DEPARTMENT OF THE INTERIOR

UNITED STATES GEOLOGICAL SURVEY

GEORGE OTIS SMITH, DIRECTOR

BULLETIN 484

THE

GRANITES OF CONNECTICUT

BY

T. NELSON DALE

AND

HERBERT E. GREGORY

Prepared in cooperation with the 

Geological and Natural History Survey of Connecticut

WASHINGTON

GOVERNMENT PRINTING OFFICE 

1911

CONTENTS.

	Pago.

INTRODUCTION.___________________________________.._ 7

PAKT I. Scientific discussion____________________._____._ 9

Salient features of Connecticut geology, by Herbert E. Gregory___ 9

Origin, nature, and classification of the rocks____________ 9

Outline of geologic history of Connecticut______________ ' 11

Economic geology of the rocks________________.__ __ 13

Granites and granite gneisses of Connecticut, by Herbert E. Gregory- 14

Name, mineral content, and origin___________________ 14

Gneiss and granite___ _ ______ ________ .16

Texture of granitic rocks___________ ________ 17

Pegmatite ___________..__________ _ _____ 18

Porphyry______________. ______ _______.__ 20

Distribution of granites and gneisses____ ________ 22

Nature of granitic intrusions_________ ____ 24

Age of the Connecticut granites________ __ _ __ 25

Structure, rock variations, weathering, and discoloration of granitic

rocks, by T. Nelson D;ile___________________________ 26

General structure____' ________________ ___ - 26

Flow structure____:___________ --___-:_ ' 26

Rift and grain__________L___________________ 26

Sheets________________________________ 29

Joints___._____________________-________ 36

Headings______ _ : 37

Faults_________'_______________________ 3S

Microscopic fractures _..______________i________ 39

Snbjoints____________________ ______ 39

Rock variations_____ 39

Dikes (granitic) ____________________________ 39

Veins____________________- _____- 40

Dikes (basic) ___________________-______ 41

Segregation^ (knots) .._- 41

Geodes__________________ ____ 42

Inclusions____._____________ ________ 42

Discoloration _______________..________________ 42

Decomposition ______ _________________________ 43

Geologic observations at the quarries, by T. Nelson Dale_______ 45

Microstructure____________________ _________ 46

Flow structure-______________________________ 47

Inclusions _________________________________ 47

Plicated gneiss structure_________________________ 47

Granite dikes________________________________ 48

Pegmatite dikes_______________________________ 48

Aplite dikes__________________________________ 49

Mineral veins_________________________________ 50

Contacts____________________________________ 50

Sheet structure _____________________________ 50

Joint structure-_____ _____________________ 51

3
4 CONTENTS.

PART I. Scientific discussion Continued.

Geologic observations at the quarries Continued, Page.

Segregations__l_.____'._________________________ 51

Geodes______________________________ 51

Secondary quartz on joint faces______________ 51

Veinlets of zeolite_______________ ___ 51

PART II. Economic discussion, by T. Nelson Dale_______________ 52

Description of the quarries and their product__________ ____ 52

Method____________________________________ 52

Fail-field County______________________________ 52

Bridgeport _______________________________ 52

Bnrlison quarry___1______________________ 52

Jail quarry__:_________ _ - _____ _ 53

Danbury ________________________________ 54

Collins quarry______________________-_- 54

Treadwell prospect:_____________________ 55

Greenwich______________________________ 55

Voorhis quarry _________________________ 55

Ritch quarry _____________________ _____ 57 

Christiano Oak Ridge quarry_______________ 58

Christiano Hamilton Avenue quarry_ __________ 59

Norwalk ____________________________. __ 59

Hall quarry __________________________ 59

Hartford County_____________________________ 60

General conditions __________________________ 60

Bristol_______i________________.__ __ ___________ 61

Dunn quarry _-_________________________ _ 61

Seymour Street quarry__________:__________ 62

Glastonbury___..________________________..__ 62

Corbin quarry.______________ _________ 62

Carline quarry____________________:____ 62

Gormau quarry________________________..'__ 63

Dauielson quarry________________________ 64

Belden quarry _______:______________: ____ 64

Cui'tis quarry______________________ 65

Brooks quarry-_____________________'_____ 66

Slater quarry_________________________ 66

Litchfield County___________________'__________ 67

Oornwall______________________________..__ 67

Benedict quarry________________________ 67

Litchfield _______________________________ 68

Mascetti quarry________________________ 68

Norfolk_____ ____________________________ 69

Crissey quarry_________________________ 69

Roxbury______________________: __________ 70

Rockside quarry_________________________ 70

Thomaston _______________________________ 72

Plymouth quarry ________________________ 72

Torringtou __________________.______________ 73

Costello quarry__:________________________ 73

Michiel quarry__________________________ 73

Torringtou. Borough quarry___i_____________ 74
CONTENTS. 5

PART II. Economic discussion Continued.

Description of the quarries and their product Continued.

Litchfiekl County Continued. Page.

Warren _______________________ 76

Comstock prospect ____________ ____ 76

Middlesex County-_ _______ 70

Middietowu_______________1___________ 76

Ben venue quarries____________ _ 76

New Haven County - __________ - 78

Ansouia _______________________ - 78

Potter quarry _______________ _ 78

Davidson quarry ______________________ 78

Branford_________________________________ 79

Norcross quarry _________. _ 79

Stony Creek quarry ______________ 82

Brooklyn quarry ______________________ 84

Hoficlly Neck quarries_________________ 85

Guilford _______________________________ S7

Leete Island quarry______ 87

Sachem Head quarry.._______________ 8S

Seymour ______________________________ 90

Holhrook quarry_________________________ 90

New London County____________________________ 91

Groton ___________________________________ 91

Salter quarry______,.___________________ 91

M'lntosli quarry_________________________ 93

Eckeriein quarry_______________________ -94

Kopp quarry___________________________ 95

M'Gaughey quarry_______________________ 96

East Lynie___1 _ __ __ _______________________'__ 97

Malnati pink quarry ______________________ 97

Carl son quarry _____'.__________________________ 98

Lyrne __________________t________________ 99

Joshua Rock quarry _____________________ 99

Selden Neck quarries_____________________ 99

OJd Lynie_ ____________________________ 100

MacCurdy quarry _______________^_________ 100

Stouiugtou_______________________________ 102

Masons Island quarry_____________________ 102

New Anguiila quarry_______________________ 103

Murray quarry _______________________ 104

Waterford _______________________________ 106

Scott quarry ________________________ 106

Richards quarry _________________________ 106

Flat Rock quarry________________________ 107

Goos quarry _______________________ 10S

Millstone quarry_________________________ 109

Somers quarry __1________________________ 112

Waterford quarry________________________ 113

Tolland County ________________________________ 116

Bolton_________________________________ 116

Petersou quarry __________________________ 116
6 CONTENTS. .

PART II. Economic discussion Continued.

Description of the quarries and their product Continued. Page.

Windham County _ _ 117

Sterling .___:________ - 117

Oneco quarry______" _ 117

Marriott quarry____ _ 118

Bennett Bowlder quarry____________ ___ _ 119

Sterling quarry_____ _ 120

Windham ________________________________ 121

Larrabee quarry___ ___ _ 121

Classification of the granites__1 ___________________ ______ 122

Commercial value of the granites________________ ___ 127

Statistics of granite production, by Altha T. Coons__________ 127

General economic conclusions________ <____ ___ __ 128

Glossary_____________________________________' 130

INDEX _____________________-__________-____ - 135

ILLUSTRATIONS.

Page.

PLATE I. Preliminary geologic and economic map of Connecticut______ .7 

II. A, Gneiss from Leete Island quarry, showing gneissoid texture 

clue to squeezing and stretching of granite; B, Granite from 

Booths quarry, Waterford, showing granitic texture______ 16

III. A, Polished slab of pegmatitic biotite granite gneiss (" Bran ford 

red granite " of the trade) from the Norcross quarry at Stony 

Creek; B, Obelisk of hammered pegmatitic biotite granite 

gneiss (" Branford red granite") from the Norcross quarry 

at Stony Creek____________________________ 32

IV. A, Coarse porphyritic biotite granite gneiss from West quarry. 

I-Ioadly Point, Branford; B, Porphyritic granite gneiss from 

Derby ___________1___________________ 84 

V. Sachem Head breakwater granite quarry, Guilford________ 88 

AT. Monument of quartz numzonite from Waterford__________ 114 

VII. A, Bas-relief of quartz monzonite from Waterford; B, Monument of quartz monzonite from Groton______;________ 114 

FIGURE 1. Map of part of Greenwich, Conn., showing locations of granite

quarries ____ _..._________________ _____ 5b

2. Map of Glastonbury granite gneiss quarries___________ 60

3. Map of Branford' and GnMford granite quarries________ 80

4. Plicated biotite granite gneiss, West quarry, I-Ioadly Point,

Branford '._______________________________________________ 85

5. Section of Holbrook quarry in Seymour____ ________ 91

6. Structure at Murray quarry, Pawcatuck, Stouington______ 105

7. Map of granite quarries in south part of Waterford..______ 107

8. Details at Millstone quarry, Waterford___1_________ 111

9. East-west section of Waterford quarry_______________ 115

10. Relations of granite and gneiss in center of Waterford quarry_ 115

11. Discordant sheet structure in granite and gneiss on south wall

of Waterford quarry _________________________ 115

12. Structure at Waterford quarry __________________ 116
U. S. GEOLOGICAL SURVEY 

GEORGE OTIS SMITH, DIRECTOR BULLETIN 484 PLATE I

- - - MASSACHUSETTS !Sr~-"

b^riD.^°/ IV. ^ 'S ^ T 

/_ _ _ _/_i, _l /wcmJBlST)<ni.M£\ \

: !,,-> . \ \ i ' ,/lT^A\fc-i.-0-rR1

Maromus granite gneiss 3'n

31 ' 8

^iKf^rt N WJA-A4S

1 *)C Blotite or biotite-mascovite granite gneiss 

(Foliation more or less obscure)

uartz monzonite (Monumental)

ranite gneiss with biotite or with muacovite 

(Foliation marked)

ica diorite gneiss (Constructional) 

5V Granite gneiss with biotite and hornblende

reakwater granite gneiss 

7V JEgiriie granite gneiss (Curbing, trimming} 

S V Pegmatite, biotite granite

ted from Bulletin 6 of the Connecticut Geological 

ural History Survey, 1906, Some of the above 

n names conflict with names applied to the same 

adjoining States and wii! probably be in part 

abandoned. Their retention in this economic bulletin --' 

does not imply their adoption by the United States

L-'.'xirfi<<;~"-"-'t:- Geological Survey. Both names and geologic boundaries .^^Z^>-

are subject to extensive revision. 

eid Pt^

LONG

Base map adopted from map by 

H. E. Gregory and H. H. Robinson PRELIMINARY GEOLOGIC AND ECONOMIC MAP OF CONNECTICUT

S c ale 5 ooocTo

is Miles
THE GRANITES OF CONNECTICUT.

By T. NELSON DALE and HERBERT E. GREGORY.

INTRODUCTION.

. This bulletin, like the previous bulletins on New England granites 

(No. 313, on those of Maine; No. 354, on the principal granites of 

Massachusetts, New Hampshire, and Rhode Island; and No. 404, on 

the granites of Vermont), treats of its subject from both the scientific 

and the economic standpoint, but is so prepared as to make even the 

scientific portions intelligible to the general reader.

By arrangement between the Director of the United States Geological Survey and the superintendent of the State Geological and 

Natural History Survey of Connecticut the two surveys have cooperated in the preparation of this bulletin, Herbert E. Gregory, of Yale 

University, contributing part of the scientific discussion (Part I) and 

T. Nelson Dale, of the United States Geological Survey, contributing the rest as well as the economic discussion (Part II). Freeman 

Ward, instructor in Yale University, has contributed some observations on the Brooklyn quarry near Stony Creek. Miss Altha T. 

Coons, of the United States Geological Survey, has contributed the 

statistics of granite production.

The field work, clone by Mr. Dale in the fall of 1907 and the summers of 1908-1909, included visits to 63 quarries. He is indebted to 

F. C. Calkins, of the United States Geological Survey, for the critical 

revision of his petrographic determinations. R. C. Wells, a chemist 

of the same Survey, has determined the lime soluble in acetic acid in 

six of the granites.

The Rosiwal method of estimating mineral percentages has been 

applied as far as practicable to the types of granite described. These 

types are scientifically classified on page 123 and are commercially 

classified, with both their trade and scientific names, in the table on 

pages 124-126, which is followed by a section on their relative commercial values.

The word " granite " in the title and in Part II is primarily used 

in its popular and commercial sense, but many of the commercial

7
8 GRANITES OP CONNECTICUT.

" granites " of the State are really gneisses more exactly, granite 

gneisses and one is a mica diorite gneiss. The proper scientific 

names are given in the quarry descriptions as well as the table. The 

name " quartz monzonite " is applied to granites in which the amount 

of soda and lime feldspar is almost equal to or even exceeds that of 

the potash feldspars. The definitions of texture in the descriptions 

are to be understood as in the previous granite bulletins coarse, 

with feldspars generally over 0.4 inch, or 1 centimeter; medium, with 

feldspars under that size and over 0.2 inch or half a centimeter; and 

fine, with feldspars under 0.2 inch.

The numbers of the specimens described, to which those of the thin 

sections correspond, are given, so that the descriptions can be verified by consulting the collections at the National Museum. All the 

specimens referred to except those from idle quarries were prepared 

from blocks selected by the foremen or superintendents.

A scientific account of the origin, composition, texture, and physical properties of granite, adapted to the general reader, can be 

found in United States Geological Survey Bulletin 354, pages 9-17. 

Pages 18-38 of that bulletin on the structure of granite and its variation and decomposition are reprinted here on pages 26-45. Such 

scientific terms as have unavoidably been used in one or both parts 

of the bulletin are explained in the glossary at the end, where also 

some of the quarrymeh's terms are made intelligible to the general 

and the scientific reader.

The quarries enumerated include all those that are in operation 

and a few that are idle, as well as some prospects.. The descriptions 

of their location are based on the topographic maps published by the 

United States Geological Survey.

The granites of all quarries east of longitude 73° have been referred to their provisional formation names and numbers on the 

preliminary geological map of the State, by Gregory and Robinson, 

1906, in Bulletin No. 1 of the Geological and Natural History Survey 

of Connecticut. These names, it must be understood, are given only 

for reference and may differ from those which will be finally adopted 

by the United States Geological Survey in its geologic folios.
PART I. SCIENTIFIC DISCUSSION. 

SALIENT FEATURES OF CONNECTICUT GEOLOGY.

By HERBERT E. GREGORY. 

ORIGIN, NATURE, AND CLASSIFICATION OF THE ROCKS.

An examination of the geologic map of Connecticut (PI. I) reveals 

the fact that the three large groups of rocks namely, sedimentary, 

igneous, and metamorphic are represented in the State. About 20 

per cent of the State is occupied by sedimentary rocks, approximately 

5 per cent by unaltered igneous rocks, and the remaining 75 per 

cent by metamorphic rocks.

The sedimentary rocks of Connecticut include sandstones, conglomerates, and shales and occupy the great central lowland. Originally these rocks were sands and gravels and muds deposited by 

water. They have since been consolidated into rock, chiefly by the 

addition of cementing material between the individual grains.

The igneous rocks are chiefly granites and traps. These rocks were 

once in a molten state and their present solidity is due to cooling. 

The Connecticut trap rocks are of two classes diabase, a rock which, 

like granite, cooled at a depth below the surface; and basalt, a lava 

which cooled after being poured out on the surface. Diabase is represented by East Rock, Mount Carmel, and the Barndoor Hills; 

basalt is well exhibited in the Hanging Hills at Meriden.

Metamorphic rocks are either igneous or sedimentary rocks which 

have been profoundly changed from their original condition. They 

have therefore a much more complicated history than either sedimentary or igneous rocks. They are of great antiquity and have 

been subjected to many of the disturbances which have taken place 

within the earth's crust since early geologic time.

In order to understand the structure and appearance of metamorphic rocks which include the gneisses, schists, and marbles of 

the State it is necessary to have in mind the physical and chemical 

forces operating within the earth's crust. Owing to the changing 

shape of the earth in response to the change from molten to solid 

form, continuous adjustment among the rocks is taking place both 

near the earth's surface and below the surface. Adjustments among

9
10 GRANITES OP CONNECTICUT.

the rock masses are also required by the fact that material is constantly being removed from parts of the land and heaped upon other 

parts, a process illustrated by the Mississippi, which removes millions of. tons of soil and rock from lands along its course and deposits 

this mass of material 1,000 miles or more from its place of origin. 

When these adjustments within the earth take place, rocks in different places behave very differently, their behavior depending upon 

their position with respect to the earth's surface. Rocks at the surface that are subjected to lateral pressure break and leave crevices, 

large or small, between the broken parts. The fractures may appear as open cracks, or " joints," or as zones of crushed rock, or may 

be so tightly closed as to escape notice. In places the pressure to 

which the rocks have been subjected was so great that strata have 

been broken into blocks, some of them lying obliquely, others tipped 

on end, and still others retaining their original horizontal position. 

Such giant blocks are illustrated by the masses of lava forming the 

broken ridge extending from Meriden to the Massachusetts line.

Rocks buried within the earth to the depth of a mile or more can 

not adjust themselves by breaking when pressure is applied. The 

weight of the overlying strata is so great that crevices and cracks 

can not form, and equilibrium is attained not by sudden breaking 

but by movement from the place where the pressure is great to other 

places where the pressure is relieved. The rocks that lie far below 

the surface behave as if they were so much tallow or wax; in other 

words, they may be said to flow. Such are the conditions under 

which metamorphic rocks are developed conditions entirely unlike 

those attending the formation of igneous or sedimentary rocks.

The structure and general appearance of metamorphic rocks is 

accordingly unlike that of igneous and sedimentary rocks and is due 

to the fact that the rock mass has been forced to move under great 

pressure pressure which, with generated heat, is adequate to change 

completely the shape and texture of the rock, as well as its mineral 

content. These profound changes that metamorphic rocks have undergone, no matter whether they were originally igneous or sedi^ 

mentary, have given them their characteristic appearance.

When a ledge of metamorphic rock is viewed from above it is seen 

to be traversed by innumerable lines, which are the edges of planes, 

along which the rock may be divided into slabs or sheets. When 

viewed from the side, as in a quarry or railroad cut, these lines or 

bands are seen to be vertical or oblique. In some places the lines are 

far apart, so that the rock has the appearance of bedded sandstone or 

other sedimentary rock which has been turned on end. A little 

examination, however, will detect the difference, for these metamorphic rocks are composed of crystals, whereas the sedimentary rocks 

are made of grains held together by cement. The bedding is there-
OUTLINE OF GEOLOGIC HISTORY OF CONNECTICUT. 11

fore apparent, not real; it is not an original structure in the rock but 

is rather the result of pressure. When a metamorphic rock is broken 

it separates more easily along these lines or bands than in any other 

direction, and a rock which thus separates along parallel planes is 

said to be fissile or to possess fissility or foliation that is, it separates as if it were made of a series of leaves placed together. " r[

Fissility is a phenomenon produced in the deep-seated zone, where 

rocks may flow but not break. Under pressure the minerals of the 

original rock have been flattened, and new minerals, chiefly mica, 

have been developed along the planes of movement. The result is 

that when a gneiss or schist is separated into layers along these 

bands the surface of the rock often appears to be coated with black 

mica. It should be remembered that the metamorphic rock has the 

same chemical composition as the original from which it was formed 

and that the change is in structure rather than in composition. Generally speaking, the planes of schistosity in Connecticut run northsouth to northeast-southwest, indicating that the pressure must have 

come from the east or southeast, but there are many local variations. 

Met amor phi crocks that actually separate along the planes of schistosity -that is, instead of a tending to separate are actually separated 

are said to be fissile or to possess fissility. Fissility may be produced at the surface by weathering or at a short distance below the 

surface by fracture induced by pressure. Oftentimes in Connecticut the minute crevices opened in this manner may be filled by material carried in ground water or by films of igneous rock thrust into 

the open spaces. The result is to give the rock a banded appearance, 

and in some rocks this has gone so far that their entire exposed outcrop seems to be painted over with a series of wavy lines and bands.

In addition to the incipient cracks making up the fissile structure, 

every ledge shows a series of cracks called joints, which commonly 

occur in two or more sets, as a rule nearly at right angles to each 

other. These joints may be parallel with the planes of schistosity, or 

may cut across them. They are common to metamorphic, igneous, 

and sedimentary rocks alike, and are not to be considered a fundamental part of metamorphic structure.

OUTLINE OF GEOLOGIC HISTORY OF CONNECTICUT.

Whether the area now occupied by Connecticut was land or sea 

at the beginning of geologic time is unknown. It is probable, however, that some of the gneisses and schists antedate the appearance 

of life on the earth. Unfortunately no fossils have been found in 

the older rocks of the State, and all that can be said with assurance 

regarding the age of these formations is that they wefe in existence 

long prior to Triassic time. Pre-Cambrian time is believed to be 

represented by the Becket gneiss, which outcrops over wide areas in
12 GKANITES OF CONNECTICUT.

northern Litchfield County. This rock is, however, so profoundly 

changed that it is impossible to determine with accuracy the original 

from which the present complex mass was derived. The limestone 

and marbles of Canaan and Danbury were probably deposited in 

Cambro-Ordovician time, and the material forming these rocks is 

believed to have been furnished by high land masses located east 

of the Rhode Island border lands which long ago disappeared.

The geologic history of the immensely long time represented by 

the Silurian, Devonian, and Carboniferous ages has not yet been 

completely deciphered. Whether rocks belonging to these ages exist 

in western Connecticut is unknown, but the metamorphosed equivalents of Carboniferous sediments are represented in the eastern part 

of the State. Though much doubt exists regarding the Paleozoic 

sedimentary record, there is abundant evidence for the statement that 

at frequent intervals during these ages igneous intrusions occurred. 

Masses of igneous rock, which occur as minute dikes and sheets, may 

be considered as remnants of larger masses, which were poured out 

on the surface or hidden beneath the overlying strata.

Moreover, an examination of the schists and gneisses of the State 

reveals the fact that all rocks older than the Triassic sandstone have 

been involved in movements within the earth's crust, arid have accordingly been so much metamorphosed as to destroy all fossils which 

they may have contained, and to modify the rocks themselves beyond 

recognition. The dates when these far-reaching changes took place 

are believed to coincide with the mountain-making epochs marking 

the close of Ordovician and of Carboniferous time. The extent of 

these changes and their fundamental character are revealed by a study 

of the metamorphic rocks of the State.

These rocks are chiefly schists and gneisses, and accordingly have structures

indicating that they have been profoundly changed from their original sedimentary or igneous character. The original component minerals have been 

rearranged, stretched, and drawn out in lines; new minerals have been 

produced; parts have been fused and recrystallized. Instead of horizontal 

layers or uniform igneous masses, we find twisted and broken rock with layers, 

bands and ribbon structures in every conceivable position. Moreover, this 

tangle of structure is further complicated by the presence of dikes, seams, and 

veins which have made their way into the rock at different stages of its history. In looking at this confused mass of rock which forms the Connecticut 

crystallines it seems apparent that it has taken part in manifold changes which 

went on in the earth's crust for ages.1

The mountains and plateaus of Carboniferous time were worn 

down during Triassic time, and the materials of which they were 

composed have gone to'make the sandstone of central Connecticut. 

The amount of rock removed from Connecticut prior to Triassic time 

may be judged from the appearance of the rock immediately under1 Bull. Connecticut Geol. and Nat. Hist. Survey No. 6, p. 80.
ECONOMIC GEOLOGY OF THE BOCKS. 13

lying the Mesozoic strata. The structure of the schists which form 

the floor of the Triassic is such as can be produced only at depths a 

mile or possibly several miles below the earth's surface. We may be 

reasonably sure, therefore, that mountains of folded strata once 

occupied Connecticut and that the granites and gneisses and schists 

Avhich we see are but the stumps of lofty land masses " rivaling the 

Alps in height and ruggedness."

During the formation of the conglomerates, sandstones, and shales 

a time proved by dinosaur and fish remains to be Triassic lava was 

poured out over central Connecticut and possibly over the entire State. 

Remains of these flows of basalt now stand as a ridge separating the 

valleys of Farmington and Connecticut rivers. During Cretaceous 

time the highlands were lowered and the entire surface was reduced 

practically to a plain sloping from northwest to southeast, and the 

Cretaceous sediments now exhibited on Long Island probably also 

covered southern Connecticut. This plain (peneplain) formed during Cretaceous time was uplifted during early Tertiary time, and 

the streams were thereby given greater eroding'.power and began at 

once to deepen and widen their valleys. Continued erosion during 

the millions of years comprehended in Tertiary time resulted in giving to Connecticut the larger features of valley and hill, highland, 

and lowland, which exist at the present time.

During the Pleistocene (" glacial") epoch the surface features of 

Connecticut were again remodeled. The more prominent erosion 

forms of Tertiary time remained, but the details of the scenery were 

completely changed. Hills were rounded off, valleys were filled, and 

the entire State was covered with a mantle of glacial debris. Drainage lines were rearranged and the lakes, swamps, and bogs so characteristic of the State were formed. Decomposed rock and " rotten 

rock " Avere largely removed from the ledges, leaving fresh rock^near 

the surface. This last-mentioned result of glaciation is of interest 

to quarrymen, as the expense and difficulty of procuring commercial 

stone have thereby been greatly lessened.

ECONOMIC GEOLOGY OF THE BOCKS.

Four types of rocks in Connecticut are used commercially. The 

limestone or marble of the western and northwestern parts of the 

State has in times past been used extensively as structural material; at present it is chiefly used for making lime. In 1908 Connecticut ranked No. 12 among the lime-producing States.

The Triassic brownstone of the central part of the State, quarried 

chiefly at East Haven and Portland, has long been used' for structural 

purposes in the larger eastern cities. In fact, the quarry at Portland 

is, so far as known, the first sandstone quarry worked in America, and
.14 GRANITES OF CONNECTICUT.

has supplied stone for several buildings, monuments, and bridge 

piers dating from prerevolutionary days.

The trap, 'including both diabase and basalt, which extends in two 

irregular lines from Long Island Sound to the Massachusetts border, 

is widely used for concrete construction, road making, and railroad 

ballast. Connecticut is one of the six States which produce trap 

rock in large quantities.

Granite, though quarried at relatively .few places in this State, has 

steadily increased in importance until.its annual production exceeds 

in value the sandstone, limestone, and trap. The increasing demand 

for granite and the relative ease with which it may be quarried in 

Connecticut, taken in connection with facilities for transportation by 

rail and boat and nearness to New York and other large cities using, 

this stone, promise a satisfactory future for this industry. It is 

also probable that the granite gneisses of the State not now largely 

used will become important in the stone industry of New England. 

Several localities would doubtless repay extensive development, as 

sources of structural materials and certain of the finer grained varieties are destined to be used as road metal. The pegmatites, or 

" giant granites," furnish feldspar f01; commercial uses, and the wide 

distribution and favorable location of rock of this type has given 

Connecticut first rank among the States as a producer of crude feldspar.

GRANITES AND GRANITE GNEISSES OF CONNECTICUT.

By HERBERT E. GREGORY. 

NAME, MINERAL CONTENT, AND ORIGIN.

Granites are igneous rocks composed chiefly of feldspar and quartz.

Some granites include no other minerals, but all the Connecticut 

granites so far observed contain other minerals in large or small 

amounts. If feldspar and quartz are considered as essential ingredients it is easy to classify granite in accordance with the presence 

of the additional minerals, and thus we have biotite granite, hornblende granite, and other varieties. As used commercially the term 

granite includes not only granite but many granite-like rocks which 

differ considerably in structure and in composition, and to which 

.names are given that are suggested by some unimportant surface 

appearance. Thus, although the scientific classification of Connecticut granites, including gneisses, recognizes ten groups, the 

commercial or trade classification includes twenty varieties, discriminated by structure, texture, composition, and appearance.

In addition to feldspar and quartz, the Connecticut granite and 

granite gneiss contain muscovite, biotite, hornblende, pyroxene.
NAME, MINERAL CONTENT, AND ORIGIN. 15

titanite, allanite, pyrite, apatite, zircon, and magnetite. Most of 

these minerals are of rare occurrence and few of them are of economic importance. In fact, all the igneous rocks, including the 

granites and granite gneisses, consist chiefly of but five minerals; 

feldspar forms 59 per cent, quartz 12 per cent, biotite 4 per cent, hornblende and pyroxene taken together 17 per cent; in all, 92 per cent. 

A knowledge of the mineral composition of a granitic rock that is 

offered for sale as a building material is of distinct practical value 

to the intending purchaser, but the ability to recognize only these five 

minerals and pyrite, which is a source of weakness and discoloration, 

is sufficient for all ordinary purposes.

Quartz occurs in granite as irregular, widely scattered grains, apparently filling spaces between the other minerals. Its hardness, 

glassy appearance, and diverse or irregular form serve to distinguish it from other minerals.

Feldspar is of many varieties and in its scientific classification 

much is made of the different species, but most of these different 

varieties can be distinguished only by the proficient petrographer, 

and in an examination of the rock with the naked eye all the feldspar 

may be considered as of one variety. In the finer-grained rocks, 

especially those in which the feldspar has been crushed (such as 

gneiss), feldspar may be mistaken for quartz by the careless observer, 

but ordinarily it may be distinguished from quartz by its opaqueness 

and by the fact that it cleaves along plane surfaces, from which 

light is reflected. In the coarser-grained rocks the feldspar crystals 

tend to assume rectangular shapes and in some of the porphyries they 

are large and are nearly perfect in shape.

Biotite, a dark mica, appears in the granites as dark specks and 

may be distinguished from all other minerals by its tendency to 

split into thin flakes, the surfaces of which are lustrous. The 

larger crystals of biotite which occur in the coarser-grained rocks 

and in the gneisses are so readily recognized that they do not require description, and the plates of mica (both muscovite, a light 

mica, and biotite), several inches in diameter, which are found in 

certain pegmatites and furnish the mica of commerce, are even 

better known.

Hornblende and pyroxene can not usually be distinguished from 

each other except by a trained mineralogist. Both are commonly 

black, but may be distinguished from biotite by their greater hardness and their lack of elasticity, and by the fact that. ordinarily they 

occur in little prisms or needles, instead of flakes, the common form 

of the micas. Biotite, hornblende, and pyroxene occur together in 

many kinds of rocks, but in those in which quartz is present, such as 

the granites and granite gneisses, biotite may be common, hornblende 

much less so, and pyroxene may be absent, so that practically the only

97730° Bull. 484 11 2
16 GKANITES OF CONNECTICUT.

dark-colored minerals other than quartz and feldspar which need to 

be distinguished are biotite and hornblende.

Pyrite occurs in granites and 'granite gneisses in scattered crystals 

in amounts so small that it ordinarily escapes observation. This 

mineral is well known because of its resemblance to gold in luster 

and color, though it differs from gold in that it is harder and in 

that its particles are of angular form. The presence of pyrite in a 

building stone should be noted, for it weathers more readily than any 

other common mineral, and the stone containing it is thereby weakened and is liable to discoloration.

As has been already stated, granites are of igneous origin, that is, 

they were formerly in a molten state and have crystallized by cooling. 

Both their texture and their mode of occurrence indicate that they 

attained their present character while they were deeply buried within 

the earth. The removal of thousands of feet of. rock that rested upon 

these granite masses has had little effect upon their composition, 

texture, or general appearance, and the rock exposed in the quarries 

is essentially like that which lies deeply buried but which may be uncovered by erosion in other parts of the State at some future time.

GNEISS AND GRANITE.

Before the.structure and texture of rocks usually called granite are 

described it may be of advantage to understand the difference between 

granite and gneiss, both of which are quarried in Connecticut. 

Granite is a massive rock in which the minerals are not definitely 

arranged in sheets or bands; neither in the hand specimen nor in the 

ledge will-marked variations in the size of crystals and their arrangement be observed. (See PL II, B.} Both granite gneiss and 

granite consist of crystals resulting from igneous fusion and are thus 

entirely unlike sedimentary rocks which are aggregates of preexisting 

fragments. Gneiss differs from granite in being a metamorphic rock 

and thus in possessing gneissoid and other structures not found in 

granite. Gneissoid structure in a rock is marked by lines or bands 

that divide surfaces along "which the rock may be separated into 

sheets, slabs, or " beds." The sheets may be all of the same material 

or may be of different materials; for instance, sheets consisting largely 

of biotite and feldspar may alternate with sheets that are prevailingly 

quartzose, and even in rocks in Avhich bands and sheets are not well 

developed a distinct parallel arrangement of the minerals is noticeable. (See PL II, A.)

Granite gneisses have been formed from granites, the change being 

chiefly a rearrangement of the mineral particles. The micas and 

other minerals are drawn out along well-marked planes, and new 

micas, both muscovite and biotite, have been produced. Gneiss may
U. S. GEOLOGICAL SURVEY BULLETIN 484 PLATE I

A. GNEISS FROM LEETE ISLAND QUARRY. 

Showing gneissoid texture due to squeezing and stretching of granite. See page 16.

]',. GRANITE FROM THE BOOTH QUARRY, WATERFORD. 

Showing granitic texture. Seepage 16.
TEX'TUBE OF GRANITE BOCKS. 17

also contain tourmaline, garnet, and other minerals that are not 

generally found in granite. The chemical composition of the rock 

may remain unchanged after the metamorphism, the only difference 

between the granite and the gneiss being a change in structure and 

in the relative abundance of minerals. If the original granite was 

porphyritic, the granite gneiss is likely to be a porphyritic granite 

gneiss. The difference in appearance between the granite and the 

gneiss will depend on the amount of metamorphism the rock has 

undergone. Occasionally the two types will appear in the same 

quarry, as in the Stony Creek region. Elsewhere the granite will 

have been so profoundly changed that all likeness to the original 

granite mass has been destroyed.

The common types of gneiss in Connecticut are mica or granite gneiss and 

hornblende or diorite gneiss. The mica gneisses are ordinarily squeezed,

mashed, and drawn-out modifications of granite and related igneous types. The

production of gneiss is facilitated if granite intrusions occur in the region and 

thus furnish feldspar, to be added to the rock during the process of alteration. 

The hot mass promotes the formation of solutions that carry abundant feidspathic material out of which feldspar can be made. Much of the beautiful 

banding in gneiss is produced, not by the common process of development of 

minerals under pressure but by the intrusion of foreign material along the 

planes of schistosity. An outcrop of ordinary granite gneiss exhibits bands of 

granitic material separated by thin micaceous bands, but certain granite gneisses 

have, in addition to the foliation- structure effected in the zone of flowage, a 

series of bands composed of light or dark colored rock which were originally 

no part of the constituents.1

TEXTURE OF GRANITIC ROCKS.

The texture of granite and granite gneiss is important economically as well as scientifically. By texture is meant the smaller details 

or features of a rock " the fabric of the mass " such as would be 

noticed in a hand specimen, as contrasted with structure, a term 

which signifies the larger features, to be observed only in the field. 

Igneous and metamorphic rocks show great variations in texture. 

The individual grains or imperfect crystals of which a granite is 

' composed may be all of one size or may be of two or more different 

sizes; they may be too small to distinguish \vith the unaided eye or 

they may be an inch or even several inches in diameter. This Avide 

variation in the appearance of granite is the result of the conditions 

under which the rock was consolidated and has little, to do with its 

chemical composition. In fact, a large granite mass may show all 

the differences mentioned above. The physical factors chiefly concerned in determining the texture of granite are the presence of water 

vapor and the rate of cooling. Water vapor is held in rock at great 

depths and its presence tends to lower the fusing point and to proiBull. Connecticut Geol. and Nat. Hist. Survey No. 6, p. 67.
18 GEANITES OF CONNECTICUT.

mote circulation in the uncooled mass. The presence of water vapor 

in large quantity causes the formation of coarse crystals, such as are 

seen in pegmatite. (See below.) The rate of cooling is also of fundamental importance in determining size of grain. Rapid cooling 

allows no time for crystallization, and in general it may be said that 

the slower and more evenly a molten mass cools the larger and more 

regular are its crystals. As different minerals crystallize at different 

temperatures, minerals will form in a molten rock mass in a more or 

less regular order as the mass cools. For the chief constituents of 

granites' this order is pyrite, hornblende, biotite, feldspar, quartz. 

It is thus easy to understand why well-formed crystals of pyrite are 

seen in some granites that contain poorly developed crystals of feldspar and in which quartz seems merely to occupy the space left between the better-formed crystals.

Two textures observed in Connecticut granites and granite 

gneisses, are worthy of special mention the pegmatitic and the 

porphyritic.

PEGMATITE.

Pegmatite is essentially a coarse-grained rock composed largely 

of feldspar, quartz, and mica. In color the quartz may be gray, 

Avhite, or pink (rose quartz), and it may occur in masses that range 

in diameter from 6 inches to several feet, or may be intergrown 

with feldspar to form large masses of these two minerals alone, with 

practically no mica. Both muscovite and biotite are commonly 

present in the pegmatites, the crystals of muscovite having dimensions of 2 to 6 inches across and in some rocks being so large and 

pure as to make this mineral commercially valuable. Biotite is more 

likely to occur in small sheets or along flat plates set into the rock at

all angles and when viewed on the surface gives the ledge the appearance of being cut across by thin dark blades of this mineral. 

" Slashed granite " is a term used locally to distinguish rock having 

this appearance. In addition to the quartz, feldspar, and mica, 

other minerals occur sparingly or abundantly in pegmatite, chief 

among them being garnet, beryl, and tourmaline. Some pegmatite' 

dikes are so rich in minerals that they serve as collecting ground for 

museums. The pegmatite veins along Connecticut River have 

yielded sphalerite, gahnite, magnetite, chrysoberyl, bismutite, orthoclase (crystals), albite, oligoclase, beryl, iolite, garnet, epidote, tourmaline, muscovite (crystals), lepidolite, biotite, columbite, samarskite, monazite, triplite, torbernite, autunite, and uraninite. From a 

single pegmatite mass at Branchville twenty-seven minerals were 

collected. Single crystals taken from this mass weighed 100 to 200 

pounds. The proportions of the chief minerals in pegmatites varies 

greatly. Some dikes or veins contain quartz, feldspar, and mica in
PEGMATITE. 19

about the same proportions as those found in normal granites. In 

other dikes feldspar and quartz make up practically the entire mass, 

and in some localities quartz alone constitutes probably 90 per cent 

of the entire rock.

Pegmatite or pegmatitic granite is associated with nearly all the 

granite and granite gneiss bodies in Connecticut. In the granite 

quarries it commonly occurs in irregular masses, more or less lensshaped, and may appear within the granite mass itself, where it 

grades imperceptibly into the even-textured variety, or may exist as 

dikes having distinctly defined walls. Outside the granite quarries, 

in the granite gneiss of the State, it occurs either as definite veins or 

dikes or as groups of veins, and in certain localities, particularly in 

the towns of Plymouth and Portland, it forms large .masses a quarter 

to a half mile wide and a mile or more long. Considering the 

State as a whole the pegmatites are rather more common and more

widely distributed than the true granites. Where pegmatite forms 

the surface rock the topography is controlled by it and is characterized by an irregular surface of knobs and ridges. On most of the 

higher land in regions of granite gneiss the pegmatite stands out 

prominently and may be recognized from a distance by its white 

color, which has given the name "White Eocks" to several places 

in the State.

The contact between the pegmatites and the gneiss or other rock 

into which they have been intruded is clearly defined, showing no 

gradation between the pegmatite and the gneiss. In the feldspar 

quarries of Glastonbury, Avhere the contact may be clearly traced, the 

gneiss immediately adjoining the pegmatite retains all the minute 

structures of foliation and differs in 'no way from the main body of 

granite gneiss.

Pegmatite may be regarded as a form of granitic intrusive that 

originated in parts of the igneous mass which were abundantly supplied with water vapor. Most masses of pegmatite \vere formed in 

a manner somewhat different from that in which ordinary granite 

was formed, and their composition varies with their distance from the 

granite mass. For instance, in the Collinsville granite gneiss area 

the pegmatites that are closely associated with the granite mass, such 

as those at Canton, are of essentially the same mineral content as the 

granite. The pegmatite farther away, which cuts the schist overlying the granite, is composed chiefly of quartz and feldspar, and that 

which lies still more distant is formed entirely of quartz. It is 

believed that the schist overlies the granite gneiss and that the pegmatite dikes are veins or stringers originating in the granite mass 

but extending for considerable distances into the overlying rock. 

The upper part of such stringers was far removed from the molten 

mass and is believed to owe its existence chiefly to water vapor. It
20 GRANITES OF CONNECTICUT.

therefore seems necessary .to assume that pegmatite results either from 

aqueous solution or igneous injection or from a combination of the 

two, and thus may possess the character either of true veins or 

of dikes.

Only the pegmatites that occur as phases of granite or granite 

gneisses are used for structural purposes, and these rocks are of economic value only because they are the source of quartz, feldspar,1 

and mica. Pegmatite veins or dikes are commonly found at the 

borders of granite gneiss areas, as in the Middletown district, Avhere 

four quarries are in operation at the contact of the Glastonbury 

granite gneiss with the " Bolton " schist and two at the edge of the 

Maromas granite gneiss. The chief active pegmatite quarries now 

worked for feldspar are along Connecticut River, in the towns of 

Middletown, Haddam, Chatham, Portland, and Glastonbury, but 

feldspar is also quarried in Fairfield, Litchfield, and New Haven 

counties.

PORPHYRY.

Generally speaking, the granite and granite gneiss of Connecticut 

are composed of crystalline grains of nearly uniform size. Certain 

granites and gneisses, however, exhibit a marked variation from this 

texture in that one or more of the constituent minerals occurs in much 

larger crystals than the others. The rock thus has the appearance of 

a fine-grained granite in which larger crystals are embedded. A rock 

having this texture is known as porphyry, the larger crystals of 

which are called phenocrysts that is, easily seen crystals and the 

remainder of the rock the groundmass.

The principal mineral that occurs as phenocrysts in the Connecticut gneisses and granites is feldspar, and the largest crystals are a 

hundred times larger than the crystals forming the groundmass.

Porphyritic texture is believed to indicate in general an interruption 

in the process of crystallization. It is assumed that at first the conditions were favorable to the formation of large crystals but that 

before the rock could completely solidify on this scale a change in 

physical conditions occurred, by which the material not yet crystallized was solidified in smaller grains. Gneisses showing porphyritic 

texture may have been formed from preexisting porphyritic granite 

or the phenocrysts may have developed during the change from 

igneous to metamorphic rock. If the latter supposition is correct the 

phenocrj^sts formed after the development of the gneissoid structure 

seem to be the result of absorption and enlargement of crystals during 

the period of relative quiet which followed the period in which great 

dynamic forces produced metamorphism. Great heat and moisture

1 For detailed description of feldspar quarries of Connecticut see Bull. U. S. Geol. 

Survey No. 420.
PORPHYRY. 21

in the rocks Avould be necessary conditions of this change. In those 

rocks in which further metamorphic change has occurred after the 

phenocrysts -were formed the crystals are drawn out along the planes 

of schistosity, and some have assumed a lenticular shape, and their 

ends have been drawn out into lines o-f broken fragments. This is 

well shown in the porphyritic gneiss about Derby. 1

The character of porphyritic gneiss, its general appearance, and the 

theory of its origin may be understood from the following detailed 

description of the porphyritic Prospect granite gneiss, one of the 

Connecticut rock types which is destined to be used commercially.

The formation consists of a light-gray porphyritic gneiss. The 

gneissoid appearance is produced by bands of granular quartz and 

feldspar interbedded with layers composed chiefly of biotite. Muscovite, garnet, chlorite, zircon, and titanite occur with the more 

abundant constituents. Within the groundmass formed of these

minerals there are set larger crystals of feldspar, mostly orthoclase, 

white or pink in color, thus giving the gneiss a porphyritic texture 

(PI. IV, /?, p. 84). These phenocrysts vary from one-sixteenth of an 

inch to 3 inches in their longest diameter, are quite fresh and regular, 

and nearly all show twinning structure. Besides the typical coarse 

porphyritic gneiss there occur in this formation small areas of porphyritic granite with inconspicuous gneissoid development and narrow bands of mica schist distributed unevenly and not attaining the 

prominence which these beds have in the Becket gneiss. Pegmatite 

is rarely found.' At its extreme northern limit the Prospect gneiss 

is prevailingly less porphyritic and more quartzose and contains areas 

of intrusive basic rocks.

This formation is believed to have been originally a mass of porphyritic granite intruded into the Hartland (Hoosac) schist. No 

contacts are visible, however, and direct proof of the date and nature 

of the intrusion is not at hand. Metamorphic processes have converted the rock into a gneiss with planes of schistosity whose strike 

averages about N. 25° E. The character of the original rock was so 

clearly marked that the changes induced by folding and metamorphic 

action are readily traced. The phenocrysts of orthoclase were originally set at various angles in a granite groundmass. Some of these 

were so oriented as to resist effectively the metamorphic forces and 

consequently remain in their original condition, except that they 

are someAvhat flattened, crushed at the ends, and converted into 

microcline. The phenocrysts less favorably situated have been 

squeezed, broken, and rotated into parallelism with the planes of 

schistosity. Many original crystals are represented by lenses arid 

eyes of granular feldspar and quartz, and in some all traces of the 

crystal are lost in the general gneissoid structure of the groundmass.

1 Kull. Connecticut Geol. and Nat. Hist. Survey No. G, p. GO.
22 GRANITES OP CONNECTICUT.

Besides the granular bands produced by metamorphism of the quartz 

and feldspar of the original rock, much new biotite and garnet have 

been formed, and, in less amounts, the other minerals mentioned 

above. The mica wraps about the feldspar phenocrysts and is closely 

adjusted to it. Because of the unequal amount of metamorphism the 

Prospect gneiss varies from porphyritic granite, through gneiss containing flattened nodules, to a rock in which crushing and rearrangement has been so great that it has become a feldspathic mica schist.

The prospect gneiss is not porphyritic throughout its extent. Its 

western extension assumes a typical granitic texture. 1

DISTRIBUTION OF GRANITES AND GNEISSES.

The areas of granite gneiss in Connecticut are shown on the map 

forming Plate I. The true granites occur in masses so small that 

they are not shown on this map. In fact, unchanged granite occupies 

probably less than one-half of 1 per cent of the 4,990 square miles of 

the State. It will be noticed that the granite gneisses occur either as 

long, narrow bands, as illustrated by the Glastonbury and Monson 

gneisses, in larger areas of irregular outline like the Sterling and 

Becket gneisses, or in rock masses surrounded entirely by schist, as 

at Bristol and Collinsville. As all of the granite gneisses of the 

State are adapted for use as structural material, and some of them 

also for road metal, and as those who are interested in the quarry 

industry may wish to examine these various types of granite gneiss, 

the following brief description is given of the more important formations : -

Becket gneiss. Is light gray in color, of firm texture, and .lias a uniform 

banded structure. In many places the rock is highly quartzose and granular. 

The formation includes many veins of quartz and pegmatite. Supposed to be 

of pre-Cambriau age.

Prospect porphyritic gneiss. Is. light gray in color. The gneissoid appearance is produced by bands of granular quartz and feldspar interbedded with 

layers composed chiefly of biotite. The porphyritic mineral is usually orthoclase, white or pink in color, varying from one-sixteenth inch to 3 inches in 

length. The rock is believed to have been a granite porphyry intruded into 

the Hartlaud schist.

Bristol granite gneiss. Typical rock is light gray, with gneissoid structure 

more or less developed by the presence of layers of biotite; more schistose 

layers contain mnscovite. An evenly banded hornblende gneiss occupies part 

of the area. Garnet is nearly everywhere present and in places rises to the 

rank of a principal mineral. The rock was originally a mass of granite and 

diorite intruded into Hartland schist.

Collinsville granite gneiss. Two types appear intermingled without order, a 

light gray, heavy-bedded rock, grading into massive granite, and a very dark 

gray to black variety, which grades by imperceptible stages into evenly banded 

hornblende gneiss. The rock consists of feldspar, largely orthoclase, quartz in

1 Bull. Connecticut Geol. and NaL Hist. Survey No. 6, pp 102-104, and (50.

- Abstrated from Bull. Connecticut Geol. and Nat. Hist. Survey No. 7, pp. 33-38.
DISTRIBUTION OF GRANITES AND GNEISSES. 23

irregular grains, and biotite. Was originally granite and diorite intruded into 

Hartland schist.

Brookfleld diorite, Is usually massive, but shows also gueissoid and even 

schistose phases. Both light and dark types are present, the former containing 

much quartz, and in extreme cases no dark mineral except biotite. The dark 

variety sbows an almost complete ansence of quartz, and in its place dark hornblende. It is an igneous mass intruded into the quartzite and schists of this 

region.

Daribury granodiorite gneiss. The rock presents two important facies a 

biotite granite and a diorite in which hornblende' becomes an important constituent and quartz is less prominent. There are gradations between the two 

types. It is prevailingly porphyritic, with pink or white phenocrysts of feldspar, is igneous in origin, and was intruded prior to the time when metarnorphic action converted igneous and sedimentary rocks alike into gneisses and 

schists.

Th-omaston granite gneiss. Rock varies in structure from an almost massive 

granite to a rock with distinctly schistose phases. It is of igneous origin,- as 

shown by the fact that it often occurs as dikes, and fragments of other rocks are 

included in it.

Glastonbury gramte gneiss. Two types a granitic biotite gneiss or a biotite 

granite, in a narrow band along the eastern border, and a darker, well foliated 

gneiss, with biotite, hornblende, and epidote, in the remainder of the area. 

Both massive and schistose phases sometimes become angen gneiss. Believed 

to be of igneous origin.

Monson granite gneiss. Where typically exposed, the rock is a fine-grained, 

dark-gray, uniform biotite-hornblende. gneiss, marked at short intervals by 

parallel seams of quartz, and with bands of biotite and hornblende. It is 

believed to be of igneous origin.

Eastford granite gneiss. In general, a light or dark gray gneiss, fine grained, 

or in places even porphyritic. The composition and texture show the rock to 

be of igneous origin.

Sterling granite gneiss. The rock is pink or gray in tone, and is made up of 

two distinct types a porphyritic gneiss with an abundance of biotite along 

foliation planes, and an aplite or granite gneiss practically free from mica. 

The p'orphyritic type is always highly gneissoid and the phenocrysts of pink 

feldspar are drawn out into lenticular forms. Where phenocrysts are absent 

the rock shades into a normal granite, which is intermediate between the two 

above-mentioned types. The aplitic type is probably a later intrusion than 

the porphyritic and normal types. Origin, igneous.

Willimantic gneiss. In general, the rock is coarse grained and often porphyritic in structure, usually considerably crumpled and folded. There are two 

varieties, the light and the dark. The light variety consists of quartz, feldspar, and biotite, in the proportions of a normal granite. The dark variety 

contains a relatively smaller amount of feldspar and quartz, with a larger 

amount of biotite and some hornblende. Origin, igneous.

Canterbury granite gneiss. The formation consists essentially of a muscovitebiotite gneiss, varying in texture from a fine, even-grained rock to a porphyry 

with, feldspars a quarter of an inch or so in length. Metamorphism has produced irregular wavy bands of biotite separated by flattened layers of quartz 

and feldspar. Origin, igneous.

Ma-romas gramte gneiss. It is in some places massive, but usually well 

foliated. Composition is that of a normal granite. (See Sterling granite 

gneiss.) This rock is eruptive, and is intruded into the Bolton schist.
24 GRANITES OP CONNECTICUT.

Haddam granite gneiss. It is a light-colored, rather fine-grained, granitic 

aggregate of quartz and feldspar, through which are scattered small isolated 

flakes of biotite. In the outcrops the rock is a moderately thick-bedded gneiss. 

Origin, igneous.

Branford granite gneiss. The rock is a medium-grained granite with a 

banded structure, consisting very largely of white feldspar. In the feldspars 

are embedded small round quartz grains, and biotite is also present in about 

equal amount. Small reddish garnets commonly occur, but may fail entirely. 

The rock has a pronounced tendency to weather, .with a brownish stain on the 

cleavage surfaces of the feldspar. Origin, igneous.

Stony Creek granite gneiss. See Sterling granite gneiss.

Lyme granite gneiss. See Sterling granite gneiss.

New London granite gneiss. See Sterling granite gneiss.

Mamacolce gneiss. The rocks occupying the larger areas of this formation 

are decidedly gneissic, sometimes containing much biotite, and more rarely 

hornblende, and are frequently granitic in appearance. The typical rock is 

uniformly medium grained, light to dark gray in color, and consists of white 

feldspar and quartz, with brilliant black mica, and sometimes small amounts 

of hornblende and garnet. The dark. minerals constitute about one-third of 

the rock, but the range in both directions is considerable, in one case giving 

rise to a biotite gneiss, in the other a granitic one. Origin, igneous.

NATURE OF GRANITIC INTRUSIONS.

The stages of the process whereby the granite masses of Connecticut have attained their present form are not altogether understood. 

It is, however, certain, as stated above, that the granites and granite 

gneisses have been revealed by the removal of overlying material; 

and if we assume erosion to have proceeded much farther and an additional thousand feet or so to have been removed "from the rocks 

of the State- we should find that, instead of the limited areas of 

granite gneiss and the few patches of granite now exposed, large 

areas of granite surrounded by gneisses and schists would exist.

There are several ways in which molten rock may find its way into 

strata already existing. It may be actually forced into other rocks 

in such a way as to crowd them apart or to lift them bodily. On 

the other hand, the molten mass which later becomes granite may 

work its way quietly into the surrounding rock, melting and assimilating the overlying strata. This is believed to be the method of 

intrusion by which the Connecticut granites were formed, and a 

mass like the Stony Creek granite gneiss or the Sterling granite 

gneiss is to be considered as merely surface portions of igneous intrusions which extend to great depth. It is quite likely, as previously 

stated, that some of these granite areas represent deep-seated portions of volcanoes from which at one time granitic lavas were poured 

out over the State. If such lava flows ever existed all traces of them 

have been removed by the erosion of thousands of feet of rock.

The Bristol and Collinsville granite gneisses represent another type 

of intrusion. In both these localities the Hoosac (" Hartland ")
AGE OF THE CONNECTICUT GRANITES. 25

schist is seen to lap up over the granitic rock, and the gneiss exposed 

shows evidence of being near the top of the original igneous mass.

AGE OF THE CONNECTICUT GRANITES.

It is generally supposed that the granites, and particularly the 

granite gneisses of Connecticut, date from the earliest geologic ages 

that, in fact, they represent " parts of the original earth's crust," 

and this popular view coincides with the opinion expressed by geologists who have not studied the occurrence of these rocks in detail; but 

there is little to justify this view of the great age of most of the 

granitic rocks. With the possible exception of the Becket gneiss, 

no gneisses in Connecticut are regarded as of pre-Cambrian age, 

and the fact that the Sterling granite gneiss cuts metamorphosed 

Carboniferous sediments makes it unnecessary to ascribe a date 

earlier than the Carboniferous for most of the intrusives in the 

eastern part of the State.

The last of the great earth movements that gave the structure to 

the metamorphic rocks of Connecticut occurred, presumably, at the 

close of Carboniferous time, and though the structure of some of the 

granite gneisses indicates that they have been subjected to more than 

one series of earth movements, the structure of others may be explained on the theory that they have passed through only one period 

of metamorphism. For example, the gneissoid character of the. 

Sterling granite gneiss is believed to date from post-Carboniferous 

time. If this hypothesis is correct, the igneous gneisses are, in part 

at least, younger than the schists with which they are associated; 

The granites which are little or not at all metamorphosed are probably of tAvo periods, the first coincident with the movements which 

produced the gneissoid and schistose structure in the rocks, and the 

second at some later date. This second date of intrusion is proved 

by the fact that the massive granites have not been subjected to the 

pressure which produced the gneisses and that they cut into and 

through the granite gneisses. Occasionally, moreover, fragments of 

gneiss are included in the granite itself. The descriptions of Stony 

Creek granite gneiss and Westerly granite (pp. 81, 110, and 115) 

makes this relationship clear. The relative age of the various granites and gneisses may be stated as follows: The granite gneisses intruded into the ancient sediments are the oldest. The less metamorphosed granites come next; the pegmatites were formed at the 

same time as the granites or at a slightly later date, and dikes of 

granite were intruded after most of the pegmatites were formed. 

For instance, part of the granite quarried at Westerly is intrusive 

in pegmatites, granite and granite gneiss alike, and appears* to be 

the latest formed rock in southeastern Connecticut.
26 GRANITES OF CONNECTICUT.

STRUCTURE, ROCK VARIATIONS, WEATHERING, AND 

DISCOLORATION OF GRANITIC ROCKS.

By T. NELSON DALE. 

GENERAL STRUCTURE.

The term " structure " embraces all the divisional planes that traverse the rock. These occur at intervals ranging from a microscopic 

distance to one measured by scores of feet, and either cross or, very 

rarely, give a course to the texture resulting from crystallization.

FLOW STRUCTURE.

Where two varieties of granite lie in contact the dividing line between them indicates the direction of their flow, for the same reason 

that the course of the flow of a stream would be shown by the demarcation between its water and that of a muddy tributary a little 

below their junction. In some places this direction is also indicated 

by streaks or sheets of mica scales parallel to the direction of the line 

between the granites. Such streaks, therefore, when alone are regarded as indicating flow structure. They may be inclined at all 

angles or be in horizontal undulations with axes pitching 10° to 40°. 

In some Massachusetts and New Hampshire quarries the structure is 

parallel to the surface of the granite at its contact with overlying 

rocks, or surrounds in parallel bands the surface of large inclusions. 

Flow structure also is conspicuous in the granite of Milford, Mass., 

and in some of the quarries of Milford, N. H. The very local character of such structural features indicates that they are not due to 

pressure which affected the entire region, but that they originated 

while the granite masses were still plastic. A granite that exhibits

flow structure is called by some writers a floAv gneiss.

RTFT AND flRAIN.

The rift in granite is a feature of considerable scientific interest 

and of much economic importance. It is an obscure microscopic 

foliation either vertical, or very nearly so, or horizontal along 

which the granite splits more easily than in any other direction. 

The grain is a foliation in a direction at right angles to this, along 

which the rock splits with a facility second only to that of the fracture along the rift. After a little experience an observer can detect 

the rift with the unaided eye, where it is marked.

The earliest mention of rift in geologic literature appears to be 

that by J. F. W. Charpentier 1 in 1T78, who noticed that granite millstones which were cut with their largest diameter parallel to the rift 

were much more readily worn than those cut at right angles to it, 

that is, parallel to the " hard way." He attributed this to a parallel

1 Mineralogische Geographic des chursiichsischen Lande, .1778. See also his Beobach- 

 tnngen fiber die Lagerstiitte cler Erze, 1779.
GENERAL STHUCTUBE. 27

arrangement, of the mineral particles. The next reference to rift is 

by Potsch 1 1803, who described it in the granites of Lausitz, in 

Saxony. In 1833 it was referred to by Enys and Fox 2 as characterizing the granites of Penrhyn, and was referred to in 1834 by De la 

Beche; 3 also in 1855 by Adam Sedgwick,4 who attributed it to 

crystalline action at the time of consolidation. In 1860 C. F. Naumann n attributed it either to local differences of cohesion or to an 

inner strain possibly related to the direction of original consolidation. 

In 1864 G. vom Rath ° described a diorite from Monte Adamello, in 

the Tyrol, without dominant rift, and observed that, the rift course 

was, on the contrary, uniform in the granite of Monte Motterone 

(Baveno). In 1876 James D. Dana stated that "granite often has a 

direction of easiest fracture due to the fact that the feldspar crystals 

have approximately a uniform position in the rock bringing the 

cleavage planes into parallelism." 7 This is true in those places where

the directions of flow structure and rift chance to coincide, and it may 

be true in some porphyritic granites that the porphyritic crystals are 

arranged with some reference to the rift, but that it is not the cause 

of rift is shown by the fact that the feldspar cleavages generally intersect the rift face at all angles. In 1879 Reyer 8 attributed rift to an 

original arrangement of particles by flowage. As rift in places crosses 

flow structure this explanation is also inadequate. In 1893 Carl C. 

Biiber, in a work on the granite industry of Norway ° described an 

augite syenite with inferior rift and grain, in which the cleavage 

planes of the individual feldspar crystals were parallel 'to the two 

cleavages, rift and grain, of the rock. Finally, in 1894, F. Zirkel,10 

after reviewing the opinions of his predecessors, tentatively suggested 

that rift may be the result of conditions of strain brought about by 

pressure from one side only, which failed to find adequate relief in 

jointing. <'

The only available recent American data on this subject are 

furnished by Tarr, Whittle, and Finley. 11

I Bemerkungen nncl Beobachtungen fiber das Vorkommen des Granits in geschlchtete 

Lngen, p. 140.

-London anrl Edinburgh Phil. Mag., 3d ser., vol. 2, pp. 321-327.

II Researches in theoretical geology, and Report on the geology of Cornwall.

4 Trans. Geol. Soc. London, 2d ser., vol. 8, pt. 3, p. 488.

D Lehrbuch der Geognosie, vol. 2, 2d ed., Leipzig, 1860, pp. 191-102.

"Beitriige Kiir Kenntniss der ernptiven Gesteine der Alpen : Zeitschr. Deutsch. geol. 

Gesell., vol. 16, pp. 249-260.

7 Manual of Geology, 2d ed., 1876, p. 628.

s Reyer, Ed., Tektonik der Granit Ergiisse von Neudeck und Carlsbad, etc. : Jahrb. K.-k. 

geol. Reichsanstalt, vol. 29, 1879, p. 415.

0 Norges granit industri: Norges Geol. undersogelse, Aarbog for 1893, No. 12, p. 45.

10 Lehrbuch der Petrographie, 2d ed., vol. 2, 1894, pp. 52-53, p. 415.

11 Tarr, R. S., The phenomena of rifting in granite : Am. Jour. Sci., 3d ser., vol. 41, 1891, 

pp. 267-272, figs. 1-4; also Economic Geology of the United States, 1895, p. 124. Whittle, Charles L., Rifting and grain in granite : Eng. and Min. Jour., vol. 70, 1900, p. 161, 

figs. 1 and 2. Finlay, G. I., The granite area of Barre, Vt.: Report of Vermont State 

Geologist! new ser., 1902, p. 54.
28 GBANITES OF CONNECTICUT.

Tarr presents four figures reproduced from drawings made from 

enlarged views of thin sections showing the rift in Cape Ann hornblende-biotite granite. These figures and his descriptions indicate 

that rift consists of microscopic faults, most of which meander across 

feldspar and quartz alike, although some go around the quartz 

particles rather than through them. In the feldspars rift generally 

follows the cleavage. These minute faults are lined with microscopic 

fragments of the mineral they traverse and some of them send off 

short, minute diagonal fractures on either side. In examining such 

a structure it is important to make sure that the grinding of the 

section has not in any way modified the original fractures. Tarr 

adds that at Cape Ann the rift does not traverse the "knots" or 

the basic dikes that cross the granite.

Whittle gives two sketches made from polished surfaces of a wellknown granite quarried by the Maine & New Hampshire Granite 

Co. at Redstone, N. H. One of these sketches, made from a surface running at right angles to the rift, shows quartz and feldspar 

grains traversed by a generally parallel set of lines corresponding to 

the rift planes. The lines are more numerous in the feldspar than in 

the quartz grains. The other sketch, made from another specimen, 

shows besides the rift lines another less pronounced set intersecting 

these at right angles. This second set corresponds to the grain. 

Whittle calls attention to the fact that notwithstanding the marked 

rift and grain at this quarry the stone stood a compression test of 

22,370 pounds to the square inch, and was therefore not appreciably 

weakened by the microscopic fractures. A visit made by the writer 

in 1906 to the quarry at Bedstone, N. H., has corroborated Whittle's 

observations. 1

Finlay, in describing the quartz of Barre granite, says: " The pronounced cracks which are seen to cross from one crystal to its neighbor, without interruption, are an indication of pressure phenomena 

in the magma after its consolidation. These cracks are notable as 

containing microscopic dendritic growths, which are analogous to the 

arborescent forms of MnO,, and possibly identical with them."

Another peculiarity of rift is that the angle of its inclination may 

at some places be modified by gravity. Thus, in some localities a 

block will split at one angle from the top, but at another from the 

side; or, again, at one angle where the mass of the block is at the 

right and at another where it is at the left of the line of fracture. 

Experienced granite workmen at Concord, N. H., and Quincy, Mass., 

report that at some places a block that would show a horizontal rift 

when split from one point of the compass (say the north) acquires an 

inclined rift if split from the south or the east or west. The cause 

of this is not apparent. There are also indications that a slight alter1 For details see Bull. U. S. Geol. Survey No. 354, 1908, p. 42.
GENERAL STRUCTURE. 29

ation of the feldspars may improve the rift. Finally, as is Avell 

known to granite quarrymen, rift and grain are modified by temperature, the effect of winter cold in New England (frost?) being to intensify the rift and grain where they are weak.

Herrmann * states that in Saxony the rift is parallel to the horizontal sheets or joints. That is true for short distances in the New 

England quarries, but where the rift is horizontal and the sheets 

curve it crosses the sheets, and of course where the rift is vertical it 

crosses them throughout. Exceptionally, in one- of the quarries at 

Quincy, Mass., a foreman reported to the writer a deflection of the 

rift in apparent relation to the increasing inclination of the sheets.

Rift and grain are not always pronounced. Either or both may be 

very feeble or may be absent.

At the Armbrust quarry, in Vinalhaven, Me., there is a horizontal 

rift confined to a 4-foot mass striking across the granite hillock.

The presence of fairly good rift or grain is an important economic 

factor in the granite industry, for it diminishes both the amount of 

labor in drilling for blasts and in splitting. .

That the rift is a factor in the crushing strength of granite is 

shown by the results of tests of Mount Waldo granite from Frankfort, Me., blocks of which when place.d on the bed that is, with 

pressure applied at right angles to the rift showed an ultimate 

strength to the square inch of 31,782 to 32,635 pounds (average, 

32,208), but when placed on the side that is, with pressure applied 

parallel to the rift showed an ultimate strength of from 29,183 to 

.30,197 pounds (average, 29,690). In the first test the first crack appeared in the block at a pressure of from 120,000 to 123,300 pounds 

(average, 121,650) and in the second test it appeared at one of 107,400 

to 112,600 pounds (average, 110,000 pounds).2 Rift and grain in 

their relations to fiuidal cavities are discussed on pages 42-47 of 

Bulletin 354.

SHEETS.

The division of granite into " sheets " or " beds " by joint]ike 

fractures which are variously curved or nearly horizontal, being 

generally parallel with the granite surface, attracted the attention of 

geologists long ago. In 1797 De Dolomieu, and shortly before that 

De Sanssure, described granite sheet structure. 3

In 1803 Potsch 4 published a paper on the subject. In 1841 Edward 

Hitchcock described what he termed the " Pseudo-stratification of

1 Herrmann, 0., Steinbruchindustrie und Steinbruchgeologie, Berlin, 1899, p. 109. 

2 Reilly, -T. W., Ordnance Kept., tests of materials, etc. (1900). 1901, p. 11.1.9. See also 

result of test of Concord granite, Bull. U. S. Geol. Survey No. 354, p. 147.

3 .Tour, des mines, vol. 7, No. 43, p. 426.

4 Bemerkungen und Beobachtungen iiber das Vorkommen des Granits in geschichtete 

Lagen.
30 GKANITES OF CONNECTICUT.

granite," near Worcester and Fitchburg, Mass., as a concentric, 

onion-like structure generally conforming to the rock surface.1

In 1860 C. F. Naumann 2 dealt with the subject in his textbook.

In 1863 F. von Adrian described the structure in Bohemia and 

regarded it as the result of cooling. 3

In 1879 Reyer 4 described it from another part of Bohemia, and in 

1894 Zirkel 5 also treated the subject in his petrography.

Although this is the most striking feature in every granite quarry 

and largely makes, the granite industry possible, there is a great 

diversity of opinion as to its cause. Whitney ° writes:

The curves are arranged strictly with reference to the surface of the masses 

of rock, showing clearly that they must have been produced by the contraction 

of the material while cooling or solidifying, and also giving very strongly the 

impression that, in many places, we see something of the original shape of the 

surface as it was when the granitic mass assumed its present position.

Shaler, a few years later,7 attributed the sheet structure to expansion due to solar heat.

C. H. Hitchcock 8 notices in New Hampshire granite " numerous 

joints, the planes of which correspond very nearly with the slope of 

the hill," but does not undertake to explain them.

Vogt 9 states that the sheets in granites of southeastern Norway 

measure from 6 inches to 6 feet in thickness and dip from 8° to 33° 

on the sides of the mountains, toward the valleys, but that they are 

horizontal on top and approximately parallel to the surface. He 

shows that they are of preglacial origin, attributes them to the -same 

cause that is postulated by Whitney for those in California, and 

regards them as parallel to the original surface of the granite masses.'

Harris,10 referring to the English granite quarries, writes: "In 

every quarry we visited we found that the direction of the ' b#ds' 

approximately corresponded with the outline of the hill on which it

was situated." He offers no explanation of the phenomenon, 

however.

J. J. Craw ford " describes the sheet structure at granite quarries in 

Madera and Tulare counties, Cal., as consisting of " concentric layers

I Final Report, Geology of Massachusetts, p. 683. 

- Lehrbuch der Geognosie, p. 191.

3 Jahrfo. K.-k. geol. Reichsanstalt, vol. 13, pp. 155-182.

4 Idem, vol. 29, 1879, p. 405.

B Petrographie, vol. 2, p. 52.

0 Whitney, J. D., Geology of California, vol. 1, 1865, Geology, p. 872 ; also pp. 227, 417, 

and figs. 49-54.

. 7 Shaler, N. S., Notes on the concentric structure of granitic rocks : Proc. Boston Soc. 

Nat. Hist., vol. 12, 1869, pp. 289-293.

s Geology of New Hampshire, vol. 2, 1877, pp. 511-512 and plate opposite p. 158, showing sheet structure at the " Flume."

0 Vogt, J. H. L., Sheets of granite and syenite in their relation to the present surface: 

Geol. Foreningens i Stockholm, Fo'rhandl., 1879, No. 56, vol. 4, No. 14; also Nogle, Bemaerkninger om Granit: Christiania Videnskabsselsk. Forhandl., 1881, No. 9.

30 Harris, George F., Granites and our granite industries, London, 1888.

II Twelfth Kept. State Mineralogist of California, 1894, pp. 384-387 and 3 plates.
GENERAL STRUCTURE. 31

conforming in a general way to the contour of the hills," but suggests 

no cause for them.

Herrmann,1 who made a special economic study of the granites of 

Saxony, writes:

Upon closer inspection it appears that the granite sheets are elongated lenses 

overlying one another, of which the upper one, as a rule, has its bulging part 

lying in the depression formed by the two underlying lenses where they come 

together.

Branner 2 describes the exfoliation of the granitoid gneisses in 

Brazil, which he attributes only in part to changes of temperature. 

He calls attention to the fact that the linear expansion of a mass of 

gneiss 300 feet long at a depth of 15 feet from the surface under a 

surface temperature of 103° F. would amount to only 0.072 inch; 

and he quotes the results of Forbes, Quetelet, and others to show 

that the annual change of temperature can penetrate rock only to a 

depth of 40 feet in temperate regions and still less in the Tropics.

Merrill 3 describes Stone Mountain, in Georgia, as a boss of granite 

2 miles long by 1^ miles wide and 650 feet high, which owes its form 

wholly to exfoliation parallel to preexisting lines of weakness. The 

mass appears to be made up of imbricated sheets of granite which 

he regards as the result of torsional strains. The bosslike form is 

incidental and consequent. Intermittent expansion and contraction 

from changes of temperature have so affected the sheets that bound 

the mass at the sides that they have found relief in expansion in 

an upward direction. These ruptured sheets are rarely more than 

10 inches thick, but are 10 or 20 feet in diameter.4

Herrmann 5 sums, up his conclusions on the subject substantially as 

follows: The so-called sheets are thin near the rock surface, generally 

only a few centimeters thick, but become gradually thicker with 

increasing depth. This downward increase in the thickness of the 

sheets is generally more rapid where the texture of the stone is 

coarser. The course of the sheets is not, as Vogt claims, parallel to 

the original surface of the consolidating rock. It is not governed by 

internal strains. The attitude of the sheets corresponds to the form 

of the present rock surface. The sheet structure is to be looked .upon 

as the effect of the beginning and progress of weathering from the

1 Herrmann, 0., Technische Verwerthung der Lausltzer Granite: Zeitschr. prakt. 

Geologic, Nov., 1895, Heft 2, p. 435.

2 Branner, John C., Decomposition of rocks in Brazil: Bull. Geol. Soc. America, vol. 7, 

1896: Exfoliation, pp. 269-277, Temperature and exfoliation, pp. 285-292.

3 Merrill, George P., Eocks, rock-weathering, and soils, 2d edition, 1906, p. 321.

4 For description and representations of Stone Mountain see Merrill, as aboTC, PI. I; 

Purington, Chester W., Geological and topographical features of the region about Atlanta, 

Ga. : Am. Geologist, vol. 14, 1894, pp. 105-108 and PI. IV; also Watson, Thomas L., 

Bull. Georgia Geol. Survey No. 9-A, 1902, p. 113, and Pis. I-VIII. See also description 

of another granite dome Stone Mountain, in North Carolina by Watson and Laney, in 

Bull. North Carolina Geol. Survey No. 2, 1906, PI. XXV.

G Herrmann, O., Steinbruchindustrie und Steinbruchgeologie, 1899, pp. 109-111,

97730° Bull. 484 11 3
32 GRANITES OF CONNECTICUT.

surface inward. These weathering cracks are determined by the 

form of the rock surface instead of that being determined by them.

Turner 1 calls attention to the sheet structure and exfoliation of 

Fairview Dome, in the Yos'emite.

Gilbert 2 shows that sheet structure occurs in synclinal as well as 

in anticlinal attitude in other words, is parallel to hollows' as well 

as hills which he considers unfavorable to the theory that it is an 

original structure. He suggests that sheet structure may possibly 

be due to expansive stress consequent upon relief from compressive 

stress brought about by the removal of the mass into which the 

granite was intruded. Subordinately he notes that in the Sierras, 

at least, the dome structure and the parallel joint structure do not 

occur in the same place and that the former has resisted general 

erosion more successfully than the latter.

G. F. Becker, in a recent conversation with the writer, stated 

that he had found the granites and gneisses at the bottom of the 

Colorado Canyon both vertically and horizontally jointed. If these 

are true granites and are still in contact with the rocks into which 

they were intruded and show genuine sheet structure the phenomenon 

would conclusively prove that such structure may occur independently of solar heat and load.

S. F. Emmons similarly stated that in the Mosquito (Park) 

Range, in Colorado, the pre-Cambrian granite and schist are cut by 

horizontal joints to a depth of 50 feet below their contact with the 

overlying Cambrian, the- joints diminishing in number downward. 

The original load upon the granite here consisted of at least 10,000 

feet of Paleozoic and between 5,000 and 6,000 feet of .Cretaceous rocks. 

As the granite, however, was not intruded into Cambrian sediments 

it must have been exposed to atmospheric erosion before they were

deposited. These horizontal joints may therefore have been related 

to solar temperature.

G. K. Gilbert has recently studied the granite domes of Georgia 

and attributes their sheet structure to compressive strains. He finds 

that the granite in these domes 3 is not naturally divided into plates, 

but that the outer parts of the granite the parts nearest the surface are in a condition of compressive strain, which results in slow 

exfoliation and which enables quarrymen, by means of carefully 

regulated blasts, to develop joints that run approximately parallel 

to the surface, so that the granite is detached in sheets. As these 

sheets are divided into blocks in the process of quarrying, the blocks 

expand horizontally as they are released from the general mass. In

1 'Turner, H. W., The Pleistocene geology of the south-central Sierra Nevada, with especial reference to the origin of the Yosemite Valley: j*rbc. California Aca'd. Sci., 3d ser., 

Geology, vol. 1, No. 9, 1900; Formation of domes, pp. 312-315, and PI. XXXVII.

2 Domes and dome structure of the high Sierras: Bull. Geol. Soc. Am.-, vol. 15, pp. 

29-36, and pi. 3, 1904.

3 Letters to writer, dated May 4 and .Tune 11, 1906.
.GENERAL STRUCTURE. . 33

these granitic domes parting planes also develop naturally within a 

few inches of the surface, and the expansive force is there so great as 

to induce conspicuous buckling in the thin sheets thus formed. The 

jar of blasting precipitates this sheeting action, so that several of 

the domes at which quarrying is in progress show long lines of 

freshly formed disrupted arches. Mr..Gilbert found that the horizontal elongation, or rather the elongation coincident approximately 

with the contour of the dome surface, amounted, by one measurement, to three-fourths inch in a length of 40 feet.

The effects of compressive strain on granite were observed by the 

writer in 1907 at a quarry at the west foot of Black Mountain, a 

domelike mass in West Dummerston, near Brattleboro, Vt. New 

thin sheets have thus been formed and one of the sheet fractures 

opened 3^ inches.

The artificial production of sheets in granite, as practiced at

Bangalore, in southern India, shows similar phenomena. It is 

described by H. Warth* in substance as follows: At the surface there 

is a horizontal sheet of rather weathered rock 4 feet thick; below this 

lies a sheet of fresh rock 3 feet thick, but below this lies fresh rock 

without split. These sheets " are probably due to the variations of 

temperature, daily and seasonal." By means of wood fires plates 60 

by 40 feet by 6 inches in thickness are detached in one piece. A line 

of fire 7 feet long is gradually elongated and moved over the granite. 

The effect of the fire is tested by hammering the granite in front of 

it, and then the fire is moved forward. The maximum length of the 

arc of fire is 25 feet. The burning lasts eight hours; the line of fire 

is advanced 6 feet per hour. The area passed over by line of fire is 

460 square feet. The amount of wood used is 15 hundredweight. 

The average thickness of stone is 5 inches and its specific gravity is 

2.62. These data show that 30 pounds of stone are quarried with 

1 pound of wood. Some plates are taken out in inclined position. 

The action of fire is independent of the original surface of rock; also 

of the direction of lamination (the granite is gneissose) and of veins. 

The uniformity in the thickness of the sheets is attributed to the 

regulating influence of preexisting cracks.

Van Hise, in his treatise on metamorphism,2 is inclined to attribute 

sheet structure to solar temperature.

Sheet structure, as exposed at the Maine quarries, is described in 

Bulletin 313. on pages 33-35, and is illustrated in Plates II, B, III, V, 

VI, and IX, A, of that bulletin. Its general character is illustrated 

in Plates III, A, and V, A, of Bulletin 354; its relation to surface 

form in Plate VII, A, and to overlying rocks in Plates VI, A, and 

IX, A, of that bulletin.

1 The quarrying of granite in India: Nature, vol. 51, 1895, p. 272. 

- Mon. U. S. Geol. Survey, vol. 47, pp. 434-439.
34 GRANITES OF CONNECTICUT.

The observations as to sheet structure, made at over 100 granite 

quarries in New England are here summarized:

1. There is a general parallelism between the sheets and the rock 

surface, resulting in a wavelike joint structure and surface over large 

areas.

2. The sheets increase in thickness more or less gradually downward.

3. The sheets are generally lenses, though in some places their 

form is obscure. Their thick and thin parts alternate vertically with 

one another. The joints that separate these superposed lenses therefore undulate in such a way that only every other set is parallel.

4. On Crotch Island, Maine, the sheet structure extends to a depth 

of at least 140 feet from the surface, and at Quincy to 175 feet.

5. There are indications here and there that the granite is under 

compressive strain, which tends to form vertical fissures or to expand 

the sheets horizontally so as to fill up small artificial fissures or to 

extend the sheet partings horizontally.

The observations made in Europe and in this country, taken in 

connection with the various inferences geologists have drawn from 

them, indicate that sheet or " onion " structure in granite rocks is due 

to the following possible causes:

1. To expansion caused by solar heat after the exposure of the 

granite by erosion.

2. To contraction in the cooling of the granite while it was still 

under its load of sedimentary beds, the sheets being therefore approximately parallel to the original contact surface of the intrusive.

3. To expansive stress or tensile strain brought about by the diminution of the compressive stress in consequence of the removal of the 

overlying material.

4. To concentric weathering due to original texture or mineral composition. This action would be chiefly chemical and would be aided 

by vertical joints and by any superficial cracks due to expansion and 

contraction under changes of temperature.

5. To compressive strain akin to that which has operated in the 

folding of sedimentary beds.

6. To the cause named under 1 at the surface, but to the cause 

named under 5 lower down.

These propositions will be considered in the order given: 

1. Solar heat may produce a certain amount of exfoliation in thin 

sheets .at the surface, as is proved experimentally in the fire method 

of granite quarrying in'India (p. 33), but as it penetrates only to a 

depth of 40 feet and as sheet structure is known to occur on Crotch 

Island, Me., at a depth of 140 feet and at Quincy, Mass., at a depth 

of 175 feet, it is quite inadequate to account for sheets that are 20 to 

30 feet thick and 100 to 175 feet below the surface.
GENERAL STRUCTURE. 35

2. In view of the load under which granite was generally formed, 

and the gradual rate at which, therefore, it probably cooled, which is 

also indicated by the general coarseness of its texture, it is very improbable that the temperature at its contact surface and the temperature at depths 100 or 200 feet below could have so greatly differed as 

to bring about such a system of joints by contraction.

3. As Gilbert states, in suggesting the theory of fracture by relief 

of tensile strain through the erosion of overlying masses, we have no 

distinct knowledge of it. It is a possible explanation.

4. Careful inspection of the rock on both sides of the sheet joints, 

fails to show any difference in texture or mineral composition. The 

sheet structure traverses both rift and flow structure, and it would be 

possible to procure specimens showing a sheet joint traversing a single 

crystal of feldspar. Whatever chemical action has taken place along

the sheet joints is of secondary character. Acid waters may have

gained access to the joint, but have not caused it.

5. The condition of strain described by Merrill and Gilbert as existing in the granite domes of Georgia and by Niles and Emerson in 

the gneiss at Monson, Mass.,1 and by the writer at West Dummerston, 

Vt., and occurring to a lesser extent in some Maine quarries, shows 

that granite and gneiss are in places still under compressive strain. 

Another instance occurs at the quarry of the New England Granite 

Works, at Concord, N. H. The foreman at this quarry was in the 

habit of calling certain sheets, marked by the absence of discoloration, " strain sheets," to distinguish them from the others. At one 

place a northwest-southeast compressive strain had actually extended 

the strain sheet about 5 feet, and also caused a vertical fracture that 

extended over 15 feet diagonally from the north-south working face 

to a point on a vertical east-west channel 5 feet back of the face, 

closing up the channel to half its original Avidth. Evidences of compressive strain were also noted at Quincy and Rockport, Mass., and 

at Westerly, R. I., and have also been observed by the writer in some 

of the Barre and Woodbury, Vt., quarries. The practicability of 

developing sheet structure by -the use of explosives and compressed 

air, as is done in some of the North Carolina granite quarries, shows 

that the rock is under a compressive strain there. 2

-All these observations bring this theory within the domain of 

inductive science. If sheet structure is due to compressive strain, it 

is due to such a strain as would produce a series of undulating fractures extending entirely across a granite mass several miles in diam-'

1 Niles, W. H., Some interesting phenomena observed in quarrying: Proc. Boston Soc. 

Nat. Hist., vol. 14, 1872, pp. 80-87, and vol. 16, 1874, pp. 4.1-43. Emerson, B. K., Geology of Old Hampshire County, Mass. : Mon. TJ. S. Geol. Survey, vol. 29, 1898, pp. 63-65.

s Watson, T. L., and Laney, F. B., The building and ^ornamental stones of North Carolina: Bull. North Carolina Geol. Survey No. 2, 1906, pp. 157-160.
36 GRANITES OP CONNECTICUT.

eter and to a depth, as far as observed, of 175 feet from the rock 

surface.

6. In view of the undoubted sheeting effect of expansion under 

solar heat within a short distance of the surface and of the fact that 

some of the sheets near the surface measure but a. few inches in 

thickness, it is quite possible that very thin surface sheets have 

originated in this way; but in view of what was stated under heading 5 it seems probable that compressive strain is the main factor in 

producing massive sheets. At the surface both causes may have 

cooperated. The progressive thickness of the sheets downward indicates that the operation of this strain is evidently also dependent 

upon distance either from the present surface or from a former surface or contact.

According to this view sheet structure may be said to exert a controlling influence upon surface forms, yet it seems quite admissible 

that granite domes as conspicuous as Stone Mountain, in Georgia, 

and Fairview Dome, in California, notwithstanding all the exfoliation that has taken place on them or the. erosion they may have 

suffered, may. still retain some degree of parallelism between their 

present form and the original contour of the granitic intrusions of 

which they are parts. This may be true, also, of the granite hills 

of Mount Desert.

The probability being admitted that the general parallelism between the present surface and the sheet structure is the result of 

erosion that followed the sheeting, the question still remains, What 

has determined the form and location of the domes? These may 

possibly be referred to major arches (anticlines) in the folds of the 

stratified rocks which originally overlay the granite. The crustal 

movement that produced .these folds may also have brought about the

intrusion of the material that formed the domes beneath them.

Although the sheet structure and the rock surface are very generally parallel, they are not universally so.

Sheet structure in granite so much resembles the structure of 

folded stratified rocks that underground water circulates in practically the same way along the fracture planes of one and bedding 

planes of the other. The exudation of water along sheet joints on 

vertical rock faces is seen in many"of the Maine quarries, and also in 

some Rockport and Niantic quarries. (See Bulletin 313, PI. VI, #, 

and Bulletin 354, PL V, A, and IX, A.)

JOINTS.

Herrmann 1 divides joints in-two groups joints formed by lateral 

compression, whose distances from one another are related to the

1 Herrmann, 0., Stenibruchindustrie und Steinbrucbgeologie, 1899, p. 103.
GENERAL STR.UCTURE. . 37

coarseness of the rock, texture, and joints due to expansion, some of 

which are parted and filled with calcite, quartz, pegmatite, or volcanic rock. That many joints are due to compressive or torsiqnal 

strain, and that every such strain resolves itself into two components, 

resulting in two sets of joints that intersect at an angle of about 90 °, 

each forming an angle of about 45° with the direction of the strain, 

are facts now generally recognized. Crosby 1 has suggested that 

torsional strains may have been supplemented by vibratory ones in 

causing joints. Becker,2 in a recent paper, shows that four or even 

more than four systems of joints may be due to a single force. He 

also shows that subsequent strain on a region thus jointed would 

tend to produce motion along the previously formed joints rather 

than a new -system of jointing. It is conceivable that if a region had 

been jointed and afterwards subjected to a tensile strain, some of its 

joints might be parted, and if they were very deep the openings

might become filled with volcanic matter from below, or, if not, with 

matter from above, infiltrated from overlying rocks. That motion 

has occurred along some of the joints in the quarries is evident from 

the polished and striated surfaces of the joints as well as from the 

faulting of the sheets.

Joints are exceptionally as curved " as the side of a ship." (See 

Bulletin 313, PI. VI, B.)

Possibly related to such curved joints are what some New England 

quarrymen term " toe nails." -These joints strike with the sheets, 

but extend only from one sheet surface to the next, and have a curve 

which sharply intersects that of the sheet structure. Such joints 

seem to be due to a strain different from that which produced the 

sheets. They were noted at Quincy, Westerly, and Milford, N. H.

The spacing of the joints varies considerably, ranging from 1 foot 

to 500 feet, but usually from 10 to 50 feet.

In some localities the jointing is very irregular. The granite is 

broken up into various polygons, which at the surface, where weathering has made inroads, resemble bowlders. Quarries opened in such 

places are called bowlder quarries. Another'sort of irregularity in 

joint consists in their discontinuity or intermittence, their strike and 

dip for the short spaces in which they occur being uniform.

HEADINGS.

In some places joints occur within intervals so short as to break 

up the rock into useless blocks. For a space of 5 to 50 feet the joints 

may be from 6 inches to 3 feet apart. A group of close joints is

1 Crosby, W. 0., The origin of parallel' and intersecting joints: Am. Geologist, vol. 12. 

1893, pp. 368-375.

2 Becker, George F., Simultaneous joints: Proc. Washington Acacl. Sci., vol. 7, July, 

1905, pp. 267-275, PI. XIII.
38 -GRANITES OF CONNECTICUT.

called by quarrymen a " heading," possibly because, when practicable, 

such a mass is left as the head or wall of the quarry. (See Bulletin 

313, Pis. VIII, A, and IX, B, also Bulletin 354, PL VI, B.) Head* 

ings afford ample ingress for surface water, and consequently the 

granite within a heading is generally badly stained, if not decomposed. This will be referred to more fully under the heading 

" Decomposition."

An interesting feature of both headings and joints shown in 

some of the deeper quarries at Quincy, Mass., is their vertical discontinuity. A heading occurring at the surface may disappear 

below, or a heading may abruptly appear a hundred feet beloAv the 

surface and continue downward.

Headings are not easily accounted for. They may be produced by 

vibratory strains that recur at intervals of time. If they are so 

caused, the character of the fractures in some headings indicate that 

the strains are very complex.

FAULTS.

The polished and grooved faces (" slickensides ") observed on many 

of the joints at the quarries show that faulting has occurred along 

them. The discontinuity of the sheets at some of the joints, causing, 

where the joints are slightly inclined, what quarrymen call " toeing 

in," may probably be attributed to faulting. This supposition 

assumes, of course, that the sheet structure was formed prior to the 

jointing. Faulting occurs also along sheets, displacing vertical flow 

structure, or vertical dikes. (See Bulletin 313, PI. VIII, B.} It 

may occur along one of two intersecting dikes, displacing the other, 

as at the Deep Pit on Cape Ann. (See Bulletin 354, PL V, B.)

In some quarries the granite near the surface acquires a marked

foliation, which appears to be parallel to the sheet structure, and 

in places to the rift. This foliation is known by quarrymen as 

" shakes." It occurs both at the top and at the bottom of the sheet, 

through a maximum thickness of 6 inches. It is coextensive with 

the discoloration known as " sap " and occurs at many places near 

vertical joints. Under the microscope this structure proves to consist of minute, nearly parallel fissures, of no great continuity, which 

traverse the mineral particles and which in the thin section examined 

are especially conspicuous in the quartz and the mica. The distance 

between these fissures measures from a tenth to a half a millimeter, 

or from one two-hundred-and-fiftieth to one-fiftieth inch. The 

parallelism, both to the sheets and the " sap," and its relation to the 

vertical joints indicate that the structure may be due to the freezing 

of surface water which has found its way to the sheets through the 

vertical joints and has entered the rift fissures.
ROCK VARIATIONS. 39 

MICROSCOPIC FRACTU'RES.

The writer's attention was called to a similar structure in a quarry 

at Milford, N. H., consisting of short parallel fractures along the 

rift, from one-half inch to 2 inches apart, having no apparent connection with joints or discoloration. This is probably due to strain 

affecting part of the granite mass and producing miniature sheet 

structure.

SUBJOINTS.

Careful inspection shows that the joint structure in granites does 

not everywhere consist of a simple fracture, but that it is at many 

places complex. Minute fractures branch off from the joint at an 

acute or right angle and penetrate the rock a few inches, or the rock 

for a few inches on either side of the joint is traversed by microscopic 

fissures that are roughly parallel to it. All such structural features 

may properly be called sub joints.

Woodworth has studied analogous and related structures in various 

rocks and has described them as " joint fringe" and " feather 

fractures." x

BOCK VARIATIONS.

Under the term " rock variations " are grouped all those variations 

from typical granite that are due to injection, segregation, infiltration, inclusion, and steam cavities.

DIKES (GRANITIC).

The granitic "dikes in the quarries are of three kinds: Extremely 

fine grained granite (aplite), very coarse grained granite (pegmatite), 

and fine or medium grained granite.

In thickness they range from a fraction of an inch to over 20 feet, 

but generally from 2 inches to 2 feet.

Aplite differs from ordinary granite by the greater fineness of its 

texture and its scant content of mica. It is known by quarrymen as 

" salt horse " or " white horse."

Aplite dikes are supposed to have originated in the same deepseated molten mass as the granite they traverse, but they represent 

a later stage of igneous activity. The fissures they fill were the 

result of various tensional strains or contractions, possibly consequent 

upon the cooling of the granite.

In color these dikes vary from bluish gray to light and dark reddish. The texture of some aplites is so fine that the mineral particles 

can not be distinguished with the unaided eye; that of others is so 

coarse that the feldspar and mica may be thus detected. Under the

1 Woodworth, J. B., On the fracture system of joints, with remarks on certain great 

fractures: Proc. Boston Soc. Nat. Hist., vol. 27, 1896, pp. 169-173, pis. 1, 2.
40 GRANITES OF

microscope the dimensions of the particles range from 0.05 to 0.75 

mm., the average being about 0.16 mm. for the finer ones and 0.50 

mm. for the coarser ones. Some aplites have a porphyritic texture.

Most aplites contain a slightly higher percentage of silica than 

granite. Five analyses of aplites from the Far West made at the 

laboratory of the United States Geological Survey 1 show a range of 

silica from 71.62 to 76.03 per cent and an average of 74.08, which is 

near the maximum of silica for granite generally.

Pegmatite lies at the other extreme. Its mineral constituents range 

generally from one-half to 1 foot or even several feet in diameter. 

It is reported that the crystals in some pegmatite dikes measure from 

10 to 30 feet in length by 1 to 3 feet in width. The chief minerals in 

pegmatite dikes are the same as in granite, but they occur in different 

though varying proportions. With these minerals are commonly 

associated tourmaline, garnet, beryl, etc. Chemically these dikes generally contain more silica than the granite. Dikes of pegmatite are, 

as a rule, more irregular in width than those of aplite. They generally range in thickness from 1 inch to 10 feet.

The origin of pegmatite has been much discussed both in Europe 

and in this country.2 The coarseness of its constituent minerals 

indicates slow crystallization, and the irregularity of the dikes shows 

tensional rather than torsional strain. The banding of some pegmatite dikes and the isolated lenticular character of others indicate 

that the dikes were filled from heated solution, and many of them 

differ in no respect from dikes of igneous origin except by the coarseness of their texture. For these reasons it is thought that pegmatite 

dikes in granite have been formed in openings and fissures that were 

due, possibly, to contraction while the granite was still hot and that 

some of these openings were filled with matter in a state of both 

molten plasticity and solution under pressure, and others by heated 

solutions that gathered matter from the adjacent granite. Howsoever derived, this dike material crystallized very slowly.

Granite. Finally, there are dikes that differ from all those just 

described, formed simply of fine or medium-grained granite.

VEINS.

Quartz veins occur rarely in the Maine granite quarries (see Bulletin 313, p. 46) and at but few of the other New England quarries. 

Some of these seem to be clearly of pegmatitic origin.

1 Bull. U. S. Geol. Survey No. 148, 1897, pp. 124, 150, 206, 219.

2 The principal American writings on the subject are : Williams, G. H., The general 

relation of the granitic rocks in the middle Atlantic Piedmont Plateau: Fifteenth Ann. 

Kept. U. S. Geol. Survey, 1895, pp. 675-684 ; Crosby, W. O., and Fuller, M. L., Origin of 

pegmatite: Tech. Quart, vol. 9, 1896, pp. 326-356; Am. Geologist, vol. 19, 1897, pp. 

147-180 ; Van Hise, C. R., A treatise on metamorphism : Mon. U. S. Geol. Survey, vol. 47, 

1904, pp. 720-728; Bastin, E. S., Geology of the pegmatites and associated rocks of 

Maine, including feldspar, quartz, mica, and gem deposits: Bull. U. S. Geol. Survey No. 

445, 1911.
ROCK VARIATIONS. 41

DIKES (BASIC).

Dikes of dark-greenish or black, hard and dense rock (diabase, 

rarely basalt) are of very common occurrence in the Maine and 

Massachusetts quarries. Some of them are represented: in Bulletin 

354, Plate V, A and B.

Most of these dikes are so firmly welded to the granite that hand 

specimens that are one-half granite and one-half diabase are readily 

obtained. Thin sections of the glassy rims of dikes show that the 

dike sent out microscopic branches for short distances into the 

granite, in places surrounding some of its quartz particles.

The geologic age of these dikes has not been precisely determined. 

They are considerably more recent than the granite they traverse or 

the dikes of aplite and pegmatite which traverse the granite.

The diabase dikes are the result of an earth movement that-either

opened previously formed joints or made new ones deep enough to be 

injected with volcanic material. How far this may have penetrated 

the rocks which overlay the granite, or whether it overflowed at 

their surface, can not even be conjectured.

At the granite quarries, wherever this course is possible, the dikes 

and the headings are left to form the bounding walls of the excavations. ...

SEGREGATION S ( KNOTS ) .

Quarrymen know too Avell that granite is commonly disfigured by 

gray or black " knots " of circular or oval irregular curved outline, 

ranging in diameter from half an inch to 3 feet and exceptionally even 

10 feet. These were studied by geologists long ago.1 They are finer 

grained than the granite in which they occur, contain nearly 10 per 

cent less silica, much more black mica or hornblende (which accounts 

for their darkness), and a little more soda-lime feldspar, and their 

specific gravity is about 0.09 per cent higher.

Plate V, A, of Bulletin 313 shows twelve small knots in one of 

the Sullivan quarries, and on pages 49 and 50 of that bulletin thin 

sections of knots from the Maine quarries are described. Several 

varieties from the Quincy quarries are described on page 95 of Bulletin 354 and one of exceptional character from Rockport on pages 

64, 125, of the same bulletin.

In none of the knots is there a definite boundary separating them 

from the granite, excepting such as is caused by the change in the 

proportionate abundance of the darker minerals. The cause of knots

1 Phillips, J. A., On concretionary patches and fragments" of other rocks contained in 

granite: Quart. Jour. Geol. Soc. London, vol. 36, 1880, pp. 1-22, PI. I. Merrill, G. P., 

On the black nodules or so-called inclusions in the Maine granite., Proc. U. S. Nat. Mus., 

vol. 6, 1883, pp. 1.37-141. Grimsley, G. P., Basic segregations : The granites of Cecil 

County in northeastern Maryland ; Jour. Am. Soc. Nat. Hist., Apr. and July, 1894. Daly, 

Reginald A., Basic segregations: The geology of Ascutney Mountain, Vermont: Bull. 

U. S. Geol. Survey No. 209, 1903, p. 164.
42 GRANITES OF CONNECTICUT.

is not perfectly understood. They are collections (segregations) 

generally of the darker, heavier, iron-magnesia minerals that took 

place while the rock was in a plastic state.

 GEODES.

Small cavities lined with crystals occur in granite. They have 

been found by the writer at the Jonesboro and Marshfield quarries 

in Maine and at Redstone, N. H. Their greatest diameter was about 

12 inches, and the lining crystals were quartz, more or less amethystine, and feldspar. These were commonly coated with epidote, 

chlorite, and calcite, the calcite generally in very obtuse rhombohedra 

up to half an inch across. A geode at Redstone is surrounded by a 

band of aplite.

Such cavities are attributed to bubbles ^of steam or gas that were 

in the rock while it was in a molten state, which gave room for the 

growth of crystals and later became filled with epidote and calcite.

INCLUSIONS.

Not to be confounded with "knots," although some of them are 

equally dark and occur near them, are irregular or angular particles 

of various schistose rocks which the granite incorporated into itself 

during its intrusion. They can usually be distinguished from the 

knots by their different microscopic structure. In the Maine quarries they range from an inch to 40 feet in length. Part of the jagged 

edge of the lower part of a large schist inclusion in granite at Freeport, Me., is shown in Plate VII, #, of Bulletin 313; specimens from 

schist inclusions in Vermont granite are shown in Plate II, B, of 

Bulletin 404.

DISCOLORATION.

Rusty (limonite) staining along the upper and lower parts of the 

sheets and also along the joints and headings is common in granite 

quarries, although some quarries are almost entirely free from it. 

The zone of discoloration along the sheets in the Maine quarries is 

from one-half to 12 inches, exceptionally even 18 inches, wide on each 

side of the sheet parting. Its width, however, decreases gradually 

from the surface sheets downward. In places the sap consists of two 

parts an outer dark brownish zone from three-fourths to 1^ inches 

wide and an inner more yellowish zone from one-fourth to one-half 

inch wide. Generally, however, the discoloration diminishes gradually from without inward. In some quarries there seems to be a 

connection between the " shake " structure and the discoloration, since 

these are coextensive.

When the stone is intended for facing or trimming buildings the 

presence of sap is a serious matter, as the stained edge of each block 

must be split off, which adds somewhat to the cost of production.
DECOMPOSITION". 43

This discoloration has been supposed to be always due to the oxidation of the ferruginous minerals of the granite, biotite, hornblende, 

magnetite, and pyrite, but the Maine thin sections examined by the 

writer do not bear out this theory. (See Bulletin 313, p. 53 and fig. 2.)

These observations lead to the inference that the discoloration 

called " sap " is,- in some Maine granites, not due chiefly to the oxidation of the ferruginous minerals of the granite by "underground 

water," but chiefly to the deposition of limonite by ferruginous surface water. The water descended along the vertical joints and then 

flowed along the sheet partings and permeated the rock above and 

below them. Whether the postglacial submergence of the Maine 

coast had anything to do with the discoloration is not clear.

Another kind of discoloration, which is even more serious in its 

consequences, appears on fresh faces of granite, either in the quarry 

or after its removal. This consists of sporadic rusty stains from half

an inch to an inch in diameter, arising from the oxidation of minute 

particles of some undetermined ferruginous mineral, possibly allanite. Such stains generally, however, arise from pyrite particles or 

crystals.

Daly * describes a bluish-gray syenite from Windsor, Vt. (feldspar, 

quartz, hornblende, augite, biotite), that after 24 hours' exposure 

assumes a greenish tinge, which eventually becomes more or less 

brownish. He has demonstrated by experiment with oxygen that 

this change is due to the oxidation of minute blackish granules of 

ferrous oxide within the feldspar, giving a yellow which, in combination with the original bluish tint of the feldspar, produces a green. 

The large columns of the library of Columbia University, in New 

York, are made of this rock.

Another kind bf discoloration occurs on either side of diabase or 

basalt dikes, caused mainly by various alterations of the feldspars 

and their consequent change in shade or color. (See Bulletin 313, 

p. 91, and the examples at Rockport, Mass., and Milford, N.- H., 

described on pp. 125 and 163 of Bulletin 354.) Discoloration is thus 

of five kinds that due to the infiltration of ferruginous water, that 

due to the oxidation of the generally disseminated ferruginous minerals (biotite, hornblende, and magnetite) by nonferruginous water, 

that due to the oxidation of sporadic ferruginous minerals, that arising from the oxidation of ferrous oxide within the feldspars, and that 

due directly or indirectly to dikes and veins.

DECOMPOSITION.

Notwithstanding the strength and durability of granite, it is liable, 

under certain conditions and in the course of long time, to decompose

1 Dnly, Reginald A., The geology of Ascutney Mountain, Vermont: Bull. U. S. Geol. 

Survey No. 209, 1903, pp. 51-53.
44 GKANITES OF CONNECTICUT.'

into a clayey sand. This is the result of its physical, -mineralogical, 

and chemical constitution arid properties. One of the most striking 

illustrations of this is the occurrence in some of the Maine quarries 

of "beds" of sand or decomposed granite within the fresh granite, 

either between the sheets away from headings or within the headings 

and along or across the sheets. Thus at the Palmer quarry, in Vinalhaven, 20 feet below the surface in the face of the quarry, there is a 

bed of granite sand 18 inches thick between two sheets, which at 

that point dip about 10° into the hill. On the southeast side of the 

Longfellow quarry, near Hallowell, some of the sheets within a wide 

heading include granite sand beds that are about 10 inches thick. At 

the Shattuck Mountain quarry, near Eedbeach, a 6-foot heading 

includes a vertical layer of granite sand 8 inches thick. Specimens 

taken from these various sand beds show that the disintegration begins with microscopic fractures; in some cases the enlarged rift 

cracks, producing the " shake " structure described on page 38, and is 

followed by more or less kaolinization of the feldspars. This process 

consists in the loss of alkali and the taking up of water, resulting in 

the passing of the feldspar into a white clay (kaolin).

The joint and sheet structure affords ingress to surface water, 

containing its usual percentage of carbonic acid, and the " rift" or 

" shake" structure facilitates the kaolinization of the feldspar on 

either side of the sheet parting by this water. As the feldspars pass 

into clay the rock crumbles into sand' consisting of quartz, mica, arid 

kaolin, and of feldspar in various stages of kaolinization. Iri some 

places within the range and depth of frost a large part of this work 

may have been done by frost alone. The sand would there be mainly 

the product of the " shake " structure.

In regions which have not been swept by a continental gla'cier any 

granite mass would be covered with the products of the decomposition of its own surface. .In the Tropics the abundant rainfall and 

the organic acids from a luxuriant vegetation materially hasten the 

decomposition, and granitic rocks in such regions are for these reasons 

commonly covered with many feet of sand and soil. 1

The incipient stage of weathering may be observed in any longexposed granite ledge iri the milky whiteness of the feldspars. This 

charig'e usually attacks the soda-lime feldspars first. The black rriica, 

owing to its content of iron oxide, is also liable to early decomposition. The process of weathering, as it affects the rock as a whole, 

involves the following chemical changes: A loss of lime, magnesia, 

potash, and soda; a gain of water, and a relative gain of silica, alumina, and iron oxide that is, relative to the reduced weight of the

1 Branner, John C., Decomposition of rocks in Brazil: Bull. Geol. Soc. America, vol. 7, 

1896; Exfoliation, p. 31.
GEOLOGIC OBSERVATIONS AT THE QUARRIES. 45

weathered rock.- The subject of weathering of granite is fully treated 

in the writings of Merrill, Keyes, and Watson.1

The changes in granite after it has entered into buildings or other 

constructions are less marked than those in the natural rock, because 

the blocks are not then traversed by anything analogous to sheet and 

joint structure, and also because the years of historic time are few 

compared to those of geologic time. Much has been written on the 

decay of granite in monuments and buildings.- Such decay is mainly 

attributable to microscopic fissures produced by the unequal and 

repeated expansion and contraction of the different minerals of the 

granite under changes of solar temperature. In countries where the 

winter temperature is very low the action of frost within such fissures 

powerfully assists the process of disintegration. Thus the obelisk 

now in New York suffered more from three years' exposure to our

climate.than it had during over three thousand four hundred years 

in Egypt, although the fissures along which frost operated were 

started long before it reached this country. A minor factor in decay 

is the chemical action of water along fissures.3

It is supposed that these causes of decay operate more effectively 

in coarse granites than in fine ones. Merrill points out that a sawn or 

properly prepared polished surface resists weathering more effectively 

than a cut or hammered one, as the latter is full of minute fractures, 

parallel to the surface, produced by impact, which facilitate scaling.

GEOLOGIC OBSERVATIONS AT THE QUARRIES.

By T. NELSON DALE.

The geological observations made in visiting the quarries of the 

State are recorded in detail in the quarry descriptions in Part II. Although the exposures at many of the quarries are of considerable 

scientific interest, yet the quarries which combine more interesting 

features are those of Stony Creek and Hoadly Point, in Branford; 

the Millstone and Waterford quarries, in Waterford; the Borough 

quarry, in Torrington; and the quarry on Mine Hill, in Eoxbury.

1 Merrill, G. P., Disintegration of the granite rocks of the District of Columbia: Bull. 

Geol. Soc. America, vol. 6, p. 321., 1895 ; also A treatise on rocks, rock-weathering, and 

soils, New York, 1897, pp. 206-214, 236, 244, 245, 257. Keyes, Charles It., The origin 

and relations of central Maryland granites : Fifteenth Ann. Kept. U. S. Geol. Survey, 1895, 

p. 725, and pis. 42-45. ( See also Proc. Iowa Acad. Sci., vol. 1, pt. 3, pp. 22-24, and Vol. 2, 

pp. 27-31, Pis. II-IV, 1895. Watson, Thomas L., A preliminary report on a part of the 

granites arid gneisses of Georgia, 1902, pp. 299, 300, 308, 329, 331, 333.

2 Julien, A. A., The Durability of building stones in New York City : Tenth Census, 

vol. 10, 1884; Granite, pp. 370-371. Merrill, Geo. P., Physical, chemical, and economic 

properties of building stones : Maryland Geol. Survey, vol. 2, 1898 ; Granite, pp. 92-94. 

Also Men-ill's Stones for building and decoration, 3d ed., 1903 ; Weathering of granite, pp. 

434, 435.

3 Julien, A. A., A study of the New York obelisk, as a decayed bowlder: Annals NewYork Acad. Sci., vol. 8, 1893, pp. '93-166.
46 GRANITES OF CONNECTICUT.

The more important observations made at the quarries are grouped 

or summarized in the following paragraphs:

MICBOSTRUCTUBE. .

Attention has been called in another bulletin1 to the fact that when, 

a thin section of granite is made at right angles to the rift many of 

the microscopic cavities in the quartz particles are found to be 

arranged in parallel sheets, and that where the rift is well developed 

rift cracks will be observed parallel to or coinciding with these 

sheets of cavities. As noted in the microscopic descriptions of Part 

II of this bulletin, this arrangement of cavities in sheets was observed 

in the mica diorite gneiss of Greenwich and of the Torrington 

Borough quarry; in the granite gneiss of the Bridgeport Jail quarry, 

and of the Norwalk, Ansonia, Norfolk, Roxbury, Benvenue, StonyCreek, Hoadly Point, Leete Island, Sachem Head, Selden Neck, and 

Flat Rock and Goos quarries in Waterford; in the quartz monzonite 

of Mystic and Niantic; and also in the granite of Pawcatuck, the 

flow gneiss of Masons Island, the pegmatite of Lyme village, and the 

aplite of the Ritch quarry, at Greenwich. Rift cracks were observed 

parallel to or coinciding with such sheets of cavities in the granite 

gneiss of Roxbury and of Joshua Rock in Lyme; in that cut by the 

pegmatite of the MacCurdy quarry, at Lyme village; in the elongated 

porphyritic gneiss of Bolton, near the Glastonbury line; in the gneiss 

of the Michiel quarry, near Torrington; in the quartz monzonite of 

Center Groton; and in quartz monzonite and pegmatite of the Torrington Borough quarry.

Rift in the gneisses was always found parallel to the foliation except in the gneiss of Selden Neck, in Lyme, in which it is parallel to 

the long axes of the biotite lenses and at right angles to the foliation,

and again in the banded gneiss of the Mclntosh quarry, near Groton, 

where the rift is also transverse to the foliation, both rift and grain 

fractures being smoother than those along the banding.

In the fine-grained quartz monzonite of the Waterford quarry 

(p. 113) the long axes of the slender biotite scales, fewr of which are 

over 0.1 inch long, are parallel to the rift, as they probably are in 

some of the other quartz monzonites of the State. . Of interest in this 

connection is a statement made by a Cornish granite quarryman, Mr. 

W. B. Stephens, now superintendent of the Rockside quarry in Roxbury, to the effect that in the granite quarried by John Freeman & 

Sons at Colcerrow, in Cornwall, the feldspars, which are about 2 by 

0.5 inches, are arranged with their long axes parallel to the rift and 

the short axes parallel to the hardway. Prof. J. D. Dana 2 attributed

1 Bull. U. S. Geol. Survey No. 354, 1908, pp. 42-47, fig. 1. 

» Manual of geology, 2d ed., 1876, p. 628.
GEOLOGIC OBSERVATIONS AT THE QUARRIES. 47

rift in all granites to such an arrangement of the feldspars, which, 

however, proves to be exceptional. 1

FLOW STRUCTURE.

Flow structure consists of .a distribution of the mica scales in 

greater or less abundance in alternating bands, the general course of 

which was governed by that of the flow of the granite in its original 

molten state. Flow structure should not be confounded with any 

rearrangement of the mica in the complex physical and chemical processes of metamorphism. Flow structure at the Stony Creek quarries 

strikes N. TO0 W., and also N. 65° E.; at Masons Island in Stonington it strikes about north. At Millstone Point the quartz monzonite 

has a meandering flow structure, as shown in figure Sc (p. Ill), striking N. 45-60° W. At the Anguilla quarry in Stonington a similar

granite has a flow striking east-west. At Pawcatuck, near Westerly,

the biotite granite shows flow structure with the same course.

INCLUSIONS.

Inclusions are important, for they are specimens of the rocks that 

originally overlay the granite and they indicate the age of the intrusion. At the Stony Creek quarries they consist of diorite gneiss and 

mica diorite gneiss. At the Hoadly Point east quarry an inclusion of 

mica diorite gneiss appears to have been elongated in the direction of 

the floAv structure. Inclusions abound at the Millstone quarry, and 

the two largest have diameters of 20 and 36 feet. Most of them are 

biotite gneiss like the capping, but some are diorite gneiss. They are 

generally associated with lenses of pegmatite or are inclosed by pegmatite dikes, or the granite has become banded about them. (See 

fig. 8, «, 5, d, p. 111.) One of these diorite gneiss inclusions is much 

cross veined with quartz, some of the. veins starting from the surface 

of the granite, others from within it. The quartz monzonite of the 

Waterford quarry (p. 116) contains inclusions of gneiss resembling 

that which overlies it. The same is true at the McGaughey quarry, 

at Mystic. The quartz monzonite of Keynolds Bridge (p. 72) contains an inclusion of plicated quartz monzonite gneiss, evidently a 

part of the capping. At the Torrington Borough quarry a pegmatite dike, 20 feet thick, contains two inclusions of the adjacent 

biotite granite gneiss, each 10 feet in diameter.

PLICATED GNEISS STRUCTURE.

The change from the granitic to the gneissic texture has been 

dwelt upon by Prof. Gregory (pp. 16-18). At Hoadly Point the 

coarse porphyritic granite gneiss has undergone a further change in

iSee Bull. U. S. Geol. Survey No. 354, 1908, pp. 19-22. 

97730° Bull. 484 11 4
48 GRANITES OF CONNECTICUT.

consequence of lateral pressure,.so that the gneissic foliation has become coarsely plicated and in one place faulted, as shown in figure 4. 

In consequence of its acquired foliaceous texture the granite has acted 

under lateral pressure precisely as would an unaltered sedimentary 

rock or a schist of metamorphic sedimentary origin. At the Scott 

quarry, in Waterford (p. 106), the gneiss foliation is plicated along 

the strike.

GRANITE DIKES.

The fine quartz monzonites of Connecticut, like those of Khode 

Island, occur as dikes, or apparent dikes,1 in various gneisses. At the 

Waterford quarry there are two such parallel dikes with an intervening strip of gneiss. The relations are shown in figures. 9 and 10. 

The thickness of the various dikes measured at a right angle to their 

inclination ranges from 12 to 40 feet, but at the Millstone quarry the 

relations are not clear. The granite is exposed for a depth of 50 to 

125 feet and a width of 50 to 300 feet, approximately, and is capped 

here and there by 25 feet of gneiss, but no underlying gneiss is yet 

exposed, although the abundance of inclusions at the bottom of the 

quarry may indicate its proximity. If the width of the granite at 

right angles to the flow, which appears to dip 35° SW., be taken 

as 200 feet, the thickness of the granite would be about 114 feet. It 

is possible that a part of this quarry overlies the vertical portion of a 

granite dike.

At the Torrington Borough quarry a finely banded biotite granite 

gneiss associated with pyritiferous quartz-mica diorite gneiss is 

crossed by a network of dikas the largest 6 inches thick of bluish 

gray quartz monzonite, which has acquired a gneissic texture.

PEGMATITE DIKES,

Pegmatite in lenses or in small dikes occurs at nearly all the 

quarries described. The 20-foot dike, with large gneiss inclusions, 

at the Torrington Borough quarry has been referred to, also the presence of pegmatite near or about such inclusions at the Millstone 

quarry (fig. 8, 6, d, p. 111). Small dikes of pegmatite recur at frequent intervals at that quarry, intersecting one another with dip 30° 

NW. and SE. The permeation of Stony Creek granite gneiss 

with pegmatite differentiates it from many granites and partly 

accounts for its very irregular texture. (See p. 81 and PL III, A) 

The biotite granite of the MacCurdy quarry, at Lyme, is really a 

pegmatite occurring as dikes, 15 to 22 feet thick, cutting a mass of 

finely banded granite gneiss. (See p. 102.) At the Slater quarry, in 

Glastonbury (p. 67), a 12-inch pegmatic dike in fine porphyritic 

biotite granite gneiss contains muscovite crystals, the largest 5 inches

1 gee Bull. U. S. Geol. Survey No. 354, 1908, p. 190,
GEOLOGIC OBSERVATIONS AT THE QUARRIES. 49

across and 4 inches thick. At the Center Groton quarry the quartz 

monzonite on either side of a 4-foot pegmatite dike has been darkened. 

Dikes from 6 inches to 2 feet thick abound in the Holbrook quarry 

at Seymour. (See p. 91 and fig. 5.) At the Ben venue quarry in 

Middletown small pegmatite, dikes are bordered with bands of 

feldspar and hornblende and the granite gneiss itself also contains 

hornblende.

Generally pegmatite dikes contain the same minerals as the granite 

they penetrate, but in larger particles. In the very fine granites such 

dikes afford a ready means of observing in the field the chief constituents of the granite they penetrate.

The pegmatite of Lyme village contains apatite, that of the Oneco 

quarry fluorite and epidote, that of Pawcatuck allanite, that of the 

Mascetti quarry in East Litchfield and the Potter quarry in Ansonia

black tourmaline, and that of several other quarries garnets, all in 

small particles or crystals. No time was spent searching for rare 

minerals.

The pegmatite of the Collins quarry in Danbury (p. 54), owing to 

crustal motion, has all its quartz granulated like that of the gneissoid 

granite of -Milford, Mass., and its feldspars crossed and bordered 

with crushed feldspar. Crushed feldspar borders occur also in the 

pegmatite of the Torrington Borough quarry.

APLITE DIKES.

Dikes of aplite were observed at the Roxbury, Benvenue, Bolton, 

Greenwich, and Sterling quarries. Aplite is also associated with 

pegmatite at several other quarries.

At Roxbury some of the aplite is rose colored, and the larger dikes 

are 4 feet thick. Its particles are all under 0.1 inch, and consist of 

oligoclase andesine, smoky amethystine quartz, microcline, rare muscovite, and microscopic garnets. The feldspars have crush borders, 

the dikes having been exposed to the same pressure that made a 

gneiss of the inclosing granite. A white aplite from the same quarry 

has oligoclase albite as its chief feldspar.

At Benvenue the aplite is white to rose colored, and the larger 

dikes are a foot thick. Its particles are all under 1 millimeter, and 

consist of quartz, orthoclase and microcline, oligoclase, and rare biotite with accessory pyrite, titanite, allanite.

At the Peterson quarry, in Bolton, an 18-inch bluish-gray aplite 

of slightly gneissose texture has quartz and feldspar particles from 

0.11 to 0.33 millimeter, with some porphyritic ones from 0.54 to 0.84 

millimeter, and consists of smoky quartz, bluish microcline and 

orthoclase, white plagioclase, and rare biotite.
50 GKANITES OF CONNECTICUT.

The diorite gneiss of Greenwich is crossed by a network of aplite 

dikes, the largest 3 inches thick, of bluish-gray color, with particles 

under 0.76, mostly under 0.57 millimeter, and consists of quartz with 

cavities in sheets, microcline and orthoclase, andesine, and probably 

oligoclase andesine, rare and minute biotite, with accessory pyrite, 

apatite, titanite', zircon.

At the quarries near Oneco, in Sterling, the larger aplite dikes are 

a foot thick and the aplite is cream colored, with particles ranging 

in diameter from 0.05 to 1.11 millimeters. It consists of clear, colorless quartz with cavities, microcline, and orthoclase, rare and minute 

biotite, and accessory ilmenite, garnet, and apatite. A small dike 

contains a central band of ilmenite.

MINERAL VEINS.

At the Eoxbury quarry, owing to the proximity of a vein of 

siderite which was formerly mined, three veins, each not over 8 

inches thick, consisting of siderite, pyrite, chalcopyrite, galena, and 

secondary quartz coating crystals of siderite, occur within and parallel to three vertical headings which strike northwest.

CONTACTS.

Granite is in contact with gneiss at Thomaston (p. 72) ; at Groton 

(p. 9) ; at the Millstone and Waterford quarries, in Waterford 

(pp. 110, 115, and figs. 9, 10) ; at the Anguilla quarry, in Stonington 

(p. 103) ; at the Niantic quarries (p. 98) ; and at Mystic (p. 96). At 

the Holbrook quarry, in Seymour (p. 91, fig. "5), the rock that overlies the granite gneiss is very schistose, biotitic, and in places much 

plicated. The most impressive features of these contacts are (1) the

irregularity of the contact surface, particularly at the Millstone 

quarry, where its outline is rudely serrate; (2) the vast amount of 

erosion which has taken place to reduce an original gneiss mass of 

sufficient magnitude to afford adequate pressure for the formation of 

granite to remnants hardly 25 feet thick; (3) the evidence afforded 

by the superposition of a granite gneiss upon a granite that granitic 

intrusions recurred here, and, in those places where the lower granite 

is somewhat gneissose, that regional metamorphism also recurred.

SHEET STRUCTURE.

At the Waterford quarry, as shown in figure 11, the granite sheets 

are not continuous with those of the overlying gneiss, a discontinuity 

that may be attributed either to textural differences between the two 

rocks or to the fact that the sheet structure of the gneiss was formed' 

prior to the intrusion of the granite and under a different kind of 

stress. At the Salter quarry, in Groton, the sheets of granite dip 20° 

SW., those of the gneiss cap dip 15° S.
GEOLOGIC OBSEKVATIONS AT THE QUABEIES. 51

In the more schistose granite gneisses sheet structure is in general 

parallel to the gneiss foliation.

At the Norcross quarry, in Stony Creek, a few inches of " shake 

structure," or miniature sheet structure, occur along the sheet surfaces. This structure occurs on a more extensive scale at Sachem 

Head quarry, where in places it appears on the whole working face.

JOINT STRUCTURE,

Ninety-nine compass observations were taken on different sets of 

joints "in fifty quarries. Of these the most frequently recurring sets 

are those striking about north (N. 10° E. to N. 10° W.); about .eastwest (N. 75°-90° E. and N. S5°-90° W.); about northeast (N. 40°- 

50° E.); about north-northeast (N. 15°-35° E.); and about northnorthwest (N. 15°-35° W.). Then follow those striking N. 40°-55° 

W. and N. 60°-70° E,, which are about equally abundant.

SEGREGATIONS.

Biotitic segregations were noticed at the Stony Creek, Waterford. 

and Benvenue quarries. At the last they attain a length of 3 feet 

8 inches and taper in the direction of the gneiss foliation.

GEODES.

At the Murray quarry in Pawcatuck, Stonington, a 5-inch geode 

lined with crystals of pyrite was found.

SECONDARY QUARTZ ON JOINT FACES.

At the Hall quarry, in Norwalk (p. 60), the parted joints of a 

heading are coated with secondary quartz or injected with quartz 

dikes to a thickness of 2 inches.

VEINLETS OF ZEOLITE.

At the McGaughey quarry, in Mystic village in Groton (p. 96), 

the quartz monzonite has veinlets of two zeolites. One of these 

minerals replaces some of the feldspar.
PART II. ECONOMIC DISCUSSION.1

By T. NELSON DALE.

DESCRIPTION OF THE QUARRIES AND THEIR PRODUCT.

METHOD.

The quarries will be taken up by counties in alphabetical order: 

Fairfield, Hartford, Litchfield, Middlesex, NCAV Haven, New London, Tolland, Windham, and the towns in each county will be taken 

up in like order. The particulars of each quarry will be given in the 

following order:

1. Name and location of quarry; name and office address of 

operator.

2. The granite, its technical and trade names; its color, texture, 

minerals, estimated mineral percentages; its chemical composition 

and physical qualities, as shown by any available analyses or tests.

3. The quarry, date of opening, its approximate dimensions, and 

thickness of stripping.

4. Rock structure, comprising sheets, joints, headings, their strike, 

dip, and spacings; rift and grain, now structure, dikes, veins, 

" knots," discoloration, and weathering. Where the structure is complex, a diagram of the courses is given. ,

5. The plant, with the number of machines of each kind, and of

air tools, to show its capacity.

6. Transportation, including distance to clock or railroad and 

method of transportation.

7. Use of explosives and method of quarrying wherever these are 

of special interest.

8. The- product, its uses and chief market, and the names and 

location of a few specimen buildings and monuments.

FAIRFIELD COUNTY.

BRIDGEPORT. 

BTJRLISON QUARRY.

The Burlison quarry (formerly known as the Parsons quarry) is 

in the township of Bridgeport, on the Trumbull Koad, about 750 feet

1 Some of the names used in this economic discussion are those by which the granites 

are known to the trade and are not used in a geologic formational sense.

52*
FATKFIELD COUNTY. 53

south of the Trumbull line and about 3^ miles north-northeast of the 

Bridgeport railroad station. (See map, PI. I, p. 8.) Operator, Dr. 

Henry H. Burlison, 133 Kossuth Street, Bridgeport, Conn.

The granite (specimen D, XXX, 40, a) is a muscovite-biotite 

granite gneiss of medium bluish-gray color and fine-grained gneissose 

texture, with finely laminated, implicated foliation, its particles being 

under 0.2 inch. Its constituents, in descending order of abundance, 

are bluish translucent potash feldspar (microcline and orthoclase) ; 

clear, colorless quartz; bluish translucent soda-lime feldspar (oligoclase-andesine) ; muscovite (white mica) ; biotite (black mica). Accessory zircon and apatite. Secondary white mica and calcite, but 

not enough to effervesce with muriatic-acid test.

Owing to its foliaceous texture the stone looks very different on its 

rift, grain, and hardway sides, and the muscovite gives its rift face a

brilliant sheen. .

.The quarry measures about 100 by 50 feet and is 25 to 30 feet deep. 

The stripping consists of 3 feet of sand and bowlders.

Eock structure: The gneiss foliation strikes N. 30° E. and is vertical. The sheets, from 6 inches to 3 feet thick, dip 25° NE., and 

are in places horizontal. There are three sets of joints: Set A, striking N. 50° W., dips 40° to 50° NE. and is spaced 3 to 40 feet; set 

B, striking N. 55° W., dips 60° SW., forms a heading at the northnortheast wall, one 50 feet south of it, and a third at the south-southwest wall; set C, striking about north, dips steep east and forms a 

heading on west side. The rift seems to correspond to the foliation 

(N. 30° E., vertical) and the grain to be horizontal and the hardway vertical, N. 50° W. Pegmatite occurs parallel to the foliation.

The plant comprises a derrick, small hoisting engine, and steam 

pump.

Transportation is by cartage to Bridgeport.

The product is used for cellars, walls, and sills, for which its even 

foliation well adapts it. Specimen: The trimmings of the Bridgeport railroad station.

JAIL QTJAKRY.

The Jail quarry is in the city of Bridgeport, on Madison Avenue, 

on the county jail property, about 1£ miles northwest of the railroad 

station. (See map, PI. I.) Operator, Bridgeport Stone Co., Bridgeport, Connt

The granite (specimen D, XXX, 41, a) is a biotite granite gneiss 

of dark bluish-gray color and fine gneissose, in places banded texture, 

Avith particles under 0.1 inch. In a thin section they measure up to 

0.72 millimeter, but mostly under 0.56 millimeter. It is less micaceous and less foliaceous than the Burlison quarry stone. Its constituents, in descending order of abundance, are bluish potash feldspar
54 GRANITES OF CONNECTICUT.

(microcline and orthoclase) ; clear, colorless quartz with cavities in 

sheets; bluish translucent to milk-white soda-lime feldspar (oligoclase), somewhat kaolinized and intergrown with quartz, somewhat 

circular in cross section; biotite (black mica) and a little muscovite or 

bleached biotite. Accessory apatite. Secondary kaolin. No effervescence with muriatic-acid test.

The quarry is on the southwest side of a northwest-southeast ledge 

400 feet ih' length and 15 to 20 feet high, which is the working face.

Rock structure: The gneiss foliation strikes N. 40° E. and dips 

45° NW. The mass is broken up by many intersecting headings into 

fragments from 4 to 12 inches and exceptionally 3 feet square.

The plant comprises a steam drill and a stone crusher.

The product consists of crushed stone for cement cellar work, 

also for artificial building stone and curbing, which are made on 

the premises. Where the headings admit the gneiss is split up for 

wall stone. The quarry is practically worked by the county, as the 

prisoners in the jail are the workmen, but the product reaches the 

market through the Bridgeport Stone Co.

DANBTTRY.

COLLINS QUARRY.

The Collins quarry is in Danbury township, at the north foot of 

Town Hill, 1£ miles south-southeast of Danbury railroad station. 

(See map, PL I.) Operator Daniel W. McNamara, 100 South Street, 

Danbury.

The granite (specimens D, XXX, 56, «, 5) is a biotite granite 

gneiss of medium inclining to dark bluish-gray color and very fine 

gneissose texture, with fine whitish and dark gray and black bands. 

The thin section shows particles up to 0.84 and 1.12 millimeters or 

about 0.04 inch. Its constituents, in descending order of abundance, 

are clear bluish potash feldspar (microcline) ; light, smoky quartz 

showing effects of strain; translucent whitish soda-lime feldspar 

(oligoclase) ; and biotite (black mica). Accessory pyrite and zircon. 

Secondary calcite. Some of the feldspars have crush borders. The 

rock effervesces with cold dilute muriatic acid.

The quarry measures about 150 by 75 feet with a working face on 

the south 15 to 40 feet high.

Rock structure: The gneiss foliation strikes N. 25° to 35° W. and 

dips 80° NNE. to 90°. There is no proper sheet structure, but there 

are discontinuous fracturesrfrom 6 inches to 3 feet apart, clipping 10° 

W. Pegmatite dikes up to a foot thick run parallel to the foliation. 

This coarse pegmatite consists largely of light-gray to cream-colored 

potash and soda-lime feldspar (oligoclase), more or less kaolinized 

and micasized. The oligoclase is obscurely intergrown, probably
PAIRFIELD COUNTY. 55

with albite. The feldspars are crossed and bordered by veinlets of 

crashed feldspar. Then comes quartz, which is clear, colorless, 

granulated, and contains hairlike crystals of rutile and cavities in 

parallel sheets; lastly very little biotite and still less bleached biotite.

The plant comprises a derrick, small hoisting engine, and a small 

stone crusher with meshes of 2, 1£, and one-half inches.

Transportation is by cartage.

The product consists of crushed stone for streets and roads. The 

pegmatite is mixed with the gneiss. The operator claims that an 

18-years' test of this crushed gneiss, and pegmatite shows fair results, 

even when compared with a like test of crushed trap on the same 

road.

TREA])W E LL fKOS1 'EC'1'.

The Treadwell prospect is in Danbury township, If miles northnorthwest of the Danbury railroad station, on a ridge east of .the 

Fadanaram road, on the farm of 

Stephen B. Treadwell. (See 

map, PL I, p. 8.)

The granite is an unevenly 

banded, fine-grained, dark to 

medium pinkish gray biotite 

gneiss. It consists of pinkish 

and milk-white feldspar, smoky 

quartz, and black mica.

Stone has been quarried for 

underpinning, off and on for 10 

to 15 years, from small openings 

250 and 500 feet east of the 

house.

Eock structure: The gneiss 

foliation strikes N. 45°-55° W. 

and dips 50° NE. to 90°. It is *

injected with pegmatite. The ledges are probably extensive, but are 

concealed by a thin cover of gravel and clay.

GREENWICH. 

VOORHIS QUARRY.

The Voorhis quarry is in Greenwich Township at the head of 

Byram Harbor, a mile southwest of the Greenwich railroad station. 

(See maps, PL I and fig. 1.) Operator, Jacob Voorhis, Greenwich, 

Conn.

The Greenwich blue-black granite (specimen D, XXX 43, a) is a 

mica diorite gneiss of extremely dark bluish-gray color '(darker than 

"-.Quincy extra dark ") and of coarse porphyritic gneissose texture,

2 Miles

Contour interval 40 feet

FIGURE 1. Map of part of Greenwich, Conn., 

showing locations of granite (diorite 

gneiss) quarries. 42' Hitch ; 43, Voorhis ; 

47, Christtano, Oak Ridge; 48, Christiano, 

Hamilton Avenue.
56 GBANITES OF CONNECTICUT.

with feldspars, mostly twins, forming lenses up to 2 by 0.4 inches, 

but mostly not over 1 by 0.3 inch, and down to 0.3 by 0.1 inch. The 

long axes of these lenses are parallel to the rock foliation and the 

plane between the twin crystals is nearly so. The constituents 

of the rock, named in descending order of abundance, are medium 

bluish translucent gray soda-lime feldspar (andesine, -with possibly 

oligoclase-andesine), some in large twins, a little micasized and koalinized; biotite (black mica) ; clear, colorless potash feldspar (microcline) ; clear, colorless quartz; and green hornblende. Accessory 

minerals: Pyrite, titanite, apatite, allanite,- and zircon; the three first 

in some abundance. Secondary minerals: Epidote, kaolin, a white 

mica, calcite. The rock effervesces slightly with cold dilute muriatic 

acid.

Two tests of the ultimate transverse strength of this granite made 

at the United States Arsenal at Watertown in November, 1896, on 

pieces 15 inches long between supports, yielded these results:

Results of transverse tests of Greenwich blue-blade granite and Quincy granite.

Greenwich. .......................................

Do............................................

Test No.

9762

9763

9765

Breadth.

Inches. 

1.01

1.02

1.01

Depth.

Inches. 

1.02

1.02

1.02

Breaking 

weight.

Pounds. 

152

177

177

Modulus of 

rupture.

Pounds. 

o3,257

o3,757

2,164

,° Average modulus of rupture of Greenwich granite, 3,507 pounds.

The rock is exceedingly tough under the hammer. It is dark yet 

brilliant, and the contrasts between its black mica and bluish-gray 

feldspars are very marked and pleasing. Its apparent texture and 

shade differ on its three sides. The side parallel to the foliation,

show-ing hardly any feldspar, is black; the side at right angles to 

the foliation and parallel to the long axes of the lenses shows the 

feldspar most conspicuously; and the side transverse to those axes 

shows the light and dark minerals more evenly mixed. Were the 

stone to be set on the edge of its foliation the structure would be 

almost black. Its appearance would differ somewhat according as 

the grain face or the hardway face were alone exposed, and if the 

stones were laid promiscuously, without.regard to texture, the effect 

would be still different.

The quarry, opened before 1833, measures about 500 feet from 

north to south by 200 feet from east to west, and 50 feet in depth.

Eock structure: The gneiss foliation strikes N. 15°-20° E. and is 

vertical. . The sheets, from 1 to 35 feet thick, strike N. 80° W., dip 

20° S. and are mostly separated by small aplite dikes. One set of 

joints only; strike N. 65° W., dip vertical or very steep and slickensided. The rift is reported as parallel to the foliation, the grain as
FAIBFIELD COUNTY. ' 57

vertical with N. 80° W. course and the hardway horizontal. Small 

dikes of aplite (described under heading " Hitch quarry") run 

parallel to the foliation and also undulate horizontally.

The plant consists of three horse derricks.

Transportation is by cartage of 500 feet to a wharf, which admits 

schooners of 6$ feet draft at high tide.

The product is used for buildings and massive structures and the 

waste for riprap. Specimens: Fort Schuyler, on Throgs Neck, 

Long Island Sound; physicians' quarters at south end of Blackwells 

Island, East Eiver; Episcopal Church, Port Washington, Long 

Island; residence of C. J. Osborn, Mamaroneck, N. Y.; wall about 

Trinity Cemetery, One hundred and fifty-third Street and Broadway, New York City.

BITCH QUARRY.

The Kitch quarry is in Greenwich Township on the west side of

Byram Harbor, Ijj? miles southwest of Greenwich railroad station. 

(See map, fig. 1, p. 55.) Operators, W. and S. Kitch, Port Chester, 

N. Y.

The granite (specimens D, XXX, 42, a, 6), Greenwich blueblack granite, is a mica diorite gneiss of extremely dark bluish-gray 

color and coarse porphyritic gneissose texture identical with that 

of the Voorhis quarry, fully described on page 55.

The quarry is about 200 feet square, with working faces 15-40 

feet high on the north, south, and west.

Bock structure: The gneiss foliation strikes N. 20° E. and dips 

90°. The sheets, from 2 to 3 feet thick and generally separated 

by thin aplite dikes, dip 25° W. There are two sets of joints: 

A, striking N. 80° W., vertical, forms the north and south walls, 

and two headings near the center, and is spaced 2 to 10 feet; B, 

striking N. 15°-20° W., vertical, is spaced 10 feet or more. The 

rift is reported as parallel to the foliation, the grain vertical 

with N. 80° W. course, and the hardway horizontal. Pegmatite 

dikes, mostly of feldspar, the largest 16 inches thick, meander vertically along the foliation. Dikes of aplite from one-fourth inch 

to 2 inches thick (specimen D, XXX, 42, c), are of medium bluishgray color and very fine texture with particles under 0.1 inch. A 

thin section shows them under 0.76 millimeter and mostly under 

0.5T millimeter. The constituents of the rock, named in apparent 

descending order of abundance, are quartz with cavities in sheets; 

potash feldspar (microcline and orthoclase); soda-lime feldspar 

(andesine and probably oligoclase-andesine), a little of it micasized; 

and very sparse minute biotite. Accessory minerals: Pyrite, apatite, titanite, zircon. Secondary minerals: A white mica, calcite. 

This aplite thus differs from the gneiss only in its poverty of mica 

and richness of quartz. Rusty stain affects sheet and joint faces 

to an inch in thickness.
58 GKANITES OP CONNECTICUT.

The plant consists of a horse and a hand derrick.

Transportation requires cartage of 500 feet to wharf, which admits schooners of 7 feet draft at high tide.

The product is used for buildings and street work and the waste 

for riprap. Specimens: Catholic churches in Flushing, Long Island, 

Mamaroneck, N. Y., and Stamford, Conn.; Catholic cathedral and 

bishop house at intersection of Vanderbilt, Lafayette, Clermont and 

Green avenues, Brooklyn.

CHRISTIANO OAK RIDGE QUABRY.

The Christiano Oak Ridge quarry is in Greenwich Township at 

the north end of the ridge between Bush and Byram Harbors, about 

three-fifths mile west-southwest of the Greenwich railroad station. 

(See fig. 1.) Operator, Joseph Christiano, Greenwich, Conn.

The granite (specimen D, XXX, 47, a), Greenwich blue-black 

granite, is an extremely dark bluish gray mica diorite gneiss, identical with that of the Voorhis quarry, described on page 55, excepting that it has a little augite besides the hornblende.

The quarry, opened in 1901, measures about 175 by 150 feet and is 

from 10 to 20 feet deep.

Rock structure: The gneiss foliation strikes N. 15°-20° E. and 

dips 90°. The sheets, from 2 to 10 feet thick, are horizontal or 

dip very low east. There are four sets of joints: Set A, striking N. 

75° W., vertical, is spaced 1-10 feet; set B, striking N. 20° E., 

vertical or steep west, spaced 3-10 feet, coinciding with the small 

aplite dikes; set C, striking N. 30° W., vertical (exceptional), 

spaced as low as 5 feet; set D (one only), striking N. 85° W., dipping 55° about north. Pegmatite dikes, in bead-like lenses up to 

8 inches thick, are either parallel to the foliation or branch from it.

The numerous aplitic dikes, from 0.25 to 3 inches thick, strike with 

the foliation, but have plications from 1 to 6 feet across. This aplite 

(specimen D, XXX, 47, 6) is of very light gray shade and very 

fine texture, with feldspars under 0.1 inch. Its constituents, in descending order of abundance, are quartz, andesine, and probably 

oligoclase-andesine, some of it micasized; microcline, with orthoclase, 

possibly as abundant as the other feldspar; sparse biotite, with secondary white mica and calcite. ^

The plant consists of a portable boiler, a steam drill, hand derrick, and portable stone crusher, with screens of 2, 1, and one-half 

inches.

Transportation is by cartage.

The product is used for buildings and the waste is crushed for 

roads. Specimen buildings: Catholic Church, Bruce Memorial gate 

(Bruce Park, Greenwich Avenue and Steamboat Road), and residence of Charles Hirshhorn, North Street, Greenwich. .
F AIRFIELD COUNTY. ' 59 

 ' ' CHRISTIANO HAMILTON AVENUE QUARRY.

The Christiano Hamilton Avenue quarry is in Greenwich Township, half a mile northwest of the Greenwich railroad station. (See 

fig. 1, p. 55.) Operator, Joseph Christiano, Greenwich, Conn.

The granite (specimen D, XXX, 48, «), Greenwich blue-black 

granite, is a mica diorite gneiss of extremely dark bluish gray color 

and identical with that of the Voorhis quarry, described on page 55.

The quarry, opened in 1873, measures about 60 by 30 feet and is 

from 10 to 20 feet deep.

Rock structure: The gneiss foliation strikes N. 15° E. and is 

about vertical. Sheets are hardly developed. There are two sets of 

joints: Set A, striking N. 45° W., vertical, is spaced 8 to 15 feet; 

set B, loose, striking N. 15° E., vertical, is spaced 10 feet. The 

rift is reported as parallel to the foliation, the grain at right angles

to it and vertical, and the hard way horizontal.

Transportation is by cartage.

 The product is used for buildings. Specimens: Residences of 

George E. Weed, Rockside Park, and of James McCutcheon, Belle 

Haven Park, Greenwich.

NORWALK. 

HALL QUARRY.

The Hall quarry, (formerly known as the Bates quarry) is in 

Norwalk Township, about 1£ miles northeast of the Norwalk railroad station. Operator, Irving Hall, 106 Main Street, Norwalk, 

Conn.

The granite (specimen D, XXX, 44, a) is a muscovite-biotite 

granite gneiss of light warm gray shade and of gneissose medium 

inclining to fine texture, with feldspars and mica to 0.25 inch. It 

is brightly spangled with mica on its foliation face. Its constituents, 

named in descending order of abundance, are light cream colored 

potash feldspar (microcline), but little kaolinized; pale, smoky 

quartz, with cavities in sheets; milk-white soda-lime feldspar (oligoclase albite) much kaolinized, micasized, and with calcite; muscovite, 

(white mica); and biotite (black mica). Accessory minerals: Garnet, apatite. Secondary minerals: Kaolin, a white mica, calcite, 

some in veinlets. The rock effervesces freely in places with cold 

dilute muriatic acid.

The quarry is about 50 feet square and from 20 to 30 feet deep. 

. Rock structure: The gneiss foliation dips 5° to 20° NW. The 

sheets, 1 to 4 feet thick, parallel to the foliation, are but imperfectly 

developed. There are two sets of joints: Set A, striking N 40° E., 

vertical, forms the north wall; set B, striking northwest, vertical, 

forms the east and west walls and an 8-foot-wide heading near
60 GRANITES OF CONNECTICUT.

the north wall and is spaced 2 to 8 feet. Some of the joints of this 

heading have been parted 0.25 to 2 inches and filled with quartz. 

Both sets of joints are slickensided. The rift is along the foliation.

Transportation is by cartage.

The product is used for walls, underpinning, steps, etc. The 

quarry is worked only occasionally.

HARTFORD COUNTY. 

GENERAL CONDITIONS.

There are two quarries in Bristol which, when fully opened, may 

yield serviceable structural granite.

The rock is a garnetiferous quartz monzonite gneiss of finebanded texture.

3 Miles

Contour interval 40 feet

FIGURE 2. Map of Glastonbury granite gneiss quarries. 32, Corbin; 33, German; 34, 

Danielson; 35, Belden quarry ; 36, Curtis ; 37, Brooks: 38, Slater; 39, Carllne.

The other quarries are in the township of Glastonbury. As will 

be seen on the map (fig. 2), these are scattered along a S. 48° W. 

to N. 48° E. ridge, the north part of which is now known as.Minnechaug Mountain, called also locally Birch Mountain, and the 

south part of which goes by the name of Eightmile Hill. The gneiss 

foliation at the quarries strikes N. 45°-80° E., averaging about N. 

60° E., and thus differs but little from the trend of the ridge. The 

strike at Curtis quarry, however, is about north.
HAKTFORD COUNTY. 61

The Peterson quarry in Bolton, in Tolland county (p. 116), is on 

the northeast continuation of the same ridge. The strike there is 

N. 10° E.

.The rock at these quarries is a more or less obscurely porphyritic 

biotite granite gneiss, with feeble mineral contrasts <and a marked 

foliation, but its texture and shade vary slightly at different quarries. It is designated on the State preliminary geologic map as 

the " Glastonbury granite gneiss," No. 15. The Glastonbury quarries have long supplied curbing and crosswalks to the city of Hartford, for which the foliation of the stone admirably adapts it.

BRISTOL.

])tJNN QUARRY.

The Dunn quarry is on Divinity Street, in Bristol, about a mile 

west-southwest of the center of the borough. (See PL. I.) Operator, Edward Dunn, Northside Hotel, Bristol, Conn.

The granite (specimen D, XXX, 62, #, "Bristol granite gneiss," 

No. 10, of the State preliminary geologic map) is a garnetiferous 

quartz monzoriite gneiss of light inclining to medium bluish gray 

color, and of gneissose banded fine texture with feldspars up to 0.2 

inch, mica to 0.1 inch, and garnets to 0.08 inch. It lias wavy 

bands and lenses of light and dark and reddish color, the light 

bands up to 0.5 inch width, the dark to 0.3. inch, and the reddish 

to 0.1 inch. Its constituents, in descending order of abundance, are 

clear to whitish soda-lime feldspar (albite), some of it slightly 

kaolinized; clear bluish quartz, with cavities in sheets; a little potash 

feldspar (orthoclase) ; biotite (black mica), some of it chloritized. 

Accessory minerals: Garnets (fourth or fifth in order of abundance), 

magnetite, apatite. Secondary minerals: Kaolin, chlorite, limonite.

This is a hard, serviceable, and attractive stone.

The quarry consists of two openings, one measuring about 100 by 

50 feet, and 5 to 10 feet deep, the other 50 feet square, from which, 

however, only the soil and weathered rock have been removed.

The gneiss foliation strikes east-west and dips steeply south. The 

sheets, 3 to 8 feet thick, are irregular. There are three sets of joints 

A, striking about north-south, with headings 12 feet wide; B, striking 

about east-west; C, diagonal. The spacing of joints in the smaller 

opening admits the quarrying of blocks 10 feet square by 3 to 5 feet, 

which is the thickness of the sheets there. The rift in both openings 

is across the foliation. ' *

The plant consists of a derrick, small hoisting engine,' and large 

steam drill.

Transportation is by cart, a mile to railroad.
62 GKANITES OF CONNECTICUT.

The product is used for foundations and buildings. " Brightwood," Mrs. W. A. McKay's castle mansion on West Street, in Bristol, 

was built of. this granite, but some of it came from another now disused quarry, and some from the site of the mansion itself.

SEYMOUB STREET QUARRY.

The Seymour Street quarry, in Bristol, is operated occasionally 

by the Pierson Engineering & Construction Co., Bristol, Conn.

The granite is like that of the Dunn quarry; the opening is small 

and irregular, and the plant consists of a hand derrick.

GLASTONBURY. 

COKB1N QUARRY.

The Corbin quarry is in Glastonbury, at the top of Birch Mountain, 5 miles east-northeast of Glastonbury village. (Seefig. 2, p. 60.) 

Operator, John Arthur Corbin, North Manchester, Conn.

The granite (specimen D, XXX, 32, a) is a biotite granite gneiss 

of medium gray shade and of fine gneissose texture, with porphyritic 

feldspars up to 0.3 inch and matrix with particles under 0.05 inch. 

In places it has minute brownish stains. Its constituents, in descending order of abundance, are cream-colored to milk-white potash 

feldspar (microcline and orthoclase), somewhat kaolinized; clear, 

colorless quartz; clear to translucent, colorless soda-lime feldspar 

(oligoclase); and biotite (black mica), some of it chloritized with a 

little muscovite or bleached biotite. Both feldspars are intergrown 

with quartz more or less circular in cross section. Accessory minerals : Epidote,1 apatite, allanite, titanite. Secondary minerals: Kaolin, limonite proceeding from allanite and producing the brown spots 

referred to, chlorite. No effervescence with muriatic-acid test.

The quarry is a small, irregular opening up to 10 feet deep, begun 

in 1905.

Eock structure: Gneiss foliation and rift dip about 10° north 50° 

west. The sheets, up to 3 feet thick, are horizontal or dip low N. 

50° W. Pegmatite dikes measure up to 4 inches in thickness.

The plant consists of .one hand derrick.

Transportation is by cartage of 12 miles to Hartford.

The product is used entirely for curbing and circulars.

CABLING QUARRY.

The Carline quarry is in Glastonbury Township, in the village of 

Buckingham, 4^ miles east of Glastonbury village. (See fig. 2.)

1 Rice and Gregory regarded the epidote as probably of primary origin. See their 

Manual of the Geology of Connecticut, 1906. Bull. Conn. State Geol. and Nat. Hist. 

Survey No. 6, p. 118. Some of it forms rims about allauite.
HAKTFORD COUNTY. 63

Operator, Harry Carline (Enrico Carlini, anglicized), E. F. D., 

Glastonbury, Conn.

The granite (specimen D, XXX, 39, a) is -a biotite granite gneiss 

of medium inclining to dark gray shade (thus darker than the 

Corbin quarry stone) and of fine gneissose texture, with porphyritic 

feldspars, the largest 0.3 inch, and matrix with particles under 0.1 

inch. Its constituents, named in descending order of abundance, are 

cream-colored potash feldspar (microcline somewhat kaolinized and 

orthoclase) ; medium smoky quartz; whitish soda-lime feldspar 

(oligoclase to oligoclase-andesine) slightly micasized, some of it 

intergrown Avith quartz more or less circular in cross section; biotite 

(black mica), some of it chloritized, and a little muscovite or bleached 

biotite. Accessory minerals: Epidote, titanite, allanite, apatite, zircon. Secondary minerals: Kaolin, chlorite, a white mica, limonite

stain, hematite. No effervescence with muriatic-acid test.

The quarry, opened in 1908, is about 40 feet square by 20 feet deep> 

and the surface consists of 5 feet of sand and bowlders.

Kock structure': Gneiss foliation and rift strike N. 80° E. and dip 

25° N. The sheets, 10 feet thick, dip with the foliation. The grain 

and hardway are equal. No joints. A minute vein of quartz and 

biotite runs diagonal to the foliation.

The plant consists of a hand derrick.

Transportation is by cartage of 10 miles to Hartford.

The product is used for curbing, crosswalks, and steps.

QOBMAN QUARRY.

The German quarry is in Glastonbury, at the foot of Birch 

Mountain, a little south of the Manchester line, about 5f miles eastnortheast of Glastonbury village. (See fig. 2, location approximate.) 

Operator, Patrick German, 166 Main Street, South Manchester, 

Conn.

The granite (specimen D, XXX, 33, a) is a biotite granite gneiss 

of medium very slightly bluish gray shade, and of fine gneissose 

texture, with porphyritic feldspars to 0.3 inch in a matrix with 

particles under 0.1 inch, in a thin section mostly from 0.11 to 0.39 

millimeter. Its constituents, in descending order of abundance, are 

milk-white potash feldspar (microcline, kaolinized, and orthoclase) ; 

pale smoky quartz showing effects of strain and with some cavities; 

translucent whitish soda-lime feldspar (oligoclase) ; biotite (black 

mica) and a little muscovite or bleached biotite. Accessory minerals: 

Epidote, magnetite, apatite, garnet, allanite. Secondary minerals: 

Kaolin and limonite stain. Both feldspars are intergrown. with 

quartz circular in cross section. No effervescence with muriaticacid test.

97730° Bull. 4S4 11 5 '
64 GBANITES OF CONNECTICUT.

This stone-is less weathered than that of the last two quarries and 

is therefore harder. It has been used for buildings as well as 

steps, etc.

The quarry, not in operation in 1908, was not visited.

DANIELSON QUARRY.

The Danielson quarry is in Glastonbury Township, on the south 

side of the top of Eightmile Hill, 3-| miles southeast of Glastonbury 

village. (See fig. 2.) Operator, A. Danielson & Co., 98 Babcock 

Street, Hartford, Conn.

The granite (specimen D, XXX, 34, a) is a biotite granite gneiss 

of dark inclining to medium brownish-gray color and of fine marked 

gneissose texture with porphyritic. feldspars to 0.3 inch in a matrix 

with particles under 0.1 inch, in thin section mostly between 0.11 and 

0.84 millimeter. Its constituents, in descending order of abundance, 

are pale buff to pinkish potash feldspar (microcline and orthoclase) 

somewhat kaolinized; medium smoky quartz showing effects of 

strain and with some cavities in- sheets; grayish translucent sodalime feldspar (oligoclase) slightly kaolinized; and biotite (black 

mica). Accessory minerals: Epidote (fifth in order of abundance), 

apatite, magnetite, allanite. Secondary minerals: Kaolin, limonite, 

and hematite (stain). No effervescence with muriatic-acid test.

The quarry, opened in 1908, measures about 60 by 35 feet, and is 

3 to 10 feet deep!

Rock structure: Gneiss foliation and rift strike N. 55° E. and 

dip 25° N. The sheets, 1 to 2 feet thick, are also parallel to these. 

There is one joint on north side striking N. TO 0 E. and dipping 55° 

S. 20° E. Some veinlets of quartz and biotite (up to 0.1 inch thick)

crossing the foliation do not weaken the stone. Vertical pegmatite

dikes, 3 to 6 inches thick, strike N. 80° W. Some of smoky quartz 

up to 4 inches thick.

The plant comprises a hand derrick.

Transportation is by cartage of 10 miles to Hartford.

The product is used for curbing and steps.

BELDEN QUARRY.

The Belden quarry is in Glastonbury -Township, on Eightmile 

Hill, three-tenths mile south of the Hartford turnpike and 3 miles 

southeast of Glastonbury village. (See fig. 2.) Operator, H. T. 

Lingner, East Glastonbury, Conn.

The granite (specimen D, XXX, 35, a) is a biotite granite gneiss 

of medium buff-gray color (a trifle lighter than Concord granite) 

and of fine gneissose texture, with feldspars to 0.2 inch and mica, 

in aggregates, up to 0.5 inch, conspicuous along the foliation. Por-
HAKTFORD COUNTY. 65

phyritic texture not apparent. Its constituents, in descending order 

of abundance, are cream-colored potash feldspar (microcline and orthoclase) somewhat kaolinized; pale smoky quartz, some of it in 

long laminae 0.28 millimeter wide; whitish soda-lime feldspar 

(oligoclase) somewhat kaolinized; 'biotite (black mica) and a little 

muscovite or bleached biotite. Accessory minerals: Garnet (fifth in 

order of abundance), epidote, magnetite, allanite. Secondary minerals : Kaolin, limonite stain, calcite. No effervescence with muriaticacid test.

The quarry consists of several openings, some of Avhich were made 

in 1863. The one now worked, made in 1905, measures 50 by 40 feet, 

and is 20 feet deep. The stripping consists of 3 to 9 feet of clay, 

angular blocks, and pebbles.

Eock structures: Gneiss foliation and rift strike northeast and dip 

10° to 20° NW; The sheets, 6 inches to 5 feet thick, are parallel to

these. There are two sets of joints: Set A, striking N. 20° E., vertical, forms the north wall; set B, striking N. 65° W., vertical, 

forms the east and west walls and recurs in center, discontinuous. 

The grain is reported as vertical with north-south course. Pegmatite 

dikes are up to 6 inches thick. Some smoky quartz veins or lenses.

The plant comprises a horse derrick.

Transportation is by cartage of 10 miles to Hartford.

The product is chiefly used for curbing and crosswalks, and smaller 

blocks for paving. -Blocks H to 2 inches thick are prepared for lining 

tubes at feldspar crushing works instead of the oak timber formerly 

used for that purpose.

CURTIS QUARRY.

The Curtis quarry is in Glastonbury Township, on Eightmile Hill, 

one-fourth mile southwest of the Hartford Turnpike and 2f miles 

southeast of Glastonbury village. (See fig. 2, p. 60.) Operator, 

Frank Curtis, E. F. D., Glastonbury, Conn.

The granite is a biotite granite gneiss identical with that of the 

Belden quarry, described on page 64.

The quarry, opened before 1901, measures about 200 feet from 

north to south by 40 feet across and has a working face 20 to 40 

feet high on the west.

Eock structure: Gneiss foliation and rift dip 10°-15° W., as do the 

sheets, which are 1 to 8 feet thick. There are two sets of joints: 

Set A (one only), striking N. 20° E., dipping 40° S. 70° E.; set B, 

striking north, dipping 50° W., is spaced 10 to 20 feet or more. 

Pegmatite dikes, 2 to 8 inches thick, striking N. 60° E., dipping 35° 

S. 30° E., recur at intervals of 10, 15, and 40 feet. A 4-inch one 

strikes nearly east-west. Quartz veins 0.25 to 1 inch thick have 

irregular courses.
66 GRANITES OF CONNECTICUT.

The plant consists of two hand derricks. 

Transportation is by cartage of 9^ miles to Hartford. 

The product is used for curbing and like stonework. The quarry 

was worked in 1907 but not in 1908.

BROOKS QUARRY.

The Brooks quarry is in Glastonbury Township, on the northeast 

side of Eightmile Hill, 3£ miles east-southeast of Glastonbury village. (See fig. 2.) Operator, Henry R. Brooks, R. F. D., Glastonbury, Conn.

The granite is a biotite granite gneiss of medium gray shade and 

fine gneissose porphyritic texture, identical in composition with that 

of the Corbin quarry, described on page 62, and with the same minute 

brown spots, due to allanite.

The quarry, opened in 1889, measures about 400 feet from east to 

west by 150 feet across at one end and 50 at the other, and is from 

5 to 60 feet deep.

Rock structure: The gneiss foliation and rift strike N. -70° E. and 

dip 25° N. 20° W. The sheets, from 1 to 6 feet thick, are parallel 

to these. There are two sets of joints: Set A, striking N. 75° E., 

dipping steep S. 15° E., is spaced 10 to 20 feet; set B, striking N. 35° 

W., vertical, is spaced 20 feet. The grain is vertical, north to south, 

but the stone breaks with equal facility along the hardway. Four 

vertical pegmatite dikes, the largest 10 inches thick, strike N. 77° 

W., and are 10 feet or more apart. This pegmatite (specimen D, 

XXX, 37, 6) consists of cream-colored feldspar and smoky quartz, 

with sparse minute garnets and rare scales of biotite and muscovite.

The plant consists of five hand derricks.

Transportation is by cartage of 10 miles to Hartford or of 5J 

miles to rail at South Manchester, or of 5 miles to wharf at Naubuc 

(Glastonbury landing), on the Connecticut.

The product is used for curbing and building.

Specimens: Curbing and steps, Cheney Park, South Manchester, 

and trimmings on Methodist Church at Windsor, Conn.

SLATER QUARRY.

The Slater quarry is in Glastonbury township, one-fourth mile 

west-southwest of the Brooks quarry and about 3f miles southeast of 

Glastonbury village. (See fig. 2.) Operator, Nelson Slater, R. F. D., 

Glastonbury, Conn.

The granite is a biotite granite gneiss, identical with that of the 

Corbin quarry described on page 62.

The quarry, opened in 1905, is 20 feet square and 15 feet deep. 

The stripping consists of 3 feet of sand and bowlders.
LJTCHFIELD COUNTY. 67

Rock structure: Gneiss foliation and rift strike N. 55° E. and dip 

30° N. 35° W. The sheets, from 2 to 4 feet thick, are parallel to 

these. There are two sets of joints: Set A, striking northeast, dipping 40° SE., is spaced 15 feet; set B, striking northwest, vertical, 

one only. The grain is vertical north to south, but the1 rock breaks 

equally well along the hardway. Four-inch pegmatite dikes strike 

N. TO 0 W., and dip steep S. 20° W. A 12-inch vertical dike strikes 

N. 10° E., carries-muscovite in plates (the largest 5 inches square and 

4 inches thick) about 6 inches apart, the rest of the dike being mostly 

feldspar. There are 2 to 3 inches of rusty stain on the upper sheets.

Transportation is by cartage of 9£ miles to Hartford. The product 

is used for curbing, crosswalks, and steps.

LITCHFIELD COUNTY.

CORNWALL. 

BENEDICT QUARRY.

The Benedict quarry is in Cornwall Township, on the north side 

of White Rock, three-fourths mile east of Cornwall village. (See 

PL I, p. 8*.) Owner, Trusten H. Benedict, Cornwall, Conn. (Recent 

operator, Felix Jordan, Newark, N. J.)

The granite (specimens D, XXX, 60, a, &, c) is a biotite-muscovite 

granite gneiss of medium bluish gray color and of medium inclining 

to fine gneissose texture, with feldspars to 0.3 inch and mica to 0.1 

inch; also with rare porphyritic clear feldspars, the largest 0.4 inch. 

Its constituents, in descending order of abundance, are clear bluish 

potash feldspar (microcline and orthoclase) intergrown with quartz 

that is circular in cross section; clear, colorless quartz; translucent 

to milk-white soda-lime feldspar (oligoclase) somewhat kaolinized 

and with calcite; biotite (black mica); muscovite (white mica). 

Accessory minerals: Ilmenite (probably) surrounded by titanite, 

apatite, allanite, zircon. Secondary minerals: Calcite, epidote, kaolin, and a white mica. There is a little minute vermicular intergrowth of quartz and feldspar and some granulation of the feldspars. Slight effervescence with cold dilute muriatic acid.

This is a bright bluish foliaceous stone, without marked mineral 

contrasts.

The quarry is 75 feet square by 10 to 15 feet deep.

Rock structure: Gneiss foliation and rift strike N. 50° E., and are 

vertical. The sheets, 2 to 4 feet thick, dip low northwest. There 

are two sets of joints: Set A, striking N. 60°-75° W., vertical^ forms 

a heading on the south wall and is spaced 20 to 25 feet; set B, striking N. 10° E., vertical, is spaced 15 feet. The grain is vertical with 

northAvest course. Pegmatite dikes to 2 inches thick strike N. 15°
68 GRANITES OF CONNECTICUT.

E., and dip 90° to steep W. Between the quarry and the cemetery 

on the north side of the road a similar gneiss is in contact with (or 

contains an inclusion of) a fine-grained biotite gneiss with particles 

to 1 millimeter, consisting of quartz, biotite, microcline, oligoclaseandesine with accessory apatite, titanite, zircon, and striking N. 10°- 

20° E.

The plant consists of a hand derrick.

Transportation is by cartage of 4% miles to rail at Cornwall Bridge.

The product is used for trimmings, for which its foliation and 

color well adapt it.

LITCHFIELD. 

MASCETTI QUARRY.

The Mascetti quarry, 2-| miles south of Torrington, is in the township of Litchfield, three-fourths mile northwest of East Litchfield 

village, and on the west side and south end of a knoll rising 480 

feet above the village. (See PL I.) Operator, Joseph Mascetti, 

229 Oak Avenue, Torrington, Conn.

The granite (section D, XXX, 53, a) is a muscovite-biotite granite 

gneiss of medium inclining to light bluish gray color and of fine 

gneissose texture, with feldspars under 0.2 inch and mica mostly 

under 0.1 inch. Its constituents, named in descending order of 

abundance, are clear bluish potash feldspar (microcline) ; light 

smoky quartz with cavities; milk-white soda-lime feldspar (oligoclase) somewhat kaolinized and intergrown with quartz, circular in 

cross section; muscovite (white mica); biotite (black mica) in 

smaller flakes, some of it chloritized. Accessory minerals: Garnet 

(sixth in order of abundance), tourmaline, apatite, zircon. Secondary minerals: Kaolin, calcite, chlorite. The rock effervesces 

slightly with cold dilute muriatic acid.

This rock is brilliant, with muscovite on its foliation face.

The quarry, opened about 1903, is about 200 feet long, with a 50- 

foot high working face on the east.

Rock structure: Gneiss foliation and rift strike N. 20° E. and dip 

20°. The sheets, 2 to 4 feet thick, dip 20° and 50° NW. One set of 

joints only, strike N. 5° E., dip 65° E., spaced 3 to 20 feet, and over. 

Pegmatite dikes, with black tourmaline and bordered with aplite, 

1 to 2 feet thick, meander vertically with a N. 15° E. course. Others 

up to an inch thick are parallel to the foliation.

The plant comprises a steam derrick, two hand derricks, a hoisting 

engine, and steam drill.

Transportation is by cartage of If miles to East Litchfield, or of 

2£ miles to Torrington. 

The product is used for curbing and steps, for which it is well 

adapted.
LITCHFIELD COUNTY 69

NORFOLK. 

CRISSEY QUARRY.

The Crissey quarry is in Norfolk Township, on the southeast side 

of Bald Mountain, 2£ miles north-northwest of the village of Norfolk. (See PL I.) Owner, R. I. Crissey, Norfolk, Conn.

The granite (specimen D, XXX, 61, a, &) is a biotite-muscovite 

granite gneiss of medium very slightly greenish gray shade' and of 

even-grained, fine, obscurely gneissose texture with feldspars under 

0.2 inch and mica under 0.1 inch. Its constituents, in descending 

order of abundance, are clear, colorless potash feldspar (microdine and orthoclase) ; clear, colorless quartz, with some cavities in 

sheets; milk-white soda-lime felspar (oligoclase), mostly kaolinized, micasized, and with calcite; biotite (black mica), some of it 

chloritized; and muscovite (white mica). Accessory minerals: 

Magnetite, apatite, allanite (rimmed with epidote), zircon. Secondary minerals: Kaolin, calcite, a white mica, epidote, limonite stain. 

There is some feldspar granulation and also vermicular intergrowth 

of quartz and feldspar.

The stone effervesces with cold dilute muriatic acid. R. C. Wells, 

a chemist of the United States Geological Survey, finds that it contains 0.36 per cent of CaO (lime), soluble in warm dilute (10 per 

cent) acetic acid, which indicates a content of 0.64 per cent of CaC03 

(lime carbonate, calcite).

This is a bright, fine-grained, gray granite, without mineral contrasts and without shade contrasts between cut and polished faces.

The quarry, opened before 1880, consists' of four excavations, the 

highest and largest of which measures about 150 feet southeastnorthwest, and has a 50-foot high working face on the northeast.

Rock structure: The sheets, from 6 inches to 5 feet thick (some 

reported as 7 feet but now covered), dip 10° NW. and are normal. 

There are two sets of joints: Set A, striking N. 80° E., dipping south 

steep to 90°, forms the northwest and southeast walls; set B, striking 

N. 20° E., vertical, discontinuous, is spaced 5 feet or more. The rift 

is reported as about horizontal, but the rock splits southeast-northwest.

Transportation is by cartage of a mile to Central New England 

Railroad.

The product was used for buildings, monuments, and coping. 

Specimens: Chapel of Congregational Church and the railroad station at Norfolk; the Egbert T. Butler and Anson Gaylord monuments, in Norfolk Center Cemetery. -

This quarry, originally opened for coping for the Hoesac Tunnel, 

in Massachusetts, was closed in 1893, owing to a difficulty with the 

railroad as to freight rates.
70 GEANITES OF CONNECTICUT.

ROXBURY.

ROCKS1DE QUARKY.

The Eockside quarry is in Eoxbury Township, on the east side of 

Mine Hill, four-fifths mile north of Eoxbury Station. (See PL I.) 

Operator: Mine Hill Quarry Co., Eoxbury Station, Conn.

The granite (specimen D, XXX, 57, a) is a muscovite-biotite 

granite gneiss of medium bluish gray color and of fine-grained, even, 

implicated, gneissose texture, with particles under 0.2 inch and conspicuous white mica along its foliation.1 In thin section the particles, 

aside from muscovite, range from 0.11 to about 2 millimeters. Its 

constituents, in descending order of abundance, are bluish translucent 

potash feldspar (mostly microcline with some orthoclase), slightly 

kaolinized; clear, colorless quartz with cavities in sheets, one conspicuous set with cracks parallel to it, another less abundant at right 

angles to the first; muscovite (white mica); whitish soda-lime feldspar (oligoclase; the stone of an upper opening shows oligoclase to 

oligoclase-andesine) somewhat kaolinized and micasized; biotite 

(black mica). Accessory minerals: Apatite rather abundant, zircon. 

Secondary minerals: Kaolin, one or two white micas, calcite. No 

effervescence with muriatic-acid test.

The quarry, opened in 1890, measures about 800 feet northeastsouthwest by 275 feet across, with a working face on the northwest 

side measuring in height 35 to 75 feet. The stripping consists of 

4 to 5 feet of sand. Another quarry, now disused, near the top of 

Mine Hill, owned by the same firm, was begun in a small way in 

1850.

Eock structure: The gneiss foliation dips gently southeast on the 

outer east side of the quarry but 15° S. 20° W. at the working 

face, tending to become horizontal within the hill. The sheets, from 

4 inches to 18 feet thick, correspond to the foliation. The upper 30 

feet of the working face consists of thin sheets. There are two sets 

of joints. Set A, striking northwest and vertical, forms a heading at 

the southwest wall; another, 6 to 8 feet wide, is 200 feet northeast 

of that wall; and another, 3 feet wide, is 300 feet farther northeast. 

The rock left unquarried about these two headings is about 50 feet 

wide. These joints are spaced 2 to 20 feet. Set B, striking northeast, dips 7° NW. One of these is 50 feet below the rock surface, another 25 feet lower. The rift corresponds to the foliation. 

The grain is reported as striking N. 35° E. and dipping 85° 

S. 55° E., and the hardway as vertical, with N. 55° W. course.

1 Prof. W. H. Hobbs regards the muscovite as secondary and formed at the time of the 

foliation. He "also describes the feldspars as crushed and granulated. See Rice and 

Gregory, Bull. Connecticut Geol. and Nat. Hist. Survey No. 6, p. 110.
LITCHFIELD COUNTY. ' 71

There are white aplitic dikes, from 0.12 to 8 inches thick, almost 

parallel to the foliation. These are very quartzose, without biotite 

and Avith rare muscovite. Some of this aplite is very light gray 

to white and of even-grained very fine granitic texture, with feldspar and light smoky quartz under 0.1 inch and the finer particles 

between 0.05 and 0.56 millimeter. It effervesces with cold dilutemuriatic acid. Some of these dikes have oligoclase-albite and microcline in about equal parts. Smoky quartz veins, the largest 0.25 

inch thick, run parallel to them. Others have a gneissose texture 

and show quite a little muscovite, evidently secondary and forming 

"membranes covering the foliation'planes," as described by Prof. 

Hobbs. The main gneiss is also crossed by dikes of rose-colored 

aplite from 0.5 inch to 4 feet thick, dipping, like the joints of set.B, 

7° NW. One of these consists chiefly of oligoclase-andesine with

crush borders, smoky to amethystine quartz and a little micrccline, rare muscovite but no biotite, in places with microscopic garnets. All its particles are under 0.1 inch. One of the smaller dikes 

contains microcline, quartz, a little albite, garnet, muscovite, apatite, 

named in descending order of abundance. Its feldspars are under 

0.05 inch and its quartz particles up to 0.2 inch.

Within the second heading from the south end is a mineral vein 

up to 8 inches thick, Avhich tapers out horizontally at a point 200 feet 

from the east side of the quarry. It contains pyrite, chalcopyrite, 

siderite, galenite, and secondary quartz coating crystals of siderite. 

Similar veins occur in the first and third headings. These are evidently all related to the larger siderite vein which was formerly 

mined on the hill and. to which it owes its name. Away from the 

headings the gneiss has little, if any, rusty stain.

The plant comprises two 25-ton derricks, ten 3 to 8 ton ones, ten 

hoisting engines, a 10-ton locomotive crane, an air compressor (capacity, 1,128 cubic feet of air per minute), two large air rock drills, 

sixteen air plug drills, and two surfacers, besides another derrick at 

the idle quarry.

Transportation is by siding from the Litchfield branch of the 

New York, New Haven & Hartford Railroad.

The product is used chiefly for buildings and railroad.bridges, and 

the waste blocks, with aplite or other blemishes, for retaining walls. 

The stone is sought after because of its color and low price. Specimens: Four rock-faced houses, corner Seventy-second Street and 

Tenth Avenue, and the retaining wall of the New York Central & 

Hudson River Kailroad, extending from Sixty-seventh to Seventysecond streets, New York. The length of this wall is 1,350 feet, 

height, 58 feet; width of base at Seventy-second Street, 21 feet.
72 GRANITES OF CONNECTICUT.

THOMASTON. : 

PLYMOUTH QUARRY.

The Plymouth quarry is in Thomaston Township, about 1-| miles 

south of Thomaston village and nearly half a mile north of Reynolds 

Bridge. (See PL I.) Operator, Plymouth Quarry Co., Thomaston, 

Conn.

The granite (specimen D, XXX. 54, a) is a quartz monzonite of 

medium bluish gray color (a trifle lighter and.more bluish than Concord granite) and of even grained fine granitic texture, with feldspars and mica up to 0.1 inch. Tts constituents, named in descending 

order of abundance, are light smoky quartz, with hairlike crystals 

of rutile and cavities in sheets; translucent bluish soda-lime feldspar 

(oligoclase), some of it micasized and kaolinized; clear colorless 

potash feldspar (microcline and orthoclase) biotite (black mica) ; 

muscovite (white mica). Both feldspars are intergrown with quartz 

more or less circular in cross section. Accessory minerals: Apatite, 

rutile. Secondary minerals: Kaolin, a white mica. No effervescence 

with muriatic-acid test.

This is a bright fine-grained monumental granite which is without 

mineral contrasts, but which cuts and hammers light. Prof. Newberry, in 1884, referred to the adaptation of this stone to monumental 

work.1

The quarry measures about 200 feet from north to south by 50 feet 

across, with a working face (20 to 40 feet high) on the east. The 

firm is said to have another opening higher up on the ridge.

Rock structure: The granite is capped by 10 to 20 feet of quartz 

monzonite gneiss, gray or consisting of white feldspar and quartz

bands, 0.2 to 0.3 inch wide, alternating with black bands of biotite

less than 0.05 inch wide. The constituents of this gneiss, named in 

descending order of abundance, are light smoky quartz with cavities; 

milk-white oligoclase; whitish orthoclase; biotite and a little muscovite or bleached biotite. Accessory minerals: Magnetite, apatite, 

titanite. Secondary minerals: Kaolin, a white mica. This gneiss is 

intricately plicated. In places its foliation is abruptly intersected by 

the granite.. The bpundar}' between the two rocks is very irregular 

and pegmatite .occurs along part of it. A tapering inclusion of the 

gneiss, 10 feet by 14 inches or more long and 3 feet wide, occurs 8 

feet below the contact. The sheets, from 6 inches to 3 feet thick, dip 

gently west, but are less regular in the gneiss capping. There are two 

sets of joints: Set A, striking N. 35° E., vertical, is spaced 8 to 30 

feet, continuing into the gneiss; set B, striking N..800 W., vertical, 

is spaced 3 to 10 feet or more. 

The plant comprises a derrick and small hoisting engine.

1 ! Tenth Census, vol. 10, 1884, p. 321.
LITCHFIELD COUNTY. 73

Transportation is by short siding, the quarry being but a few feet 

east of the New York, New Haven & Hertford Railroad.

The product is used for monuments. The quariy was not in operation in August, 1908, although a few blocks had been recently cut.

TOREINGTON. 

COSTELM) QUARRY.

The Costello quarry is in the township of Torrington, 2^ miles 

northwest of Torrington and 550 feet above it. (See PI. I, p. 8.) 

Operator, Martin B. Costello, E. F. D., Torrington, Conn.

The granite (specimen D, XXX, 50, a) is a muscovite-biotite 

granite gneiss of medium gray faintly buff shade and of fine, very 

gneissose texture, with feldspars under 0.2 inch, but with larger micas 

conspicuous on the foliation face and with sparse garnets to 0.2 inch.

Tts constituents, named in descending order of abundance, are creamcolored potash feldspar (microcline), intergrown with quartz that is 

more or less circular in cross section; light smoky quartz with cavities in sheets; cream-colored soda-lime feldspar (oligoclase-albite to 

albite); muscovite (white mica); bjptite (black mica). Accessory 

minerals: Garnet, apatite. Secondary mineral: Limonite. 

. The quarry, opened in 1898, measures about 250 feet in a N. 60° E. 

direction by 50 feet across and 25 feet in depth. .

Rock structure: The foliation strikes N. 50° E. and dips 55° N. 35° 

W. The sheets, from 8 to 12 feet thick (exceptionally, near the surface, 1 foot thick), are horizontal or inclined to 30° NNW. There 

are two sets of joints: Set A, striking N. 30° E., dipping 30° to 70° 

N. 60° W., is spaced 8 to 10 feet; set B, striking N. 20°. W., dipping 

70° N. 70° E., forms a heading at the west end and is spaced over 

100 feet. The rift corresponds to the foliation, and there is little 

difference between the grain and the hardway. Garnetiferous pegmatite dikes are up to 2 inches thick. There is little or no rusty 

stain on sheet surfaces.

The plant comprises one horse derrick, one hand derrick, two steam 

derricks, two hoisting engines, and a steam pump.

Transportation is by cartage of 3 miles to Torrington or of 11 

miles to Winsted.

The product is used for building, trimming, and curbing: Specimens: Parish house of Third Congregational Church, Torrington, 

entire; Winsted Hosiery Co.'s office, Winsted, entire; trimmings on 

public library, Winsted; trimmings on factories of Standard Manufacturing Co. and of Union Hardware Co., Torrington.

MICPIIEL QUARRY.

The Michiel quarry is in the township of Torrington, more than a 

mile west of Torrington and 340 feet above it. Operator, Ino de 

Michiel & Bro., 352 High Street, Torrington, Conn.
74 .GRANITES OF CONNECTICUT.

The granite (specimen D, XXX, 52) is a muscovite-biotite granite 

gneiss of medium inclining to dark bluish gray shade and of medium 

very gneissose texture, with feldspar to 0.4 inch and large micas, 

which are very conspicuous on the foliation faces. Its constituents, 

named in descending order of abundance, are: Translucent bluish 

potash feldspar (microcline and orthoclase) ; light smoky quartz with 

cavities in sheets and cracks parallel thereto, the sheets of cavities 

passing uninterruptedly from one particle to the next; a little milkwhite soda-lime feldspar (oligoclase) somewhat kaolinized; muscovite (white mica) ; biotite (black mica). Accessory minerals: Garnet, apatite, zircon. Secondary mineral: Kaolin. Both feldspars are 

intergrown with quartz that is more or less circular in cross section.

No effervescence with muriatic-acid test. ? The quarry, opened in 1901, is about 150 feet square and 15 to 30

feet deep.

Rock structure: The gneiss foliation is vertical, "with N. 35° E. 

course. The sheets, from 1 to 14 feet thick, are horizontal in the 

center of the quarry, curving over gently on the sides. There are two 

sets of joints: Set A, striking^ north west, vertical or dipping steep 

southwest, is spaced about 20 feet; set B, striking N. 20° E., dipping 

steep N. 70° W., is spaced 50 feet. The rift corresponds to the 

foliation, and the-grain and hardway are reported as equally pronounced.

The plant comprises a hand and a steam derrick, a hoisting engine, 

and steam pump.

The product is used mainly for buildings; some for trimming and 

curbing. Specimens: Methodist Church, Winsted, entire; Italian 

Catholic Church, Torrington, entire; L. Ripley residence, Litchfield,

entire; trimmings on Litchfield library and on the State armory in 

Meriden, Conn.

TORRINGTON BOROUGH QUARRY.

The Torrington Borough quarry is in the township of Torrington. 

about 1£ miles north-northwest of Torrington and several hundred 

feet above it. (See PL I.) Owned and operated by the borough of 

Torrington, H. I. Holcomb, superintendent, Torrington, Conn.

The granite (specimen D, XXX, 51, a) is a biotite granite gneiss 

of general dark-gray shade, finely banded with black, and very fine 

to fine schistose texture, with feldspars under 0,1 inch. Its constituents, named in descending order of abundance, are: Medium-gray 

potash feldspar (microcline and possibly orthoclase) ; medium smoky 

quartz, with cavities in sheets; light-gray soda-lime feldspar (oligoclase), mostly kaolinized and micasized; biotite (black mica); and
LITCHFIELD COUNTY. 75

a little muscovite. Accessory minerals: Pyrite, apatite, zircon. Secondary minerals: Kaolin, a white mica, calcite.

Associated with this gneiss is a mica diorite gneiss (specimen D. 

XXX, 51, 6), a heavy black rock of fine schistose texture. Its constituents, named in descending order of abundance, are: Biotite (black 

mica) ; smoky quartz, with cavities in sheets; green hornblende; 

soda-lime feldspar (andesine), with accessory pyrite (fifth in order 

of abundance); apatite; and secondary calcite. It has veinlets of 

quartz under a millimeter.

Both biotite gneiss and diorite gneiss are crossed by meandering 

dikelets from under 1 inch to 6 inches thick of (specimen D, XXX, 

51, c] a quartz monzonite gneiss of medium bluish-gray color and 

fine gneissose texture, with feldspar, under 0.1 inch and very fine 

micas. Its constituents, named in descending order of abundance, 

are: Light smoky quartz with cavities in sheets and cracks parallel

thereto; milk-white soda-lime feldspar (oligoclase-andesine), some 

of it kaolinized, micasized, and with calcite; bluish potash feldspar 

(orthoclase) slightly kaolinized; biotite (black mica); and a little 

muscovite or bleached biotite.

The quarry measures about 400 feet from northeast to southwest, 

with a working face from 30 to 65 feet on the northwest.

Rock structure: The foliation of the main gneisses strikes N. 

35°-40° E. and dips 45°-60° W. As stated, they are cut by a 

network of meandering grayish veinlets of quartz monzonite (specimen c), but they are also crossed by several dikes of pegmatite from 

3 to 20 feet thick, the largest and central one of which contains two 

inclusions of the gneiss measuring 5 by 10 and 2 to 4 by 10 feet. 

This pegmatite (specimen D, XXX, 51, e) is of medium pinkish 

gray color and of very coarse texture, with large feldspars and quartz 

particles up to 0.5 inch. Its constituents are: Reddish microcline and 

orthoclase, but slightly altered; amethystine quartz with cavities in 

parallel sheets and cracks parallel and at right angles thereto; a little 

oligoclase, much micasized and kaolinized; muscovite; biotite. There 

are crush borders about the feldspars. There are two sets of joints: 

Set A, striking northeast, vertical, forms a heading near the outside 

of quarry; set B, striking N. 70° W., dipping 55° and 30° S. 20° W., 

is spaced 3, 30, and 100 feet. Both sets are slickensided.

The plant consists of a large stone crusher, with meshes of onehalf, three-fourths, 1, and 1£ inches. '

The product is used entirely for macadamizing roads in the 

borough of Torrington. As little as possible of the pegmatite is used, 

and that is mixed with the gneisses. Tailings are used in the subgrade.
76 GEANITES OF CONNECTICUT.

WAREEN.

COMSTOCK PROSPECT.

The Comstock prospect is in the township of Warren, a mile northnortheast of Warren village and 2£ miles east of North Kent. (See 

PI. I.) Owner, Eeuben Tree Voss, 26 Frankfort Street, New York.

The granite (specimen D, XXX, 59, a) is a biotite granite of 

medium gray shade and of medium inclining to fine texture, with 

feldspars to 0.2 and 0.3 inch and mica to 0.2 inch. Its constituents, named in descending order of abundance, are clear, colorless 

potash feldspar (microcline) ; pale, smoky quartz, with some cavities 

in sheets; milk-Avhite soda-lime feldspar (oligoclase), a little kaolinized; biotite (black mica); and a little muscovite or bleached 

biotite. Secondary minerals: Kaolin and limonite. Both feldspars 

are intergrown with quartz circular in cross section or in vermicular 

form. No effervescence with muriatic-acid test. The specimen, coming from a long-exposed upper sheet, hardly does justice to the stone.

The opening, made a number of years ago, is 100 feet square and 

up to 5 feet deep.

Rock structure: The sheets, from 6 to 14 inches thick, are horizontal. There is a 12-inch-pegmatite dike on one side. The exposed 

surfaces are speckled with limonite stain.

Transportation is by cartage of 3 miles to North Kent, on the New 

York, New Haven & Hartford Railroad.

MIDDLESEX COUNTY. 

MIDDLETOWN.

BENVENUE QUARRIES.

The Ben venue quarries are in the township of Middletown, about 4-| 

miles east-southeast of the Middletown railroad station, on the mass 

south of the bend in Connecticut River and from 200 to 350 feet 

above it. The nearest railroad stations are Ben venue and Maromas, a 

mile and half a mile from the openings. (See PL I, p. 8.) Owner, 

Benvenue Granite Co., 41 Park Row, New York.

The granite (specimen D, XXX, 29, a, "Maromas granite gneiss," 

No. 30, of the State preliminary geologic map) is a biotite-hornblende granite gneiss of dark bluish gray color and of fine-grained 

gneissose texture, with porphyritic feldspars up to 0.3 inch and 

mica up to 0.1 inch. Its constituents, in descending order of abundance, are: Bluish translucent potash feldspar (microcline and orthoclase) ; clear, colorless quartz, showing effects of strain and with 

cavities in sheets; milk-white soda-lime feldspar (oligoclase) somewhat kaolinized; biotite (black mica) ; and hornblende. Accessory 

minerals: Pyrite, magnetite, titanite, apatite, allanite, zircon. Sec-
MIDDLESEX COUNTY. 77

ondary minerals: Kaolin, epidote. No effervescence with muriaticacid test.

Twelve crushing tests made on 2-inch .cubes of this granite by Ira 

H. Woolson, M. E., show an ultimate compressive strength ranging 

from 29,400 to 34,075 pounds per square inch. 1

This is a bright, somewhat foliaceous bluish gray stone, with 

strong mineral contrasts.

The Benvenue quarry, about a mile southeast of Benvenue station, 

and half a mile southwest of Maromas, and 200 feet above the river, 

measures about 400 feet from north to south by 200 feet across, and 

is from 10 to 60 feet deep. The stripping of sand is up to 8 feet 

thick. The upper quarry, three-fourths of a mile south-southeast 

of Benvenue station and 350 feet above the river, measures about 

300 feet from east to west by 75 feet from north to south, with a

working face on the south ranging in height from 40 to over 60 feet.

Rock structure: At the Benvenue quarry the gneiss foliation strikes 

northwest and dips 10°-20° SE. The elongation of the gneiss is 

in a N. 65° E. direction. The sheets, from 6 inches to 6 feet thick, 

dip 10°-20° E; There are two sets of joints: Set A, striking N. 

10° E., and dipping vertical to 70° E., forms a 10-foot heading on 

the west side, and is spaced 5 to 20 feet; set B, discontinuous, with 

strike east-west, and dip vertical to steeply south, forms a 10-foot 

heading 100 feet from the east end, and is spaced 5 to 20 feet. The 

rift corresponds to the foliation; the grain is vertical, east-west, and 

the hardway vertical north-south. Dikes of white to rose colored 

aplite, 1 to 12 inches thick, strike N. S0°-90° W., dipping 20°-35° 

N., also strike N. 35° W., and are vertical. Its particles, under a 

millimeter, consist of quartz, orthoclase, and microcline, oligoclase, 

scarce biotite, with accessory pyrite, titanite, and allanite. There are 

pegmatite dikes of smoky quartz bordered with alternating streaks of 

oligoclase with microcline and hornblende, up to 3 inches thick, striking N. 75° E. and dipping 35° N. 15° W. There are also dark-gray 

elliptical segregations from 2 inches to 3 feet long by 0.5 to 8 inches 

wide, tapering in the direction of the gneiss foliation. The minerals 

of these segregations in descending order of abundance are, microcline with orthoclase, quartz, biotite, oligoclase, hornblende, with, 

accessory apatite, titanite, and zircon. Brownish limonite stain 

measures up to 6 inches thick on sheet surfaces. 2

The rock structure at the upper quarry is like that at the Benvenue quarry.

Product: In 1908 the company was abandoning these quarries 

because of their numerous joints, knots, and dikes. Its large plant

!Day, Wm. C., Stone: Eighteenth Ann. Kept. U. S. Geol. Survey, pt: 5 (continued), 

1897, pp. 959, 960.

3 For a description of the .gneiss of this quarry and its structure see Westgate, Lewis 

G.; A granite-gneiss in Central Connecticut: Jour. Geology, vol. 7, 1899, pp. 638-654.
78 GRANITES OF CONNECTICUT.

was being transferred to a quarry on the west "side of Crotch Island, 

in Stonington, Me., which the company opened in 1906-7, and where 

the sheet structure is remarkably uniform and the granite is relatively free from defects due to geologic accidents.

NEW HAVEN COUNTY.

ANSONIA. 

POTTER QUARRY.

The Potter quarry is in Ansonia, about three-fourths mile northnortheast of the center of the village. Operator, William Potter, 

Rockwood Avenue, Ansonia.

The granite (specimen D, XXX, 45, a) is a muscovite-biotite 

granite gneiss of medium bluish-gray color, brightly spangled with 

mica on the foliation faces, and of fine-grained, unplicated, finely 

gneissose texture, with feldspars not over 0.2 and mostly under 0.1 

inch, but with mica to 0.5 inch. Its constituents, in descending 

order of abundance, are clear, bluish potash feldspar (microcline 

and less orthoclase) ; clear, colorless quartz, with cavities in sheets; 

bluish translucent soda-lime feldspar (oligoclase), slightly kaolinized; muscovite (white mica); biotite (black mica). Accessory 

minerals: Apatite, garnet. Secondary minerals: Kaolin, calcite. 

It effervesces with cold dilute muriatic acid.

The stone glistens brightly with mica on its foliation face, but its 

other two sides are bluish gray without contrasts. Its foliation adapts 

it for all uses requiring long, flat stones.

The quarry, opened about 1890, measures' about 200 by 150 feet, 

and is from 10 to 50 feet deep, with a working face on the northwest 5.0 feet high. The stripping consists of 3 feet of sand and

loam.

Rock structure: Foliation and rift strike N. 35° E. and dip 45° 

S. 55° E. The sheets, 6 inches to 4 feet thick and normal, nearly 

coincide with the foliation. There are three sets of joints: Set 

A, striking north, vertical, spaced 10 to 30 feet, forms a heading 

at the west wall, one (20 feet wide) 40 feet from the northeast wall, 

and another at that wall; set B, striking east-west, vertical, and 

discontinuous vertically, is spaced very irregularly, 3 to 5 feet or 

more; set C, striking N. 75° E., dipping 30° N. 15° W., discontinuous vertically, occurs at rare intervals. There are several pegmatite dikes, the largest a foot thick. A vertical dike striking N. 

15°-22° W. crosses the entire quarry. A group of such dikes, 2 

feet wide, has a like course, and one of these sends a branch westward. The .pegmatite consists of quartz, feldspar, muscovite, and 

black tourmaline. Rusty stain occurs up to 6 inches thick on the 

lower sheet surfaces.
NEW HAVEN COUNTY. . 79

The plant comprises two derricks, two small hoisting engines, two 

air compressors (capacity 40 and 80 cubic feet of air per minute), 

three air plug drills, a deep-hole air driller, large rock drill, and 

steam pump.

Transportation is by cartage to Ansonia.

The product is used for curbing, crosswalks, steps, coping, and 

supplies mostly local demands. The Holbrook quarry in Seymour 

is on the same belt of rock.

DAV1DSON QUARRY.

The Davidson quarry is on Wakelee Avenue, in Ansonia, on the 

west side of Naugatuck River. Operator, Ansonia Trap Rock Co., 

273 Wakelee Avenue, Anspnia, Conn.

The granite (" Prospect porphyritic "gneiss," No. 9, of the preliminary State geologic map) is a biotite granite gneiss of darkgray shade and of medium texture, with porphyritic milk-whitish 

feldspars up to 1.5 inches by 0.5 inch, many of them twins.

The quarry measures about 200 feet in a northwest direction by 

40 feet across and 40 feet in depth.

The gneiss foliation strikes about northeast and dips steeply southeast. A 30-foot diabase dike crosses the gneiss parallel to its foliation.

The plant consists of a stone crusher with meshes of one-half, ! £, 

2, and 2^ inches in diameter.

The gneiss is crushed for concrete.

BRAN FORD. 

NORCROSS QUARRY.

The Norcross quarry is in the township of Branford, about 1| 

miles north of Stony Creek village. (See PI. I, p. 8, and fig. 3, p. 80.) 

Operators, The Norcross Bros. Co., Worcester, Mass.

The granite (specimens D, XXIX, 93, a, rubbed; 6, c, polished; #, 

rough, " Stony Creek granite gneiss," No. 33, of the State preliminary geologic map), "Branford red granite," is a biotite granite 

gneiss of medium reddish-gray color and of very variable but mostly 

from medium to coarse, not porphyritic, gneissoid texture, with feldspars from 0.1 to 0.3 and even 0.8 inch and mica to 0.2 and 0.3 inch. 

Its constituents, in descending order of abundance, are reddish potash 

feldspar (microcline, some intergrown with plagioclase, and less 

orthoclase) somewhat kaolinized, some micasized, and some bent; 

medium smoky or smoky amethystine quartz, showing effects of strain 

and with cavities in streaks and sheets; milk-white or greenish-white 

to cream-colored soda-lime feldspar, (oligoclase to oligoclase-andesine)

97730 ? Bull. 484 11 6 ' 
80 GRANITES OF CONNECTICUT.

kaolinized and micasized and with more or less calcite; biotite (black 

mica), some of it chloritized, and a little muscovite or bleached 

biotite. Accessory minerals: Magnetite, pyrite, apatite, zircon. Secondary minerals: Kaolin, white micas, calcite, epidote, zoisite, chlorite, limonite. Both feldspars are intergrown with quartz more or 

less circular in cross section. The stone effervesces with cold dilute 

muriatic acid.

A specimen of the finer parts (D, XXIX, 93, j] shows feldspar to 

0.1 inch and constituents identical with those given above. A specimen of the extra coarse (pegmatitic) parts (D, XXIX, 93. e) shows

i 3 Miles

Contour interval 407feet

FIGURE 3. Map of Branford and Guilford granite quarries: 65, Brooklyn quarry ; 93, 

Norcross; 94, Stony Creek; 95, Hoadly Neck; 96, Leete Island; 97, Sachem Head.

/

feldspars to 1 and 1.5 inches. Its constituents are the same as of the 

others, ;bnt the microcline is more dominant and the rock therefore 

a little more pinkish.

A compression test made at the United States arsenal at Watertown, Mass., No. 6763, gives this granite an ultimate compressive 

strength of 22,447 pounds per square inch, rift and grain directions 

not recorded. Gillmore gave its specific gravity as 165.4 and its ratio 

of absorption as 1.201.1

1 Gillmore, Q. A., Report on compressive strength, etc., of various kinds of building 

stone from different sections of the United States, etc., Engineer Dept., U. S. Army, 

Washington, 1874, p. 12.
NEW HAVEN COUNTY. 81

The following analysis was made for the firm by Leonard P. Kinnicutt at the Worcester Polytechnic Institute in 1890:

Analysis of biotite granite gneiss from Stony Creek.

Silica (SiOa ) ______________________________ 72. 73

Alumina (Al^Os) and iron oxide (FeO)____________ 16.95

Lime (CaO)_____________________________ 1.05

Magnesia (MgO) ____ ____________ trace.

Potash (K::O)_____________________________ 8.15

Soda (Na^O) ___________________________ 0.90

Loss and undetermined_____________________ 0. 22

100. 00

The marked feature of this rock is its very irregular texture, which 

is due in part to pegmatitic injection, in part to flow structure, and 

in part probably to gneissic foliation. These irregularities are shown

in the polished slab shown in Plate III, A, page 48. In places the 

rock is a flow gneiss; in others a pegmatite; in others it approaches 

an aplite in fineness. It is a brilliant stone. Its mineral contrasts lie 

chiefly between the reddish aird whitish feldspars, but these are not 

everyAvhere distributed in their normal proportions. It takes a fair 

polish. The polished face shows some magnetite, some mica, and a 

little pyrite, and is therefore less suitable for outdoor than indoor 

use. That its strength and attractive color have more than counterbalanced its irregularity of texture is evidenced by the important 

structures in which it has been used.

The quarry, begun in 1887, consists of a lower opening and an 

upper one 100 feet north of it. The lower one measures about 450, 

feet north to south, by 200 feet across, and is from 15 to 65 feet deep; 

the upper one, about 500 feet north to south, by 100 feet, and 15-40 

feet in depth.

Rock structure: The sheets, from 2 to 25 feet thick, are horizontal 

or inclined 10°-20° SE.1 There are two sets of joints. Set A, 

striking east to west, vertical or steep, is spaced 5-75 feet. In the 

upper quarry these are confined to the southern 100 feet of the quarry, 

where their spacing is 5 to 20 feet. Set B, striking N. 10° E. and 

N. 5°-15° W., vertical, forms a 5-foot heading on the east side of 

the lower quarry, and, extending through the upper one, is spaced 

10 to 40 feet. The flow structure, consisting of more or less biotitic 

or nonbiotitic bands, strikes N. 70° W., and dips 35°-55° N. 20° 

E. to vertical. A slight gneissic foliation is probably also present, 

but is obscured by the flow structure and the pegmatite. Traces of 

that foliation appear under the microscope in the strained quartz,

1 A view of the sheet structure here is given in a paper by Prof. J. F. Kemp, Granites 

of Southern Rhode Island and Connecticut [etc.] : Bull. Geol. Soc, America, vol. 10, 1809,
82 GRANITES OF CONNECTICUT.

bent feldspars, and veinlets of secondary muscovite. The rift is 

reported as horizontal in the upper quarry and dipping 3°-5° W. 

in the lower, and the grain as vertical with N. 20°-30° W. course. 

A few inches of "shake structure" occur along the sheet surfaces. 

Both knots and inclusions occur. A microscopic description of a 

knot, from the neighboring quarry of the Stony Creek Eed Granite 

Co., is given on page 83. Inclusions range from 2 by 1 foot and 

under to 8 by 3 by 1 foot. One of these (specimen D, XXIX, 93, h) 

is a black schistose rock with particles under 0.1 inch and consists, 

in descending order of abundance, ,of hornblende, andesine, biotite 

with muscovite, quartz and accessory titanite, magnetite, or ilmenite, 

It. is a quartz-mica diorite gneiss. A- medium gray gneissoicl one 

(specimen D, XXIX, 93, i) with particles under 0.1 inch consists, in 

like order, of oligoclase-andesine, quartz, biotite with accessory 

zircon,- and thus is a mica diorite gneiss. Still others (specimens 93, 

k, kk] are a dark-gray fine-grained quartz-mica diorite gneiss with 

oligoclase, quartz, and biotite, and accessory pyrite, magnetite, apatite, titanite, and zircon. The coarser feldspars are zonally arranged 

about some of the inclusions; that is, they have a pegmatitic border. 

One inclusion is rimmed with biotite.

The plant comprises 11 derricks, including one of 35 tons, 11 

hoisting engines, a 20-ton overhead traveling crane, 8 hand derrick 

cars, 2 locomotives, a 30-horsepower dynamo for polishers, lathes, and 

lighting, 5 steam drills, 2 air compressors (capacity 700 and 200 

cubic feet of air per minute), 14 air plug drills, 15 air hand tools, 5 

surfacers, a gang of saws for stones 15 feet by 6 feet, 5 polishers, 2 

sets of double-pendulum polishers for straight molding, a lathe for 

stones 19 feet by 3 feet 6 inches, 2 for stones 8 feet by 2 feet,.3 polishing, lathes of corresponding sizes, and a steam pump.

Transportation is by siding from New York, New Haven & Hartford Railroad, as shown in figure 3. 

The product is used mostly for buildings and bridges and some 

for monuments. Specimens: South Terminal Station, Boston; Bessemer Building, Pittsburg; Newberry Library, Chicago; arches and 

roadway coping of Connecticut Eiver Bridge, Hartford; polished 

columns (43 feet by 6.feet 2 inches at base) of Battle Monument, 

West Point; obelisk (45 feet long) at Locks Park, Sault Ste. Marie, 

American side (see PI. Ill, B) ; pedestals of Sherman statue, Fiftyninth Street and Fifth Avenue, New York; of King Frederick statue, 

Washington; and of Gen. Hooker statue, State House grounds, 

Boston.

STONY CREEK QUARRY.

The Stony Creek quarry is in Branford Township, about 1£ miles 

north of Stony Creek village, less than one-fourth mile west-north-
U. S. GEOLOGICAL SURVEY BULLETIN 484 PLATE Ml

A. POLISHED SLAB OF PEGMATITIC BIOTITE GRANITE GNEISS ("BRANFORD RED GRANITE") 

FROM THE NORCROSS QUARRY AT STONY CREEK.

Showing irregularity in size of particles owing to pegmatization and in their arrangement owing to flow structure 

and probably also to gneissic foliation. Rule shown is 12 inches long. See page 81.

B. OBELISK OF HAMMERED PEGMATITIC BIOTITE GRANITE GNEISS , BRANFORD RED GRANITE") 

FROM THE NORCROSS QUARRY AT STONY CREEK.

Now erected to commemorate the opening of the Sault Ste. Marie Canal. See page 82.
west of the Norcross quarry and on the opposite (east) side of the 

same north-northwest trending ridge. (See fig. 3.) Operator, the 

Stony Creek Ked Granite Co., Stony Creek, Conn.

The granite (specimens D, XXIX, 94, <z, e, rough and polished, 

" Stony Creek granite gneiss," No. 33, of the State preliminary geologic map), "Stony Creek red granite," is a biotite granite gneiss 

of medium to coarse, not porphyritic texture. The stone is identical 

with that of the Norcross quarry, described on page 79, except that 

in the .average specimen submitted the potash feldspars are more 

reddish and the soda-lime feldspars are a greenish gray, instead of 

whitish or cream colored, having evidently retained more of their 

original color. The effect is to diminish the contrast between the 

feldspars. The sections also show veinlets of secondary muscovite 

and calcite in the feldspars and of muscovite in the quartz.

The stone effervesces with cold dilute muriatic acid. R. C. Wells, 

a chemist of the United States Geological Survey, finds that it contains 0.25 per cent of lime (CaO), soluble in warm dilute 10 per 

cent acetic acid, which indicates a content of 0.445 per cent of 

lime carbonate, calcite (CaC03 ).

The general characteristics and qualities of the stone are the same 

as those of the Norcross quarry stone. There is the same irregularity in texture and in'the relative proportions, of the two feldspars.

The quarry, opened about 1876, consists of two openings, an eastern one measuring about 200 feet in a north-northwest direction by 

35 to 50 feet across, with a working face on the east, and a western 

opening measuring about 400 feet in a north-northwest direction by 

75 feet across and from 10 to 30 feet in depth, with a working face 

on the west. This western opening is about 300 feet south of the 

other, but on the east side of a ridge about 80 feet high and 300 feet 

west of that which separates the eastern opening from the Norcross 

quarry.

Rock structure: The sheets, 2 to 12 feet thick, dip 15° WSW. 

There are two sets of joints: Set A, striking N. 60°-70° E., dipping 

50°-70° NNW., is spaced 10, 15, 70, and 200 feet; set B, striking N. 

30°-35° W., vertical, forms a heading, 5 to 10 feet wide, on the 

working face of the western opening, and is spaced 5 to' 40 feet. 

There is a marked flow structure, consisting of biotitic planes or 

sheets striking N. 65° E., and dipping 60°-65° NNW. The rift is 

reported as horizontal and the grain as vertical with a course N. 35° 

W. . Some of the pegmatite feldspars measure to 1.5 inches. Some 

irregular lenses of chloritic quartz measure to 12 inches in diameter. 

A dark-gray fine-grained knot consists, in descending order of abundance, of microcline and oligoclase. in almost equal amounts, biotite, 

and a little quartz, together with accessory magnetite, apatite, zircon. 

Rusty stain is up to 8 inches thick on sheet surfaces.
84 GRANITES OF CONNECTICUT.

The plant comprises six derricks, two hoisting engines, a locomotive, three steam drills, an air compressor (capacity 525 cubic feet 

of air per minute), eight air plug drills, twelve air hand tools, and 

a surfacer.

Transportation is by siding from the New York, New Haven & 

Hartford Railroad. The firm owns 2^ miles of .track. (See fig. 3.)

The product is used mostly in buildings, and its chief market is 

New York and vicinity. Specimens: Broadway Chambers Building, New York Central Kailroadj post office, and office buildings, 

New York; water tower, Brooklyn; Erie County Savings Bank, 

Buffalo, N. Y.; and First National Bank, New Haven.

BROOKLYN QUARRY.

The Brooklyn quarry, no longer worked, is on the point west of 

Stony Creek village, in Branford. It was visited by Freeman 

Ward, instructor at the Sheffield Scientific School, of Yale University, who contributes the following observations:

There are a series of openings, extending 600 or 750 feet about 

parallel with the shore line, which have not been worked for 10 or 

15 years or more.

The sheets range from the horizontal to a dip of 15°. There are 

six sets of joints: A,-striking 19° W.; B, striking N. 49° W.; C, striking N. 64°-69° W.; D, striking N. 79° W.; E, striking N. 86° E., and 

all dipping 75°-85°, but one set (E) dips 50°-55° N. A less conspicuous set (F) strikes N. 71° E. and dips 50°-55° S. 19° E. Inclusions of a biotite and of a hornblende gneiss measure up to 36 by 

12 feet, but some are thin and slablike. Perhaps some of the biotitic 

streaks are elongated inclusions. All of the inclusions, especially the 

large ones, are apt to be well injected with granite, and some of them 

have segregations of garnets. Pegmatite does not occur in definite 

dikes but in irregular streaks which have ho distinct boundaries and 

grade imperceptibly into the surrounding granite. This pegmatite 

has generally the appearance of the typical Stony Creek granite but 

may be coarser, the maximum size of its feldspars being 3 inches.

The unpegmatized granite (specimen D, XXX, 65, #," Stony Creek 

granite gneiss," No. 33, of the State preliminary geologic map, collected by Mr. Ward, but examined by the writer) is a biotite granite 

gneiss, somewhate dark reddish gray in color and of even-grained 

medium texture, with feldspar to 0.3 inch and mica to 0.05 inch. Its 

constituents, in descending order of abundance, are pale reddish 

potash feldspar (microcline and orthoclase), slightly kaolinized; 

medium smoky quartz, strained and with cavities in sheets; slightly 

greenish soda-lime feldspar (oligoclase to oligoclase-andesine), more 

or less micasized and kaolinized; biotite (black mica),some of itchlo-
U. 8. GEOLOGICAL SURVEY BULLETIN 484 PLATE IV

A. COARSE PORPHYRITIC BIOTITE GRANITE GNEISS FROM HOADLY POINT "WEST" QUARRY,

BRANFORD.

Showing the lenticular shape of the feldspars and the distribution of the mica and quartz in bands. The large 

lenses are mostly microcline feldspar. See page 85.

B. PORPHYRITIC GRANITE GNEISS FROM DERBY. 

The phenocrysts are feldspar. See page 21.
NEW HAVEN COUNTY, 85

ritized, with a little muscovite or bleached biotite. Accessory minerals: Garnet (fifth in order of abundance), pyrite, zircon. Secondary minerals: Kaolin, a white mica, calcite, chlorite. The stone 

effervesces with cold dilute muriatic acid.

HOADLY NECK QUARRIES.

The Hoadly Neck quarries are in the town of Branford, at the 

end of Hoadly Point. (See fig. 3, p. 80.) Operator, estate of John 

Beattie, Peter and John Beattie, jr., executors, Leete Island, Conn.

FIGUHE 4. Upper : Block of plicated biotite granite gneiss from West quarry, Hoadly 

Point, Branford. Lower: Plicated and faulted band of fine biotite granite gneiss 

within tbe coarser gneiss of same quarry. Hammers 20 inches long. (From photographs.)

The granite (specimens D, XXIX, 95, c, d, from West quarry, 

" Stony Creek granite gneiss," No. 33, of the State preliminary geologic map), "Hoadly Neck, West quarry, granite," is a biotite granite gneiss of general medium, inclining to dark reddish gray color, 

and of coarse to very coarse .banded, plicated gneissose porphyritic 

texture, consisting of reddish gray or whitish lenses and bands alternating with or bordered by thin sheets of black mica and with some 

thin bands of smoky quartz. The lenses, which are distorted feldspar 

crystals, commonly twins, measure to 3 inches in length and 1 inch in 

width, and the mica bands 0.1 to 0.2 inch. The texture as seen in 

hand specimens is shown in Plate IV, A. The foliation is coarsely 

plicated, the plications up to 10 inches in width, and these are in
86 GRANITES OF CONNECTICUT".

places faulted, as shown in figure 4. The constituents of this biotite 

granite gneiss, in descending order of abundance, are reddish potash 

feldspar (microcline, somewhat kaolinized, with some orthoclase) ; 

medium smoky quartz, with cavities in sheets; whitish soda-lime 

feldspar (oligoclase), intergrown with quartz more or less circular 

in cross-section or in vermicular form, and generally much micrasized; biotite (black mica), some chloritized; a little green hornblende. 

Accessory minerals: Garnet, pyrite, zircon, apatite. Secondary minerals : A white mica, kaolin, limonite about pyrite, calcite. The stone 

effervesces slightly with cold dilute muriatic acid.

This stone has marked mineral contrasts and striking textural features, as shown in Plate IV, A. It is a coarse constructional granite 

gneiss of warm gray tint.

The stone of the East quarry (specimens D, XXIX, 95, Z, m) lacks 

the coarsely banded porphyritic texture of the other. Its color is 

medium reddish gray and its texture is gneissose, even grained medium, inclining to fine, with feldspars to 0.3 inch and mica under 

0.1 inch. Its constituents are the same as the others, but a thin section shows the light feldspar as oligoclase-albite.

The quarry, opened in 186T, consists of two openings the west 

quarry, about 1,500 feet east to west by 800 feet across, with a working face from 30 to 70 feet above sea level, and the east quarry, about 

2,000 feet long and curving from west to east by 400 feet across, with 

working face like the other.

Kock structure: In the West quarry there is a plicated gneissic 

foliation about horizontal, faulted in places with displacement of 

a few inches. The sheets of that quarry, 2 to 8 feet thick, are horizontal or dip 10° NE. Those of the East quarry 6 inches to 2 

feet thick, turn from the horizontal to dip 10° E. There are three 

sets of joints in the West quarry: Set A, striking N. 80° W., vertical,'forms a heading at east end, one, 5 to 8 feet wide, through 

the center, and-is spaced 5 to 150 feet; B, striking about northeast, 

vertical, is spaced 40 to 200 feet; C, striking N. 20° W., vertical 

is spaced 10 feet or more. There are two other sets in the East 

quarry; set D, striking N. 15° E., dips 77° E. and is spaced 5 to 

10 feet or more; E, striking N. 60° W., vertical, forms occasional 

small headings and is spaced 5 to 10 feet. The rift is reported as 

horizontal and the grain as vertical, with N. 65° E. course at the 

West quarry and N. 75° E. at the East quarry, but the difference 

in their fissility appears to be slight. Pegmatite dikes (specimen 

95, a), 1 to 3 feet thick, strike N. 20° E. and N. 45° E. They 

consist of the same minerals as the gneiss, but in extra coarse particles. There are dikes or bands of fine biotite granite gneiss up 

to 4 inches thick. Some of these in the West quarry are parallel 

to the foliation and have been plicated with it, as shown in figure 4.
NEW &AVEN

The rock is of medium pinkish gray color and of very fine to fine 

gneissose banded texture, with feldspars to 0.1 inch. The bands 

of the coarse gneiss are reddish or light and dark gray or black, 

from 0.05 to 0.4 inch wide, and result from the distribution of 

the various minerals in parajlel laminae. The constituents of this 

gneiss are identical with those of the coarse rock. Allanite is among 

its accessories. In the East quarry there are dark bands of mica 

diorite gneiss (specimen D, XXIX, 95, k) up to 2 feet thick, striking 

N. 62° E. and dipping 75° -N. 28° W., consisting in descending order 

of abundance of biotite, oligoclase-andesine, green hornblende, and 

quartz. These are either inclusions elongated in the direction o.f the 

flow or more probably altered basic dikes.

The plant comprises 10 derricks, including one of 25 tons; 14 hoisting and drawing engines, an air compressor (capacity 1,000 cubic 

feet of air per minute), 8 large steam drills, 16 air plug drills, a 12- 

ton overhead pneumatic crane, 4 surfacers, and a polisher. The plant 

includes also 7 schooners.

Transportation is either by siding from New York, New Haven & 

Hartford Railroad at Leete Island station or by water. There are 

seven docks near the quarries with 8 feet of water at low tide.

The product is used for massive bridge work, buildings, and monument pedestals. Specimens: Anchorage of Suspension Bridge, 

Niagara; anchorage of'first Brooklyn Bridge; approaches and abutments of Madison Avenue Bridge, Harlem River; piers and abutment 

of Connecticut River bridge, Hartford; pedestal of statue of Liberty, 

New York Harbor; of Gen: Anderson Monument, Fort Sumter, S. C.; 

of Soldiers and Sailors Monument, Riverside Drive, New York. 

A polished slab of the West quarry stone 6 by 3 feet, exposed for 20 

years at a house near the quarries, has stood exposure well, notwithstanding the coarseness of its mica.

GUILFORD.

LEETE ISLAND QUARRY. .

The Leete Island quarry is in the township of Guilford, about 350 

feet north-northeast of Leete Island station on the New York, New 

Haven & Hartford Railroad. (See fig. 3.) Operator, estate of John 

Beattie, Peter and John Beattie, jr., executors, Leete Island, Conn.

The granite (specimen D, XXIX, 96, a, " Stony Creek granite 

gneiss," No. 33, of the State preliminary geologic map), Leete 

Island granite, is a biotite granite of medium reddish gray color and 

of granitic or obscurely gneissose even-grained medium texture, with 

feldspars to 0.25 inch and mica to 0.2 inch. Its constituents, named 

in descending order of abundance, are reddish potash feldspar 

(microcline and orthoclase, the latter intergrown with soda-lime
88 GRANITES OP CONNECTICUT,

feldspar), generally fresh; medium: smoky quartz with cavities in 

sheets; cream-colored soda-lime feldspar (oligoclase-albite), micasized, kaolinized, and with calcite; biotite (black mica), some of it 

chloritized, and a little muscovite or bleached biotite. The microcline is intergrown with quartz more or less circular in cross section. 

There are crush borders about some of the feldspars and veinlets of 

muscovite. Accessory minerals: Magnetite and zircon. Secondary 

minerals: Kaolin, white micas, calcite, chlorite. It effervesces with 

cold dilute muriatic acid.

This stone resembles that of the Norcross and Stony Creek quarries (pp. 79, 82), but its texture is finer and more regular. Yet it 

contains here and there some pegmatitic streaks with feldspar to 

2 inches across. Whatever apparent gneissic texture it has is due 

mainly to flow structure.

The quarry is on the southwest side of a knoll and measures about 

650 feet from southeast to northwest by 50 to 150 feet across, with a 

working face on the northeast about 60 feet high but divided by 

unequal quarrying into an upper 20-foot and a lower 40-foot one.

Rock structure: The sheets, from 1 to 6 feet thick, are arched, 

being level in the center of the hill and dipping to 20'° W. on its west 

.side and 10° E on its east side. There is but one set of joints, strike 

nearly east to west, vertical; spacing, 5 to 100 feet. There are black 

knots (specimen 96, &) up to 1 by 4 feet, of very irregular outline, of 

fine-grained black quartz-mica diorite gneiss, consisting (in usual 

order) of oligoclase, quartz, and biotite, with much magnetite and 

accessory apatite, and zircon.

The plant comprises two derricks.

Transportation is by siding from the adjoining station.

Product: The quarry has not been worked very recently, because

of the cheaper transportation by water afforded by the location of 

the firm's other quarries. (See p. 85.)

SACHEM HEAD QUARRY.

The Sachem Head quarry is in the township of Guilford, on 

Sachem Head, on the south side of Great or Sachem Head Harbor. 

(See PI. I and fig. 3.) Operator: Breakwater Co., Hickok Building, Cleveland, Ohio, and 115 Broadway, New York.

The gra-nite (specimens D, XXIX, 97, <z, &, c, <#, " Stony Creek 

granite gneiss," No. 33, of the State preliminary geologic map), 

Sachem Head granite, is a biotite granite gneiss of medium more 

or less reddish gray color and of very variable gneissose texture, 

ranging from medium inclining to fine, even grained, with feldspars 

to 0.3 inch, to porphyritic, with a matrix of same character containing isolated reddish-buff feldspars to 0.7 inch, and also with
U. S. GEOLOGICAL SURVEY 

SACHEM HEAD BREAKWATER GRANITE QUARRY, G

Looking northeast, showing the working face of biotite granite gneiss with horizontal sheets, the long drill holes 

the dock. See page 89.
ft COMMIT.

pegmatitic streaks with feldspars to 1 inch. The mica is mostly 

under 0.1 inch and the pegmatitic portions to 0.2 inch. The constituents of this rock, in descending order of abundance, are reddish-buff potash feldspar (microcline and some orthoclase), but 

slightly kaolinized; medium smoky quartz with cavities in sheets 

and some cracks roughly parallel thereto; striated milk-white sodalime feldspar (oligoclase-albite) more or less micasized and with 

calcite; biotite (black mica), some of it chloritized, and very little 

muscovite or bleached biotite. Accessory minerals: Magnetite, apatite, zircon. Secondary minerals: One or two white micas, kaolin, 

calcite, hematite, chlorite, epidote. Veinlets of muscovite and also 

of calcite. Both feldspars are intergrown with quartz, more or less 

circular in cross section. The stone effervesces with cold .dilute 

muriatic acid.

Gillmore gave the specific gravity of this granite as 163.7 and its 

ratio of absorption as 1.162.1

This is a brilliant granite, with greater variations of shade, color, 

and texture than those of granite of the Norcross and Stony Creek 

quarries. The prevalence of " shake structure " has probably prevented its use in buildings and also facilitated its exploitation for 

other purposes.

The quarry, opened before 1893, has a working face on the east 

about 1,000 feet long and from 25 to 50 feet high, averaging about 

35 feet, which in the course of excavation has receded from 450 to 

500 feet. (See PL V..)

Rock structure : A flow structure or gneiss foliation strikes N. 70° 

E. and curves vertically. The sheets, from 3 to 8 feet thick, are 

horizontal, as shown in Plate V. There is also a coarse horizontal 

shake structure spaced 0.5 to 3 inches and even 6 inches. In places 

these minor sheets are 6 inches thick over the whole face. There are 

two sets of joints: Set A, striking N. 70° E., vertical, spaced 200 to 

500 feet; set B (one only), striking N. 40°-45° E., dipping 80°. 

Rusty stain is a foot wide along the sheet surfaces.

The plant comprises fourteen 10-ton derricks, fourteen hoisting 

engines, two 20-ton locomotives, nine large and five small steam rock 

drills, two 1,500-ton double, derrick barges, and one dump scow.

Transportation is effected by a system of tracks which, starting 

near the working face, converge at the dpck where the barges are 

moored. (See PI. V.)

In quarrying, a line 150 feet long of plain drill holes is made 12 

feet back of the working face. The holes are 7 feet apart and up to 

30 feet deep, not quite penetrating the lower surface of a sheet.

1 Gillmore, Q. .A., Report on compressive strength, etc., of various kinds of building 

stone from different sections of the United Statec, etc., Engineer Dept, TJ. S. Army, 

Washington, 1874, p. 12.
00 GRANITES OF

After these have been fired a second lower tier of like holes is made*, 

and after these have been fired a third but diagonal set is made at the 

foot of the wall and inclined toward it. Both dynamite and powder 

are used. The drill holes are shown in the plate.

The product is confined to riprap for breakwaters. Material for 

the Point Judith (R. I.) breakwater was supplied from this quarry, 

and in 1907 it was furnishing stone for the New Haven breakwater.

SEYMOUR.

HOLBROOK QUARRY.

The Holbrook quarry is in Seymour Township, a mile east of the 

Naugatuck River, and near the Ansonia line. (See PL I, p. 8.) 

Operators: Seccombe Bros., Ansonia, Conn.

The granite (specimens D, XXX, 46, &, &) is a muscovite-biotite 

granite gneiss of medium marked bluish gray color, spangled with 

mica on the foliation face, and of fine-grained slightly plicated finely 

gneissose texture, with feldspars not over 0.2 inch and mostly under 

0.1 inch but with mica to 0.5 inch. Its constituents, in descending 

order of abundance, are clear bluish potash feldspar (microcline and 

less orthoclase) ; clear, colorless quartz; bluish translucent soda-lime 

feldspar (oligoclase) slightly kaolinized; muscovite (white mica); 

biotite (black mica). Secondary kaolin. No effervescence with 

muriatic-acid test.

The granite is identical in composition with that of the Potter 

quarry in Ansonia (p. 78), which lies three-fourths mile south, but 

this' is more markedly bluish. The stone glistens brightly on its 

foliation face, but its other two sides afford no contrasts. Its foliation adapts it well for all uses requiring long flat stones.

The quarry, opened about 1877, measures about 300 feet from 

southwest to northeast by 150 feet across, and from 50 to 70 feet in 

depth.

Rock structure: The gneiss foliation strikes N. 25°-30° E. and dips 

47° S., 65° E. The sheets, 2 to 5 feet thick, incompletely developed, 

dip 25°-30° E. There are three sets of joints: Set A, striking N. 75° 

W., vertical, forms a heading, at the south wall, a heading 10 feet 

wide, 75 feet north of it, and is spaced 2 to 30 feet. Set B, strikes 

N. 25° E., dips 45°-75° S., 65° E., and vertical, forms the west wall, 

and at south end undulates like sheets, and is spaced 3 to 10 and 30 

feet. Set C, undulating, strikes N. 30° E., dips 30° N., 60° W.; one 

at east side. The rift coincides with gneiss foliation and the grain 

with the same strike dips 25° W. On the east the gneiss is in contact 

with an overlying mass of biotite-quartz feldspar schist. (Seefig. 5.) 

This schist (specimens D, XXX, 46, c, d) is more or less intensely
NEW LONDON COUNTY. 91

plicated. In thin section it consists, in descending order of abundance, of quartz, biotite, microcline with orthoclase, pyrite, and 

garnet. It is probably of igneous origin. Pegmatite (of feldspar, 

smoky quartz, muscovite and black tourmaline) appears in numerous 

dikes from 6 inches to 2 feet thick. Of a set striking N. 10°-15° 

W., there are five spaced 15 to 20 feet. Another set of three striking N. 35° E. is spaced 10 to 18 feet. There is very little stain.

The plant comprises two 6-ton derricks, a hoisting engine, steam 

rock drill, steam pump, and stone crusher with capacity of 100 

tons a day, and screens with meshes 2 inches, 1 inch, and one-half 

inch.

Transportation is by cart 1£ miles to railroad at Ansonia.

The product is used for curbing, circulars, marking, and hitching 

posts, cross walks, trimmings and concrete for local demands.

Specimens: Trimmings on Fountain Hose Fire Co. building, Ansonia, and on St. Francis Parochial School, Naugatuck, Conn. The

FIGUUE 5. Section of Holbrook quarry in Seymour. -Sheet structure less regular than

drawn.

crushed stone of grades 1 and 2 is used for road and concrete foundations, of grade 3 for sideAvalks and flooring; that of a fourth grade, 

the sand sifted out of grade 3, is used for superior walks.

NEW LONDON COUNTY.

GHOTON.

SALTER QUARRY.

The Salter quarry is in Groton Township, on the Thames River, 

three-fifths mile south-southeast of the Groton ferry landing. (See 

PL I.) Operator: John Salter & Son, Groton, Conn.

The granite (specimen D, XXX, 4, «, " Westerly granite " of Rice 

and Gregory's Manual of Geology of Connecticut), Groton granite, 

is a quartz monozonite of medium, slightly greenish gray color, and 

of even-grained fine granite texture, with feldspars and slender 

micas to 0.15 inch, but mostly not over O.i inch. Its constituents,
92 GRANITES OP CONNECTICUT.

in descending order of abundance, are light-gray soda-lime feldspar 

(oligoclase) mostly kaolinized and micasized and with calcite; light 

smoky quartz with hair-like crystals of rutile; medium slightly 

greenish gray potash feldspar (microcline slightly kaolinized with 

orthoclase) ; biotite (black mica) some of it chloritized, and a little 

muscovite or bleached biotite. Accessory minerals: Magnetite, apatite, allanite. Secondary minerals: A white mica, kaolin, calcite, 

limonite, chlorite.

An estimate of the mineral percentages by the Eosiwal method, 

applied to a camera-lucida enlargement (25 diameters) of a thin 

section, yields these results with a mesh of 0.7 inch and total linear 

length of 43.4 inches:

Estimated mineral percentages m Groton quartz monzonite.

Soda-lime feldspar (oligoclase) __________________ 41.25 

Quartz ___________________________________ 38. 00

Potash feldspar (inicrocline and orthoclase)________. 16.35 

Black mica (biotite)________________________ 2.80 

Magnetite __________________________j.___ 1.60

100. 00

The average diameter of the particles calculated from the same 

measurements is 0.0235 inch.

The stone effervesces with cold dilute muriatic acid. R. C. Wells, 

a chemist of the United States Geological Survey, finds that it contains 0.18 per cent of CaO (lime) soluble in warm dilute (10 per cent) 

acetic acid, which indicates a content of 0.32 per cent of CaC03 

(lime carbonate, calcite).

This is a monumental granite closely related to the blue Westerly, 

R L, granites, but of about half as fine a texture. (See p. 95.) 

The floral carving reproduced in Plate VII, B (p. 128), shows its 

adaptation to sculpture. As in quartz monzonites generally the contrast between its polished and cut face is marked. Minute particles 

of magnetite and pyrite appear on the polished face.

The quarry, opened about 1835. measures about 550 feet in a 

northeast direction by 50 to 100 feet across and from 20 to 30 feet 

in depth. The stripping consists of 5 to 15 feet of clay and sand. 

The working face is on the east, and the west side is being filled 

with grout as the face recedes.

Rock structure: The granite forms an apparent dike, 12 feet 

thick, dipping about 20° E. between two masses of gray and black 

diorite gneiss (specimen D, XXX, 4, &, " New London granite 

gneiss," No. 35, of the State preliminary geologic map), with a 

foliation striking N. 65° W., and .dipping 75° N. 25° E., which is 

injected with pegmatite. This gneiss. consists of quartz, oligoclase, 

microcline, and hornblende, named in the usual order, The granite
NEW LONDON COUNTY. 93

sheets are short lenticular, 2 to 12 feet thick, dipping 20° SW. The 

sheets in the gneiss capping, which is 10 to 20 feet thick, are 6 inches 

to 5 feet thick and dip 15° S. There are no joints. The rift is reported as dipping about 10° NE., and the grain as vertical with 

N. 70° E. course. Niles in 1876 reported evidences of compressive 

strain at this quarry. 1

The plant comprises two derricks, a hoisting engine, and two steam 

drills.

Transportation is by cartage to wharf or rail at Groton.

The product is mostly monumental stone and some for trimmings. 

Its market is general. The gneiss is sold for breakwater use. Specimens : Monument to Col. William Ledyard (killed in battle of Groton 

Heights, 1781) in Ledyard Cemetery, Groton; monument to first four 

founders of Stonington at Wequetequock burying ground, Stonington; Edward Newman obelisk, Woodlawn Cemetery, New York; Rev. 

Byron A. Woods sarcophagus, Forest Hill Cemetery, Philadelphia; 

Charles Tyler statue, Druid Hill Ridge Cemetery, Baltimore; and the 

Kennard Celtic cross, Kensico Cemetery, Valhalla, N. Y., shown in 

Plate VII, B.

M'INTOSH QUARRY.

The Mclntosh quarry, is in Groton Township, on Broad Street 

extension, a mile northeast of Groton village, on the E. W. Crouch 

farm. (See PL I.) Operator, D. Mclntosh, 64 Belden Street, New 

London, Conn.

The granite (specimen D, XXX, 2, #, " Mamacoke gneiss," No. 36, 

of the State preliminary geologic map) is a biotite granite gneiss of 

general medium pinkish gray color and of gneissose banded texture 

with pinkish and grayish bands from 0.5 to 0.3 inch wide. Its 

particles are fine, with feldspars to 0.2 inch. Its constituents, in descending order of abundance, are light pink potash feldspar (microcline somewhat kaolinized) intergroAvn with quartz more or less 

circular in cross section; light smoky quartz; milk-white soda-lime 

feldspar (oligoclase to oligoclase-andesine) mostly much kaolinized 

and micasized and with calcite; biotite (black mica) much chloritized and a little muscovite or bleached biotite. Accessory minerals: 

Magnetite, pyrite, garnets, tourmaline, zircon. Secondary minerals: 

A white mica, kaolin, chlorite, calcite. A band of quartz and microcline is 1.12 millimeters wide. The stone effervesces with muriaticacid test. . This is an attractive stone, both on account of its delicate color and 

banded texture.

The quarry is a small opening without plant.

1 Niles, W. H., The geological ngency of lateral pressure exhibited by certain movements 

of rocks: Boston Soc. Nat, glgf. Proc,, vol. 18 (1875-6), P< 279,
94 GRANITES OF CONNECTICUT.

Rock structure: The gneiss foliation is vertical with about east to 

west course. The rift is transverse to the foliation. Both rift and 

grain fractures are smoother than those along the foliation.

Transportation is by cartage to Groton.

The product has been used for coping on a sea wall on the Plant 

estate at Eastern Point, 2^ miles south of Groton.

ECKERLEIN QUARRY.

The Eckerlein quarry is in the township of Groton, about onehalf mile east-southeast of Center Groton, near the top of a north to 

south ridge. (See PL I.) Operator, Robert Eckerlein, R. F. D., 

Groton, Conn.

The granite (specimen D, XXX, 13, «, related to " Westerly granite"), Center Groton granite, is a quartz monozonite of medium 

inclining to dark greenish gray color and of even-grained fine gran-. 

itic texture, with feldspars. and slender micas to 0.1 inch. Its constituents, in descending order of abundance, are greenish-gray sodalime feldspar (oligoclase) micasized and kaolinized and with calcite; light smoky quartz, with hairlike crystals of rutile and cavities 

in sheets, with cracks parallel thereto; slightly buff gray potash feldspar (microcline and orthoclase), some of the microcline kaolinized 

and micasized in center and also intergrown with quartz more or 

less circular in cross section; biotite (black mica), mostly chloritized 

and with needles, probably of rutile; and some muscovite or bleached 

biotite. Accessory minerals: Magnetite, apatite, allanite, rutile. 

Secondary minerals: Kaolin, white micas, calcite.

Some of the granite (specimen D, XXX, 13, 5) is of medium gray 

shade and warm tint. Its texture and constituents are like those of 

the other. The potash feldspar is, however, faintly pinkish, and 

the soda-lime feldspar (oligoclase to oligoclase-andesine) is milk 

white. Zircon is accessory. Both rocks effervesce with the muriaticacid test.

An estimate of the mineral percentages made by applying the 

Rosiwal method to a camera-lucida enlargement (25 diameters) of a 

thin section yields these results with a mesh of 0.8 inch and a total 

linear length of 45.7 inches:

Estimated nvineral percentages in Center Groton quartz monzonite.

Soda-lime feldspar (oligoclase)________________ 35.18

Quartz ________________________________ 29.90

Potash feldspar (microcline and orthoclase)__________ 29.67

Black mica (biotite)_________________________ 4.16

Magnetite ________,____________________ 1.09

100.00

The average diameter of the particles calculated from the samej 

measurements is 0.0256 inch,
NEW LONDON COUNTY. 95

These are fine-grained monumental granites, about half as fine as 

"Blue Westerly " and of different color.1

Like other quartz monzonites, these cut and hammer light, the 

cut or hammered face affording not a little contrast of shade to the 

polished face, which is darker than the rough face.

The quarry, opened in 1855, measures about 150 feet by 100 feet 

and from 25 to 40 feet in depth. The stripping consists of 5 to 14 

feet of sand and bowlders.

Rock structure: The darker granite (specimen 13, a) is 10 feet 

thick and overlies the lighter (specimen 13, 5). The sheets, 22 

inches to 13 feet thick, dip gently east and south. There are two :j 

sets of joints, set A striking N. 15° W., dipping 65° E., spaced 5 to 

50 feet; set B, striking N. 80° E., vertical, one only in center. The 

rift is reported as having a north to south course and steep eastward dip, and the grain as east to west, with steep southward dip. 

Both are equally marked. A 4-foot pegmatite dike, with feldspars up 

to 12 inches and muscovite to 6 inches, strikes N. 10° W. and dips 

50° W. The granite is slightly discolored on either side of this dike. 

Ilusty stain is 2 to 4 inches thick on sheet surfaces.

The plant comprises a hoisting engine, two steam derricks and 

siphon pipe.

Transportation is by cart 4^ miles to Groton.

The product is used for monuments. Specimens: Beckwith and 

Rogers monuments, Cedar Grove Cemetery, New London.

KOPP QUARRY.

The Kopp quarry is in Groton Township, about one-half mile 

southeast of Center Groton and one-fourth mile S. 30° W. of the 

Eckerlein quarry. Operator: Jacob K. Kopp, 2 Bishop Street, New 

London, Conn.

The granite (specimen D, XXX, 12, #, related to " Westerly 

granite ") is a quartz monzonite of medium faintly greenish gray 

color and of even-grained fine to very fine granitic texture, with feldspars and mica to 0.05 inch.

This is a monumental granite of finer texture than that of the 

Eckerlein quarry, more nearly like that of "Blue Westerly," 1 , and 

of shade intermediate between specimens a and 5 of the Eckerlein 

quarry.

The quarry opened in. 1890 is undeveloped.

The stone has been used for monuments, and cuts light.

1 Compare descriptions of " Westerly Blue " granites in Bull. U. S. Geol. Survey No. 

354, 1908, pp. 192, 1.95, 205; also description of other fine Connecticut granites on 

pp. 124 and 125 of this bulletin. ' .

97730° Bull. 4S4 11 7
96 GRANITES OF CONNECTICUT.

M'G'AUGHEY QUARRY.

The McGaughey quarry is in Groton Township, in the village of 

Mystic, one-half mile northwest of Mystic station. Operator: William R. McGaughey, Mystic, Conn.

The granite (specimens D, XXX, 20, #, &, related to " Westerly 

granite ") is a quartz monzonite of medium inclining, to dark faintly 

greenish gray color, and of even-grained fine granitic texture, with 

feldspars and mica under 0.2 inch. Its constituents, in descending 

order of abundance, are grayish translucent soda-lime feldspar (oligoclase-andesine) partly kaolinized and micasized; medium. smoky 

quartz with hairlike crystals of rutile and cavities in sheets; clear, 

colorless to faintly pinkish potash feldspar (microcline and orthoclase) intergrown with quartz more or less circular in cross section;, 

biotite (black mica), some of it chloritized, and a little muscovite or 

bleached biotite. Accessory minerals: Magnetite, pyrite, apatite, 

allanite, zircon, and purple fluorite. Secondary minerals: Kaolin, a 

white mica, calcite, chlorite. It effervesces with muriatic-acid test.

This is a monumental granite, almost as fine as " Blue Westerly " 

but with more abundant black mica and thus of darker shade. It 

cuts light gray and polishes dark gray. The polish is fair, but shows 

pyrite and magnetite. The stone is reported as " very hard."

The quarry, opened before 1827, measures about 100 feet from, east 

to west by 35 feet across with a 50-foot working face (cliff) on the 

south.

Rock structure. The granite forms an apparent dike, 25 feet thick, 

underlain by a coarse biotite granite gneiss (specimen D, XXX, 

20, d, " Mamacoke gneiss," No. 26, of the State preliminary geologic 

map) and dipping gently south into the base of the cliff, and also 

overlain near its top by a similar gneiss. The sheets, 6 inches to 5 feet

thick, but mostly under 13 inches, are about horizontal. The foliation of the gneiss dips steep north or vertical. The only set of joints 

strikes N. 40° E., dips 65° S. 50° E., forms a 10-foot heading 

in middle, and is spaced 5 to 30 feet. A vertical " blind seam," striking N. 60° E., proves to be a veinlet, -a millimeter wide, of a 

fibrous light-brownish zeolite (natrolite ?) with a more minute parallel branch, one-half millimeter away, of another zeolite near stilbite. 

This mineral has replaced some of the adjoining oligoclase-andesine 

and also sends microscopic veinlets across quartz particles. The 

granite is discolored for one-half inch on either side of the veinlet.

O

A vertical pegmatite dike strikes N. 30° W. There are also dikes 

of pegmatite and aplite in the gneiss. An inclusion of the gneiss, 4 

by 2-| feet, lies in about center of granite mass.

The plant consists of two hand derricks.

Transportation is by cartage to New York, New' Haven & Hartford 

Railroad.
NEW LONDON COUNTY. 97

The product is used for monuments. Specimen: McGaughey monument, Elmgrove Cemetery, Mystic.

EAST LYME. ' 

MALNATI PINK QUARRY.

The Malnati Pink quarry is in the township of East Lyme, 2 miles 

northwest of the Niantic station and 160 feet above it. (See PL I.) 

Operator: Angelo Malnati, 76 Liberty Street, Quincy, Mass.

The granite (specimen D, XXX, 7, a, rough; <?, polished and ham: 

mered, related to " Westerly granite "), " Golden pink Niantic," is 

a quartz monzonite of medium pinkish-gray color and of evengrained fine granitic texture, with feldspars and mica to 0.1 inch. 

Its constituents, named in descending order of abundance, are 

light smoky quartz, with hair4ike crystals of rutile and with few

cavities; quite pinkish translucent to milk-white soda-lime feldspar 

(oligoclase), considerably kaolinized, micasized, and Avith calcite; 

clear, colorless to translucent white potash feldspar (microcline and 

a little orthoclase); biotite (black mica), some of it chloritized and 

a little muscovite or bleached biotite. Both feldspars are intergrown 

with quartz more or less circular in cross section. Accessory minerals : Magnetite, apatite. Secondary minerals: Hematite from magnetite, kaolin, a white mica, calcite.

A somewhat darker granite (specimen D, XXX, 7, &), "Golden 

pink dark," from the same quarry, is of medium inclining to dark 

pinkish gray color and of the same texture and composition as the 

other, but the quartz is more smoky (section shows cavities in sheets), 

the oligoclase is more altered and darker, and zircon appears." Both 

granites effervesce with cold dilute muriatic acid.

o

An estimate, of the mineral percentages by the -Rosiwal method, 

applied to a camera-lucida enlargement (25 diameters) of a thin section, yields these results with a mesh of 1.5 inches and total linear 

length of 27 inches:

Estimated mineral percentages in Niantic quartz monzonite.

Quartz___ . _ ____ 35. 41

Soda-lime feldspar (oligoclase)_________________ 82.74

Potash feldspar (microcline and orthocla.se)_________ 29.48

Black mica (biotite)________________________ 1.93

Magnetite _ __ ___ ___ _____ . 44

100.00 

The average diameter of the particles, calculated from -the same

measurements, is 0.0275 inch.

These granites are reddish monumental granites of about half the

grade of fineness of " Blue Westerly." Owing to streaks which are
98 GKANITES OF CONNECTICUT.

said to appear on large polished faces, the stone is used chiefly for 

rough and hammered or carved work, but is admirably adapted for 

inscriptions, the light pinkish gray hammered face contrasting 

strongly with the reddish-brown polished face (specimen 7, e).

The quarry, opened in 1900, measures about 250 feet from east to 

west by 65 feet across and 75 feet in depth.

Rock structure: The granite occurs in a dike-like mass, 40 feet 

thick, dipping about 20°, between a lower and an upper1 mass of 

gneiss, which has a foliation striking N. 30° E., and dipping 50° 

S. 60° E. This ("Mamacoke granite gneiss," No. 36, of the State 

preliminary geologic map) is a biotite granite gneiss of medium, 

slightly pinkish gray color and of medium gneissose texture. Its 

quartz is light smoky with cavities in sheets; its feldspars are lightpink microcline and orthoclase and milk-white oligoclase. The overlying mass is 20 feet thick and is more altered and weathered, its 

feldspars having largely passed into crystalline kaolin, making the 

rock very friable. The granite sheets, 3 to 10 feet thick, are short, 

irregular lenses. There are two sets of joints: Set A, striking N. 

5°-10° W., vertical, is spaced 3 to 15 feet; set B, striking east-west, 

vertical, is spaced 3 to 15 feet. The rift is reported as north-south 

and the grain as east-west, both vertical and of like fissility. Rusty 

stain is 2 to 4 inches thick on sheet surfaces.

The plant comprises two derricks, a hoisting engine, a steam drill, 

a vertical polisher and engine for same, and two steam pumps.

Transportation is by cart over 2 miles to Niantic.

The product is used for monuments, which are finished at Quincy, 

Mass. .

CARLSON QUARRY.

The Carlson quarry is in the township of East Lyme, about 2 

miles north west of Niantic station, and about 600 feet southwest of the 

Malnati quarry. (See PL I.) Operator: The Golden Pink Quarry 

Co., Peter M. Carlson, proprietor, Niantic, Conn.

The granite, " Golden pink," is a quartz monzonite of medium 

pinkish gray color and of even-grained very fine granitic texture, 

identical in composition and qualities with that of the Malnati 

quarry, described on page 97.

The quarry, opened in 1900, measures about 125 by 75 feet, and 

from 10 to 30 feet in depth.

Rock structure: The granite occurs in a dikelike mass, 40 feet 

thick, dipping about 30° south between masses of biotite granite 

gneiss identical with that at the Malnati quarry. The foliation of the 

overlying gneiss, which is 20 feet thick, strikes N. 80° W. and dips 

25°-30° N. 10° E. The granite sheets, up to 10 feet thick, are short 

shelly lenses with irregular dip. There are two sets of joints: Set A, 

striking N. 40°-55° E., curving certically, is spaced 5 to 12 feet; set
LONDON COUNTY. 99

B, striking about north, vertical, forms a heading at east side and 

one or two at west side. One pegmatite dike only.

The plant comprises one hand and one steam derrick and engine, 

and a steam pump.

Transportation is by cart 2 miles to Niantic.

The product is used for monuments.

% L LYME.

*.'.) JOSHUA ROCK QUA Kill

The Joshua Rock quarry is in Lyme Township at Joshua Rock on 

the east shore qf; Connecticut River, 2 miles north of Essex Wharf. 

(See PI. I, p. 8.) Operator: Joshua Rock Granite Co., care of C. E. 

Pratt, Essex, Conn.

The granite (specimens D, XXX, 17, <z, 6, " Lyme granite gneiss,'

No. 34, of the State preliminary geologic map), variegated granite, 

is an aegirite granite gneiss of general medium inclining to dark 

slightly purplish gray color with fine reddish, pinkish, greenish, and 

black bands also cherry-reddish spots. Its texture is fine gneissose, 

banded with -feldspar and black silicate under 0.2 inch. Its cdnstituents, named in .descending order of abundance, are clear, colorless to 

dense pinkish potash feldspar (microcline) more or less kaolin ized 

and coarsely intergrown with quartz; light smoky quartz with cavities in sheets and cracks parallel thereto; milk-white soda-lime feldspar (oligoclase-albite) more or less kaolinized; and black aegirite 

(green in thin section). Accessory minerals: Magnetite (or ilmenite), titanite, yellow colophonite (lime-iron garnet), these three in 

some abundance, and zircon, allanite. Secondary minerals: Hematite and limonite stain, calcite, kaolin. There is no effervescence with 

muriatic acid test. The banding is due to the varying abundance or 

absence of segirite, or the preponderance of quartz or feldspar in 

parallel planes. The quartz and feldspar are stained cherry red from 

hematite either evenly in bands or else in irregularly disseminated 

spots.

The quarry is on. the west side of a cliff over 60 feet high, which is 

the working face.

Rock structure: The gneiss foliation strikes N. 75°-80° W. and 

dips 45° N. 10°-15° E. There are passages of biotite and other black 

silicates (dikes or knots?) 1 to 3 feet thick (specimen D, XXX, 17, c). 

Vertical joints strike north.

The quarry has not been in operation for several years.

SELDEN NECK QUARRIES.

The Selden Neck quarries are in Lyme Township, on Selden Neck, 

on the east shore of Connecticut- River, opposite Deep River station 

(See PI. I.) Owner, j|L W. Parker Co., 361 Fulton Street, New 

York.
100 GRANITES OF CONNECTICUT.

The granite (specimens D, XXX, 15, &, 6, " Mamacoke gneiss." 

No. 36, of the State preliminary geologic map) is a hornblendebiotite granite gneiss of medium inclining to dark reddish gray color 

streaked with black, and of fine gneissose texture with lenses and 

laminae of black silicates 0.1 to 0.2 inch apart, and with feldspar 

particles under 0.1 inch. Its constituents, named in descending order 

of abundance, are reddish gray potash feldspar (orthoclase and less 

microcline) ; light smoky quartz, with cavities in sheets; a little 

reddish gray soda-lime feldspar (oligoclase); greenish hornblende; 

biotite (black mica). Accessory minerals: Apatite', zircon. Secondary minerals: Hematite, limonite, kaolin, calcite. Both feldspars are somewhat kaolinized. The stone effervesces slightly with 

muriatic-acid test.

1 This is a fine-grained reddish constructional granite with conspicuous bright black streaks and lenses, but without other mineral 

contrasts.

There are two quarries: A southern one, east-southeast of Deep 

River station, and a northern one due east of it. The former measures about 250 by 40 feet, with a working face on the east. The 

other, about one-fourth mile west-northwest of it, measures about 

200 feet from east to west, with a working face on the north 60 

feet high.

Rock structure: At the south quarry the gneiss foliation strikes 

N: 80°-85° E. and dips 20°-25° N. 5°-10° W. The sheets, 1 to 3 

feet thick, dip with the foliation. There are four sets of joints: Set 

A, striking N. TO0 E., dipping 75° S. 20° E. is spaced 2 to 5 feet; 

set B, striking north, vertical, is spaced 2 to 5 feet; set C, striking 

N. 40° E., is vertical; set D, striking N. 75°-80° W., dips 30° S.

10°-15° W. At the northern opening the gneiss foliation strikes N.

75° E. and dips 25° N. 15° W. The sheets, 2 to 6 feet thick, dip with 

the foliation. There are two sets of joints: Set A, striking N. 50° E., 

vertical; set B, striking N. 10° E., vertical or steep east, forming an 

8-foot wide heading at east edge of quarry. Pegmatite dikes, 1 inch 

to 2 feet thick, dip low northeast. The rift at both quarries is parallel to the long axes of the lenses and at right angles to the gneiss 

foliation. The grain is parallel to that foliation and the hardway 

is transverse to it and to the lenses.

These quarries were not in operation in 1908 and had evidently 

been idle for a number of years. Transportation was by cart or car 

one-fourth mile to dock.

OLD LYME. 

MACCUEDY QUARRY.

The MacCurdy quarry is in the township* of Old Lyme, on Duck 

River, between Lyme village and the Lyme & Blackball station.
NEW LONDON COUNTY. 101

 (See PI. I.) Owner, Mrs. Evelyn MncCurdy Salisbury, 237 Church 

Street, New Haven, Conn.

The granite (specimens D, XXX, 49, £>, <?, d, the last being a polished cube with edges 3.5 inches), MacCurdy granite, is a pegmatite 

with the composition of a biotite granite. Its general color is medium pinkish-reddish gray spotted with black. Its texture is very 

coarse porphyritic with feldspars to 1.5 inches (exceptionally *to 4.5 

inches) and mica mostly under 0.5 inch (exceptionally to 1 inch). 

Its constituents., named in descending order of abundance, are pinkishreddish potash feldspar (orthoclase and microcline, both minutely 

intergrown with oligoclase) somewhat micasized; light to medium 

smoky quartz with cavities in parallel or intersecting sheets; light 

pinkish to cream-colored and milk-white, rarely clear, striated sodalime feldspar (oligoclase), generally micasized; and biotite (black 

mica), some of- it chloritized. Accessory minerals: Magnetite,

pyrite, apatite quite a little, and zircon. Secondary minerals: White 

micas, calcite, hematite, chlorite. 1

. The stone effervesces with cold dilute muriatic acid. R. C. Wells, 

a chemist of the United States Geological Survey, finds that it contains 0.46' per cent of CaO (lime) soluble in warm dilute of 10 per 

cent acetic acid, which indicates a content of 0.82 per cent of CaCO 

(lime carbonate, calcite), the presence of which mineral is also shown 

by the microscope.

W. P. Blake, in 1880, determined the specific gravity of the reddish 

feldspar as 2,580 and that of the granite as 2,643, and the weight of 

a cubic foot of it as 165.2 pounds, or 12.106 cubic feet to 2,000 pounds.

The contrasts between its minerals, the cleavage planes of the large 

porphyritic feldspars reflecting the light, the iridescence of some of 

the feldspars and the attractiveness of its general color make this an 

unusual rock. The polished face brings out the colors still more 

strongly. It is well adapted in the rough for monumental use. and. 

when polished, for internal decorations. Between 1871 and 1881 this 

pegmatite was brought to the attention of and examined more or less 

thoroughly by James D. Dana,' A. Daubree, Des Cloiseaux, G. W. 

Hawes, W. P. Blake, and C. U. Shepard, and specimens of it were 

exhibited at the expositions of Philadelphia, 1876, and Paris, 1878. 

Prof. Newberry referred to it in his Tenth Census Report on buildiiig 

stones.2

TQhe quarry, not worked for a number of years, measures about 50 

by 30 feet and from 5 to 10 feet in depth from the present ledge 

surface.

1 This granite was first examined microscopically by Des Cloiseaux, who regarded the 

feldspar intergrown with the microcline as albite. See Am. Jour. Sci., 3d ser., vol. 20, 

3880, p. '335.

2 Vol. 10, 1884, p. 321.
102 * GEANITES OF CONNECTICUT.

Rock structure: Several dikes of the pegmatite, 15 to 22 feet thick, 

have penetrated a mass of banded gneiss parallel to its foliation, 

which strikes N. 50°-60° E. and dips 40° to 45° N., 30° E. 

At one point the pegmatite apparently crosses the foliation of 

the gneiss horizontally. The gneiss (specimen D, XXX, 49, a, 

" Lyme granite gneiss," No. 34, of the State preliminary geologic 

map) is a biotitic quartz monzonite gneis? of medium inclining to 

dark gray color with fine bands of various gra.ys and of fine gneissose 

texture, with particles under 0.2 inch and bands from 0.1 to 0.3 inch. 

The constituents of the bands crossed, by one thin section are, in the 

usual order, quartz with cavities in many parallel sheets, with rift 

cracks parallel thereto, some of them filled with fibrous muscovite, 

also with a set of sparser and finer cracks at right angles to the first 

set (the rift coincides with the foliation of the rock) ; oligoclase, 

orthoclase, and biotite.

Transportation is by cart about one-half mile to New York, New 

Haven & Hartford Railroad.

Product: The Channing Memorial Church, with its steeple, at 

Newport, R. I., was built of this stone in 1881. The trimmings, 

however, were of light and dark gray granite.

STONINGTON.

MASONS ISLAND QUARRY.

The Masons Island quarry is in the toAvnship of Stonington, at 

the northwest end of Masons Island, on Pine Hill. (See PI. I.) 

Operator: E. S. Belclen & Sons, Hartford, Conn.

The granite (specimens D, XXX, 21, <z, " Mamacoke gneiss," No. 

36, of the State preliminary geologic map) is a quartz monzonite 

flow gneiss of banded light and dark gray shade. Its texture is 

even grained, fine banded, with feldspars under 0.2 inch and mica 

under 0.1 inch. Its constituents, named in descending order of abundance, are pale smoky quartz, with cavities in sheets, milk-white sodalime feldspar (oligoclase, probably), some of it micasized; clear, 

colorless potash feldspar (microcline, probably a little orthoclase 

also) ; biotite (black mica).' Accessory minerals: Magnetite, garnet, 

allanite, zircon.

The quarry, opened in 1880, measures about 200 feet from east 

to west, with a working face 30 to 60 feet high on the north. The 

stripping consists of 7 feet of gravel.

Rock structure: The rock appears to be a granite with flowage 

bands caused by the different distribution of the biotite in parallel 

bands. The banding dips low west. There are lenses of coarse pegmatite (white and pink feldspar and biotite) parallel to the bands. 

There are also dikes of this pegmatite, some vertical, some dipping
NEW LONDON COUNTY. 103

southeast, others northwest. 1 The sheets, 6 inches to 4 feet thick, are 

horizontal. One joint only, strike about east-west.

The plant comprises three derricks, three hoisting engines, a cable 

engine, and three large rock drills.

Transportation is by a 450-foot track to clock on Mystic Harbor.

The product is used entirely for riprap for breakwater construction 1 (Port Jefferson breakwater and*others).

NEW ANGUIIVI.A QUARRY.

The New Anguilla quarry is in the township of Stonington, a mile 

east of Anguilla Creek, and 1^ miles west-northwest of the Westerly, 

R. I., station. (See PL I.) Operator: Morrison Granite Co., 48 

Morgan Street, Westerly, E. I.

The granite (specimen D, XXX, 19, &), "New Anguilla," is a 

quartz monzonite of medium slightly bluish gray shade and of evengrained fine granitic texture with feldspars under 0.1 inch and mica 

under 0.05 inch. Its constituents, named in descending order of 

abundance, are light, smoky quartz with cavities; milk-white sodalime feldspar (oligoclase) much kaolinized, micasized and with calcite; in about equal amount slightly bluish gray potash feldspar 

(microcline and orthoclase) intergrown with quartz more or less circular in cross section; biotite (black mica), some of it chloritized, and 

a little muscovite or bleached biotite. Accessory minerals: Titanite, 

apatite, magnetite, purite, zircon. Secondary minerals: Kaolin, a 

white mica, calcite. The stone effervesces with cold dilute muriatic 

acid.-

This is a monumental granite resembling " Blue Westerly" in 

color and texture. 2 Like other quartz monzonites, it cuts and hammers light.

The stone from another opening (specimen D, XXX, 19, c) is of 

light buff inclining to medium gray color and of even-grained, 

medium texture, with feldspars to 0.25 inch and mica under 0.1 inch. 

It consists of cream-colored feldspar, medium smoky quartz, and 

black mica. It effervesces with muriatic-acid test. This is hardly 

suitable for monumental use.

The quarry, but recently opened, measures about 100 feet from 

east to west by 30 feet across and averages 4 feet in depth. Another 

opening 500 feet south is 40 feet by 20 and 5 to 8 feet deep.

Hock structure: The bluish-gray quartz monzonite has a capping 

of gneiss 3 to 5 feet thick. This (specimen D, XXX, 19, a), probably " Putnam gneiss " of Rice and Gregory,3 is a biotite granite

1 .T. F. Kemp described this pegmatite in his Granites of southern Rhode Island and 

Connecticut: Bull. Geol. Soc. America, vol. 10, .1890, pp. 373, 374.

2 See Bull. U. S. Geol. Survey No. 354, p. 195.

3 Manual of the geology of Connecticut: Bull. Connecticut Geol. and Nat. Hist. Survey 

No. G, 1906, p. 132.
104 . GKANITES OF CONNECTICUT.

gneiss of medium gray shade, finely banded with dark gray, and of 

fine to very fine implicated gneissose texture with feldspars under 

0.1 inch and mica under 0.05 inch. Its constituents, named in the 

usual order, are microcline5 quartz, oligoclase, biotite with accessory 

magnetite, apatite, zircon, allanite. The foliation strikes nearly 

east to west and dips 5° N. to vertical. The contact between granite 

and gneiss is in places very jagged or bordered with 12 inches of 

pegmatite and aplite, which also penetrate the gneiss. The granite 

sheets, 6 inches to 5 feet thick, are not yet fully exposed. There are 

three sets of joints: Set A, striking from east to west, vertical; B, 

striking north to south, vertical and discontinuous; set C (one only), 

striking N. 60° W., dipping 55° S. 30° W. The rift is reported as 

horizontal and the grain and hardway as equally fissile. The flow 

structure dips 25° S. At the south opening a dike or band of the 

quartz monzonite, 10 feet wide, has the medium-grained granite, described on page 103, on both sides of it. Flow structure dips 50°-70° S.

Transportation involves cartage of about 2 miles to Westerly, R. I.

The blue-gray quartz monzonite will be used for monuments.

MURRAY QUARRY.

The Murray quarry is in the village of Pawcatuck, in the township 

of Stoningtpn, about three-fourths mile northwest of Westerly 

station. (See PI. I.) Operator, A. Murray & Co., Westerly, R. I.

The granite (specimen D, XXX, 18, <z, " Sterling granite," No. 24, 

of the State preliminary geologic map), " Red Westerly," is a biotite granite of dark inclining to medium reddish gray color and of 

even-grained, granitic medium inclining to coarse texture, with feldspars to 0.4 inch (exceptionally 0.5 inch) and mica to 0.2 inch, but 

mostly under 0.1 inch. Its constituents, named in descending order 

of abundance, are reddish potash feldspar (microcline and orthoclase) slightly kaolinized; amethystine smoky quartz with cavities 

in sheets; cream-colored striated soda-lime feldspar (oligoclase to 

oligoclase-albite) much kaolinized and micasized, in places stained 

red from hematite; biotite (black mica) some of it chloritized, and 

a little muscovite or bleached biotite. Accessory minerals: Magnetite, 

P3'rite; .apatite, allanite, zircon. Secondary minerals: White micas, 

kaolin, chlorite, calcite, limonite from allanite, hematite from magnetite. There is marked effervescence with cold dilute muriatic acid.

This a brilliant constructional granite of attractive tint. Its mineral contrasts are confined to those between its black mica, pink and 

cream-colored feldspars. The stone is identical with that of the Redstone quarry at Westerly, R. I., which contains 35.40 per cent of 

potash feldspar, 29.87 per cent of quartz, 28.35 per cent of soda-lime 

feldspar, and 6.74 per cent of black mica.1

1 See Bull. U. S. Geol. Survey No. 354, p. 200.
NEW LONDON COUNTY. 105

The acetic acid test of that granite shows 0.25 per cent of CaO 

(lime) or 0.446 per cent of CaOO3 (lime carbonate). This one contains fully as much, if not a little more, CaCO3 .

Another biotite granite (specimen D, XXX, 18, &) from the same 

quarry is of dark inclining to medium slightly reddish gray. It is 

a little darker and less reddish than the above. Its texture is evengrained medium, with feldspar to 0.3 inch and mica to 0. inch. Its 

constituents are like those of the other, but the soda-lime feldspar 

is of greenish-gray color. The effect of this and of the finer texture 

of the stone is to darken its general shade.

The quarries, opened about 18%9, are two, a northern one, measuring about 150 by 75 feet, with a 40-foot working face on the west, 

and a southern one, separated from the other by a 50-foot mass, and 

consisting of two 50-foot square openings, one east of the other.

Rock structure: The sheets, 2 to 10 feet thick, dip gently north and,

at south end, west. Joint, flow, grain, and dike courses are shown in 

figure 6. Joint set A dips 65° N; 

30° W., is spaced 4 to 20 feet and 

over; set B is vertical, reddish, 

coated with epidote, forms east 

 and west walls, is spaced 2 to 20 

feet. Flow structure dips 60° 

N. The rift is reported as horizontal and grain vertical. The 

unquarried mass between the two 

quarries and about 10 feet of the 

south end of the northern quarry 

consist of the finer darker granite (specimen Z>), which constitutes a dike Or band. Dikes of FrouitK O. Structure at Murray quarry,

pegmatite (specimen D, XXX, Pawcatuck, stonington. 

18, G of pink and cream-colored feldspars, smoky quartz, biotite, 

and allanite, with aplite), some of it very coarse, dip 50° S. 30° 

W. and measure up to 6 inches thick. There is a milky quartz 

lens or dike a foot thick. A 5-inch geode, lined with crystals of 

pyrite, was found. Rusty stain in places to 9 inches thick averages 

about 2 inches on sheet surfaces.

The plant comprises two derricks, a hoisting engine, a steam rock 

drill, an air compressor (capacity,- 75 cubic feet of air per minute), 

two air plug drills, and a steam pump.

Transportation is by cartage of a mile to railroad at Westerly, R. I.

The product of the main quarry (specimen a) is used for building 

and trimming. That of the smaller (5) for monuments. Specimens: 

Trimmings on building at northwest corner of Broadway and Fourth
106 GRANITES OF CONNECTICUT.

Street, New York; trimmings on addition to Providence Hospital 

(1905-6) ; trimmings oh State armory, Westerty, E. I.

AVATERFORD. 

SCOTT QUARRY.

The Scott quarry is in Waterford Township, 3 miles north of New 

London, on Bolles Hill, about half a mile south of Quaker Hill village. (See PI. I, p. 8.) Operator: W. F. Scott, E. F. D., Waterford. 

Conn.

The granite (specimen D, XXX,, 9, &, " Mamacoke gneiss," No. 36, 

of the State preliminary geologic map) is an aegirite granite gneiss 

of medium pinkish-purplish gray color and of very fine slightly 

gneissose, in places banded, texture, with feldspars under 0.1 inch 

(rarely to 0.15 inch) and black silicate under 0.05 inch. Its constituents, named in descending order of abundance, are grayish-pinkish 

potash feldspar (microcline and orthoclase) intergrown with sodalime feldspar (oligoclase-albite) and somewhat kaolinized; light 

smoky quartz with cavities in sheets; a little separate soda-lime feldspar of the same kind; black segirite (green in thin section). Accessory minerals: Magnetite, titanite. Secondary minerals: Kaolin and 

hematite stain. No effervescence with muriatic-acid test.

A specimen (D, XXX, 9, a] of a part with alternating black, gray, 

and reddish plicated bands from 0.1 to 0.3 inch wide, shows the same 

minerals with zircon, but the soda-lime feldspar is albite or oligoclasealbite and all separate. Some of the bands are largely quartz, others 

largely feldspar, still others mainly segirite.

The quarry, opened in 1898, measures 150 feet along the highway 

by 50 feet from it and averages 5 feet in depth, with a woring face

20 feet high at the back.

Eock structure: The sheets, 1 to 4 feet thick, are about horizontal. 

Two sets of joints occur at rare intervals: Set A, striking N. 10° W., 

dips 60° W.; set B, striking N. 65° E., dips vertical. The gneiss 

foliation strikes N. 10° W. and N. 20° E. and dips eastward. At one 

point this is sharply plicated along the strike. The rift is reported as vertical east to west, and the grain as vertical north to 

south. Dikes or lenses of pegmatite and aplite, to 2 feet thick, 

run with the foliation.

The plant comprises a hand derrick.

The product is underpinning, curbing, trimmings, steps, and paving. The quarry is worked only occasionally.

RICHARDS QUARRY.

The Eichards quarry is in Waterford Township, 3 miles north of 

New London, and about 700 feet west of the Scott quarry. Operator: 

N. A. Eichards, E. F. D., Waterford, Conn. ,
NEW LONDON COUNTY. 107

The granite is an segirite granite gneiss identical with that of the 

Scott quarry, described on page 106.

The quarry at the top of a knoll is small and has not been worked 

for two or three years.

Eock structure: The sheets> 1 to 4 feet thick, dip low east and 

northeast. There are few pegmatite dikes and some quartz veins.

The plant comprises two hand derricks.

3 Miles

Contour interval 40 feet

FIGUUE 7. Map of granite quarries in south part .of Waterforcl. 1, Flat Uock-quarry ; o, 

Goos ; 5, Waterforcl; 0, Millstone ; 14, Somers.

FLAT ROCK QUAIHIY.

The Flat Rock quarry is in Waterforcl Township, about 3 miles 

northwest of New London, on Flat Rock. (See PI. I and lig. 7.) 

Operator: J. J. Ryan, 105 Blackball Street, New London, Conn.

The granite (specimen D, XXX, 1, a, " Mamacoke gneiss," No. 

36, of the State preliminary geologic map) is an a^girite granite 

gneiss of dark, inclining to medium, very faintly purplish gray color 

and of medium-grained gneissose texture, with feldspars to 0.3 inch
108 GKANITES OF CONNECTICUT.

and black silicate under 0.1 inch. Its constituents, in descending 

order of abundance, are medium smoky quartz, with cavities in 

sheets; milk-white potash feldspar (orthoclase and less microcline), 

coarsely intergrown with soda-lime feldspar (oligoclase); separate 

milk-white oligoclase; black segirite (green in thin section). All 

the feldspars much kaolinized. Accessory minerals: Magnetite, 

titanite, zircon, apatite. Secondary minerals: Kaolin, hematite, and 

limonite stain from the magnetite and segirite. No effervescence 

with muriatic-acid test.

Specimen D, XXX, 1, 6, from this quarry, is of medium inclining 

to dark pinkish gray, and of fine grieissose texture, with feldspars to 

0.2 inch (mostly under 0.1 inch), and black silicate to 6.2 inch. Its 

constituents are like those of 1, a, but the second feldspar is oligoclase-andesine or oligoclase. The pinkish tinge is due to more abundant hematite from the magnetite particles.

These granites are devoid of contrasts and brilliancy. One is 

nearly smoke colored, the other pinkish.

The quarry is about 100 feet square by 10 to 20 feet deep.

Rock structure: The gneiss foliation strikes N. 50°-55° W. and 

dips 30° S. 40° W. Joints of set A strike N, 10° E., dip 75° E., and 

are spaced 10 to 30 feet. Those of set B striks N. 8° W., dip 75° S., 

and are spaced 10 to 30 feet. The rift is reported as horizontal.

The plant comprises a derrick and small hoisting engine.

Transportation is by cart 3 miles to New London.

The product is used for trimmings, curbing, and paving. Specimens: Trimmings on Harbor School and on First Congregational 

Church, Groton.

GOOS QUARRY.

The Goos quarry is in Waterford Township, 2^. miles northwest of 

New London. (See fig. 7.) Operator: Charles Goos, 46 Ashcraft 

Eoad, New London, Conn.

The granite (specimen D, XXX, 3, a, " Mamacoke gneiss," No. 36, 

of the State preliminary geologic map) is an a3girite granite gneiss 

of medium buff gray color, and of fine inclining to medium-gneissose 

texture, with feldspars and mica to 0.2 inch. Its constituents, named 

in descending order of abundance, are clear, colorless potash feldspar, microcline, and orthoclase, the former coarsely intergrown with 

soda-lime feldspar and slightly kaolinized; pale, smoky quartz with 

cavities in sheets; cream-colored soda-lime feldspar (pure albite) ; 

black segirite (green in thin section). Accessory minerals: Magnetite (fifth in order of abundance), titanite, allanite, zircon. Secondary minerals: Kaolin, hematite^ and limonite stain from magnetite 

and segirite. No effervescence with muriatic-acid test.
NEW LONDON COUNTY. 109

This is a dull grayish foliaceous stone, with fine dark particles and 

sparse cherry reddish stains.

The quarry, begun in 1897, consists of two small openings.

Eock structure: A marked gneiss foliation strikes N. 80° W. and 

dips 65° N. 10° E. Imperfectly developed sheets, 2£ to 4 feet thick, 

dip gently west. There are three sets of joints: Set A, striking north, 

vertical to steep east, are spaced 2 to 30 feet; set B, coinciding with 

the foliation, are spaced 12 to 15 feet; set C, striking N. 50° E., 

occur at irregular intervals. The rift is reported as horizontal and 

 the grain as parallel to the foliation.

The plant consists of a hand derrick.

Transportation is by cart 2-| miles to New London.

The product is used for coping, facing, and steps.

MILLSTONE. QUARRY.

The Millstone quarry is in Waterford Township, on Millstone 

Point, 5 miles southwest-of New London. (See PL. I and fig. 7.) 

Operator, Henry Gardiner, Millstone, Conn.

The granite (specimens D, XXX, 6, a, &, &, polished, d> e, rough, 

related to " Westerly granite " of Rice and Gregory), " Millstone 

granite," is a quartz monzonite between medium and dark gray, 

smoke colored, and of even-grained granitic, fine texture, with feldspars to 0.2 inch, but mostly under 0.1 inch, and mica to 0.1 inch. Its 

constituents, named in descending order of abundance, are: Whitish 

to buff striated soda-lime feldspar (oligoclase-albite), much of it 

kaolinized and micasized and intergrown with quartz circular in 

cross section; translucent gray, potash feldspar (microcline and a lit-, 

tie orthoclase), little altered; medium smoky quartz, with some cavities in sheets; biotite (black mica), some of it chloritized, and very 

little muscovite or bleached biotite. Accessory minerals: Magnetite 

(fifth in abundance), allanite (sixth in abundance), pyrite, apatite, 

zircon. Secondary minerals: Kaolin, a white mica, limonite from 

allanite, calcite, chlorite.

An estimate of the mineral percentages by the Kosiwal method, 

applied to a camera-lucida enlargement (25 diameters) of a thin section, yields these results with a mesh of 1.7 inches and total linear 

length of 40.8 inches:

Estimated mineral content of Millstone quarts monzonite.

Soda-lime feldspar (oligoclase-albite)______________ 34.22 

Potash feldspar (microcline and orthoclase)______^_ 31.81 

Quartz__________________:_________________ 25.54

Black mica (biotite)J_______________.______ 7.21

Magnetite _________..____________________ . 93

Allanite_________________________________ .29

100. 00
110 GKANITES OF CONNECTICUT.

The average diameter of the particles calculated from the same 

measurements is 0.0354 inch.

This granite effervesces somewhat freely with cold dilute muriatic 

acid. K. C. Wells, a chemist of the United States Geological Survey, finds that it contains 0.31 per cent, of CaO (lime), soluble in 

warm dilute (10 per cent) acetic acid, which indicates a content of 

0.55 per cent of CaCO3 (lime carbonate, calcite), the presence of 

which mineral is also shown by the microscope. 

. A transverse test (No. 9764) made at the United States arsenal 

at Watertown, Mass., in 1896, on a piece of this granite 18 inches 

long by 1.02 by 1.02 inches and with 15 inches between end supports, 

gave a modulus of rupture of 2,029 pounds, the piece breaking under 

138 pounds.

This is a brilliant, somewhat fine-grained, smoke-colored monumental and .inscriptional granite without mineral contrasts excepting on close inspection. Its texture is about one-third as fine as 

that of the coarser " Blue Westerly " granite (New England Granite 

Works quarry, 0.0112 inch).

It takes a high polish, but the polished face shows magnetite and 

some pyrite. It hammers and cuts medium gray, thus affording a 

marked contrast of shade to the polished face, which is dark gray.1

A pinkish variety (specimen D, XXX, 6, «), "Millstone Pink," 

no longer quarried, is a quartz monzonite of medium inclining to 

dark slightly pinkish gray, with unevenly distributed cherry-red 

stains. Its texture is a trifle coarser, the feldspars and mica mostly 

under 0.15 inch. Its composition is identical with that of the other 

but includes secondary hematite, which causes the cherry-red spots.

The quarry, opened in 1830, measures .about 800. feet in a N. 

40° W. direction, with a width varying from about 150 to 300 feet 

Owing to two embayments on the northeast wall, and has a depth 

of 50 to 150 feet.2

Eock structure: The granite is capped on the northeast wall by 

several masses of gneiss up to 25 feet thick with a foliation striking N. 70° W., and dipping 25° N. 20° E. At the shore south 

the same gneiss strikes N. 85° E. and dips steep north with pegmatite dikes 2 to 3 feet thick. The plane of contact between the 

granite and the gneiss remnants is in places vertical, in others horizontal or gently inclined, the original complete outline of that plane 

having evidently been very irregular. In the central embayment 

15 to 20 feet of granite overlie a sagging strip of the gneiss 5 to 10

1 J. S. Newberry in 1884 described it as " a dark-gray granite of fine, homogeneous 

texture, -showing strong contrast of color between polished and dressed surfaces." Teath 

.Census U. S., vol. 10, 1884, p. 321.

- See Kemp, op. cit., XXXVI, fig. 2, for a view of the quarry as it appeared between 

1888 and 1898.
NEW LONDON COUNTY. Ill

feet thick. Large dikes of pegmatite, starting at the contact, penetrate the gneiss and in places the gneiss is cut up by an intricate network of pegmatite and aplite dikes. The gneiss (specimen D, XXX, 

6, /, " Mamacoke gneiss," No. 36, of the State preliminary geologic 

map) appears to be a black and white banded biotite granite gneiss 

of fine to medium texture. The granite sheets, lenticular, normal, 

and mostly 2 to 8 feet thick, but 6 to 12 inches in the upper 20 feet 

of the southeast end and 6 inches to 2 feet in the upper 15 feet; 

of central northeast side, dip 20° N. 

65° E. There are two sets of joints: 

Set A, striking N. 40° W., vertical, 

forming parts of the northeast and 

southwest Avails and a 30-foot heading at the north-northwest corner is 

spaced 6 inches to 33 feet but mostly 

3 to 10 feet; set B, striking north to 

N. 10° E., vertical to steep west, occurs at greater and irregular intervals. A little sea water enters the 

quarry at the bottom through some 

of these joints. Flow structure, indicated by biotitic bands, strikes N. 

45°-60° W. and dips 30° SW., but 

near the northwest end of quarry the 

bands are tortuous, doubling over on 

themselves, as shown in figure 8, c. 

A block in the storage yard with a 

concentric structure of this kind probably formed part of a turn in one of 

these granite currents. The rift is 

reported as dipping 5°-10° N. 80° E., 

and the grain as vertical, with N. 65° 

' E. course. Pegmatite and aplite dikes 

dip 30° both northwest and southeast 

at intervals of 3 to 10 feet, . One with 

large biotite crystals strikes N. 55° E. 

There are many inclusions. One of 

banded biotite gneiss, 20 by 8-J inches (fig. 8, 5). Another of the 

same gneiss, 20 by 20 feet, has a very irregular outline, Avith 

small outlying fragments, and adjoins a 6 by 3 foot mass of pegmatite Avith particles to 5 inches across. This mass and a smaller 

inclusion are shown in .figure 8, d. The granite is someAvhat banded 

about the large inclusion. Another, near the northwest end and bottom of quarry, measures 35 by 25 feet. It is a black diorite gneiss97730°_BuII. 484 11 8

-7 feet 2 inches - 

d

FIGURE 8. Details at Millstone quarry, 

(a) A'ertical section of pegmatite 

dike in quart/, monzonite, with inclusions of biotite gneiss (after a 

photograph by E. F. Burchard, U. S. 

Geol. Survey) ; (b), horizontal section of inclusion of biotite gneiss, 

20 by 8.5 inches, partly surrounded 

with pegmatite, in quartz monzonite; 

(c), vertical section of tortuous flow 

structure, consisting of biotite 

sheets; (d), horizontal section of inclusion of gneiss associated with 

very coarse pegmatite in quartz monzonite.
112 GKANITES OF CONNECTICUT.

(specimen D, XXX, 6, k) consisting of oligoclase-andesine, hornblende, quartz, and biotite, with accessory titanite. It is crossed by 

quartz veins, some of which start at the granite, others within the 

granite. A vertical pegmatite dike, 3 to 5 feet wide, in the upper 

granite mass referred to, contains an inclusion of biotite gneiss about 

5 feet by 6 inches, with its long axis in vertical position. (See fig. 

8, a.) Rusty stain is about 2 inches thick on sheet surfaces. Niles in 

1876 mentioned the crushing of channel cores and cramping of drills 

at this quarry by northeast-southwest compression.1

The plant comprises two derricks, one of them with a 110-foot 

mast and capacity of 50 tons, two hoisting engines, two Blondin carriers and engines, a locomotive crane, a locomotive, an air compressor (capacity under 500 cubic feet of air per minute) four large rock 

drills, twelve air hand tools, a surfacer, lathe for stones 30 by 2 feet, 

a polishing lathe, four vertical polishers, two steam pumps, a stone 

crusher (capacity 50 cubic yards a day), and a 75-horsepower steam 

engine.

Transportation is by a mile siding from New York, New Haven & 

Hartford Railroad at Millstone station, and also by short siding to 

dock, which admits vessels of 12-foot draft at low tide.

The product is used for monuments and buildings and the waste 

for breakwater riprap, road, and concrete material. Specimens: 

Saratoga Monument, interior, entrance, and all but upper 10 feet of 

exterior; also a polished inscribed tablet of the Millstone Pink; base, 

pedestal, arid cap of P. T. Barnum monument, Bridgeport; and 

George W. Childs mausoleum, Philadelphia,

SOMERS QUARRY.

The Somers quarry is in Waterford Township, 2^ miles west-southwest of New London, on the east side of Durfy Hill near Graniteville. 

(See fig. 7.) Operator, Patrick Somers, R. F. D., Waterford, Conn.

The granite (specimen D, XXX, 14, &, related to "Westerly Granite " of Rice and Gregory) is a quartz monzonite of medium inclining 

to dark buff gray color and of even-grained granitic fine texture, 

with feldspar mostly under 0.1. inch but up to 0.2 inch and mica 

mostly under 0.05 inch but up to 0.1 inch. This rock is overlain by 

a few feet of similar but pinkish granite (specimen D, XXX, 14, a). 

Both effervesce slightly with muriatic-acid test.

This granite is finer textured than that of the Millstone quarry, 

and specimen 14, b is a little lighter in shade. As the quarry deepens 

the stone will probably be found to be suitable for monuments.

1 Niles, W. H., The geological agency of lateral pressure exhibited by certain movements 

of rocks : Proc. Boston Sec. Nat. Hist., vol. 18, 1S75-1S76, p. 279.
NEW LONDON COUNTY. 113 -

The quarry, opened in 1902, is 70 feet square and averages 5 feet in 

depth.

Rock structure: The sheets are irregular, 1 to 8 feet thick, dipping 

30° E. Joints: Set A, striking nearly east to west, vertical, are 

spaced 9 to 20 feet. Set B, striking north to south, dip west, discontinuous; one only. There is some pegmatite.

The plant consists of a hand derrick.

Transportation is by cart 3^ miles to New London.

The product has thus far been used for building and trimmings.

WATERFOHl) QUARRY.

The Waterford quarry is in Waterford Township, 3-| miles southsouthwest of NCAV London, 2f miles south of Waterford station, and 

a mile east of Pleasure Beach. (See PI. I and fig. 7.) Operator, 

Booth Bros. & Hurricane Isle Granite Co., 207 Broadway, New York.

The granite (specimens D, XXX, .5 a, 5, rough, d, polished and 

hammered, related to "Westerly granite" of Rice and Gregory), 

" Connecticut white," is a quartz monzonite of medium buff gray 

shade and of even-grained granitic fine texture, with feldspars to 0.2 

inch, rarely 0.3 inch but mostly under 0.1 inch, and slender micas to 

0.15 inch, rarely 0.2 inch but mostly not over 0.1 inch. The long 

axes of the micas are parallel to the rift. Its' constituents, in descending order of abundance, are milk-white soda-lime feldspar (oligoclase-andesine) kaolinized and micasized; cream-colored potash feldspar (microcline and a little orthoclase) slightly kaolinized and intergrown with quartz more or less circular in cross section; light smoky 

quartz with hairlike crystals of rutile, rare cavities in sheets and 

some rift cracks parallel thereto; biotite (black mica), some of it 

chloritized and veiy little muscovite or bleached biotite. Accessory 

minerals: Magnetite (fifth in order of abundance), apatite, zircon, 

allanite; no pyrite detected. Secondary minerals: A white mica, 

kaolin, calcite, chlorate, limonite.

 An estimate of the mineral percentages by the R-osiwal method 

applied to a camera-lucida enlargement (25 diameters) of a thin 

section yields these resultvS with a mesh of 1 inch and a total linear 

length of 27 inches:

Estimated mineral percentages in quartz monzonite of Waterfowl quarry.

Soda-lime feldspar (oligoclase-andesine)___________ 33.63 

Potash feldspar (microcline and little orthoclase)_____ 32.29 

Quartz __________________________________ 29.92 

Black mica (biotite)_______________________ 3.65 

Magnetite ______________________________ . 51

100. 00

The average diameter of the particles, calculated from the same 

measurements, is 0.0206 inch.
114 GRANITES' OF CONNECTICUT.

. The stone effervesces with cold dilute muriatic acid. R. C. Wells, 

a chemist of the United States Geological Survey, finds that it contains 0.29 per cent of CaO (lime), soluble in warm dilute (10 per 

cent) acetic acid, which indicates a content of 0.51 per cent of CaC03 

(lime carbonate, calcite), the presence of which mineral is also shown 

by the microscope.

The following analysis (.No. 12757) of this granite, made for the 

company by Ricketts & Banks, of New York, is given here for reference:

Analysis of quartz monzonite from Watcrford quarry.

Silica (SiO2 )______________________________ 68.11 

 Alumina (A12O3 )___________________'.- -_______ 14.28 

Iron oxide (FeO)___________________,_______ 2.63 

Lime (CaO)______________________________ 1,86 

Magnesia (MgO)____________________________ .68 

Potash (KaO) _____________________________ 5.46 

Soda (Na 2O) ____________________________ 6. 57 

Sulphur (S)____________________________1 .34

99.93

Ira H. Wool son, E. M., of Columbia University, made two compression tests on cubes of 2-inch edges in 1896, with these results 

(rift and grain directions not noted) :

Test No.

1575.... 

1576....

First 

crack.

Pounds. 

65, 000 

92,000

Maximum

stress.

Pounds. 

93,100 

. 97,600

Ultimate 

strength.

Pounds per 

*(/. in. 

23,510 

23,921

This is a very fine-grained monumental and inscriptional granite 

of buff medium gray tint without mineral contrasts. It is finer than 

the Mijlstone granite and of lighter shade, and about half as fine as 

" Blue Westerly," which averages 0.0099 inch per particle.1

It takes a high polish. The polished face shows a little magnetite 

and is of medium inclining to dark gray shade, while the hammered 

face is light gray, to which lightness the stone owes its trade name. 

This property of hammering and cutting light it possesses in common 

with Westerly, Groton. Millstone, and other quartz monzonites. Its 

adaptation to fine architectural and sculptural work is shown in 

Plates VI, and VII, A, and its lightness when hammered in Plate VI.

The quarry, opened about 1878, measures about 600 feet from east 

to west by 150 feet across at east end and 250 at west end, and from 

75 feet to 125 feet in depth. The stripping, of sand and bowlders 

averages 10 feet in thickness.

!See Bull. U. S. Geol. Survey No. 354, p. 192.
U. 8. GEOLOGICAL SURVEY 434 PLATE VI

SOLDIERS' AND SAILORS' MONUMENT AT WH1TINSVILLE, MASS., SURMOUNTED BY BRONZE EAGLE.

The monument is of hammered buff-gray fine-grained quartz morzonite (" Connecticut white granite ") from the 

Booth quarry at Waterford. A. D. F. Hamlin, architect; H. A. MacNeil, sculptor. Height to top of ball, 30 feet. 

See page 114.
U. S. GEOLOGICAL SURVEY

A. PANEL WITH BAS-RELIEF AT BASE OF MONUMENT SHOWN IN PLATE VI.

This is of fine-grained quartz monzonite from Waterford, and shows its adaptation to 

lettering and carving. Height of relief, half an inch, See page 1 14.

J?. CARVED 

MON

Maximum reli
NEW LONDON COUNTY. 115

Rock structure: The granite occurs in two dike-like masses, 30 

and 40 feet thick, alternating with three masses of gneiss, the central 

one of which is 20 . . 

to 30 feet thick, all 

striking N. 80° E. 

and dipping 30°- 

45° S. 10° E. The 

relations are shown 

in figure 9. The 

gneiss foliation

Strikes N. 45° 60° FIGURE 9. East-west section of Waterford quarry. Total 

TT7 ', ,' T . length, 265 feet. VV. and dips about

40° NE., but in places is nearly horizontal. The two granite masses 

are apparently connected in the center of the quarry by a small dike

of the granite crossing 

the gneiss mass, as 

shown in figure 10. ' This 

gneiss (specimen D, 

XXX, 5, e; "Mamacoke 

gneiss," No. 36, of the 

State preliminary geo- 

.logic map) is a black 

and white banded finegrained quartz monzonite gneiss, consisting, in 

descending order of 

abundance, . of light 

smoky quartz, milkwhite oligoclase, very little microcline, and biotite. The granite 

sheets, 1 to 9 feet thick, are lenticular, irregular., dipping south and 

southeast at 15°-22°. The sheet structure of the gneiss is not continuous with that

F \AI

of the granite, as 

shown in figures 

10 and 11. 

rift, and

Water Water

FKIUKE .10. Relations of granite and gneiss in center 

of Waterford quarry. At left section looking south ; 

at right looking east.

Joint,

grain

courses are shown 

in figure 12. 

Joints: Set A is 

vertical, spaced 3

to 20 feet* Set B FIGURE ll. Discordant sheet structure in granite and gneiss 

' ' on south wall of Waterford quarry. vertical or steep

west, spaced 3 to 50 feet; set C dips 50°-75° NW. and is spaced 2 to 

75 feet. The rift dips 10° S. 15° E., with the long axes of the biotite 

scales, and the grain 75° N. 15° W., and the hardway is vertical.
116 GEANITES OF CONNECTICUT.

In splitting along the rift the granite is reported as breaking more 

readily from the west side than from the north. Biotitic knots to 

6 inches in diameter are rare. Inclusions of the gneiss, 3 inches 

across and 2 by 3 feet, occur 2^ and 6 feet above the contact of upper 

granite dike, with underlying gneiss. The granite surface tends to 

weather spheroidally. 1 Rusty stain is 2 to 6 inches thick on sheet 

surfaces.

The plant comprises a 25-ton and 20-ton derrick, two hoisting engines, a Blondin carrier and engine, a locomotive crane, a locomotive, 

an air compressor (capacity 380 cubic feet of air per minute), two 

large rock drills, a number of air plug drills, forty-five air hand tools,

three surfacers, two horizontal polishers, and two steam pumps.

Transportation is by cart a mile, 

to the dock at Pleasure Beach, 

which admits vessels of 9 feet draft 

at low tide, or 2 miles to the New 

York, New Haven & Hartford Railroad at Waterford station.

The product is used mostly for 

monuments and finds a market 

mostly in the Eastern States. Specimens: Soldiers Monument, Whitins ville, Mass., shown in Plates VI

FIGURE 12.-Structure at Waterford -quarry. and VII > A > Dudley Celtic CrOSS,

Woodlawn Cemetery, New York;

Littlefield shaft, Swan Point Cemetery, Providence; Hoy mausoleum, 

Mount Moriah Cemetery, Philadelphia; City Deposit Bank, Pittsburg; basement of Clark residence, Riverside Drive, New York;

addition to Williamsburg Savings Bank, New York.

TOLLAND COUNTY.

BOLTON.

PETERSON QUARRY. .

The Peterson quarry is in Bolton Township, in the northeastern 

part of Mirinehausch or Birch Mountain, about 2 miles southwest 

of Bolton village and If miles southeast of Highland Park post 

office, in Manchester. (See PL I, p. 8.) Operator: Lawrence E. 

Peterson, South Manchester, Conn.

The granite (specimens D, XXX, 31, a, &, "Glastonbury granite 

gneiss," No. 15, of the State preliminary geologic map) is a biotite

1 See Bull. U. S. Geol. Survey No. 354, p. 58 and PI. VIII, A, for an example of ovoidal 

weathering in Westerly quartz monzonite.
WINDHAM COUNTY. . 117

granite.gneiss of medium, slightly bluish gray shade^ with conspicuous broad black streaks on the foliation face and of medium-grained 

implicated very gneissose texture Avith porphyritic lenticular feldspars to 0.2 and 0.4 inch long. The quartz is in lamellase to 0.1 inch 

thick and the mica to 0.04 inch. The stone looks very different on its 

rift, grain, and hardway sides. Its constituents, in descending order 

of abundance,, are bluish translucent potash feldspar (microcline and 

orthoclase) somewhat kaolinized; light smoky quartz strained and 

with cavities in parallel sheets and cracks parallel to or coinciding 

therewith; milk-white soda-lime feldspar (oligoclase to oligoclaseandesine); and biotite (black mica). Accessory minerals: Garnet, 

pyrite. Secondary minerals: A white mica, kaolin. Both feldspars 

are intergrown with quartz more or less circular in cross section. 

The stone does not effervesce with cold dilute muriatic acid.

The quarry is a small opening, made in 1908.

Rock structure: The sheets, 3 feet thick, dip gently east. The 

gneiss foliation strikes N. 10° E. and is vertical. The rift is 

parallel to it and the grain horizontal and the hardway vertical, 

east-west. An 18-inch aplite dike runs parallel to the foliation. 

This (specimen D. XXX, 31, <?) is of a medium bluish gray shade and 

of fine slightly gneissose texture. Its constituents, in descending 

order of abundance, are smoky quartz; bluish microcline,with orthoclase; milk-white soda-lime feldspar; and a little sparse biotite and 

pyrite. Its quartz and feldspar particles are mostly from 0.11 to 

0.33 millimeter, with some porphyritic ones 0.54 to 0.84. No effervescence with muriatic-acid test.

The contrasts in this stone are more marked than in any of the 

gneisses of Glastonbury described on pages 62-66.

The stone is used for underpinning, cellar stone, etc.

WINDHAM COUNTY.

STERLING. 

ONECO QUARRY.

The Oneco quarry is in Sterling Township, a mile southwest of 

Oneco village, near the Rhode Island line. (See PI. I, p. 8.) Operator: 

Oneco Granite Co., Industrial Trust Co. Building, Providence, R. I.

The granite (specimen D, XXX, 22, #, "Sterling granite gneiss, 1 ' 

No. 24, of the State preliminary geologic map) is a biotite granite 

gneiss of medium, inclining to dark, slightly bluish gray color and 

of fine-grained implicated gneissose texture, with porphyritic feldspars to 0.2 and 0.4 inch and mica in fine parallel streaks 0.1 to 0.2 

inch apart. Its constituents, named in descending order of abundance, are bluish potash feldspar (microcline intergrown with quartz
118 GBANTTES OF CONNECTICUT.

more or less circular in cross section, also orthoclase) somewhat 

kaolinized; light smoky quartz, with cavities in parallel sheets and 

cracks parallel thereto; a little milk-white soda-lime feldspar (oligoclase), some of it kaolinized and mlcasized; biotite (black mica). Accessory minerals: Titanite (fifth in order of abundance), magnetite 

(or ilmenite), garnet, apatite, allanite, zircon. Secondary minerals: 

Kaolin, white mica. No effervescence with muriatic-acid test.

The quarry, opened about 1868, measures about 500 feet from 

northwest to southeast by 400 feet across, and is 5 to 35 feet deep. 

The stripping consists of 3 to 6 feet of sand.

Rock structure: The gneiss foliation strikes N. 10°-25° W. and is 

vertical. The sheets, inches to 5 feet thick, dip 5°-10° SW. and NW. 

Joints: Set A strikes N. 80°-85° E., vertical, forms the south wall, is 

spaced 10 feet and much more; set B ("blind seams" with quartz 

and pegmatite dikelets) strikes N. 30° W., dips 50° E., and is spaced 

3 to 10 feet. Biotitic surfaces (flow structure?), strike N. 30° W. 

and dip 50° N. 60° E. The rift is reported as parallel to the gneiss 

foliation and the grain as vertical east to west, but not marked. 

There are pegmatite lenses of smoky quartz and pink feldspar, with 

purple fluorite and epidote .crystals. Dikes of whitish aplite to 4 

inches thick strike N. 50° W. and dip 30° N. 40° E. on the southwest wall. (See microscopic description under Marriott quarry.)

The plant "comprises three derricks, a hoisting engine, an air compressor, three surfacers, four air plug drills, and a stone crusher.

Transportation is by a siding three-fourths mile long to New York 

& New England Railroad.

The product is used for building, curbing, paving, and the waste 

for crushed stone. The quarry became idle in the spring of 1908.

MARRIOTT QUARRY.

The Marriott quarry is in Sterling Township, a mile southwest of 

Oneco station and one-fourth mile east of the Oneco quarry. (See 

PI. I.) Operator: R. B. Marriott & Sons, Oneco, Conn.

The granite (specimens D, XXX, 23 «, 5, " Sterling granite 

gneiss," No. 24, of the State preliminary geologic map) is a biotite granite gneiss of medium inclining to dark bluish gray color 

and of fine-grained implicated gneissose texture, with porphyritic 

feldspars to 0.2 inch and 0.4 inch and mica in fine parallel streaks 

0.1 to 0.2 inch apart. Its constituents are identical with those of 

the Oneco quarry stone, but the section shows secondary calcite and 

the stone effervesces slightly with cold dilute muriatic acid.

This granite gneiss is well adapted by its foliation for curbing and 

trimmings. It has a marked bluish tint and looks well hammered 

on the grain and hardway sides.
WINDHAM COUNTY. 119

The quarry, first opened in 1881, then idle till reopened in 1903, 

measures about 200 by 150 feet and 5 to 15 feet in depth. It has but 

just reached the bluer stone free from discoloration.

Eock structure: The gneiss foliation strikes north to N. 15° 

W. and is vertical. The sheets, 1 to 7 feet thick, with a few 6-inch 

ones near the top, dip 5° E. There are two sets of joints: Set A, 

striking N. 65° E., vertical, forms the south wall and is spaced 

3 to 30 feet; set B, striking north, vertical, forms east and west walls, 

and one on either side. The rift coincides with the foliation; the 

grain is horizontal and hardway vertical east to west.. The stone 

breaks somewhat readily along the hardway. There are dikes of 

aplite to a foot thick, striking northwest and dipping steep southwest. A small one of these has a central band of ilmenite 0.3 inch 

thick. The aplite (specimen D, XXX, 23, c) , like that of the Oneco 

quarry, is of light-cream color and very fine texture, with particles

under 0.1 inch. In a thin section they range from 0.05 to 1.12 millimeters. Its constituents, in descending order of abundance, are: 

Qlear, colorless quartz with cavities, microcline with orthoclase, oligoclase, minute and sparse biotite with accessory ilmenite, garnet, 

apatite. There is a 6-inch dike of smoky quartz with feldspathic 

border on the west side; also lenses of pegmatite with smoky quartz.

The plant comprises two hand and one steam derrick and a hoisting engine.

Transportation is by cart 1| miles to Oneco station.

The product is used for curbing, building, trimmings, chimney 

caps, and paving, which is sent to Providence. Specimens: Cranske 

Mill addition at Moosup, Conn.

BENNETT BOWLDER QUARRY.

The Bennett Bowlder quarry is in Sterling Township, threefourths mile east of Sterling station and about 1£ miles west of the 

Rhode Island line. (See PL I.) Operator: Nelson A. Bennett, 

Sterling, Conn.

The granite (specimens D, XXX, 24, a, d, e, " Sterling granite 

gneiss," No. 24, of the State preliminary geologic map) is a biotite granite gneiss of general light pinkish gray color with conspicuous black streaks on the foliation face and of fine-grained, obscurely 

plicated gneissose much elongated porphyritic texture. It is marked 

by long tapering parallel lenses from 0.1 to 0.3 inch Avide consisting 

of quartz or feldspar or mica. The rock has very different aspects 

on its rift, grain, and hardway faces. The rift or foliation face 

(specimen a] shows the lenses of black mica, pink feldspar, and 

smoky quartz. Along the grain (specimen «, smallest side) which 

is vertical to the foliation but parallel to the lenses, the mica is in
120 GRANITES OF CONNECTICUT. .

very thin streaks, while along the hardway (specimen e), which is 

at right angles to the lenses, the rock is mottled with pink, gray, 

and black. The feldspar particles are to 0.2 inch. The constituents, 

in descending order of abundance, are light-pinkish potash feldspar 

(microcline and orthoclase), slightly kaolinized; light smoky quartz, 

with cavities in irregular sheets; cream-colored soda-lime feldspar 

(oligoclase-albite), somewhat kaolinized; biotite (black mica); and 

very little hornblende. Accessory minerals: Allanite, apatite, zircon. Secondar}^ minerals: Calcite, kaolin. Slight effervescence with 

cold dilute muriatic acid.

A more pinkish granite (specimen 25, a), from a point about 1£ 

miles north-northeast of Sterling station, a little north of Quaduck 

Brook, is of identical texture and composition, but the feldspars are 

more pinkish and more altered, the oligoclase-albite being much 

kaolinized and carrying calcite.

These stones are well adapted for the manufacture of paving 

blocks on account of their marked rift and grain and their smooth 

fracture along the hardway. The contrasts of shade and color in 

the fresh rock and its foliation make it suitable and attractive for 

other uses.

The quarry, if such it can be called, is part of a bowlder train about 

1-J miles north to south by one-half mile in width, consisting of 

bowlders of one gneiss, which range from 5 to 30 feet in diameter 

and correspond to the underlying gneiss of the region. Indeed, some 

of the quarried "bowlders" are the weathered tops of ledges.

Rock structure: A 30-foot high ledge of the gneiss shows the 

gneiss foliation striking north and dipping 55° to 70° W. Sheets 2 

to 5 feet thick dip 25° N. 70° W., and vertical joints striking east 

to west are spaced 1 to 10 feet. The rift coincides with the foliation,

and the grain is at right angles to it but parallel to the lenses. 

Slight discoloration extends 10 inches from the surface.

The plant consists of five hand derricks and a forge, which are 

moved around to the bowlders.

Transportation is by cart to a 200-foot siding one-quarter mile 

east of Sterling station.

The product is used for curbing, sills, caps, steps, buttresses, 

underpinning, and paving. The paving, which is the chief product, 

finds a market in Providence. The operator pays a royalty to the 

landowners on the bowlders he splits up.

STERLING QUARRY.

The Sterling quarry, an abandoned quarry three-fifths mile eastsoutheast of Sterling station, in the same township, is of interest 

because of the texture of its stone.
WINDHAM COUNTY. 121

The granite (specimen D, XXX, 26, a) is a biotite granite gneiss 

of medium inclining to dark bluish gray color and of fine gneissose 

texture, with fine matrix (particles under 0.2 inch) and porphyritic 

feldspars to 0.5 inch. Its constituents are the same as those of the 

Bennett bowlders, but the potash feldspar is bluish, the quartz 

clear and colorless, and the oligoclase milk-white to buff or faintly 

pinkish. The porphyritic texture is less obscured by elongation, and 

the biotite, while in parallel arrangement, is evenly distributed, as is 

also the quartz. Titanite is among the accessory minerals. This 

gneiss evidently originated in the same granite as that of the Bennett 

bowlders, but is less metamorphic; that is, its minerals have not been 

redistributed to the same extent, nor have its feldspars been subsequently as greatly altered.

Rock structure: The gneiss foliation strikes north and dips 70° 

W. to 90°, and the sheets are from 6 inches to 3 feet thick.

WINDHAM. 

LARRABEE QUARRY.

The Larrabee quarry is in Windham Township, three-fourths mile 

northwest of the Willimantic railroad station. (See PI. I.) Operator, Charles Larrabee, jr., Willimantic, Conn.

The granite (specimens D, XXX, 27, «, &, d, " Willimantic gneiss," 

No. 25, of the State preliminary geologic map) is a biotite granite gneiss of interbanded medium and very dark gray shades, with 

a few pinkish bands of muscovite gneiss, and some of pinkish 

pegmatite. Its texture is fine-grained gneissose with an implicated 

lamination and particles under 0.1 inch, the feldspars in the pegmatite bands to 0.3 inch. The .constituents of the medium gray bands, 

in descending order of abundance, are translucent potash feldspar 

(microcline partly kaolinized and orthoclase) ; light smoky quartz 

with some cavities; whitish soda-lime feldspar (oligoclase or oligoclase-andesine), some of it kaolinized and micasized and with calcite, 

also intergrown with quartz more or less circular in cross section; 

biotite (black mica), some of it chloritized. and a little muscovite or 

bleached biotite. Accessory minerals: Garnet (fifth in order of 

.abundance), magnetite, pyrite, apatite, zircon, titanite. Secondary 

minerals: Kaolin, a white mica, calcite, chlorite. Much quartz is in 

lenses 0.28 by 2.24 millimeters. There are many fine particles of 

quartz and feldspar between the larger ones. In some specimens 

garnets are 'so abundant as to make minute pinkish bands. No 

effervescence with muriatic-acid test.

A thin section of a pinkish (not pegmatitic or garnetiferous) 

band shows the same potash feldspar pinkish and much kaolinized, 

light smoky quartz, oligoclase-andesine much altered, and muscovite
122 . GRANITES OF CONNECTICUT. '

instead of biotite., with allanite among the accessories. This is a 

muscovite gneiss.

The very dark bands are evidently due to more abundant biotite.

The quarry, opened about 1878, measures about 300 feet from east 

to west by 150 feet across and 40 feet in depth. The stripping consists of 5 to 10 feet of clay and sand.

Rock structure: The gneiss foliation strikes east to west and dips 

10° S. The sheets, 6 to 12 inches thick, coincide with the foliation. 

There are three sets of joints. Set A, striking N. 40° E., vertical, 

spaced 2 to 8 feet, coated with quartz; set B, striking N. 5°<E., vertical; set C, striking N. 80° W., vertical, spaced 20 feet. The rift 

coincides with the foliation, but the grain is vertical, north to south, 

and difficult, and the hardway more so. Pegmatite and smoky quartz 

veins up to 2 feet thick coincide with the foliation and some with 

joints B and C. Some small pegmatite dikes carry a little apatite.

The plant comprises two steam derricks and one hand derrick, 

a hoisting engine, large rock drill, and a steam pump.

Transportation is by cart three-fourths mile to Willimantc.

The product is used for curbing, crosswalks, steps, and flagging, 

for which its uniformly straight foliation and its great toughness 

in transverse, directions well adapt it.

CLASSIFICATION OF THE GRANITES.

The granites described in the foregoing pages may be divided 

scientifically into 10 groups, namely:

1. Biotite granite and granite gneiss.

2. Pegmatite biotite granite.

3. Biotite-muscovite granite gneiss.

4. Muscovite-biotite granite gneiss.

5. Biotite-homblende granite gneiss.

6. Hornblende-biotite granite gneiss.

7. jJEgirite granite gneiss.

8. Quartz monzonite.

9. Quartz monzonite gneiss.

10. Mica diorite gneiss.

Some of these groups, however, need subdivision. The biotite 

granite may have white or pinkish feldspars. The biotite granite 

gneiss may be finely banded with white or pinkish feldspars, or 

may be injected with pegmatite, or plicated or porphyritic, etc. 

There are also differences in the lamination of some, and the quartz 

monzonite may have one or two micas. Including the division into 

granite and gneiss and other subdivisions, the quarried granites of 

the State fall into 20 well-defined varieties.

In the following list these varieties are systematically arranged 

and referred to some quarry or quarries where they are well exposed.
CLASSIFICATION OF THE GEANITES. 123 

Varieties of granite and gneiss quarried in, Connecticut.

Biotite granite (a pink feldspar), Murray quarry, Stonington.

Biotite granite (white feldspars), Comstock quarry, Warren.

Biotite granite gneiss, finely banded (a pink feldspar), Mclutosh quarry, Groton.

Biotite granite gneiss, finely banded (white feldspars), CoHins quarry, Danbury; Borough quarry, Torrington.

Biotite granite gneiss, finely laminated, banded (white feldspars), Larrabee 

quarry, Windham.

Biotite granite gneiss, pegruatitic, Norcross quarry, Branford.

Biotite granite gneiss, porphyritic in places, Sachem Head quarry, Guilford.

Biotite granite gneiss, porphyritic and plicated, Hoadly Point, West quarry, 

Branford.

Biotite granite gneiss, porphyritic, much elongated, Glastonbury quarries and 

Webster quarry. Sterling.

Pegmatite biotite granite, MacCurdy quarry, Old Lyrne.

Biotite-niuscovite granite gneiss, Criss'ey quarry, Norfolk Benedict, Cornwall.

Muscovite-biotite granite gneiss, Kocksicle.qum.Ty, Roxbury; Mascetti quarry, 

Litchfield.' ' . Muscovite-biotite granite gneiss, finely laminated, Burlison quarry, Bridgeport;

Hoi brook quarry, Ansonia.

Biotite-hornblende granite gneiss. Benvenue quarry, Middletown. 

Hornblende-biotite granite gneiss, Selden Neck quarries, Lyme. 

^Bgirite granite gneiss, Joshua Rock quarry, Lyme; Flat Rock, Waterford. 

Quartz monzouite (biotite), Millstone and Waterford quarries, Waterford;

Salter quarry, Groton.

Quartz monzonite (biotite-musomte), Plymouth quarry, Thomaston. 

Quartz monzonite gneiss (biotite), Dunn quarry, Bristol. 

Quartz monzonite flow gneiss (biotite), Masons Island quarry, Groton. 

Mica diorite gneiss, Voorhis, Christiano, and Ritch quarries, Greenwich.

Economically considered these granites may be classified according 

to their uses as constructional, monumental, inscriptional (that is, 

giving by the contrast between their polished and hammered faces 

legibility to inscriptions), curbing and trimming (that is, adapted 

by their foliation for supplying long and thin pieces), and paving 

(that is, adapted by their marked rift and grain and smooth hardway 

fracture for the manufacture of paving blocks). Some granites. are> 

quarried alone for breakwater material (riprap) and others for road 

and concrete uses, not so much because of their peculiar fitness for 

these purposes as because of their unfitness for others and the location 

of the quarry with reference to transportation. These constitute a 

sixth or miscellaneous class.

In the following table all the granites described are grouped in 

these six economic classes. The trade name, scientific name, real 

general color and shade, and the texture of the stone are added in 

separate columns, and page references to the detailed descriptions of 

the granites and quarries are given. In defining their general color 

references to the black spots.or spangles are only given where they 

are A^ery characteristic.
Economic classification of Connecticut gran

Class.

a 

o

g

1

"3

g

E . 3 

§

a

Locality.

.....do..................

Guilford.

Norfolk.................

Street extension, Groton.

.....do..................

ford.

terford. 

Durfy Hill, Waterford. . .

.....do..................

Stonington.

Trade name or quarry.

Creek Red. 

Hoadly Neck, West

quarry.

quarry.

General color and shade.

reddish gray.

.....do......................

bluish gray.

reddish gray streaked with 

black.

ish gray.

bluish gray, with much 

mica on foliation face.

colored.

buff gray.

gray.

greenish gray.

gray.

Texture

variable, gneissoid, i

titic.

ed, plicated, porphy

nse of black silicate.

inch).

inch).

inch).

inch).
Mystic, Groton.........

Niantic, East Lyme....

Reynolds Bridge, Thomaston. 

Lyme village, Old Lyme

Millstone Point, Waterford.

Waterford quarry, Waterford.

Groton.................

Center Groton. 

....do........

Near Anguilla Creek,

Stonington. 

Niantic, East Lyme

Birch Mountain, Glastonbury. 

....do..................

Birch Mountain, Bolton.

Eight-mile Hill, Glastonbury. 

....do..................

Buckingham, Glastonbury. 

Near Oneco, Sterling...

Near Cornwall village,

Cornwall. 

Torrington.............

....do.................

East Litchfleld..........

Mine Hill, Roxbury.....

Seymour................

McGaughey quarry....

Golden Pink...........

Plymouth quarry......

MacCurdy quarry......

Millstone quarry.......

Connecticut White.....

Salter quarry..........

Eckerlein quarry.......

Kopp quarry..........

New Anguilla..........

Golden Pink............

Corbin, Brooks, and Slater quarries. 

German quarry.........

Peterson quarry.

Belden and Curtis quarries. 

Danielson quarry.......

Carline quarry..........

Marriott and Oneco

quarries. 

Benedict quarry........

Costello quarry. 

Michiel quarry.

Mascetti quarry.........

Rockside quarry........

Holbrook quarry........

faintly greenish gray. 

Medium pinkish gray .......

gray, spotted with black.

colored.

gray.-

greenish gray.

gray.

gray.

gray.

black streaks on foliation 

face.

gray.

gray.

bluish gray.

bluish gray, much mica 

on foliation face.

bluish gray.

mica on foliation face.

much mica on foliation 

face.

Fine, granitic (particle

inch).

inch).

inch).

inch).

inch).

inch).

.....do...............

porphyritic.

.....do...............

.....do...............

.....do..........-.....

finely laminated.
Economic classification of Connecticut granites C

Class.

bi>

a

6

*C

 o <

a

c3

to

a

 s

ing .

«

O

a

<u

a

S

Locality.

port.

.....do..................

Bolles Hill, Waterford..

. Sterling.

ington.

Trade name or quarry.

.....do..'................

quarries.

.....do..................

granite.

granite

General color and shads.

mica on foliation face. 

.. . ..do......................

mica on foliation face.

very dark gray.

very faintly purplish gray.

pinkish gray.

gray.

streaks on foliation face.

ish gray.

bluish gray with fine whitish, dark gray and black 

bands.

bands.

Textur

.....do..............

ose.

much elongated.

fine, even grained 

and pegmatitic.

 pegmatite lenses.

to 0.04 inch). 
STATISTICS OF GEANITE PRODUCTION. 127

COMMERCIAL VALUE OF THE GRANITES.

As the price of a granite is usually an index of its quality the 

current prices (1907-9) of a few granites of each class are here 

given. All, unless otherwise specified, are f. o. b. cars, per 'cubic 

foot, ordinary sizes, in the rough.

Constructional granites. Stony Creek, " Branford Red," $0.75 

for dimension stock, $0.53 for random. Hoadly Neck, $0.70. 

Greenwich (Blue-black), $0.45, boat, for dimension stock; $2.75, 

boat, per long ton, for large random ashlar; $3.75, boat, per long 

ton, for small random ashlar; $1.75, boat, per long ton, for rubble, 

"Millstone Granite," for building, in pieces up to 30 cubic feet, 

average about $0.40, f. o. b. quarries.

Monumental granites. Waterford, " Connecticut White," $1.20 to

$1.80, and " Millstone Granite," $1,25, cars or boat, from 1 to 30

cubic feet. Niantic, "Golden Pink," $1.25 to $2.25, from 5 to 30 

cubic feet.

Curbing and trimming granites. Oneco (Marriott), $0.50; Sterling 

(Bennett), $0.35. Glastonbury (Belden) curbing, $0.45 per running 

foot at quarry, with cartage of 10 miles to rail. Seymour (Hoibrook) , $0.40 per running foot, 18 inches deep and 4 inches wide. 

Roxbury (Mine Hill), $0.30 to $0.40. Waterford (Flat Rock), 

$0.45, delivered in New London.

Miscellaneous. Guilford (Sachem Head) breakwater granite, 

$0.999 per long ton dumped at breakwater, 12 miles from quarry, 

minimum weight of blocks 500 pounds. Greenwich riprap, per long 

ton, boat, $1.25.

STATISTICS OF GRANITE PRODUCTION.

By ALTHA T. COONS.

The figures presented in the following table show the value of the 

granite quarried in Connecticut during the last 10 years, according 

to the reports by the quarrymen to the United States Geological 

Survey. The values given represent the selling value to the quarryman free on* board at point of shipment, but exclude all freight, 

rates. When the stone is cut or dressed at the quarry the value of 

the dressed stone is given. This applies especially to the stone 

quarried and sold for uses as building and as monumental stone. 

The greater part of the'stone sold for riprap and rubble was used for 

jetty and breakwater work. 

97730° Bull. 484 11 9
128 GRANITES OF CONNECTICUT.

The following table shows the value of granite quarried in Connecticut from 1899 to 1908, inclusive, by uses:

Production of granite in Connecticut from 1899 to 1908, inclusive, l)ij uses.

Year.

1899...........................

1900...........................

1901...........................

1902........;..................

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

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

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

1906. ..........................

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

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

Year.

1899

1900. ..........................

1901...........................

1902. ..........................

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

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

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

1906. ..........................

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

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

Building.

Rough.

o 878,855 

090,379 

108, 959 

116, 745 

 59,421 

87, 955 

158, 126 

158, 189 

31,928 

33,833

Curbing.

812, 

25, 

14, 

23, 080 

24, 398 

21, 690 

22, 091 

19, 064 

24, 551 

25, 324

Dressed.

3167, 889 

110,583 

94, 611 

200, 262 

408, 875 

289, 772 

230, 736 

428, 915 

110, 600 

117, 242

Flagstone.

364 

224 

358 

371 

805 

386 

1/383 

2,235 

2,357 

999

Monumental.

Rough.

( b ) 

(*) 

326, 267 

28,862 

26, 164 

23, 371 

28, 238 

44, 433 

26, 302 . 

; 23, 218

Riprap 

and rubble.

$16, 876 

31, 492 

31,342 

40, 894 

124. 339 

32, 698 

90,530 

174, 287 

233, 008 

303, 101

Dressed.

882, 766 

52,535 

70, 894 

66, 899 

58, 811 

42, 202 

52, 125 

64, 019 

112,393 

58,672

Crushed 

stone.

821,060 

32, 450 

14, 300 

8,882 

12, 169 

8,364 

5,336 

6, 657 

10, 510 

5,890

Paving blocks.

Number of 

blocks.

c 483, 000 

c 372, 600 

c 652, 000 

c 817, 000 

c 1,581, 500 

1. 422, 656 

999, 215 

806, 863 

854, 136 

292, 485

Other 

purposes.

812, 600 

4,329 

93, 699 

3,998 

4, 816 

13, 920 

1,838 

9,674

Value.

325, 722 

14, 903 

29,340 

34, 305 

63, 260 

47, 898 

42, 98S 

62, 305 

37, 666 

14, 951

Total value.

8406, 132 

357, 566 

402. 671 

524'. 629 

871J941 

558, 334 

636, 364 

974, 024 

591, 153 

592.904

^Includes rough monumental. b Included in rough building. c Estimate.

GENERAL ECONOMIC CONCLUSIONS.

In reviewing the economic data brought together in this bulletin 

several general facts will impress themselves on the reader. One is 

notably the varied character of the granites of the State. They range 

in grade of texture from the coarse pegmatite of Lyme and the coarse 

granite gneiss of Branford and Guilford to the fine quartz monzonites of Waterford, Niantic, and Groton. They vary, too, in kind of 

texture from the coarsely porphyritic of Hoadly Point and Greenwich to the medium and finely porphyritic of Glastonbury and Sterling, the finely laminated of Ansonia and Willimantic to the finely 

granitic of the quartz monzonites. Some of the gneisses present a 

very different texture in three directions. In some of the granites 

the micas are aligned with the rift. There is also considerable 

variety of color, shade, and mineral contrast. The diorite gneiss of 

Greenwich is a blue-black, the quartz monzonites are smoke-colored 

or medium greenish, bluish, or pinkish gray, but cut in light grays of 

corresponding tints. The pegmatite of Lyme is pinkish-reddish, the 

granite gneiss of Stony Creek and the granite of Pawcatuck are reddish. The gneisses of Sterling, Bolton, and Selden Neck are streaked
GENERAL ECONOMIC CONCLUSIONS. 129

with black and many of the gneisses are gray of various tints brightly 

spangled with mica on -their foliation face.

There is also a great variety in the use made of these " granites." 

They are employed for the construction of breakwaters, forts, retaining walls, bridges, churches, libraries, universities, railroad stations, banks, business blocks,.residences; for street paving, flagging, 

curbing, circulars, crosswalks; posts, steps, underpinning, buttresses, 

trimming for brick buildings, coping, chimney caps, tube linings; 

crushed granite for roads, concrete, artificial stone and curbing; obelisks, columns, sarcophagi, crosses, and other monuments, some of 

them delicately carved, as shown in Plate VII, and also bases for 

bronze statues.

The location of the granites and gneisses has much to do with the 

success of the industry. The constructional granites of Greenwich, 

Hoadly Point, and Stony Creek, and the monumental granites of

Waterford, Millstone, and Groton are all near both rail and tidewater. The breakwater quarries of Sachem Head and Masons Island 

are necessarily at tidewater. The Glastonbury gneisses have long 

supplied the city of Hartford with curbing by means of one cartage 

of 8 to 10 miles. The Sterling quarries have easy rail communication with Providence for their curbing, trimming, and paving. In 

the western part of the State the Koxbury, Norfolk, and Thomaston 

quarries are on rail lines connecting with lines to the cities and the 

Cormvall and Torrington quarries are not far from the same lines. :

The most notable products of the Connecticut granite quarries are 

the recently completed Connecticut Eiver bridge at Hartford, consisting of nine arches of cut granite with a total length of 1,192 feet 

and width of 82 feet; the pedestal to the statue of Liberty in New 

York Harbor; the Soldiers and Sailors Monument at Whitinsville, 

Mass, (shown in PL VI) ; the obelisk at Sault Ste. Marie (shown 

in PL III, B, p. 48) ; the Battle Monument at West Point; the Channing Memorial Church at Newport, R. I., and the Catholic Cathedral 

at Brooklyn.

An industry which at one extreme enables a man to support his 

family by splitting up glacial bowlders into paving blocks and besides to pay the farmer a royalty on his bowlders, and which at the 

other commands sufficient capital and skill to bridge the Connecticut 

with granite arches or to finish such a work of art as the Soldiers 

Monument at Whitinsville, certainly has a wide economic extent.
130 GRANITES OF CONNECTICUT.

GLOSSARY OF SCIENTIFIC AND QUARRY TERMS.

ACCESSORY MINERALS in granite are original constituents of the rock, found 

only in small, often only in microscopic quantity.

ACIDIC.' A term applied to rocks in which silicic acid (silica) or quartz 

predominates.

ALLANITE. An opaque black mineral (silicate), brown in thin section, one of 

the primary less common accessory constituents of granite, which contains from 12 to 17 elements, including 6 of the rarer ones. For analyses 

see Dana, E. S., System of Mineralogy, 6th ed., 1892, pp. 522-526.

ANTICLINE. A term applied to granite sheets or sedimentary beds that form an 

arch.

APLITE. Fine-grained granite, generally occurring in dikes and containing little 

mica and a high percentage of silica.

BASIC. A term applied to rocks in which the iron-magnesia minerals and feldspars with lime and soda predominate, such as diabase or basalts.

BLACK HORSE. .Term used by quarrymen to denote a dark biotite gneiss in contact with the granite.

BLIND SEAMS. Quarrymen's term for incipient joints.

BOWLDER QUARRY. One in which the joints are either so close or so irregular 

that no very large blocks of stone can be quarried.

CHANNEL. A narrow artificial incision across a mass of rock, which, in the 

case of a granite sheet, is made either by a series of contiguous drill 

holes or by blasting a series of holes arranged in zigzag order.

CLEAVAGE, when applied to a mineral, designates a structure consequent upon 

the geometrical arrangement of its molecules at the time of its crystallization.

CLOSE-JOINTED. A term applied to joints that are very near together.

CROCUS. A term used in some quarries to denote gneiss or any other rock in 

contact with granite.

CRUSH BORDER. A microscopic granular structure sometimes characterizing adjacent feldspar particles in granite in consequence of their having been 

crushed together during or subsequent to their crystallization.

CUT-OFF. Quarrymen's term for the direction along which the granite must be 

channeled, because it will not split. Same as " hardway."

DENDEITES. Plantlike crystallization of iron or manganese oxides on the surfaces of fissures in any rock or mineral. Frost crystals on window 

panes are of like character.

DIKE. A mass of granite, diabase, basalt, or other rock which has been erupted 

through a narrow fissure.

DIMENSION STONE. A term applied to stones that are quarried of required 

dimensions.

DIP. The inclination from the horizon, given in terms of degrees, of a sheet, 

joint, heading, dike, or other structural plane in a rock.

DRIFT. Sand and bowlders deposited by the continental glacier.

DRUMUN. Oval hillock of clay and bowlders formed beneath the ice sheet of 

the glacial epoch.

EROSION. The wearing away of portions of a rock by such natural agencies as 

stream or ice action.
GLOSSAKY. 131

EXFOLIATION. The peeling of a rock surface in sheets owing to changes of

temperature or other causes.

FAULTING. The slippage of a rock mass or masses along a natural fracture. 

FLOW STRUCTURE. The parallel arrangement of the minerals in granite or other

igneous rock in the direction of its flowage during its intrusion. 

GEODE. A rock cavity lined with crystals. Geodes in granite are attributed to

steam or gas bubbles. 

GRAIN in granite is practically the direction in which the stone splits "next

easiest," the " rift" being that in which it splits most readily. 

GROUT. A term applied to the waste material of all sizes obtained in quarry-.

ing stone. i 

GROW-ON. Quarrymen's term to designate the place where the sheet structure

dies out, or the place where two sheets appear to grow onto one another. 

HARDWAY. The direction at right angles to both rift and grain in which

granite does not split readily. (See Cut-off.)

HEADING. A collection of close joints.

HEADING-SEAM. See Joint.

HEMATITE. An oxide of iron (Fe-Oa), which, when scratched or powdered, gives

a cherry-red color.

IGNEOUS. A term applied to rocks that have originated in a molten condition. 

JOINTS. More or less steeply inclined fractures which cross the granite sheets

and which are attributed to various stresses.

KAOLIN. A hydrous silicate of alumina derived from the alteration of feldspar. 

KAOLINIZATION. The process by which a feldspar passes into kaolin. 

KNOTS. A term applied by quarrymen to dark gray or black objects, more or

less oval or circular in cross section, which are segregations of black mica

or hornblende formed in the granite while in a molten state. English

quarrynieii call them " heathen." 

KNOX HOLE. A circular drill hole with two opposite vertical grooves which

 direct the explosive power of the blast. 

LEWIS HOLE. An opening made by drilling two or three holes near together and

chiseling out the intervening rock. 

LIMONITE. A hydrous oxide of iron (2Fe2O3 , SILO) ; a hydra ted hematite,

which, when scratched or powdered, gives a brownish rust color. 

MATRIX. The general mass of a rock which has isolated crystals; sometimes

called groundmass. 

MILLIMETER. French decimal linear measure, the thousandth part of a meter or

the tenth part of a centimeter. It is equivalent to nearly 0.04 inch, the

meter being 39?£ inches.

MONOLITH. A column or monument of one stone.

MOTION. A term used in granite regions to designate small paving-block

quarries. 

OPHITIC. A term applied to microscopic rock texture to designate a mass of

longish interlacing crystals, the spaces between which have been filled

with minerals of later crystallization. 

OREI. A term applied in the Qnincy quarries to Quincy granite which has been

rendered valueless by the alteration of its segirite particles. 

PEGMATITE. A very coarse granite occurring in irregular dikes or lenses in

granites and some other rocks.
132 GEANITES OF CONNECTICUT.

PHENOCRYST. A term applied to isolated crystals visible to the unaided eye and 

lying in the mass of a rock of igneous origin.

PLAGTOCLASE. A term applied to all those feldspars that are not potash feldspars.

POLARIZED LIGHT. Light whose vibrations, unlike those of ordinary light, which 

are in all directions, are in only one plane. Polarized light is used in the 

microscopic study of rocks.

POEPHYRITIC. A term applied to rock texture to designate the presence of 

isolated crystals in a general mass (matrix or grouudmass) of finer 

material.

PSEUDOMORPH. Signifies false form, and designates a crystal in which, owing 

to various chemical changes, the original mineral has -been more or less 

replaced by others. The form of the crystal no longer corresponds to the 

mineral.

QUARTZ MONZONITE. Technical designation for a granite in which the percentages of soda-lime and of potash feldspar are nearly the same or in 

which the former exceeds the latter. In ordinary granites the amount 

of soda-lime feldspar is relatively small.

RANDOM STONE. A term applied by quarrymen to quarried blocks of any dimensions. (See definition of dimension stone.)

RIFT. A quarrymen's term to designate an obscure microscopic cleavage in 

granite which greatly facilitates quarrying.

RUN. A term used by quarrymen in connection with " rift." apparently to 

denote the course of the deflection of the rift due to gravity, strain, or 

other not yet understood cause.

SALT HORSE. Quarrymen's term for aplite.

SAND SEAMS. Quarry term for more or less minute veins or dikes of muscovite 

(white mica) with some quartz, in cases also with feldspar.

SAND STREAKS. Same as sand seams.

SAP. Quarrymen's term for ferruginous discoloration along sheet or joint 

surfaces.

SCHIST. A rock made up of flattisli 'particles arranged in rough parallelism, 

some or all of which have crystalli/ed under pressure.

SCHISTOSITY. The quality»of being like a schist.

SEAM. Quarryrnen's term for joint.

SECONDARY MINERALS. Minerals whose presence is due to the alteration of the 

original minerals.

SEDIMENTARY. A term designating those rocks that consist of particles deposited 

under water.

SEGREGATION. The scientific term for " knot," a collection of material separated from other material. A VEIN OF SEGREGATION is one formed by the 

filling of a fissure with mineral matter originating in the surrounding 

rock.

SERICITE. A more or less fibrous form of muscovite (potash mica), often resulting from the alteration of feldspar.

SHAKES. Quarrymen's term to designate a somewhat minute close-joint structure; which forms along the sheet surface as a result of weathering.

SHEET QUARRY. A quarry in which the granite lies in sheets, crossed by widespaced steep joints.
GLOSSAEY. * 133

SLICKENSIDES. The polished and grooved faces of a joint or bed caused by

motion and friction. 

STRAIN-SHEET. Quarrymen's term for granite sheets produced by present compressive strain. 

STRATIFIED. A term applied to rock consisting of originally horizontal beds or

strata. 

STRIKE. The direction at right angles to the inclination of a plane of bedding,

a sheet, or joint, etc. 

STRIPPING. The material (sand, clay, soil, etc.) overlying a rock of economic

value, which must be removed before quarrying. 

SPECIFIC GRAVITY. The weight of a rock or mineral compared to that of a body

of distilled water of the same bulk.

SUBJOINT. Minor joints diverging from or parallel to the regular joints. 

SYNCLINE. A geological term for the trough part of a wave-like sheet or bed

.of rock.

TILL. A mixture of clay and bowlders deposited by glaciers. 

TOEING-IN. Quarrymen's term for the wedging in of the end of a .granite sheet

under an overhanging joint, probably in consequence of the faulting of 

the sheets along the joint. It is also applied to the overlapping of lenticular sheets.

" TOE NAILS." Curved joints intersecting the sheet structure, in most cases 

striking with the sheets, in some differing from them in strike 45° or 

more.

TWIN CRYSTALS. Two adjacent crystals which have formed with the poles of 

their main axes in opposite or different directions.

WEATHERING. The decomposition of a rock owing to the action of the weather.

WHITE HORSE. Term used by quarryrnen to denote a light-colored gneiss, aplite, 

or pegmatite.

INDEX.

A. Page.

Age of Connecticut granites.................. 25

Ansonia, quarries in......................... 78-79

Aplite, description of........................ 39-40

B.

Becker, G. F., on sheet structure in granite.. 32 

Becket gneiss, description of................. 22

Bedding of granite, description of............ 29-30

Bclden quarry, description of................ 64-65

Benedict quarry, description of.............. 67-68

Bennett Bowlder quarry, description of... 119-120

Bcnvenue quarries, description of........... 76-78

Biotite, occurrence of, in granite............. 15

Bolton, quarry in.-........................ 116-117

Branford, quarries in........:............... 79-87

Branford granite gneiss, description of....... 24

Branner, J. C., on sheet structure in granite.. 31

Bridgeport, quarries in...................... 52-54

Bristol, quarries in........................... 61-62

Bristol granite gneiss, description of .......... .22

Brookfleld diorite, description of............. 23

Brooklyn quarry, description of............. 84-85

Brooks quarry, description of................ 66

Brownstone, production of.................. 13

Burlison quarry, description of.............. 52-53

C.

Calkins, F. C., acknowledgment to.......... 7

Canterbury granite gneiss, description of..... 23-24

Carline quarry, description of................ 62-63

Carlson quarry, description of............... 98-99

Christiano Hamilton Avenue quarry, description of........................... 59

Christiano Oak Ridge quarry, description of. 58 

Collins quarry, description of................ 54-55

Collinsville granite gneiss, description of..... 22

Comstock prospect, description of........... 76

Connecticut, geologic history of.............. 11-13

Geological and Natural History Survey

of, references to.................. 8

Contacts of Connecticut granites, character of. 50 

Coons, Altha T., statistics of granite production by........................ 127-128

Corbin quarry, description of................ 62

Cornwall, quarries in........................ 67-68

Costello quarry, description of............... 73

Crissey- quarry, description of................ 69

Curtis quarry, description of................. 65-66

D. °

Dale, T. Nelson, Economic discussion by... 52-133 

field'Work by............................ 7

geologic observations at the quarries by.. 45-51 

on structure, rock variations, weathering, and discoloration of granitic 

rocks............................ 26-45

Danbury, quarries in........................ 54-55

Page.

Danbury granodiorite gneiss, description of.. 23 

Danielson quarry, description of............. 64

Davidson quarry, description of............. 79

Decomposition of granite, description of..... 43-45

Dikes, aplite, occurrence of.................. 49^50

basic, description of..................... 41

granitic, description of................... 39-40

occurrence of:....................... 48

pegmatite, occurrence of................. 48-49

Discoloration, occurrence of.................. 42-43

Dunn quarry, description of................. 61-62

E.

East Lyme; quarries in...................... 97-99

Eastford granite gneiss, description of........ 23

Eckerlein quarry, description of............. 94-95

Economic conclusions..................... 128-129

Emmons, S. F., on sheet structure in granite.. 32 

Erosion by Mississippi River................ 10

F.

Fairfleld County, quarries of....... ........ 52-60

Faults, description of........................ 38-39

Feldspar, occurrence of, in granite........... 15

Finlay, G. I., on rift in granite..........:.... 27-28

Fissility, definition of......................... 11

Flat Rock quarry, description of........... 167-108

Flow structure, description of............... 26

in Connecticut granites.................. 47

Fossils, absence of, from schists and gneisses. 12

> G.

Geodes, description of....................... 42

occurrence of............................ 51

Geologic history of Connecticut.............. 11-13

Gilbert, G. K., on sheefostructure in granite.. 31 

Glastonbury, quarries in....................'. 62-67

Glastonbury granite gneiss, description of.... 23

Glossary of scientific and quarry terms.... 130-133

Gneiss, comparison of, with granite.......... 16-17

distribution of........................... 22

porphyritic, composition and occurrence

of................................ 21-22

Goos quarry, description of................ 108-109

German quarry, description of............... 63-64

Grain, description of......................... 26-29

Granite, Connecticut, age of................. 25

Connecticut, commercial value of........ 127

comparison of, with gneiss........... 16-17

distribution of....................... 22

economic classification of........... 123-126

economic conclusions on........... 128-129

intrusions of, nature of............... 24-25

mineral content of................... 14-15

production of................... 14,127-128

scientific classification of........... 122-123

specimens of......................... 8

use of the name......................... 7-8,14

135
136 INDEX.

Page. 

Greenwich, quarries in....................... 55-59

Gregory, Herbert E., oh granites and granite

gneisses of Connecticut.......... 14-25

scientific discussion by.................. 9-14

Groton, quarries in.......................... 91-97

Guilford, quarries in......................... 87-90

H.

Haddam granite gneiss, description of....... 24

Hall quarry, description of.................. 59-60

Hard way, description of.................... 20

Hartford county, quarries of................. 60-67

Headings, description of..................... 37-38

Hermann, O., on sheet structure in granite... 31 

Hoadly Neck quarries, description of........ 85-87

Holbrook quarry, description of............. 90-91

Hornblende, occurrence of, in granite........ 15

I.

Inclusions, description of.................... 42

occurrence of............................. 47

India, quarrying granite in.................. 33

Intrusions, granitic, nature of................ 24-25

J.

Jail quarry, description of ................... 53-54

Joint structure, description of............. 11,36-37

Joints, direction of............................ 51

Joshua Rock quarry, description of.......... 99

K.

Kaolinization of granite, description of....... 44

Knots, description of....................... 41-42

Kopp quarry, description of................. 95

L.

Larrabee quarry, description of............ 121-122

Leete Island quarry, description of.......... 87-88

Limestone, production of.................... 13

Litchfield, quarries in....................... 08

Litchfleld county, quarries of................ 67-76

Lyme granite gneiss, description of.......... 24

Lyme; quarries in.......................... 99-100

M.

MacCurdy quarry, description of.......... 100-102

McGaughey quarry, description of........... 96-97

Mclntosh quarry, description of............. 93-94

Malnati Pink quarry, description of......... 97-98

Mamacoke gneiss, description of............. 24

Maromas granite gneiss, description of....... 23

Marriott quarry, description of............ 118-119

Mascetti quarry, description of.............. 68

Masons Island quarry, description of...... 102-103

Merrill, G. P., on sheet structure in granite.. 31 

Michiel quarry, description of................ 73-74

Middlesex county, quarries of................ 76-78

Microstructure, character of.................. 46-47

Middletown, quarries in..................... 76-78

Millstone quarry, description of............ 109-112

Mineral veins, occurrence of................. 50

Monson granite gneiss, description of........ 23

Murray quarry, description of............. 104-106

N.

New Anguilla quarry, description of....... 103-104

New Haven county, quarries of.............. 78-91

New London granite gneiss, description of... 24 

New London county, quarries of............ 91-116 '

Norcross quarry, description of.............. 79-82

Norfolk, quarries in. ...................^..... 69

Norwalk, quarries in ........................ 59-60

O.

Old Lyme, quarry in ..................... 100-102

Oneco quarry, description of.-.............. 117-118

P.

Pegmatite, composition and occurrence of... 18-20 

description of............................ 40

Peterson quarry, description of............ 116-117

Plants, quarrying. See particular districts,

places, etc. 

Plymouth quarry, description of............. 72-73

Porphyry, composition and occurrence of.... 20-22

Potter quarry, description of................. 78-79

Prospect porphyritic gneiss, description of... 22 

Pyrite, occurrence of, in granite............. 16

Pyroxene, occurrence of, in granite.......... 15

Quarries, description of, method of.......... 52

Quarrying, methods of. Sec particular districts, places, etc. 

Quartz, occurrence of, in granite............. 15,51

R.

Richards quarry, description of............ 106-107

Rift, description of.......................... 26-29

direction of, in Connecticut granites..... 46

Ritch quarry, description of.................. 57-58

Rocks, fissility and jointing of............... 10-11

igneous, origin of........................ 9

metamorphic, origin of......'............ 9

of Connecticut, age of.................... 11-12

sedimentary, origin of................... 9

under pressure, behavior of.............. 10

Rockside quarry, description of.............. 70-71

Roxbury, quarries in........................ 70-71

S.

Sachem Head quarry, description of......... 88-90

Salter quarry, description of................. 91-93

Sap, occurrence of...........................' 42-43

Scott quarry, description of.................. 106

Segregations, description of.................. 41-42

Selden Neck quarries, description of........ 99-100

Seymour, quarry in......................... 90-91

Seymour Street quarry, description of....... 62

Shake structure, description of.... ......... 38,44

Sheet structure of granite, description of..... 29-36

Sheets, production of, in India............... 33

Slater quarry, description of... 1............. 66-67

Somers quarry, description of............. 112-113

Specimens of Connecticut granite. Sec particular districts, places, etc. 

Sterling, quarries in....................... 117-121

Sterling granite gneiss, description of ....... 23
INDEX. 137

Page. 

Sterling quarry, description 01...... 1..... 120-121

Stone Mountain, description of.............. 31

Stonington, quarries in.................... 102-106

Stony Creek granite gneiss, description of.... 24

Stony Creek quarry, description of.......... 82-84

Structure, plicated gneiss, description of...;. 47-48 

shake, occurrence of..................... 51

sheet, description of..................... 50-51

Subjoints, occurrence of..................... 39

T.

Tarr, R. S., on rift in granite................ 27-28

Texture of granitic rocks.................... 17-18

Thomaston, quarries in..................... 72

Thomastoa granite gneiss, description of.... 23

Toe-nails, occurrence of, in granite.......... 37

Tolland county, quarry of................. 116-117

Torrington, quarries in...................... 73-75

Torrington Borough quarry, description of... 74-75

Transportation. See particular districts,

places, etc.

Page.

14

55

Trap rock, production of.................

Treadwell prospect, description of........

' V.

Veins, quartz, occurrence of................. 40

zeolite in................................ 51

Voorhis quarry, description of............... 55-57

W.

Warren, quarry in........................ 76

Warth, IT., on artificial production of sheets

in granite....................... 33

Waterford, quarries in.................... 106-116

Waterford quarry, description of.......... 113-116'

Weathering of granite, description of........ 44

Wells, R. C., chemical work by............. 7

Whittle, C. L., on rift in granite............. 27-28

Willimantic gneiss, description of........... 23

Windham, quarry in...................... 121-122

Windham county, quarries of.......'...... 117-122

Z. 

Zeolite, occurrence of........................ 51

o