequently found penetrating muscovite.

Small black or dark-red garnets occur in the finer-grained portions 

of the pegmatite.

Pockets or cavities are occasionally encountered, their distribution 

being entirely irregular. The largest one found is said to have measured 4 feet by 1| feet by 1| feet, and it yielded a large transparent 

green tourmaline about 7 inches long, which is now in the museum 

of Wesleyan University at Middletown. Most of the gem tourmalines found in the pockets are transparent grass-green to olive-green. 

A single pocket, however, contained a large crystal weighing several 

pounds, of pale-blue to pale-green color, the tints being similar to 

those observed in some aquamarines. Unfortunately, this crystal 

was completely shattered in the blasting, but the fragments have 

yielded a number of small cut. gems of great beauty. Near the 

pockets granular lepidolite, white albite of the clevelandite variety, 

and opaque yellowish green beryl crystals up to 8 inches in diameter 

occur, and many of these are penetrated by black tourmaline and 

light-gray quartz.

Commute is occasionally found, the largest piece being about 2£ 

by 12 by 1 inch in size and showing good crystal faces.

The bordering rock is exposed on the northeast wall of the pit 

and is a muscovite-biotite schist much contorted, probably the Bolton schist of the Connecticut Geological Survey. The trend is somewhat variable, but is generally about north and south. The pegmatite mass now being worked appears to wedge out about 100 to 150 

feet southeast of the present working. The crest of the hill east of 

the pit is occupied principally by schist, which shows some pegmatite of commercial grade. The latter cuts directly and sharply
CONNECTICUT. 53

across the foliation of the schist, and neither show any perceptible 

change as the contact is approached.

The quarrying is done by steam drilling and blasting, and about 

fifteen men are employed. The spar is hauled by teams about 2 

miles to Connecticut River, and shipped by barge to Trenton, N. J.

NEW HAVEN COUNTY.

Southford quarry. About If miles south of Southford station is a 

quarry which is worked by the Bridgeport Wood Finishing Company 

for quartz but which contains considerable quantities of feldspar of 

pottery grade. The quarry is an open pit about 200 feet long from 

northeast to southwest, about 100 feet in maximum width, and 40 

feet in average depth.

The rock is a granite-pegmatite, richer in quaitz than in most quarries where feldspar is mined. At the southwest end of the quarry 

the material is largely quartz, mainly white, but there are masses of 

pale-rose color irregularly distributed through the white quartz. 

Some portions are translucent and milky; other portions are banded, 

the banding being due to the presence of numerous fluid inclusions. 

Some of the masses of piire quartz are 30 feet across.

The color of the feldspar ranges from buff to pink, even in the 

same crystal. The feldspar near the large quartz areas usually shows 

well-developed crystal faces. The percentage of feldspar increases 

toward the north end of the quarry. It is in some places irregularly 

or graphically intergrown with quartz. A peculiar phase of this 

pegmatite is the presence, especially between large masses of pure 

quartz, of very fine grained sugary aggregates,'composed principally 

of small grains of orthoclase feldspar, with small muscovite plates 

oriented in every direction and bands of small garnets. Material of 

this type occurs in masses up to 3 to 4 feet across, and goes to pieces 

rapidly when exposed 'to the weather.

Muscovite is abundant and occurs mainly in bladelike or spearhead-shaped "books" arranged with their long axes at right angles 

to the quartz-feldspar contact planes, though the muscovite plates 

are usually inclosed by the feldspar rather than the quartz. Some 

of the blades are 6 inches across and 1£ feet long. Muscovite also 

occurs in graphic intergrowth with quartz and also forms more or 

less rounded aggregates of small muscovite plates oriented in every 

direction, the interspaces being filled with feldspar. Wedge structure 

and ruling characterize most of the muscovite, and none is of commercial value except for ground mica.

Black tourmaline occurs in graphic intergrowth with quartz. 

Wine-red garnets of all sizes up to one-half inch (though most of them 

are smaller) are specially abundant in the fine-grained, sugary phases 

of the pegmatite. Beryl, opaque and of blue-green color, is moder-
54 FELDSPAR DEPOSITS OF THE UNITED STATES.

ately abundant. One crystal on the waste pile was 2 feet long and 

i^-feet in diameter. A few show an approach to gem quality. Chalcopyrite is occasionally found in pieces an inch or so in diameter, as 

is also one of the sulphides of bismuth and lead in intergrowth with 

small muscovite plates.

Exposures of the bordering rocks are rare in this vicinity. An 

outcrop of granite gneiss occurs about 100 yards south of the quarry, 

but the walls of the quarry are all in pegmatite, and it is not possible 

to determine the trend of the deposit. There is, however, no indication of its immediate pinching out. An overburden of till, which 

in places is as much as 12 feet in thickness, must be stripped in quarrying. The quarry is equipped with steam drills, steam pump, derrick, 

hoisting engine, and teams for hauling the quartz If miles to the 

railroad station at Southford. The quarry employs about six men. 

The feldspar could certainly be handled at a profit in connection with 

the quartz mining.

NEW YORK.

The feldspar quarries of New York are in Westchester County (in 

the southeastern part of the State) and in the Adirondack region. 

Those in Westchester County produce feldspar that is used only for 

fine grinding for the pottery, glass, and enamel-ware trades. In the 

Adirondack region feldspar for these uses is also produced, but in 

addition considerable quantities of pegmatite are crushed and sized 

for use as poultry grit and in the manufacture of ready roofing. All 

the deposits of the northern region are probably of pre-Cambrian age 

and occur near the border of the large Adirondack, area of preCambrian rocks. The details of their geologic relations are not 

known. The deposits of the southern region may .be as late. as 

Silurian. Their geologic occurrence is described farther on.

ESSEX COUNTY. 

CROWN POINT.

A feldspar mill operated by the Crown Point Feldspar Company is 

located on the Delaware and Hudson Railway about If miles south 

of Crown Point station. This company became an active producer 

in 1908. The quarry is about a mile southwest of the mill.

The quarry is a large open pit near the summit of the north slope 

of Dibble Mountain. It is about 150 feet long and 150 feet wide and 

exposes a breast of pegmatite 50 feet high. The rock is a typical 

granite-pegmatite. Most of the quartz is gray, but some of it is pale 

rose colored. It occurs in pure masses, some of them 3 or 4 feet across 

The potash feldspar is of two varieties, pale pink to flesh-colored 

microcline and gray microcline. The gray variety, which occurs in 

graphic intergrowths with quartz, furnishes the bulk of the material
NEW YORK. 55

that is ground for the manufacture of enamel ware. Some masses 

of graphic granite about 5 feet across are wholly free from ironbearing impurities. Soda-lime feldspar (oligoclase) of pale-green 

color is associated with the pink rnicrocline and is about half as 

abundant.

Biotite, the principal iron-bearing mineral, occurs in thin, irregular 

plates, most of them only a few inches across, and as a rule aggregated. 

Black tourmaline occurs sparingly, though some crystals are 2 inches 

in diameter. No transparent tourmalines have been found. Very 

perfect crystals of zircon about half an inch in length are abundant 

in a few places in close proximity to a black, anthracite-looking 

mineral which is veinlike and forking in form, but which is probably 

a thin crystal. Its maximum thickness is about 1£ inches and its 

length several feet. Careful tests show it to be allanite, a silicate of 

iron, calcium, aluminum, and the rare metals of the cerium group. 

No beryl or garnet was observed.

The pegmatite at this quarry is excavated by steam drilling and 

blasting and loaded on tram cars. The buckets of the cars, which 

hold about 500 pounds, are transferred directly to a wire cableway 

that carries the pegmatite to the mill, over a mile distant.

At the mill the pegmatite is first crushed in a Blake crusher (it is 

planned to install a gyratory crusher), and the feldspar to be used 

in the manufacture of enamel ware is then crushed in a chaser mill 

and finally ground in two small tube mills (7 by 8 feet), with a capacity 

of 2 to 2£ tons in five hours. The pegmatite prepared for poultry 

grit and for roofing purposes passes from the Blake crusher to a 

series of crushing rolls and Newago screens, which reduce it to the 

various sizes desired. The mill is on the railroad, and the product 

can be loaded directly onto the cars. It is also within a few yards 

of the shore of Lake Champlain, and on the completion of the Hudson 

and Champlain Barge Canal water shipment will also be possible.

TICONDEROGA.

Pegmatite mine of Barrett Manufacturing Company. The quarry 

and mill of this company are If miles northwest of the railroad at 

Ticonderoga. The quarry, an open pit near the eastern base of a hill, 

is about 300 feet long from northeast to southwest and 150 feet in 

average width. Its maximum depth is about 35 feet and the average 

about 20 feet.

The rock is typical granite-pegmatite. Gray quartz occurs intergrown with other minerals, rarely in pure masses more than a few 

inches across. The most abundant feldspar is pearl-gray potash 

feldspar (microcline), which seldom forms crystals more than 6 inches 

across. About one-fourth as abundant as the gray microcline is a 

light-green soda-lime feldspar (oligoclase), similar to that found at
56 FELDSPAR DEPOSITS OF THE UNITED STATES.

the quarry of the Crown Point Feldspar Company. Graphic granite 

is abundant. Biotite, the principal iron-bearing mineral, is scattered 

very irregularly and abundantly through the rock, some of the crystals being 8 inches wide, 2 feet long, and one-fourth to one-half inch 

thick. Black tourmaline is occasionally found in very perfect graphic 

intergrowths with quartz. Garnets are rare.

The rocks bordering the pegmatite are exposed on both the east 

and west walls of the pit and are garnetiferous schists which strike 

N. 55° to 60° E. and dip 35° or 40° SE.

The excavating is done by steam drills, and the pegmatite is hauled 

in tram cars to the mill, a few yards distant. Here it goes to storage 

bins, then successively^ to a Blake crusher, to 20-inch crushing rolls, 

and to Jeffrey vibrating screens, which screen it to the various sizes 

desired. All the product is used in the manufacture of ready roofing 

material, for poultry grit, as facings for cement blocks, etc. None 

is of pottery grade. The crushed and sized product is hauled by 

wagon If miles to the railroad at Ticonderoga.

Ticonderoga Feldspar Company. A small quarry has been opened 

by this company about a mile southeast of Ticonderoga. The material is not typical pegmatite, but is a coarse-grained hornblende 

granite which locally becomes slightly pegmatitic. It is intrusive in 

impure gray limestone. The quarry is a single opening on an eastern 

hillside and shows a breast 60 feet high. A small mill has been erected 

at the mine, equipped with Blake crusher and vibratory screen. At 

the time of the writer's visit, in April, .1909, the quarry had not been 

operated for several years.

FULTON COUNTY.

A feldspar quarry recently opened by the Claspka Mining Company, 

of Trenton, N. J., is located in the northeast portion of Fulton County, 

about 6-| miles south-southwest of Northville. It is on lot 4, subdivision 1 of the Glen Bleeker and Lansing patent.

The working consists of a single pit, 25 to 30 feet wide, on a southwest hill slope. The maximum depth of the pit is 40 or 50 feet. 

The rock is a typical granite pegmatite. White to light-gray quartz 

occurs in pure masses up to 4 or 5 feet across. The principal feldspar 

is pale-pink potash feldspar (microcline), finely intergrown with a 

soda feldspar, probably albite. Greenish-gray crystals of soda-lime 

feldspar (oligoclase), many of them 6 or 8 inches across, are abundant, 

so that the pegmatite as a whole is more sodic than most granite-pegmatites and will yield a slightly' ' softer'' or more fusible spar. The difference in fusibility, however, will probably not be important commercially. The largest pure feldspar masses seen were 4 to 5 feet 

across. Some graphic granite, most of it coarse, is present.
NEW YOEK. 57

The principal iron-bearing impurity is somewhat altered biotite, 

which occurs in "books," many of them 6 to 8 inches across and 6 

inches thick. The largest biotite mass seen was a flat crystal 1£ feet 

wide and 3 feet long. Very subordinate amounts of black tourmaline 

are present in intergrowth with quartz.

The pegmatite at this quarry is cut by a vertical trap dike 40 to 

50 feet wide, striking about N. 35° E. The pegmatite mass can be 

traced northwestward along the hillside for about 100 feet from this 

dike and for an equal distance southeast of the dike. Pegmatite is 

exposed on the hill slope for more than 50 feet above the bottom of 

the quarry pit. The rocks associated, with the pegmatites in this 

vicinity are schists and granite gneisses. A short distance south of 

pit the granite gneiss strikes north and south and dips about 15° to 

the east, Granite gneiss near by strikes N. 10° E., -its dip being 

obscure.

The material at this quarry is of excellent quality for pottery purposes and the deposit is probably of considerable extent. Several 

small prospect pits in this vicinity were examined but showed only 

small amounts of commercial feldspar. Further prospecting may 

reveal other deposits of workable size.

The distance by road from this quarry to Cranberry Creek station, 

on the Fonda, Johnstown and Gloversville Railroad, is about 2f 

miles. The haul from mine to railroad is downhill, but is over a 

rough road which descends 800 feet in a mile. A road over a better 

route could be constructed, or the spar could be mined in the summer 

and sledded out to the railroad during the winter. Up to the present 

time the work has consisted largely of prospecting.

SAEATOGA COUNTY. 

CORINTH.

A feldspar quarry in the town of Corinth, about 2| miles southwest 

of Corinth station, on the Adirondack division of the Delaware and 

Hudson Railway, was opened about 1899, but up to the present time 

only sample shipments have been made. The property is owned by 

the American Feldspar and Mining Company, but for a short time 

the work was carried on under the name of the Corinth Feldspar 

Company. The workings consist of a lower small pit and an upper 

larger one, at an altitude 130 feet higher, on the same southeast hill 

slope. Only a few tons have been excavated from each. The rocks 

bordering the pegmatites are garnet schists in which the foliation is 

in some places obscure and in others well defined. Their strike varies 

from north-south to N. 30° W., the average being about N. 15° W. 

The average dip is about 20° to the southwest. The trend of the 

pegmatite body seems in general to be about parallel to the strike of
58 FELDSPAR DEPOSITS OF THE UNITED STATES.

the bordering schists, for its outcrops can be traced N. 25° W. for 

nearly one-half mile beyond the present workings.

The deposit is a typical granite-pegmatite. The quartz varies from 

light to dark gray, and no pure large masses were observed. The 

feldspar is pearl-gray to bluish-gray orthoclase, which occurs in pure 

masses up to 6 inches across. Most of the material available commercially for pottery use is graphic granite. Brown biotite is the 

principal iron-bearing impurity. The best exposures of spar of pottery grade are at the lower pit, where masses of feldspar and graphic 

granite free from iron-bearing minerals are found, the largest 3 feet 

across. At the upper pit biotite is present in greater abundance, and 

it is doubtful if the spar is of pottery grade.

Some feldspar of pottery grade is undoubtedly present at this locality, but further prospecting should precede any attempts at development on a large scale.

EDINBURG.

BatcheTlerviUe guarry. A feldspar quarry operated by the Claspka 

Mining Company, of Trenton, N. J., is located about 2 miles north 

of Batchellerville, in the town of Edinburg, a few rods east of the 

Day-Batchellerville road. The mine was opened in .1906, and was 

visited by the writer in April, 1909. . ;

The rock is a granite pegmatite, which has been worked from two 

open pits. The lower and larger pit, located near the base of a steep 

northwest hill slope, is about 15 feet in maximum depth. Quartz 

occurs in pure masses several feet across and also in graphic intergrowth with feldspar. The feldspar is light-gray microcline, finely 

intergrown with small amounts of albite. It occurs in pure masses, 

the largest 4 feet across, and the feldspars of some of some of the 

coarser phases of the graphic granite are 3 feet across. The finergrained parts of the pegmatite contain " books" of muscovite oriented in every direction. Some of the "books" are 16 inches in 

diameter and 8 inches thick at right angles to the plates. Many are 

tapering. Many of even the larger "books" show nearly perfect 

six-sided or diamond-shaped outlines. None of the mica seen was 

of commercial value except for grinding. It does not split well, and 

much of it is affected by ruling and contains numerous minute magnetite inclusions between the plates. Several tons of muscovite are 

piled at the quarry. Biotite is not abundant, but one flat crystal 

observed was 4 feet long and 3 feet wide. Beryl, of dark blue-green 

color, translucent to transparent, is moderately abundant, and one 

hexagonal prism seen was 8 inches in diameter and about 30 inches 

long. Another was about 2 feet long and tapered from a diameter 

of 7 inches at one end to 3 inches at the other. The pegmatite for 2 

or 3 feet next to the contact of the pegmatite with the schist at this
NEW YORK. 59

pit is an irregular or arborescent intergrowth of quartz and feldspar 

inclosing some large m'uscovite "books." The largest areas of pure 

feldspar and quartz lie immediately inside this contact zone.

The second and smaller pit is about 100 yards east of the first pit 

and higher up on the hill slope. It is about 20 feet wide and 7 or 8 

feet in maximum depth. The pegmatite is in general similar to that 

at the lower pit, though showing certain differences. The quartz is 

white to light gray and pale rose. A pure mass exposed in the east 

" wall of the pit is 3 to 4 feet wide and continuous for 20 feet. Feldspar similar to that at the lower pit occurs in pure masses 2 feet 

across and also in graphic and dendritic intergrowth with quartz. 

Muscovite and biotite are rare. Dark-red, semippaque garnets up to 

1£ inches in diameter occasionally occur, and one garnet aggregate 

or compound crystal was 8 inches across. On the dump piles were 

highly brecciated masses of feldspar whose fragments are cemented 

by a dark-colored matrix, which appears to be largely quartz and thin 

films of a nearly black substance containing iron and some organic 

matter and which is probably a mixture of substances deposited from 

solution in the spaces between the feldspar fragments.

'At the lower pit the pegmatite is intrusive, with sharp contacts 

with a light-gray to dark-gray quartz-biotite-feldspar gneiss of variable character, locally containing pinkish orthoclase phenocrysts 

up to 1 inch in length. The contact in some places parallels the 

foliation and in other places cuts sharply across it. At the upper pit 

the gneiss exposed in the eastern wall shows no very well defined dip, 

but strikes about east and west, the pegmatite contact trending about 

N. 30° W. sharply across the gneiss folia. Between the upper and 

lower pits are numerous exposures of gneiss striking about east and 

west and dipping about 15° S.

The two pegmatite masses quarried at the upper and lower pits 

appear to be irregular in form. They may be connected beneath the 

surface, but do not appear to be so at the surface. At the upper 

working, gneiss striking N. 60° E. and dipping 20° SE. succeeds the 

pegmatite only 100 feet or so south of the pit, but the northward 

extension of the pegmatite is obscured by the soil covering.

The pegmatite is quarried in the usual way, with the aid of steam 

drills, and the product is hauled by teams 7 miles to the railroad at 

Northville. The length of haul over roads where some of the grades 

are steep is the greatest obstacle to the development of the property. 

The feldspar appears to be present in fair amounts and is of excellent 

quality.
60 FELDSPAR DEPOSITS OF THE UNITED STATES.

WESTCHESTER COUNTY. 

GENERAL STATEMENT.

The feldspar and quartz quarried in Westchester County occur as 

constituents of granite-pegmatite. The associated rocks are a mica 

schist (the Hudson schist) and scattered masses of crystalline limestone (the Stockbridge dolomite).

Both of these rocks are of sedimentary origin, though they are 

extensively altered by metamorphic action. They now lie in a series' 

of closely compressed folds, whose general trend in the region here 

described is northeast-southwest. The Hudson schist is of Ordovician age; the Stockbridge dolomite is in part Ordovician and in 

part Cambrian.

In the vicinity of the feldspar and quartz quarries and along much 

of the road between Bedford village and Mount Kisco the Hudson 

schist has been injected by granite, pegmatite, and basic igneous 

rocks, so as to show locally a gneissic texture. Here and there, as 

along the road from Bedford village to the Hobby quarry, in North 

Castle, small masses of normal granite occur. The pegmatites that 

are of commercial importance in this region are doubtless only one 

phase of the granitic intrusion and injection of the Hudson schist, 

and like the granites are probably of Silurian or later age.

The deposits which were visited by the writer in January, 1907, 

have been briefly described in a report of the New York State Museum,® and from that description a portion of the material for this 

report is taken.

BEDFORD.

Kmkle quarry and mill. The Kinkle quarry is situated on the east 

and northeast slopes of a small hill about three-fourths of a mile 

southeast of Bedford village. The excavations consist of four open 

pits, three closely adjacent ones on the upper part of the hill slope and 

one at a lower level. All the pits are elongate in a northeast-southwest 

direction, their trend probably coinciding with that of the pegmatite 

dikes. The lower pit exposes the downward and northeastward continuation of the same pegmatite mass that is revealed in the southernmost of the upper pits.

The northernmost of the upper pits is about 50 feet wide, 100 feet 

long, and 35 feet in maximum depth. The two southern pits on this 

level are larger, being 100 to 150 feet wide, about 300 feet long, and 

about 50 feet in maximum depth. Most of the rock exposed in the 

central pit of the upper group is quartz, which is mainly white, but 

here and there assumes a very beautiful rose tint. Black tourmaline 

occurs in single crystals or radiating crystal aggregates in the quartz,

oBull. New York State Museum No. 102,1905, p. 69.
NEW YORK. 61

and some of the fracture planes in the quartz are coated with thin 

layers of black tourmaline. These thin coatings, in few places over 

one-thirty-second of an inch in thickness, have plainly developed 

subsequent to the solidification and fracturing of the quartz and may 

be either secondary deposits from surface waters that percolated 

along the fractures or deposits from hot aqueous or gaseous solutions 

that penetrated the cracks in the pegmatite mass in the very latest 

stages of its solidification. Quartz with this black tourmaline coating 

is unfit for commercial use and is discarded. The quartz seems to 

be associated with the feldspar in a wholly irregular manner. It 

forms most of the northwestern and southwestern walls of this quarry, 

but in the southeastern wall is abundant only at the base, the upper 

parts of the wall being feldspathic. The feldspathic constituents of 

the pegmatite are best exposed in the other three pits, where they 

constitute a large proportion of the whole rock. The feldspar is of 

two principal varieties, one pink or flesh colored and the other white. 

When examined under the microscope, the pink variety shows the 

optical properties of microcline. It is finely intergrown with; small 

amounts of albite. There is every gradation from pure potash feldspar through, coarse-grained graphic granite into fine graphic granite. 

The pink feldspar, pure or in intergrowth with quartz, generally 

occurs in somewhat irregular but sharply bounded areas within the 

pegmatite mass. In the southernmost of the upper quarries these 

constitute about one-half of the mass. A few of the smaller pink 

feldspar areas have perfectly straight boundaries which parallel the 

cleavage directions within the crystal. One sharply outlined mass 

of pink feldspar 3 feet long by 1$ feet wide was bordered on all sides 

by white quartz. The larger'masses are, as a rule, inclosed partly by 

pure quartz and partly by irregularly associated white quartz and 

white feldspar in varying proportions with a little pink feldspar, 

biotite, black tourmaline, beryl, or other mineral. The white feldspar, which is largely albite, constitutes the second important variety 

of feldspar characteristic of this quarry. The pegmatite containing 

it is in a few places graphic granite, but for the most part shows very 

irregular texture and varying proportions of feldspar and quartz from 

point to point.

The mica of these quarries is mainly muscovite, which is commonly 

associated not with the quartz but with the feldspathic portions of 

the deposit or may lie between feldspathic areas and areas of pure 

quartz. In places the mica "books" lie with their sides parallel to 

the quartz-feldspar contacts, but more generally they stand at right 

angles to these contacts. Few of them exceed 4 to 5 inches in diameter and almost all show "A." structure and much ruling. No plate 

mica was seen and the total amount of muscovite is hardly sufficient 

to make it worth while to save it for scrap mica. Being mainly
62 FELDSPAR DEPOSITS OF THE UNITED STATES.

confined to rather definite bands in the pegmatite most of it can be 

readily separated from the highly feldspathic portions. It is not 

injurious chemically either in pottery or in glass manufacture, but 

it is difficult to grind the thin elastic plates to the requisite fineness.

Biotite (black mica) occurs in long, thin, lath-shaped crystals, 

some of which are several feet long, though most of them are much 

smaller. Black tourmaline is' associated mainly with the quartz, 

but is locally present in the feldspathic. parts of the pegmatite. 

Magnetite and garnet occur in a few places, but no gem varieties of 

tourmaline or .of beryl have been found. Columbite is present here 

and there in small crystals, as are some other rare minerals.

Three grades of feldspathic material are obtained from these 

quarries. No. 1 is selected from the purer portions of the pinkfeldspar masses and will probably run considerably less than 5 per 

cent of free quartz. All of it is shipped crude. The No. 2 feldspar 

produced at this quarry includes the coarser graphic intergrowths 

of pink feldspar (microcline) and quartz and also includes pegmatite 

material rich in the white soda feldspar, albite. This grade is 

therefore higher in free quartz and in soda than No. 1. Both the 

No. 1 and the No. 2 grades are used in the manufacture of pottery 

and must be entirely free from black mica, black tourmaline, garnet, 

and other iron-bearing minerals. The No. 2 spar is not shipped in 

the crude state, but is ground at the quarries. A No. 3 grade, made 

up mainly of the albite-quartz mixture with some of the finer grained 

pink graphic granite, is also ground at Bedford for use in glass 

manufacture. It is somewhat higher in quartz and soda than grade 

No. 2, and muscovite, biotite, and black tourmaline are not so 

carefully eliminated as in grades No. 1 and No. 2, these constituents 

not being so injurious in glass as in pottery manufacture. Microscopic examination of the No. 3 spar shows the presence of free 

quartz, microcline (potash feldspar), and albite (soda feldspar).

The quartz from this quarry is shipped in the crude state to the 

Bridgeport Wood Finishing Company at New Milford, Conn., where 

it is ground and used in the manufacture of a wood filler, of silica 

paint, etc. '

The grinding mill of Kinkle's Sons is located at the quarries and 

is similar in equipment to most feldspar mills elsewhere, except that 

the spar as it comes from the chasers goes to a vibration separator, 

only the tailings being sent to the ball mills. For pottery spar this 

separator is provided with a 140-mesh screen, but in the preparation 

of spar for glass manufacture only a 60-mesh screen is required.

The ground spar is usually shipped in bags. All the product is 

hauled by team 5 miles to Bedford station, on the New York Central 

Railroad. The No. 1 and No. 2 grades, for pottery use, are shipped
PENNSYLVANIA. 63

mainly to Trenton, N. J., and East Liverpool, Ohio, though small 

amounts have been shipped as far as Portland, Oreg.

NORTH CASTLE.

Hobby quarries. A small quarry owned by Albert Hobby, of Bedford, N. Y., opened by Otto Buresch, but now operated by P. li. 

Kinkle's Sons, is located in the town of North Castle, near the west 

side of Mianus River, about 1£ miles southeast of the Kinkle quarry. 

The quarry is situated on a steep eastern hill slope and is about 100 

feet wide, 150 feet long, and 40 feet in maximum depth. No exposures of the surrounding rocks were observed near the quarry. 

The pegmatite shows masses of pure feldspar 8 to 10 feet across, 

associated with masses of pure quartz, some of which are 15 feet 

across. The quartz is in part white and in part a beautiful-rose 

tint. There is almost- no intergrowth of quartz and feldspar. The

feldspar is buff and is shown by microscopic examination to be 

microcline potash feldspar, probably containing a little soda. 

Small and very thin plates of muscovite occur along some of the 

cleavage planes in the feldspar, but they are not abundant enough 

to affect .the quality of the spar materially. Muscovite in larger 

plates is mainly segregated in fiomewhat irregular bands in association with black tourmaline in prismatic crystals that reach 1£ inches 

in diameter.

This quarry differs from the Kinkle quarry in the fact that the 

feldspar is practically all buff microcline, and in the more complete 

separation of quartz and feldspar, graphic granite being apparently 

wholly absent. The present exposures cover only a small area, and 

it is impossible to determine the> extent or uniformity of the deposit. 

Mianus River is capable of furnishing ample water power for operating a grinding mill, and the materials could be carried by gravity 

down the hill slope to the mill. The material is hauled by teams 8 

miles to Bedford station. Little material has yet been marketed. 

It is unfortunate that this property is so far from transportation 

lines.

A small quarry owned by Mr. Hobby, situated about one-half mile 

east of the Kinkle quarry, is not now being operated and was not 

visited by the writer.

PENNSYLVANIA. 

GENERAL STATEMENT.

Nearly all the feldspar quarries of Pennsylvania are in Chester 

and Delaware counties, in the southeastern part of "the State. A 

single quarry, long abandoned, is in Montgomery County. The location of the active and inactive quarries and of the feldspar mills is 

shown in Plate VIII. Most of the pegmatite deposits are of the
64 FELDSPAR DEPOSITS OF THE UNITED STATES.

usual type of granite pegmatite, but those in the extreme southwest 

part of Chester County, near the Maryland State line, belong to an 

entirely different type, which may be designated soda pegmatite, its 

principal mineral being the soda feldspar, albite. This variety contains no quartz and its principal iron-bearing mineral is hornblende. 

The masses of granite-pegmatite that have been quarried are, as a 

rule, associated, as shown in Plate VIII, with areas of Wissahickon. 

mica gneiss, a foliated quartz-feldspar-mica rock of pre-Cambrian 

age. Most of the pegmatite masses appear to be elongate in a general way parallel to the trend of this gneiss that is, from northeast 

to southwest.

The soda pegmatites of southwestern Chester County and adjacent 

portions of Maryland are for the most part intrusive in serpentine, 

representing altered peridotites and pyroxenites that are early 

Cambrian or older. The age of the pegmatite dikes themselves is 

not definitely known. The granite-pegmatites intrude rocks that 

are supposed to be of Ordovician age. Some of them are therefore 

considered to be at least as young as Ordovician, though others 

may be older.

A part of the feldspar quarried in the State is ground at mills 

near Brandywine Summit, at Toughkenamon, and near Sylmar, Md. 

Most of the remainder is shipped crude to Trenton, N. J., or Wilmington, Del.

The quarries that were active in 1898 have been briefly described by 

T. C. Hopkins. a The1 observations of the writer were made in 1907.

CHESTER COUNTY.

Most of the quarries of Chester County that produce potash feldspar are in the vicinity of Avondale; those that produce soda

feldspar are in the extreme southwestern part of the county, near 

Sylmar, Md.

LONDON GROVE.

Pennsylvania, Marble and Granite Company's quarry. The feldspar 

quarry of this company is about one-fourth of a mile southeast of the 

large granite quarry of the same company at Baker station. At the 

time of the writer's visit in May, 1907, the deposit had been worked 

for only a short time. The quarry pit was about 50 by 30 feet and 25 

feet deep. The main pegmatite dike appears to be about 25 feet 

wide. It strikes N. 75° E. and dips about 50° to the southeast. The 

rock is pegmatite of the fine-grained gneissic type observed at the 

Eureka Flint and Spar Company's quarry, 1£ miles north-northwest of 

Avondale. The crystals of pure feldspar tend to be lens shaped

a Hopkins, T. C., Clays and clay industries of Pennsylvania, part 2: Appendix to Ann. Rept. Pennsylvania State College for 1898-99.
U. S. GEOLOGICAL SURVEY BULLETIN 4-20 PLATE VIM

J 40°76=I5'

joor 7600 45' 30'

GENERALIZED 

GEOLOGIC MAP

OF

SOUTHEASTERN PENNSYLVANIA

AND ADJACENT PARTS

or

DELAWARE AND MARYLAND

Showing location of feldspar quarries and mills

Active feldspar Inactive feldspar Feldspar mill 

quarry quarry

Base compiled from U. S. Geological Survey 

atlas sheets SEDIMENTARY ROCKS

LEGEND

IGNEOUS ROCKS

Geology compiled largely from published and 

unpublished work of Dr. F. Bascom

POST-PALEOZOIC ORDOVICIAN CAM8RO-ORDOVICIAN CAMBRIAN

PRE-CAMBRIAN ORDOVICIAN OR 

YOUNGER

Oetoraro schist Shenandoah limestone Chickies quartzite Wissahickon mica gneiss Baltimore gneiss Pegmatite

EARLY CAMBRIAN 

__ OR OLDER 

J'JLlL'S SIEN A O

Serpentine

Metapyroxenite and

metaperidotite

Gabbro Granite gneiss
 PENNSYLVANIA. 65

and few of them are more than 3 or 4 inches across. Muscovite 

plates are as a rule not more than 1£ inches across. Biotite is abundant along certain bands and renders these commercially worthless. 

There are occasional small garnets. No graphic granite was seen. Most 

of the quartz is in irregular intergrowth with the feldspar, and no pure 

masses over a foot across were observed. The material which was 

being quarried at the time of the writer's visit was mostly soft and 

could be worked with a pick and shovel. The quarry was equipped 

with a derrick and steam hoist, sixteen men being employed. It 

was not operated in 1908.

Thompson quarry. A feldspar quarry 1£ miles northwest of Avondale and three-fourths of a mile northeast of Baker station was formerly 

operated by J. N. Thompson for the Eureka Mining and Operating 

Company of Trenton, N. J. It consists of a series of narrow pits 

distributed along a pegmatite dike trending N. 55°E. and dipping,

at. the northernmost pit, about 40° to the southeast. Most of the 

pits are now filled with water, but the workings at one pit are said 

to have reached a depth of 60 feet.

The rock is a granite-pegmatite of fine grain and more or less gneissic 

texture, due mainly to the concentration along certain bands in the 

rock of small muscovite plates, most of them under one-half inch 

across. No crystals of pure feldspar over 3 inches across were seen. 

The feldspar crystals ftre mostly lens shaped, with their long direction parallel to the gneissic structure. A few crystals graphically 

intergrown with quartz are 5 inches across. There are some small 

garnets, most- of them under one-eighth inch in diameter. Biotite 

appears to be entirely absent.

As far as can be determined from a casual inspection the supply of 

feldspar at this quarry appears to be about exhausted.

Baker quarry. A small quarry just east of that of the Pennsylvania Marble and Granite Company, on the other side of the wagon 

road, was worked by Thomas Baker and was opened in 1907. At 

the time of the writer's visit, in May, 1907, only a few tons had been 

excavated. The material is in every way similar to that at the neighboring quarry and the rock seems to be a continuation of the same 

pegmatite mass. .

Chatham quarry. A quarry operated by the Brandywine Summit 

Kaolin and Feldspar Company is located three-fourths of a mile 

northeast of Chatham village. The rock is a typical granite-pegmatite. 

The quartz is white and occurs in large, pure masses, and also irregularly intergrown with feldspar. Graphic granite was not observed. 

The feldspar is pinkish-gray microcline, the largest crystals being 

1 ^foot across, though most of them are smaller. The greater part of 

the material quarried is an irregular intergrowth of quartz and feld16779 Bull. 420 10 5
66 FELDSPAR DEPOSITS OF THE UNITED STATES.

spar through which minute mica plates are scattered. Biotite is the 

principal iron-bearing impurity.

The pegmatite here worked is a more or less flat-lying mass, at 

least 25 feet thick, the base being nowhere exposed. It has been 

worked from an open pit about 100 feet long by 80 feet wide by 

40 feet deep, and in the wall of this pit the pegmatite is seen to be 

overlain by mica schist. From the southern end of the open pit a 

tunnel 12 feet high, 20 to 25 feet wide, and 40 feet long was being 

driven at the time of the writer's visit in May, 1907. The pegmatite 

in part follows the foliation planes of the schists, but also at many 

places cuts sharply across them. It is estimated that about one-half 

of the material quarried is ore and one-half waste. The quarry is 

equipped with steam pump, steam hoist, and derrick, and about 

fifteen men are usually employed. Future working must be mainly 

by tunneling, and there is some question whether this could be profitably conducted for any great distance with material of this kind. 

The spar is hauled three-fourths of a mile to Chatham and shipped 

by rail to the mill of this company near Brandy wine Summit, Delaware County.

NEW GARDEN.

TougJikenamon quarry. This quarry, which is operated for the Pennsylvania Feldspar Company of Philadelphia, is on land owned by 

Moses B. Carpenter, 1| miles northwest of Toughkenamon. The 

largest pit at this locality had long been abandoned at the time of 

the writer's visit in May, 1907, when only small openings were being 

worked, apparently located in several distinct pegmatite dikes. The 

pegmatite now worked is not so coarse as that at most feldspar 

quarries, no crystals of pure feldspar being observed which were over 

2 to 3 inches across. The pegmatite of the old abandoned pit is said 

to have been much coarser. Quartz does not occur in commercial 

quantities. The feldspar is buff to pink microcline, finely intergrown with small amounts of albite. The muscovite plates associated with the feldspar are as a rule not more than 1£ inches across. 

As at a number of other quarries in this region the pegmatite shows 

an indistinct gneissic texture.

The feldspar is hauled to the mill of the Pennsylvania Feldspar 

Company at Toughkenamon.

Touglikenaman feldspar mill. This mill, which is operated by the 

Pennsylvania Feldspar Company, stands at the side of the railroad 

in Toughkenamon village. The equipment consists of a Blake 

crusher, chaser mill, and four small tube mills. The capacity is 

stated to be 8 to 9 tons in ten hours.
PENNSYLVANIA. ' 67 

NEWLIN. *

Embreeville and Unionvitte abandoned quarries. There is an abandoned quarry near Embreeville, on the Wilmington division of the 

Philadelphia and Reading Railway. This quarry was not visited by 

the writer, but its appearance in 1898 is described as follows by 

Hopkins: a

The spar quarry at Embreeville is about 100 yards north of the Embreeville station. 

The vein, which is about 10 feet thick, crosses the railroad and has been quarried on 

both sides of the railroad track. The vein appears to correspond in dip and strike to 

the garnetiferous mica schists in which it occurs. * * * The spar is nearly snow 

white, slightly stained by dendrite markings in places. The analysis indicates a 

soda orthoclase with a slight admixture of a lime-bearing feldspar and considerable 

free quartz. * * * The continuation of this vein southwest from the quarry is 

distinctly shown by the numerous outcrops at different points along the line of strike, 

and the outcrop would indicate that other quarries might be opened with profit.

Several small feldspar quarries northeast of Unionville, now abandoned, but worked at the time of Hopkins's visit in 1898, are described by him as follows:

Feldspar was quarried from four openings during the present season, and there are 

not less than half a dozen other openings from which spar has been removed within 

the last few years. The quarries are comparatively shallow and indicate an occurrence 

of the feldspar in pockets rather than veins, although they are probably enlargements 

of veins, but the country rock has so disintegrated that the spar lies in the loose, disintegrated material, and the vein walls are not clearly defined. The rock is a mica 

schist bordering on serpentine, and some of the quarries are apparently within the 

serpentine area. Muscovite and biotite are quite abundant in places and there is 

considerable diffused quartz, but no large masses were observed. A band of green 

serpentine occurs in one of the quarries, and tourmaline crystals are reported.

WEST CALN.

Meredith quarry. A quarry 1J miles north-northeast of Sadsburyville and 2£ miles north of Pomeroy is operated by B. F. Meredith, 

of Pomeroy. The workings here are rather irregular in form. The 

largest pit, the one now being worked, is 150 feet long from north to 

south and averages about 50 feet across. The pegmatite mass is so 

irregular in form that its general trend can not be determined. On 

the east side of the largest pit, however, where it is excavated from 

a short tunnel, it is overlain by schist. Quartz seldom occurs'in 

large, pure masses. The feldspar is cream-colored to pink microcline, 

not much of it in pure masses, but most of it finely intergrown in a 

graphic manner with quartz, so that the greater part of the commercial product is fine graphic granite. Greenish mica in small 

plates is the only other abundant constituent. The pegmatite is 

very free from iron-bearing minerals. The quarrying is done by 

steam drilling and blasting, and the product is hauled by teams 2* 

miles to the railroad at Pomeroy.

a Op. cit, p. 15.
68 FELDSPAR DEPOSITS OF THE UNITED STATES. 

^ WEST NOTTINGHAM.

Three quarries, which produce only soda feldspar, are in West 

Nottingham, Md., near the Pennsylvania-Maryland State line. The 

rock obtained at these quarries is not a granite-pegmatite, but a soda 

pegmatite, the principal minerals being soda feldspar (albite) and 

hornblende.

Sparvetta quarry. The westernmost of these quarries is operated 

by the Sparvetta Mining Company, and is located about 1| miles 

west of Sylmar station, Maryland. At the time of the writer's visit, 

in May, 1907, the quarry was an open pit 400 or 500 feet long, 50 to 

150 feet wide, and 80 feet in maximum depth. The greatest length 

is in a, direction N. 55° W., and this appears to represent the general 

trend of the feldspar mass. The working taps two feldspar masses 

of nearly parallel trend, but of different dip, the dip of one being 

approximately vertical, while that of the other is so inclined that it 

joins the first near the bottom of the quarry to form a single vein. 

The southwestern of these two feldspar masses is only 5 to 10 feet 

wide near the surface, but broadens downward. There is no evidence 

that the pegmatite dies'out for some little distance in either direction 

along its trend, and presumably it also continues downward to a 

considerable depth. The wall rock is serpentine, dark green to 

nearly black in color. At the contact between the two, within a 

zone that is for the most part about a foot wide, talc and some 

fibrous serpentine are commonly developed, the fibers of the serpentine being oriented perpendicular to the contact and being mostly 

1 inch to 1^ inches in length. Neither of these minerals is utilized 

commercially.

The character of the feldspar from this and the other two quarries 

in this vicinity is described later.

The quarrying is done by steam drilling and blasting, and the 

material is hoisted by derricks and transferred to a mill at the side 

of the quarry. Here it is heated in a continuous feed kiln and when 

hot is sprayed with cold water. This operation shatters the spar 

and makes grinding much easier. It is then crushed in three chaser 

mills of the usual type and ground in tube mills. Two of the latter 

are of the small type found in most feldspar mills, grinding 2 to 3 tons 

at a charge. The other-is a large mill having a capacity of 5 to 6 tons, 

which,-as originally installed, was a continuous feed mill, but difficulty in regulating the quality of the product led to its alteration 

to the intermittent type. The capacity of the mill is stated to be 

about 25 tons in twelve hours.

Keystone guarry. A quarry operated by the Keystone Feldspar 

Company, of Philadelphia, is located a few hundred yards southeast 

of the Sparvetta quarry, probably on a continuation of the same
PENNSYLVANIA. 69

feldspar mass. The pit is about 350 feet long, 150 feet wide, and 80 

feet in maximum depth, its greatest length being from northwest to 

southeast. The spar here constitutes a single vein, and is similar *to 

that at the Sparvetta quarry. The wall rock is serpentine. The 

amount of material here seems to be large, and there is no indication 

of its dying out for some distance downward or along its trend.

The quarry is equipped with two derricks, a steam hoisting engine, 

a steam pump, and steam drills. It employs a crew of fifteen to 

twenty men. The material is hauled 1£ miles to Sylmar station and 

is all sold in the crude state.

Brandywine quarry. A quarry of the Brandywine Summit Kaolin 

and Feldspar Company, one-half mile north of the Sparvetta quarry, 

is 200 feet long, 70 to 80 feet wide, and 90 to 100 feet deep, the 

greatest length being in a direction N. 10° W. The feldspar constitutes a single dike, which is about 12 feet wide at the south end of

the pit, but broadens toward the north end. The wall rock is serpentine and the contact is marked by a zone, about 1 foot thick, of bluegreen talc, now much decomposed.

The equipment consists of a derrick, steam hoisting engine, steam 

pump, and steam drills. From fifteen to eighteen men are employed. 

It is probable that the vein extends both to the north and to the south 

beyond the present exposures, and the excavations can also with 

safety be carried to greater depths. A part of the output is sold 

to the Sparvetta Mining Company and hauled to their mill for grinding. The remainder is hauled 1$ miles to Sylmar station and shipped 

to the mill of the Bran.dywine Summit Kaolin and Feldspar Company, 

near Brandywine Summit.

Character. The feldspar at the three quarries described is entirely 

similar in character, as are also the associated minerals. The feldspar 

is of the soda variety (albite), occurring generally in crystals that are 

from 1 inch to 2 inches across, though some are as much as a foot 

across. The crude feldspar varies from white through cream to 

gray; the ground product is pure white.

So far as observed, quartz is entirely absent in pegmatites of this 

variety. The principal iron-bearing mineral is hornblende, which 

appears dark green under the microscope but nearly black as seen 

in the quarry. It is in aggregates of needle-like crystals, many of 

them radially arranged, which occupy spaces between the feldspar 

grains. Muscovite occurs in certain portions of the pegmatite, intergrown with feldspar so as to form more or less rounded aggregates 

5 to 6 inches across. Most of the single plates are not more than 1$ 

inches across. Small garnets are locally associated with the feldspar. 

Along some of the fracture planes there are thin films of ocher, but 

these do not materially damage the spar. Some asbestos of the ser-
70 FELDSPAB DEPOSITS OF THE UNITED STATES.

pentine variety and some talc, as already stated, is found along contacts between the feldspar masses and the wall rock, but they are not 

present in commercial quantities.

DELAWARE COUNTY.

Feldspar is now quarried only at one locality in Delaware County 

namely, at Elam, near Brandywine Summit but in the past was 

quarried near Chester Heights, near Glen Mills, and near Chelsea.

CONCORD.

Brandywine Summit Feldspar Company. The quarry of this company is at Elam, 1£ miles south of Brandywine Summit station, within 

the area of the West Chester topographic map of the United States 

Geological Survey. The excavations here cover an area of about 4 

acres, and consist of three partly connected open pits. The eastern and 

largest pit, now abandoned, is about 300 feet from north to south and 

250 feet from east to west. It is now filled with water to a level 

within about 60 feet of the surface, but is said to have been nearly 

200 feet deep. A second pit, west of the first and connecting with it, is 

about 125 feet from north to south and 150 feet from east to west. 

This pit is also abandoned. The pit now being worked lies just west 

of this. From the easternmost pit, now partly filled with water, 

much material was excavated from tunnels, which were driven for 

over 300 feet. The two western pits are much shallower.

The feldspar, which is of the potash varieties, orthoclase and microcline, is cream to flesh colored, and occurs in pure crystals ranging up 

to slightly more than a foot in diameter. Unlike most quarries 

yielding potash feldspar, no graphic granite was observed, most of the

quartz being irregularly intergrown with the feldspar or other pegmatite minerals. The quartz is gray in color and granular in appearance 

because of minute fracturings, and in the present workings seldom 

occurs in pure masses of any considerable size. It is not utilized 

commercially. According to Hopkins,a however, large masses of 

pure quartz were formerly exposed near the bottom of the eastern pit 

and future excavations may disclose other quartz masses.

Muscovite occurs both in small crystals and in large plates up to 18 

inches across, but none of it is of commercial grade. Delicate skeleton crystals of magnetite are common between the mica plates. 

Biotite is abundant in certain portions of the pegmatite in thin, narrow crystals, some of them several feet long; and wine-red garnets 

occasionally occur, usually associated with the mica. The mica and 

garnet-bearing portions of the pegmatite can be readily separated in 

mining from the areas of purer feldspar.

a Hopkins, T. C., Clay and clay industries of Pennsylvania, part 2: Appendix to Ann. Kept. Pennsylvania State College for 1898-99.
PENNSYLVANIA. 71

The deposit seems in general to be rather flat lying, as is indicated 

by the occurrence on the north wall of the eastern pit of about 40 feet 

of mica schist, beneath which the pegmatite dips apparently at an 

angle of about 25 °. The eastern pit is said to have been excavated to 

a depth of nearly 200 feet. In the western pit, which is now being 

worked, the pegmatite mass is at least 30 feet thick, its base not 

having yet been reached.

The soft, weathered material near the surface can be excavated 

with pick and shovel, but the material at greater depth must be 

removed by steam drilling and blasting and hoisted by derrick. The 

product is loaded into wagons and hauled about 1$ miles to the mill. 

Most of the spar is used for pottery, but the cleaner pieces, which are 

selected with extreme care, are sold by the barrel for dental purposes. 

Up to the present time the quarry has probably yielded over 150,000

short tons of crude feldspar. The appearance of this quarry in 1898 

is described on pages 14-15 of Hopkins's report.*

The mill is located on a private spur of the Philadelphia, Baltimore 

and Washington Railway, about a mile southwest of Brandywine 

Summit station. The process of grinding at this mill is similar to 

that used at most other feldspar mills, the material being first crushed 

in chasers and then ground in tube mills, the principal differences 

from other mills being in the use of a mechanical carrier for removing 

the crushed feldspar from the chasers and transferring it to bins over 

the tube mills, and in the use of large tube mills, instead of the small 

tube mills usually employed. It is said that these effect a considerable saving in power. A suction fan is also employed to collect fine 

feldspar dust, about one bag of this being obtained in the course of a 

day. This dust can be marketed for certain purposes, and the device 

serves to keep the mill much freer from dust than it otherwise would 

be and to make the work less disagreeable for the men.

Some soda feldspar from a quarry belonging to this company in 

Nottingham, Chester County, is also ground at this mill. This soda 

feldspar is burned in a kiln and cooled by a stream of cold water 

before crushing. This process fractures the spar and renders the 

crushing and grinding process less difficult. The potash spar is ground 

just as it comes from the quarry.

Chester Heights abandoned quarries. Feldspar for pottery and dental purposes was formerly quarried at this locality by the Chester 

Heights Feldspar Company. The quarries here have produced no 

feldspar for many years, and the locality was not visited by the 

writer. Its appearance in 1898 is described by Hop kins b as follows:

At Chester Heights the spar has been quarried from six different openings and 

occurs as a vein deposit in micaceous rocks, the veins having a general northeastsouthwest trend, varying in width from 8 to 20 feet. The quarries are 40 to 50 feet

oldem. 6 Idem, pp. 13,14.
72 FELDSPAR DEPOSITS OF THE UNITED STATES.

deep, except one, which is an underground working and has been started on the 

vein near the base of the hill by running a horizontal drift into the hill following 

the vein. Some of the spar consists of graphic granite, some is nearly free from 

quartz, and in one opening quartz occurs in large quantities. The spar is all shipped 

to the mill at Brandywine Summit.

MIDDLETOWN.

SJmrpless abandoned quarry. A quarry about 1| miles east of 

Glen Mills was operated many years ago, but was never a large producer. It had been idle a number of years at the time of Hopkins's 

visit in 1898. According to Hopkins,a "The spar contains large 

segregations of quartz and large muscovite crystals, some of which 

are 8 to 10 inches across."

CTielsea abandoned quarry. A quarry which was formerly productive, but has now been idle for many years, is located about midway 

between Chelsea and Boothwyn station. It has not been visited by 

the writer, but in 1898, according to Hopkms,a the quarry opening 

was about 150 feet long and 40 feet deep in a vein about 30 feet 

wide.

MARYLAND.

The active feldspar quarries of Maryland are in Cecil County and 

near the Patapsco River valley in Howard and Baltimore counties. 

The worked deposits of Cecil County are of the soda pegmatite type, 

like those just across the line in Pennsylvania, and show a similar 

association with serpentine and talc. Their location is shown in 

Plate VIII. Most of the quarries of Howard and Baltimore counties are typical granite-pegmatites, occurring near the border of 

considerable areas of granite, to which they are probably related in 

origin. The pegmatite at the Frost quarry, near Woodstock, is

more or less intermediate in composition between the typical granite-pegmatites and the soda pegmatites, as is more fully shown 

below.

The bulk of the feldspar quarried in Maryland is ground either at 

Trenton, N. J., or at Wilmington, Del. A small part of the output 

is ground at the mill of the Eastern Flint and Spar Company, in 

Baltimore. In 1908 there were nine producers in the State.

BALTIMORE COUNTY.

Eureka quarry. A quarry 2 miles north of the village of Granite 

was opened in September, 1907, and is operated by the Eureka Mining and Operating Company. When visited by the writer, in April, 

1908, it consisted of a single pit 40 by 40 feet and 25 feet deep.

The rock is a typical granite^pegmatite. No large masses of pure 

quartz were observed. The feldspar is flesh-colored microcline, much

a Idem, p. 14.
MARYLAND. S

of it graphically intergrown with quartz. White albite also occurs 

in irregular intergrowth with quartz. None of these varieties are 

found in pure crystals more than 3 or 4 inches in diameter. Biotite 

is the only other abundant mineral and occurs in small scattered 

lath-shaped crystals 3 to 4 inches long.

The trend and extent of the pegmatite mass could not be determined. At the west end of the pit the pegmatite is in contact with 

decayed mica schists that trend about 30° W. If we assume a parallel trend for the pegmatite body, it would perhaps connect with 

the pegmatite formerly worked by the Golding Sons Company, a few 

hundred yards to the southeast.

Since the writer's visit this quarry has been a heavy producer, and 

the workings are presumably considerably extended. Six men were 

employed, and the material was hauled by teams to Granite for

shipment by rail to the mill of the company at Trenton, N. J.

Parlet arid Cavey quarry. A quarry operated by Parlet and Cavey 

is on the C. H. Johnson place, a few miles^ast of Woodstock station, 

on the northeast slope of the Patapsco River valley. The deposit 

consists of several rather flat-lying masses of granite-pegmatite separated by irregular bands of mica schist. The maximum depth of 

excavation is only about 30 feet. Very little pure feldspar is encountered, most of the product being an irregular or graphic intergrowth 

of feldspar and quartz. The feldspar is prevailingly buff and is 

microcline. Biotite is the most abundant accessory mineral and renders certain portions of the deposit worthless. Some of the finergrained parts are virtually a coarse biotite gneiss, and even in the 

coarser portions a faint parallel structure is traceable. Much of the 

material is so disintegrated that it can be excavated without blasting. The spar is hauled to Woodstock station for shipment.

Guilford and Waltersville Granite Company's quarry. This company operates a feldspar quarry about 1 mile due east of Woodstock, 

on the railroad spur to Granite. The quarry consists of a single pit 

about 100 feet long, 60 feet wide, and 35 feet in maximum depth. 

The rock is a granite-pegmatite, showing a number of large areas of 

pure light-gray quartz, one of which was 11 by 10 feet on its exposed 

surface. The quartz is saved in the mining. Several masses of 

pure feldspar are 3 to 5 feet across. Most of it is flesh-colored microcline, which is here and there intergrown with a little albite. Smaller 

crystals of feldspar are white, decompose more readily, and are shown 

on testing to be albite. Biotite, which is next in abundance to the 

quartz and feldspar, occurs in lath-shaped crystals, some of them 5 

inches wide and 2 to 3 feet in length. Garnet appears to be entirely 

absent.
74 FELDSPAR DEPOSITS OF TfiE UNITED STATES.

The pegmatite mass seems to be an irregular intrusion that follows 

in general the trend of the bordering biotite schist, which at this 

locality strikes nearly east-west and dips 30° to 70° N.

The quarry was opened in 1906 and is equipped with air drills. 

About ten men are employed, and the feldspar after sorting is transferred by a chute directly to cars on the railroad siding.

French quarry. A small quarry operated by J. T. French is 

located half a mile north of Hollofield station. It is an irregular 

pit, 125 by 30 feet and 30 feet in maximum depth. It was visited 

by the writer in May, 1907. The pegmatite is similar in character 

to that at the Fagan quarry, described below, and the form of the 

mass seems to be quite irregular. The soil covering is heavy and 

interferes considerably with the economical working of the deposit. 

At the time of the writer's visit the quarry was not being operated, 

and was not equipped with any machinery. The material is of 

moderately good quality, but its extent .could not be accurately 

determined. 0

Fagan quarry. A quarry operated by E. E. Fagan is located half 

a mile south of Hollofield station, near the top of the eastern slope of 

the river valley. There are several pits at this locality, the one that 

was worked at the time of the writer's visit being about 100 feet 

long, 25 to 30 feet wide, and 20 feet in maximum depth. The largest 

diameter of the pit represents the trend of the pegmatite dike, which 

is the largest yet found in this immediate vicinity. Its trend is about 

N. 45° E., nearly parallel to that of the bordering mica schists. The 

schists are greatly contorted and together with the pegmatite are 

much decayed, even to the maximum depth of exposure, which is 

about 20 feet. The quartz is light gray and occurs in masses large 

enough to be worth saving in the feldspar mining. The feldspar is 

principally pink microcline,. much of it graphically intergrown with 

quartz. No pure masses over 3 feet across were observed, but a 

few up to 6 feet are reported to have been found in the past. In one 

place the pegmatite was cut by two small dikes of gray quartz, each 

about 4 inches across, which are slightly feldspathic here and there, 

especially at their borders, where they show crystallographic continuity with the bordering pegmatite. Besides the pink microcline 

there are small amounts of white albite, most of it irregularly intergrown with quartz. The next most abundant mineral is muscovite, 

which occurs principally in graphic intergrowth with quartz and 

feldspar and also in more or less rounded aggregates of small plates 

oriented in every direction. Biotite is also occasionally found, as is 

black tourmaline, in crystals up to 1£ inches in diameter.

The second pit, not now worked, is 60 by 30 feet and 20 feet in 

depth. The pegmatite mass appears to be rather flat-lying. Much
MARYLAND, 75

of the material can be excavated with the aid only of the pick and 

shovel and is screened to free it from soil and the more decomposed 

portions. It is hauled for shipment to -Hollofield station.

HOWARD COUNTY.

Brown quarries. A number of small quarries about three-fourths 

mile southeast of Woodstock station, on the farm of W. H. Brown, 

are worked by Parlet and Cavey. At the time of the writer's visit, in 

May, 1907, the workings were not extensive. The rock in all of the 

pits is more or less similar. It is a granite-pegmatite showing only 

small masses of pure quartz or .feldspar, most of the output being a 

graphic or irregular intergrowth of these minerals. The feldspar is 

buff microcline. Many of the other pegmatite dikes of this locality 

are similar to this one. The material here, as in most of the other

quarries of this region, is weathered for some distance from the 

surface and much of it can be excavated without blasting. It is 

hauled for shipment to Woodstock station.

A number of other small quarries not visited by the writer have 

been operated in the vicinity of Woodstock.

Frost quarry. The largest quarry in this region is about half a mile 

south of Davis station and 1| miles southeast of Woodstock, on the 

Frost farm, and is operated by the Golding Sons Company of 

Trenton, N. J.

This quarry is located in a pegmatite deposit of a character somewhat different from those described above. In April, 1908, this 

quarry was about 450 feet long by 100 wide by 65 in maximum depth, 

its greatest dimension trending about N. 60° E. The feldspar is 

of two varieties: (1) Orthoclase and microcline varying from light 

gray to pale flesh colored, and (2) white to gray soda feldspar (albite). 

The potash feldspar is in places in pure crystals, some of them as 

much as 4 feet across, and also in graphic or dendritic intergrowths 

with gray quartz. The soda feldspar is equal to if not greater than 

the potash feldspar in quantity, but is in smaller crystals, not many 

of them more than a few inches in diameter. The largest observed 

was about 1 foot across. Black mica (biotite) is entirely absent and 

white mica (muscovite) occurs only rarely and in plates less than an 

inch across. Quartz does not occur in large masses, but is mostly intergrown with feldspar. The principal iron-bearing impurity is green 

hornblende, which is found in prismatic crystals up to 1 foot in 

length. Pyrrhotite also occurs in small quantities, usually with the 

hornblende. It will be noted that in mineral character this pegmatite is intermediate between the two types previously mentioned. 

The abundance of albite feldspar, the presence of hornblende, and the 

scarcity of mica relate it to the deposits of soda spar worked near 

Sylmar, in southwestern Chester County, Pa., while the presence of
76 FELDSPAB, DEPOSITS OF THE UNITED STATES.

quartz and of potash feldspar, some of it graphically intergrown, 

relate it to the typical granite-pegmatites.

In this quarry a steam drill is used and a derrick is operated by a 

hoisting engine. The material is hauled about a quarter of a mile to 

the railroad and is shipped to Trenton, N. J., and Wilmington, Del.

CECIL COUNTY.

Only two firms are now operating in Cecil County, and these are 

quarrying talc as well as feldspar. The deposits belong to the soda 

type and are similar to those across the state line in Chester County, 

Pa., near Sylmar, Md.

Bald Friar guarry. A number of small quarries were opened in 

1906 at Bald Friar, 1£ miles north of Conowingo, by the Deland 

Mining and Milling Company, of Havre de Grace.

Talc is the principal output at this locality, and is ground at a 

mill near the quarries. Feldspar is a secondary product, and is all 

shipped in the crude state. The quarries in May, 1907, consisted of 

a number of small pits along the upper part of the bluffs bordering 

the Susquehanna. The feldspar when fresh is snowy white and is of 

the soda variety (albite). Near the surface, where the material is 

weathered to some extent, there is a slight iron discoloration along 

the fractures, but this is not sufficient to damage materially the 

quality of the product. The veins range in width up to 15 feet and 

show numerous pinchings and swellings. They occur as intrusions 

in an area of rocks which are mapped on the Cecil County sheet of 

the Maryland Geological Survey as serpentine, peridotite, and pyroxenite. The surrounding rocks have been altered locally to form talc 

schists, and in some of them there seems to have been further alteration due to contact metamorphism by the feldspar masses, as

suggested by an unusual abundance of pyrite near the pegmatite and 

by the development there of narrow zones of fibrous serpentine 

(asbestos). These pegmatite masses appear to be entirely free from 

quartz, and their feldspar, so far as observed, is all of the soda 

variety (albite). Mica and other injurious minerals are rare or 

entirely absent.

The location of these quarries on the valley slope facilitates the 

handling of the material, which is carried down by chutes to the flats 

near the railroad and the river. The quantity of material is probably 

not sufficient to warrant mining for feldspar alone, but the feldspar 

forms an important adjunct in the quarrying of talc.

Rock Springs guarry. In the spring of 1907 a small quarry was 

opened by the Verona Mining Company, of Trenton, N. J., about 3£ 

miles northeast of Conowingo. The material here is almost exactly 

similar in character and mode of occurrence to that just described 

from Bald Friar, and occurs within the same belt of basic rocks
VIRGINIA. 77

(serpentine, pyroxenite, etc.). Talc is also obtained at this quarry. 

The spar is hauled by team 3 miles to Conowingo, from which it is 

shipped by rail. Feldspar has been quarried in the past at other 

points in the vicinity of Rock Springs and along Octoraro Creek.

VIRGINIA.

The following information in regard to the feldspar deposits of Virginia is taken from a report by Thomas L. Watson.0 The writer 

has not visited this district.

Pegmatite dikes containing feldspar as an important constituent 

are widely distributed through the Virginia area of crystalline rocks 

east of the Blue Ridge, hardly a county within the Piedmont area 

being without.them. Notwithstanding their abundance and the fact 

that many of them contain commercially valuable feldspar, the 

attempts to mine this mineral have been comparatively few, and the 

production is as yet small. The principal area in which feldspar 

has been mined is in Amelia County, in the vicinity of Amelia Court 

House, where the mineral has been obtained as an accessory in the 

mining of miqa. Mining of feldspar in an extensive pegmatite mass 

was recently begun on Otter River, about 3 miles southeast of Bells 

in Bedford County, by the Blue Ridge Kaolin Company, the product 

being shipped to East Liverpool, Ohio, for pottery purposes. A 

third quarry recently opened is located near Prospect, in Prince 

Edward County. In the past some feldspar was quarried near 

Jetersville, 8 miles southwest from Amelia Court-House, and ground 

for pottery purposes in a mill located at the mine.

The mines of the Amelia Court House district all occur within a 

distance of 2 miles or so northeast of Amelia, a station on the Southern Railway. Mining for mica in the district was first done about 

1873 and has continued intermittently ever since, though of recent 

years only one property, the Pinchback mine, has been operated. 

The work has all been from open pits, the deepest of which probably 

does not exceed 100 feet. The principal rock of the district is a 

finely foliated, dark, fine-grained biotite gneiss, which may be either 

of igneous or of sedimentary origin. The pegmatite dikes intrude 

this gneiss and show feldspar, mica, and quartz as their principal 

minerals, the proportions among these three varying greatly. Some 

show dominant feldspar and mica with very little quartz, while 

others show dominant quartz and mica with little or no feldspar. 

The feldspar of these dikes includes the potash varieties, orthoclase 

and microcline, and the soda variety, albite.

In addition to the three principal minerals, a large number of rare 

minerals have been noted in the Amelia County pegmatites. These 

are microlite, fluorite, columbite, helvite, monazite, alunite, garnet, 

apatite, beryl, tourmaline, and zircon.

a Watson, T. L., Mineral resources of Virginia, Virginia-Jamestown Expos. Com., 1907, pp. 276-284.
78 FELDSPAR DEPOSITS OF THE UNITED STATES.

The rocks are everywhere weathered to a considerable depth; outcrops are rare and many of the old openings are now partly caved in. 

As nearly as can be determined the larger pegmatite dikes will 

measure more than 50 feet across.

The Pinchback mine is the only mine which has recently been operated in this immediate district for feldspar, and is located about 2 miles 

north of Amelia Court House. It was first worked about eighteen 

years ago, and half a dozen or more openings have been made. The 

most recent one, opened in the spring of 1906, has been worked to a 

depth of 28 feet. As exposed in this opening the dike is about 40 

feet wide and is composed of white feldspar, white quartz, darkcolored mica, and an occasional crystal of beryl. Much of the feldspar 

is decomposed to a high-grade kaolin, which is mined and shipped. 

The remaining feldspar, which is only partly decomposed, slakes 

rapidly on exposure to the air. It is all saved and shipped to Trenton, 

N. J., where it is used in pottery manufacture. This quarry also 

produces both sheet and scrap mica; the largest mica sheets obtainable measure about 12 by 14 inches after trimming.

MINNESOTA.

A considerable quantity of lime-soda feldspar or plagioclase, varying in composition from labradorite to bytownite, is quarried in Lake 

County and ground at Duluth by two firms. The material is used 

mainly for abrasive purposes, filter beds, etc., although a small 

quantity is used in enamel ware.

WISCONSIN.**

The feldspar deposits of Wisconsin are still undeveloped. Pegmatite deposits containing feldspar are found in the town of Stettin, 

Marathon County, about 5 miles northwest of Wausau. They occur 

as pegmatite dikes cutting granite (quartz syenite), and are very 

abundant over an area 5 or 6 square miles in extent in the central 

part of this township. The dikes vary in width from 1 foot to 20 

feet, and are said to be so abundant locally as to be nearly equal in 

quantity to the masses of granite lying between them. The principal constituents of the pegmatite dikes are feldspar and quartz, 

with subordinate quantities of white mica (muscovite) and of the 

iron-bearing minerals black mica (biotite), hornblende, pyroxene, 

and other minerals. Most of the feldspar is a fine-grained (microperthitic) intergrowth of potash feldspar and soda feldspar, and 

contains soda in nearly as large proportion as potash. It is therefore intermediate. in composition between most of the so-called 

"hard" or potash feldspars mined in Canada and the eastern United

a For a more detailed description of these deposits see Bull. Wisconsin Geol. and Nat. Hist. Survey No. 

16,1907, pp. 275-331, by Samuel Weidman.
TEXAS. 79

States, and the typical "soft" or-soda feldspars, such as are mined 

in Chester County, Pa. The crystals of pure feldspar range from 

about an inch to somewhat over a foot in diameter. The dikes are 

not so large as most of those worked in the Eastern States, but they 

may prove to be of commercial value if the iron-bearing minerals are 

not so abundant or so distributed as to injure much of the feldspar. 

These deposits are situated about 7 miles by road from the railroad 

station at Wausau and about 5 miles by road from the railroad station at Marathon, and seem worthy of investigation for commercial 

development.

TEXAS.

A pegamite deposit at Baringer Hill, Llano County, Tex., containing feldspar of the best pottery grades has been studied by Frank L. 

Hess, of the United States Geological Survey. The following are the 

portions of his report 0 of especial interest to the feldspar trade:

Baringer Hill is located about 100 miles northwest of Austin, Tex., on the west 

bank of Colorado River, near the western edge of the Burnet quadrangle of the United 

States Geological Survey maps. It is 12 miles north of Kingslancl, its nearest railroad 

point, 16 miles west of Burnet, and 22 miles northeast of the town of Llano. It is a 

low mound rising above the flood plain of the Colorado, and formed by the resistance 

to erosion of a pegmatite dike intruded in a porphyritic granite.

Few if any other deposits in the world, and certainly no other in America, outside 

of the monazite localities, have yielded such amounts of the rare-earth metal minerals 

as Baringer Hill. * * *

The hill is named for John Baringer, who discovered in it large amounts of gladolinite in 1887. * * * The property is now controlled by the Nernst Lamp Company, of Pittsburg, Pa., and is worked by that concern for yttria minerals. Since its 

acquirement by this company a considerable amount of work has been done on -the 

deposit, consisting mostly of open cuts around the edge of the pegmatite, reaching a 

depth of 30 or 40 feet. A large block, 30 feet in height and more in diameter, consisting mostly of quaHz, is left standing in the middle.

In general the " Llano region," in the heart of which Baringer Hill is located, is an 

island of pre-Cambrian rocks intruded by plutonics and surrounded by an irregular 

zone of Cambrian and other Paleozoics, including some that are possibly Devonian 

and some Carboniferous rocks. Th*e inner portion includes parts of Burnet, Llano, 

and Mason counties, and is situated at almost the geographic center of Texas. * * * 

The plutonic rocks are granitoid, of many textures, and differ considerably in composition. Large areas are composed of the rather coarse red granite, the principal 

outcrops of which occur near Marble Falls and from which the state capitol of Texas 

was built. Peculiar dikes of a chocolate-brown granite near Llano contain blue 

quartz.& Other dikes containing this blue quartz are of a reddish color. In many 

localities the granite is very porphyritic, containing feldspars from 1 inch to 2 inches 

in longer diameter. There are also gray and fine-grained red granites, and in some 

places they have taken a gneissoid form. The granites are, at least in part, intrusive 

in crystalline schists and gneisses of uncertain origin, which are here and there graphitic

a Hess, Frank Lv Minerals of the rare-earth metals at Baringer Hill, Llano County, Tex., Bull. U. S. 

Geol. Survey No. 340, 1907, pp. 286-294.

6 Described by Joseph P. Iddings, Quartz-feldspar porphyry (graniphyro-liparose-alaskose) from Llano, 

Tex.: Jour. Geol., vol. 12,1904, pp. 225-331.
80 FELDSPAR DEPOSITS OF THE UNITED STATES.

and contain interbedded strata of crystalline limestone. There are some later dikes 

of diabasic character, which are comparatively fresh. Southwest of Llano are areas 

of serpentine and other basic rocks.

In many places the granites are cut by pegmatite dikes, ranging in width from a 

few inches to 60 feet, which show a much greater percentage of quartz than of feldspar and other constituents, and afford beautiful illustrations of the most acidic phase 

of pegmatites! In a 6-inch dike there may be but a few feldspar crystals from 1 inch 

to 3 inches long fringing the edges of the dike; in other dikes, or in other portions of 

the same dike, gradations from pure quartz to almost pure feldspar may be observed.

Baringer Hill is formed by such a dike on a huge scale. It is a small mound which, 

before mining was begun, rose perhaps 40 feet above a surrounding flat, was about 100 

feet wide, and from 200 to 250 feet long. Its longer axis runs east and west and is 

nearly at right angles to the course of the Colorado River at this point. The country 

rock is a coarse porphyritic granite with feldspar phenocrysts about 1 inch long. This 

granite seems to weather and erode rather easily, and the river has cut a flood plain 

perhaps one-fourth of a mile wide at this point, while the dike, owing to its greater 

hardness and freshness, has better withstood the erosion.

The pegmatite, an unsymmetrical body with irregular walls, is intruded into the 

granite in what seems to be a pipe or short dike. At the edges of the intrusion is a 

graphic granite of peculiar beauty and definite structure, being more like the textbook illustrations than the usual graphic granite found in the field.- The altered band 

is from 1 foot to 5 or 6 feet thick, and apparently surrounds the pegmatite. No segregation of the feldspar or quartz in particular parts of the dike can be noted, except that 

the feldspar may possibly be more inclined to occupy the sides of the intrusion. As 

far as shown it occupies most of the western and southern sides, and the quartz occupies the center and much of the eastern side.

One quartz mass is more than 40 feet across. The quartz has distinct white bands, 

from one-eighth to one-half inch wide, which seem to be due to a movement akin to 

flowage and are similar to those found in many pegmatitic masses in other portions of 

the country. The white banding is due to small liquid inclusions, many of them containing bubbles which either do not move from change of inclination of the fragment 

containing them or do so but slowly. * * * At one place a vug was found large 

enough for a man to enter, lined with "smoky" quartz crystals reaching 1,000 pounds 

or more in weight. This would seem to indicate that the pegmatite had been intruded 

in a pasty or semifluid condition and that the vugs represent spaces occupied by segregated water that was squeezed from the magma as the minerals took their final solidified form.

The feldspar is an intergrowth of microcline and albite, of a brownish flesh color, 

beautifully fresh, and occurs (1) in large masses reaching over 30 feet in diameter, and 

(2) in huge crystals, many of which, though they rarely show terminal planes, have 

one or more sharply defined edges, especially where partially surrounded by quartz. 

An edge 34 inches long was measured on one crystal thus embedded. A smaller crystal 

was seen which was about a foot long, weighed 20 pounds, and showed fine terminations and twinning planes.

A large amount of feldspar has been mined and thrown on the dump, and it is possible that in time the dump material may be utilized, either for its potassium content 

as a fertilizer, or for pottery making.

Large crystals of fluorspar, measuring a foot along the edge, occur in the quartz, 

but this mineral does not form any considerable percentage of the mass. The fluorspar ranges from almost colorless to violet so dark that it is practically opaque. Where 

found alone in the quartz it was, so far as observed, of lighter color than where found 

with dark-colored minerals. Mr. Hidden informed the writer that it sometimes becomes luminous at the temperature of a living room.
TEXAS. 81

Ilmenite occurs in radiating bunches of sheets or blades ranging from 1 inch to 10 

or 11 inches in width and from one-sixteenth to one-fourth of an inch in thickness. 

In cross section the ilmenite looks like the ribs of a fan, with the outer ends from onefourth to three-fourths of an inch apart. Similar aggregations take different angles, 

and numbers of such groups are found lying close together. With them occurs biotite 

mica in like bunches, the sheets of which are said to reach 3 feet in width by an inch 

in thickness. * * * Small flakes of lithia mica reaching half an inch in diameter 

are found, generally along cracks in the quartz. No muscovite was seen, but it is 

said to be found occasionally. Compared with the mass the total amount of mica is 

very small.

Present commercial interest in the dike centers in the accessory 

minerals, particularly in the rare-earth metal minerals, which, as 

stated, probably have never been found at any other place in masses 

and quantities so large as at this locality. So far the excavations are 

comparatively shallow, and the minerals found are more or less 

weathered; many show their crystalline form, but owing to alteration the crystals are now imperfect.

The accessory minerals include allanite, autunite, chalcopyrite, 

cyrtolite, fergusonite, gadolinite, gummite, hematite, lantleanite, 

magnetite, molybdenite, nivenite, pyrite, polycrase, powellite, row- 

]andite, rutile, sphalerite, tengerite, thorogummite, and yttrialite.

It is interesting to note that among the numerous minerals in this 

dike no tourmaline, zircon, beryl, monazite, cassiterite, garnet, or 

tungsten minerals have been found. Cassiterite has been reported 

from the neighborhood, but its occurrence is extremely doubtful.

With the exception of the alteration products and probably of the 

lithia mica, which, as noted, occurs along cracks in the quartz, all 

the minerals are believed to be original constituents of the dike. 

16779 Bull. 420 10 6

INDEX.

A. Page. 

Albite, character of.......................... 7-9

Amelia County, Va., feldspar deposits in.... 77

American Feldspar and Mining Co., quarry of 57 

Analyses of feldspar, tables of................ 9

Andesine, character of....................... 7

Andrews quarry, description of.............. 50-51

Androscoggin County, Me., feldspar deposits

in............................... 23-27

Anorthite, character of...................... 7-9

Apatite, Mount, Maine, feldspar deposits at. 23-26

Ararat, Mount, quarries, description of...... 34-36

Auburn, Me., feldspar deposits at............ 23-26

feldspar deposits at, feldspar of, analysis

of............................... 24,25

Avondale, Pa., quarry near.................. 65

B. 

Baker, Pa., quarry at....................... 64

Baker quarry, description of................. 65

Bald Friar quarries, description of.......... 76

Baltimore County, Md. feldspar deposits at. 72-75 

Baringer Hill, Texas, feldspar deposits at.... 79-81

Barrett Manufacturing Co., quarry of........ 55

Batchellerville quarry, description of........ 58-59

Bedford, N. Y., feldspar deposits at.......... 60-63

Bedford County, Va., feldspar deposits in.... 77

Berry, A. K., quarry of...................... 26-27

Beryl, character of.......................... 12

Biotite, character of......................... 11-12

Blandford Quarries Co., quarries of.......... 41

Brandywine Summit Kaolin and Feldspar

Co., mill of...................... 71

quarryof....................... 65-66,69,70-71

Bridgeport Wood Finishing Co., mill of...... 6#

quarry of................................ 53

Brown quarries, description of.............. 75

Bytownite, character of..................... 7

C. 

Cathance, Me., mill at....................... 39-40

Cecil County, Md., feldspar deposits in...... 76-77

Chatham, Conn., feldspar deposits at........ 47

Chatham quarry, description of.............. 65-66

Chelsea, Pa., quarry at...................... 72

Chester County, Pa., feldspar deposits in.... 64-70

Chester Heights, quarries at................. 71-72

Claspka Mining Co., quarries of.............. 56,58

Color of feldspars, range of.................. 6,7

Concord, Pa., feldspar deposits at............ 70-72

Connecticut, feldspar deposits In.......... 15,41-54

feldspar deposits in, distribution of...... 41-42

feldspar of, prices of................. 21

production of................... 22

See also particular counties. 

Conowingo, Md., quarries near.............. 76

Page.

Consolidated Feldspar Co.'s quarry, description of........................... 49-50

Cooperation, work done under............... 5

Corinth, N. Y., feldspar deposits at.......... 57-58

Corinth Feldspar Co., quarry of.-............ 57

Crown Point, N. Y., feldspar deposits at..... 54-55

Crown Point Feldspar Co., quarry of........ 54

Crystallography of feldspars, discussion of... 6,7

D.

Deland Mining and Milling Co., quarry of... 76 

Delaware County, Pa., feldspar deposits in .. 70-72 

Dibble Mountain, New York, feldspar deposits at......................... 54

E.

East Glastonbury quarry, description of..... 43-44

Edgecomb, Me., feldspar deposits at......... 27-28

Edinburg, N. Y., feldspar deposits at........ 58-59

Elam, Pa., quarry at........................ 70

Embreeville quarry, description of.......... 07

Emery wheels, feldspar for.................. 19

Essex County, N. Y., feldspar deposits in.... 54-56

Eureka Mining and Operating Co., quarries

of................ 42,45,47,51-53,65,72

Eureka quarry, Conn., description of........ 72

Eureka quarry, Md., description of.......... 51-53

Fagan quarry, description of................ 74-75

Fertilizer, use of feldspar for................. 20

Feldspar, analyses of........................ 9

chemistry of............................. 5-9

freight on............................... 16-17

gradesof................................ 21-22

markets for.............................. 16-18

milling methods with................... 18-19

origin of................................. 10

physical properties of.................... 5-9

prices of................................. 21-22

production of............... .:.....:..... 22-23

uses of............................ 16,18,19-20

Feldspar deposits, descriptions of............ 23-81

descriptions of. See also particular

States. 

distribution of.......................... 10

mineral composition of................ 9,11-15

injurious constituents of................. 17

mining of............................... 15-16

value of................................. 16-18

Fisher's quarry, description of............... 30-37

French quarry, description of............... 74

Frost quarry, description of................. 75-76

Fulton County, N. Y., feldspar deposits in.. 56-57

83
84 INDEX.

G. Page. 

Garnet, character of......................... 12-13

Gems, occurrence of......................... 24,27

Geology of deposits, outline of.............. 10-11

Georgetown, Me., feldspar deposits at....... 31-33

Gerry, J. A., quarry of...................... 28

Glass, use of feldspar in..................... 19-20

Glastonbury, Conn., feldspar deposits at..... 42-46

Glaze, use of feldspar for.................... 19

Golding's quarry, description of............. 31-33

feldspar from, analysis of................ 31

Golding Sons Co., quarries of................ 31,75

Granite, Md., quarries near.................. 72

Granite-pegmatite, feldspars in.............. 10

minerals in.............................. 11-15

physical characters...................... 13

Graphic granite, analyses of................. 14

character of............................... 13-15

feldspar and quartz in................... 15

Guilford and Waltersville Granite Co., quarry

of.............................:.. 73-74

H.

Haddam, Conn., feldspar deposits at......... 48-49

Haddam Neck quarry, description of........ 48-49

Hartford County, Conn., feldspar deposits in. 42-46 

Hebron, Me., feldspar deposits at............ 28-30

Hess, F. L., on feldspar deposits in Texas... .79-81

Hibbs quarry, description of................. 28-29

Hobby quarries, description of............... 63

Hopkins, T. C., on Pennsylvania quarries 64,

67,71-72 

Howard County, Md., feldspar deposits in.... 75-76

Howe, L. W., mill of, description of......... 46

quarry of, description of.............. 41,45-46

K.

Keystone Feldspar Co., quarry of............ 68-69

Keystone quarry, description of............. 68-69

Kinkle's Sons, mill of, description of......... 62-63

quarries of, description of............. 60-62,63

L.

Labradorite, character of.................... 7

Lake County, Minn., feldspar deposits in.... 78

Lime-soda feldspar, character of............. 7-9

Lincoln County, Me., feldspar deposits in.... 27-28

Llano County, Tex., feldspar deposits in..... 79-81

London Grove, Pa., feldspar deposits at..... 64-66

M. 

Maine, cooperation of........................ 5

feldspar deposits in. ....*.............. 15,23-40

feldspar of, prices of.... ^........... 21

production of.................... 22

See also particular counties. 

Maine Feldspar Co., mill of...... 25,26,27,38,39-40

quarry of................................ 38,40

Marathon County, Wis., feldspar deposits in. 78-79 

Maryland, feldspar deposits in...... 10,15-16,72-77

feldspar deposits in, feldspar of, prices of. 21 

feldspar of, production of............ 22

 See also particular counties. 

Massachusetts, feldspar deposits in.......... 41

Melting point of feldspars, range of........... 6,8

Meredith quarry, description of.............. 67

Microcline, character of...................... 5-6

Page.

Middlesex County, Conn., feldspar deposits in. 47-53 

Middletown, Conn., feldspar deposits at.... 49-50

Middletown, Pa., feldspar deposits at........ 72

Milling, methods of.......................... 18-19

Mills quarry, description of.................. 29-30

Mineral composition of feldspars, table of.... 9

Mining, methods of.......................... 15-16

Minnesota, feldspar deposits in.............. 78

Minot, Me., feldspar deposits in.............. 26

Mount Marie Mining Co., quarry of.......... 29

Muscovite, character of...................... 11

New Garden, Pa., feldspar deposits at....... 66

New Haven County, Conn., feldspar deposits

in............................. 53-54

New Jersey, feldspar of, prices of............. 21

feldspar of, production of................ 22

Newlin, Pa., feldspar deposits at............. 67

New York, feldspar deposits in........... 15,54-63

feldspar deposits in, feldspar of.......... 6

feldspar of, prices of.................. 21

production of.................... 22

North Castle, N. Y., feldspar deposits at..... C3

Number Four Hills, feldspar deposits at.... 29

0. 

Oligoclase, character of...................... 7

Ontario, feldspars of......................... 6

Orthoclase, character of...................... 5-6

Oxford County, Me., feldspar deposits in.... 28-30

P.

Parlet & Cavey quarry, description of....... 73

Pegmatite. See Granite-pegmatite. 

Pennsylvania, feldspar deposits in.. 10,15-16,63-72 

feldspar deposits in, feldspar of, prices of. 21 

feldspar of, production of............ 22

See also particular counties. 

mills in.................................. 64

Pennsylvania Feldspar Co., quarry of....... 66

Pennsylvania Marble and Granite Co.,

quarry of....................... 64-05

Pinchback mine, description of.............. 78

^Tlagioclase, character of..................... 7-9

Poland, Me., feldspar deposits in............ 26-27

Portland, Conn., feldspar deposits at...'..... 50-53

Potash salts, manufacture of................. 20

Potash-soda feldspars, characters of.......... 5-6

Pottery, feldspar for......................... 19

Poultry grit, feldspar for..................... 20

Prices, range of.............................. 21-22

Prince Edward County,Va., feldspar deposits

in............................... 77

Production, statistics of..................... 22-23

QQuartz, character of.......................... 11

R.

Riverside quarry, description of............. 50

Robinson, W. S., quarry of................. 28

Rock Springs quarry, description of......... 76-77

S.

Sagadahoc County, Me., feldspar deposits in. 31-41 

Saratoga County, N. Y., feldspar deposits in. 57-59
INDEX. 85

Page.

Sharpless, Pa., quarry at.................... 72

Snow, L. T., quarry of...................... 50

Soda-potash feldspars, characters of.......... 5-6

Southford quarry, description of............. 53-54

Sparvetta Mining Co., quarry of............. 68

Sparvetta quarry, description of............. 68

Stettin, Wis., feldspar deposits at............ 78-79

Sylmar, Md., quarry near .................... 08

T.

Teeth, artificial, use of'feldspar for .......... 20

Texas, feldspar deposits in................... 79-81

Thompson quarry, description of............ 65

Ticonderoga, feldspar deposits at............ 55-56

Ticonderoga Feldspar Co., quarry of......... 56

Topsham, feldspar deposits in............... 33-41

Toughkenarnon mill, description of........... 66

Toughkenamon quarry, description of...... 66

Tourmaline, character of..................... 12

Trenton Flint and Spar Co., quarry of....... 37

Turner, E. Y., quarries of................... 25

U. 

Unionville quarries, description of........... 65

Uses of feldspar, description of............... 19-20

V. Page.

Verona Mining Co., quarry of................ 76

Virginia, feldspar deposits in................ 77-78

feldspar deposits in, feldspar of, production of........................... 22

See also particular counties.

W.

Watson, T. L., on feldspar deposits in. Virginia............................ 77-78

Weidman, Samuel, on feldspar deposits in

Wisconsin....................... 78

West Cain, Pa., feldspar deposits at.......... 67

Westchester County, N. Y., feldspar deposits

in............................ 54,60-63

West Nottingham, Pa., feldspar deposits at.. 68-70 

White Rocks, Conn., feldspar deposits at.... 49,50

Wiarda, J. C., mill of, description of......... 45

quarry of, description of................. 44-45

WUles, G. D., quarry, description of........ 38-39

Willes, William, quarry, description of....... 37-38

Wisconsin, feldspar deposits in.............. 78-79

Woodstock, Md., quarries near.............. 73,75

o