DEPARTMENT OF THE INTERIOR

UNITED STATES GEOLOGICAL SURVEY

GEORGE OTIS SMITH, DIRECTOR

BULLETIN 432

SOME ORE DEPOSITS IN MAINE

AND

THE MILAN MINE, NEW HAMPSHIRE

BY

WILLIAM H. EMMONS

WASHINGTON

GOVERNMENT PRINTING OFFICE

1910

CONTENTS.

Page.

Introduction.............................................................. 7

General statement...................................................... 7

Acknowledgments...................................................... 8

Bibliography........................................................... 8

Geography. ........................................ ----------.- --- 10

Mining development................................................... 10

Production of metals................................................... 11

Geology...............'................................................... 11

Sedimentary rocks................................................ .... 11

Ellsworth schist ................................................... 11

Islesboro formation................................................. 12

Battie quartzite ................................................... 12

Penobscot formation................................................ 12

Ames Knob formation.............................................. 12

Perry formation..................................................... 13

Igneous rocks ........................................................ 13

Castine formation.................................................. 13

North Haven greenstone............................................ 13

Thorofare andesite.................................................. 14

Vinalhaven rhyolite................................................ 14

Granite....:....................................................... 14

Diorite............................................................ 15

Basic lava flows.................................................... 15'

Basic dikes........................................................ 15

Ore deposits.............................................................. 15

Classification........................................................... 15

Deposits older than regional metamorphism.......................... 15

Distribution and character. ...................................... 15

Metamorphism................................................. 18

Origin........................................................ 20

Deposits associated with granite intrusions........................... 20

Fissure veins.................................................... 20

Molybdenite and lead deposits.................................. 21

Deposits associated with diabase and trap ........................... 22

Mineralogy............................................................ 22

Distribution of outcrops................................................ 24

Oxidation and secondary enrichment................................... 25

Future of the mines.................................................... 26

Lead, zinc, and silver.............................................. 26

Copper........................................................ 27

3
4 CONTENTS.

Ore deposits Continued. Page.

Summary of geologic events as related to ore deposits ................... 27

Pre-Cambrian and Cambrian time..................................... 28

Silurian time...................................................... 29

Devonian time. .................................................... 29

Quaternary time.................................................. 30

Descriptions of mines...................................................... 30

Mines of Hancock County.............................................. 30

General statement.................................................. 30

Douglas mine..................................................... 31

Twin Lead mine................................................... 32

Blue Hill mine..................................................... 33

Stewart mine................................... . ................. 33

Mammoth mine................................................... 34

Owen mine....................................................... 34

Owen lead prospect................................................ 34

Granger mine..................................................... 35

Weil Freddie mine................................................ 35

Tapley mine...................................................... 35

Eggemoggin mine.................................................. . 36

Deer Isle mine.................................................... 37

Cape Rozier mine................................................. 38

Hercules mine..................................................... 38

Jones & Dodge mine................................................ 38

Emerson mine.................................................... 39

Sullivan, Waukeag, and Pine Tree mines........................... 39

Gouldsborough mine................................................ 40

Franklin Extension mine.......................................... ' 41

Copperopolis mine.......................................... 1..... 41

Catherine Hill molybdenum mine................................... 42

Mines of Washington County............................................ 43

General statement................................................ 43

Cherryfield mine................................................... 43

Lubec lead mine................................................... 44

Denbow Point mine................................................ 45

Prospects in Pembroke............................................ 46

Cooper mine....................................................... 47

Mines in Somerset and Oxford counties .................................. 48

Robinson mine..................................................... 48

Mount Glines deposits............................................. 49

Milan mine, New Hampshire........................................... 50

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

Geology.......................................................... 52

Minerals of the ore................................................. 54

Ore bodies........................................................ 55

Summary of the genesis............................................ 59

Index ................................................................... 61
ILLUSTRATIONS.

Page.

PIATE I. A, Photomicrograph of schistose ore from Deer Isle mine; B, Photomicrograph of thin section of ore from Owen lead prospect..... 20

II. Geologic map of mineralized area of Blue Hill.................... 30

III. A, Polished surface of schistose ore of Milan mine; B, Photomicrograph of molybdenite ore from Catherine Hill.................. 42

FIGURE 1. Outline map of southern Maine................................... 7

2. Stringer of contorted pyrite in contorted rhyolite near the Tapley

lode.......................................................... 16

3. Quartz-pyrite veinlet leading off from Twin Lead lode............. 17

4. Plan of part of the 115-foot level, Milan mine .................... 17

5. Ore from Twin Lead mine, Blue Hill............................ 18

6. Thin section of ore from Milan mine.............................. 19

7. Thin section of schistose ore from Deer Isle mine .................. 20

. 8. Ore from Sullivan mine ........................................ 21

9. Brecciated diabase cut by quartz and sulphides, Pembroke mine.. 22

10. Section along line A-A', Plate II ............................... 31

11. Section along line B-B', Plate II ............................... 31

12. Cross section of the Sullivan mine................................ 39

Sketch showing position of principal veins in Lubec lead mine.... 44

Small vein in Lubec lead mine .................................. 45

Sketch showing position of pits of Eastern Exploration Company at 

Pembroke.................................................... 46

16. Plan and cross section of Robinson mine, near Concord............ 48

17. Vertical cross section of wall at open cut, .Robinson mine, near Concord.. ........................................................ 49

18. Plan of ore treatment at Milan mine............................. 51

19. Geologic east-west cross section through West Milan, N. H., north of

Milan copper mine............................................. 54

20. Pyrite cut by quartz, Milan mine................................ 54

21. Section of vein at east end of 115-foot level, Milan mine........... 55

22. Cross section of ore bodies, Milan mine........................... 56

23. Plan of 115-foot level, Milan mine................................ 57

5

SOME ORE DEPOSITS IN MAINE AND THE MILAN 

MINE, NEW HAMPSHIRE.

By WILLIAM H. EMMONS.

INTRODUCTION.

GENEEAL STATEMENT.

Metal mining does .not rank as an important industry in Maine,

for, aside from iron ore, the deposits of which were once worked with 

some vigor, the metallic production of the State has been small. It 

contains, however, deposits of nearly all the commoner metals a-nd,

FIGURE 1. Outline map of southern Maine.

owing to the complex relations of the rocks and the eventful geologic 

history of the region, the number of tj'pcs is not surpassed in many 

areas of equal size in regions of greater mineralization and larger 

ore deposits.
8 SOME ORE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

The economic reconnaissance described in the present paper Avas 

made during six weeks of the summer of 1909, in which time all of 

the most important deposits of the metals other than iron were visited. 

Figure 1 shows the positions of the towns and of villages near 

which the mines are located.. As many of them are in localities where 

the areal geology has been worked out in detail and Avhere the structural relations of the rocks are well understood, the history of the 

ore deposits may be stated with confidence. The conditions for 

underground work were not good, because nearly all of the mines 

were closed down and the shafts partly or entirely filled with water, 

but owing to the slight oxidation of the surface, the relations of the 

deposits and the character of the ores could be studied in many open 

cuts and at the higher levels above ground water.

In connection with this work the Milan mine, in Coos County, N. H., 

was visited. The deposit which is now successfully worked at this 

mine is only a few miles west of the Maine boundary and closely resembles some of the deposits in Maine. Its description is included in 

this report for the purpose of comparison.

ACKNOWLEDGMENTS.

The writer gratefully acknowledges his indebtedness to George 

Otis Smith and E. S. Bastin, whose published papers have supplied 

most of the geologic data for this report and who have given the 

writer unpublished notes on some of the mines; to Waldemar Lindgren, of the United States Geological Survey, for direction and criticism; to F. C. Robinson, state geologist of Maine; to Messrs. J. B. 

Carper and J. B. Morris, of Portland, for many courtesies; and to 

the owners of the mines and prospects, for the free access granted to 

their properties.

BIBLIOGEAPHY.

The following list is intended to include the most important publications on the ore deposits of Maine and their associated rock formations:

BARTLETT, F. L., Mines of Maine, Portland, 1879.

A discussion of the ores, with numerous assays and notes on the organization and capitalization of various mining companies operating in Maine. 

BASTTN, EBSON S. A pyrrhotitic peridotite from Knox County, Me. a sulphide 

ore of igneous origin: Jour. Geology, vol. 16, 1908, p. 124.

Describes a peridotite in which oliviue and cupriferous pyrrhotite are 

intimately intergrown in such a manner as to show contemporaneous age. 

 Eastport folio, Geol. Atlas U. S. (In preparation.)

Numerous geologic data soon to be published in this folio have been

freely contributed by Mr. Bastin and are incorporated in the present report.

CARPER, J. B. The Milan mine, New Hampshire. Eug. and Miu. Jour., vol..87,

1909, p. 318.

A brief note giving metal contents of ore shipments from the Milan mine.
INTRODUCTION. 9

HESS, FRANK L. Some molybdenite deposits of Maine, Utah, and California: 

Bull. U. S. Geol. Survey No. 340, 1908, p. 231.

Describes the molybdenite deposits of Cooper, Catherine Hill, and Paris, 

Me., and concludes that the molybdenite is of pegmatitic origin. 

HOLMES, EZEKIEL, and HITCHCOCK, C. H. Preliminary report upon the natural 

history and geology of the State of Maine, 1861.

This report includes many valuable geological data, with notes on the 

occurrence of bog iron .ores and magnetic iron ores at various places. 

Several occurrences of lead and zinc and other metals are mentioned, and 

extracts from a report by N. S. Mauross on the Lubec lead mine are 

incorporated.

HITCHCOCK., C. H. Geology of Maine: Second Ann. Kept. Natural History and 

Geology of Maine, Geology, 1S62, pp. 223-430.

The report includes detailed descriptions of rock formations and cross 

sections showing the geologic structure at many places along the Maine 

coast, and gives some running notes on the geology of the northern portions 

of the State. A list of mineral occurrences and a catalogue' with brief 

' descriptive notes on Mount, Mica minerals is included. Incorporated in' the 

volume is a report by G. L. Goodale on various occurrences of ore minerals

and on the economic possibilities of the iron ores.

JACKSON, CHARLES T. First report on the geology of the State of Maine, 1837. 

Some interesting notes of a geologic reconnaissance, \vilh descriptions 

of building stones and various mineral occurrences.

 Second report on the geology of the State of Maine, 183S.

Gives some cross sections in the region of Blue Hill, with descriptive notes 

 on the rocks involved. Describes granite, limestone, and shale quarries 

and the deposits of serpentine on Deer Isle. Includes notes on the technology of iron and of copperas manufacture on Jewel Island, Casco Bay.

 Third annual report of the geology of the State of Maine, 1838.

Includes notes of geologic reconnaissance, with a list of rocks, ores, and 

minerals from various localities.

KEMPTON, C. W. Sketch of the new mining district at Sullivan, Me.: Trans. 

Am. lust. Min. Eng., vol. 7, 1878, p. 349.

An account of the geology and ore deposits at Sullivan, with several 

geologic cross sections of that region. A paper of historical value, describing deposits which have not been worked for many years. 

MCCASKEY, H. D. Mineral resources of the United States for 1908, pt. 1, 

Metallic products, U. S. Geol. Survey, 1909, pp. 142, 146, 247, 658.

Notes on various metalliferous deposits of Maine.

SMITH, GEORGE OTIS. Quart/ veins in Maine and Arermont: Bull. U. S. Geol. 

.Survey No. 225, 1904, p. 81.

Describes quart/ veins at Mount Glines, Oxford County, and a pegmatite 

near Pittston, Kenuebec County, which has been erroneously regarded as a 

gold ore.

 A molybdenite deposit of eastern Maine: Bull. U. S. Geol. Survey 

No. 260, 1905, p. 197.

 Graphite in Maine: Bull. U. S. Geol. Survey No. 2S5, 1906, p. 480.

Describes occurrences of graphite near Madrid, Franklin County, and 

near Yarmouth, Cumberland County.

SMITH, GF.OKGE OTIS, BASTIN, EDSON S., and BROWN, CHARLES W. Peuobscot 

Bay folio (No. 149), Geol. Atlas U. S., U. S. Geol. Survey, 1907.

This folio furnishes the most comprehensive geologic data for Maine 

now available, and a considerable portion of the geologic descriptions of 

the present report are taken from it.
10 SOME OEE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

SMITH, GEORGE OTIS, and DAVID WHITE. The geology of the Perry Basin: Prof. 

Paper U. S. Geol. Survey'No. 35, 1905.

This paper is the result of an investigation of the rocks of the Perry 

Basin to ascertain whether there is a probability of finding coal there. The 

rocks of this basin are fossiliferous and are interbedded with the lavas, 

and their study has resulted in disclosing important relationships. The 

spherulitic rhyolites, which are devitrified and somewhat deformed by 

metarnorphism, are interbedded with fossiliferous Silurian strata and are . 

believed to be the effusive equivalent of the same magma which, solidifying 

at greater depth, formed the great granite intrusive that extends from 

Robbinston northward to the vicinity of Calais. The Perry formation, 

which rests above the Silurian and is less deformed, is made up of conglomerate and sandstone and includes beds of basaltic lavas. Since the Perry 

carries Devonian fossils the basic lavas are known to be of that age. 

Pebbles of granite are found in the conglomerate but not in the underlying 

Silurian rocks.

SMOCK, JOHN C. Mineral resources U. S. for \SS2, p. 687.

A list of "Ores, minerals, and mineral substances of industrial importance " which are mined in Maine.

STONE, GEORGE H. The glacial gravels of Maine and their associated deposits: 

Mon. U. S. Geol. Survey, vol. 34, 1899.

A comprehensive report on the glacial deposits of Maine. A discussion 

of glacial processes and a comparison of the continental, glacier with those 

of the Rocky Mountains.

GEOGRAPHY.

The State of Maine is for the most part a low plateau, the higher 

portions of which are* deeply trenched by rivers and creeks. Many 

hills and low mountains rise above this plateau, and it is thickly 

dotted by lakes and ponds. The coast line is very irregular. Long, 

narrow bays with deep water channels extend far inland and since 

these are navigable for small ocean craft transportation facilities are 

good and freight rates low.

MINING DEVELOPMENT.

Granite and limestone are quarried in large quantities and have 

a wide market. The metalliferous deposits, although they have not 

been abandoned, are not now being exploited. Mining was done in 

a small way in the early part of the nineteenth century. In the 

second report by Charles T. Jackson on the geology of the State, 

published in 1838, mention is made of a pyrite mine on Jewel Island, 

Casco Bay, where copperas and alum were manufactured. Later the 

iron ores of Mount Katahdin were developed; and for a long term 

of years, ending about 1890, these deposits produced from 2,000 to 

15,000 tons of iron a year. The Lubec lead mines, which were discovered in the late thirties, were worked with some vigor in the early 

sixties.
' . GEOLOGY. 11

The principal period of development was from 1878 to 1882, 

during which time the districts along the coast were having a mining 

boom that in all essentials resembled those periods of excitement 

notable in the history of many western camps. Mining companies 

with ample capitalization were organized to exploit the deposits of 

Blue Hill, Sullivan, and near-by districts. Substantial mine buildings were erected; expensive machinery was installed; and in some 

instances mills, concentrators, or smelters were built. At the Douglas mine, in Blue Hill, large sums were spent on smelters and roasting 

and leaching plants and several hundred tons of copper was recovered. In 1883 the price of copper dropped considerably' and the 

Douglas and other mines of Blue Hill were closed. The silver mines 

at Sullivan were closed soon afterward and have since been idle. The 

mines at Lubec and the Robinson mine, at Concord, have been worked 

in recent years, and between 1900 and 1907 prospecting was done at 

several places, but no large operations have been carried on since

the eighties.

PRODUCTION OF METALS.

The quantity of metals produced in Maine can not be given accurately. The total value of all metals other than iron is conservatively 

estimated at $400,000, the larger part of which is copper from the 

Blue Hill mines. The silver mines at Sullivan and at Byard Point 

probably yielded at least 5,000 ounces. A number of mines have 

yielded relatively small quantities of lead and zinc.

GEOLOGY.

The following discussion of the general geology of Maine is taken 

almost entirely from published papers of G. O. Smith and E. S. Bastin 

(see pp. 8-9), and from verbal statements made by them, and is 

intended to include only such data as have a direct bearing on the 

genesis and history of the ore bodies.

SEDIMENTARY ROCKS.

Ellsworth schist (pre-C ambrian?}. The Ellsworth schist is the 

oldest rock outcropping in the areas of mineralization, and is the 

country rock for many of the ore deposits. Large areas occur in 

Hancock County near Blue Hill (see PL II), and it extends eastward 

to Sullivan and beyond. It is composed of highly schistose metamorphic rocks which presumably are" the changed equivalents of 

siliceous shales and argillaceous sandstones. The rock is purple to 

greenish gray in color and is finely foliated. At most places metamorphism has obliterated all traces of bedding, but on the east.shore 

of Skilleys River in the Mount Desert quadrangle massive quartzite beds alternate with the more argillaceous layers. Under the micro-
12 SOME ORE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

scope the chief constituent minerals are seen to be quartz and chlorite. 

The chlorite occurs in thin parallel plates and gives the rock its 

schistosity. The quartz fragments have been rotated during the 

process of metamorphism so that the longer axes lie parallel to the 

chlorite leaves. Some biotite, muscovite, epidote, and magnetite are 

present in varying quantities. The schist is intruded by the Castine 

volcanic rock, by granite, and by diorite and is clearly older than all 

of these. Since formations known to be later than the Ells worth are 

very probably Cambrian, the Ellsworth is presumably very early 

Cambrian or pre-Cambrian.

Islesboro formation (Cambrian?}., Thelslesboroformation, which 

occupies a large part of Islesboro, is a series of metamorphosed slates 

and limestones at least 300 feet thick. It is everywhere strongly 

folded and at many places shows a well-developed slaty cleavage 

which intersects the bedding planes at high angles. On Seven Hundred Acre Island the slaty members contain intensely crumpled 

quartz veins. The Coombs limestone member forms the top of the 

formation and is overlain by the Battie quartzite. In the southern 

part of Job Island the limestone is interbedded with dark-green 

layers which seem to be volcanic tuffs or muds of the North Haven 

greenstone. The slate member likewise contains volcanic material of 

the same age and origin. In the metamorphism which has affected the 

formation the limestone has completely recrystallized and the shaly 

beds have at most places become schists. No»fossils have been found 

in the'formation, but on stratigraphic grounds it is thought to be of 

Cambrian age.

Battie quartzite (Cambrian?} . The Battie quartzite, which consists of massive buff quartzite and quartzite conglomerate several 

hundred feet thick, rests directly upon the Coombs limestone member 

of the Islesboro formation without any apparent unconformity. It is

well exposed at Mount Battie, a small mountain near Camden. It 

is not highly crumpled, as.is the slate phase of the Islesboro, because 

it was less yielding. It is believed to be of Cambrian age.

Penobscot formation (Cambrian?}. The Penobscot formation, 

typically developed along the west shore of Penobscot Bay, is composed of metamorphosed shaly sediments which overlie the Battie 

quartzite. A distinct and perfect schistosity is commonly present, 

and the formation is at places intensely folded into isoclinals. At 

Ducktrap Harbor the slates are intruded by granite, and garnet, andalusite, and other minerals have formed by contact metamorphic processes. The Penobscot formation is believed to be of Cambrian age.

Ames Knob formation (Silurian}. The Ames Knob formation, 

which is made up .of limestones', red shales, and conglomerate, contains Niagara fossils. It has been gently tilted in places, but the 

compressed folds and minor crumplings characteristic of the Penob-
GEOLOGY. 13

scot, Islesboro, Castine, and North Haven formations are entirely 

absent. Clearly it has been deposited since the time of the regional 

metamorphism of the country. The basal member is a conglomerate, 

which includes rounded fragments of North Haven greenstone and 

of green slate, quartzite, and vein quartz. The upper portion of the 

formation contains volcanic material, and in the Penobscot Bay quadrangle it grades into the Thorofare andesite. In the Perry Basin 

fossiliferous Silurian strata are interbedded with rhyolites.

Perry formation (Devonian}. The Perry formation,0 which in the 

Perry Basin overlies the Silurian rocks, consists of a lower conglomerate member, above which are beds of basaltic lava and breccia. 

Above the latter is coarse red and brown sandstone with included 

conglomerate and lava layers. Above this still is a green amygdaloid 

and sandstone. The plant remains show the formation to be of 

Devonian age. Except for certain glacial deposits formed in comparatively recent times by the ice sheet which covered the entire State, 

no sedimentary beds younger than the Perry are known to occur in 

the areas of mineralization.

IGNEOUS ROCKS.

Castine fomnation (Cambrian?}. The Castine formation, which 

is typically developed on the Castine Peninsula, is made up of lightcolored lavas and pyroclastic rocks including rhyolite, dacite, and 

andesite. These rocks occur as flow breccias, conglomerates, tuffs, 

intrusive sheets, and dikes. The great bulk of them are metamorphosed dynamically, and some, which were presumably volcanic 

muds, are highly schistose. Some of the tuffs seem to have been rich 

in lime carbonate. Chlorite, sericite, biotite, and cordierite have in 

places been developed in the Castine by secondary processes. Tremolite, biotite, and other jninerals have developed by contact metamorphism. A similar association of minerals with sulphides and 

abundant garnet is found at the Deer Isle mine. (See p. 37.) The 

Castine formation is in a general way contemporaneous with the 

Islesboro formation and is believed to be of Cambrian age.

North Haven greenstone (Cambrian ?). The North Haven greenstone, which is extensively developed on the. island of North Haven 

and on neighboring smaller islands, is made up of regionally metamorphosed diabase, basic trachyte, and albite-augite syenite, which 

occur as tuffs, flows, dikes, and sills. The different varieties, which 

are at many places indistinguishable, are associated in the most intimate and irregular manner and are believed to be contemporaneous. 

At some places these rocks show highly developed schistosity. 

Fibrous actinolite, zoisite, calcite, muscovite, biotite, and chloritic

» Smith, G. 0., and White, David, Prof. Paper U. S. Geol. Survey No. 35, 1905, p. 28.
14 SOME QBE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

minerals are developed by regional metamorphism. The North 

Haven greenstone is older than the Silurian sediments; and since 

the Islesboro formation contains much fragmental material of common age and origin with the North Haven greenstone, the latter is 

believed to be contemporaneous with the Islesboro and nearly contemporaneous with the Castine. Both formations are probably 

Cambrian.

Thorofare andesite (Silurian). The Thorofare andesite, which is 

extensively developed along the Fox Island Thorofare, includes 

massive porphyritic andesite, amygdaloid, tuffs, flow breccias, and 

conglomerate. These volcanic rocks, which are not regionally metamorphosed, overlie the upper members of the Ames Knob (Silurian) 

formation and have about the same attitude. The red shales at the 

top of the Ames Knob contain volcanic dust, which probably represents the earliest Thorofare eruptions.

Vinalhaven rhyolite (Silurian). The Vinalhaven rhyolite, exposed in the northwestern part of the island of Vinalhaven, is made 

up of surface flows. Some are glassy and show flow structure; some 

are taxitic and spherulitic. They overlie the Thorofare andesite, 

and at some places fragments of the latter are mixed with the rhyolite 

flows, the rhyolite constituting the matrix. They are in the main 

younger than the Thorofare, but near' the line of contact of the two 

formations beds of rhyolite alternate with beds of andesite. It 

seems probable that the two kinds of lavas were erupted from separate neighboring vents, the volcanic activity beginning with the 

eruption of the andesite and ending with that of the rhyolite. The 

andesites and rhyolites are of post-Niagara age, probably late Silurian, and older than the granite.

Granite. Along the Maine coast from Calais to Portland and 

beyond granite covers large areas. At most places it is gray or pink 

an/1 medium grained. The common constituents are orthoclase, 

micrpcline, albite, biotite, and muscovite. The granite shows no 

schistosity such as results from regional metamorphism. It cuts the 

Ellsworth, the Castine, and other pre-Silurian formations and sends 

off apophyses into them. The intruded rock is frequently recrystallized near the contact, where some andalusite has formed, but no extensive garnet zones are developed. The granite cuts rocks which are 

known to "be younger than the Ames Knob formation, and it is therefore as late as Silurian. In the Perry Basin no granite pebbles are 

found in the Silurian, but late Devonian conglomerates (Perry) contain abundant rounded fragments of the granite. The coast granites 

of Maine were therefore intruded in late Silurian or early Devonian 

time, and it has been suggested ° that they are about contemporaneous

"Smith, G..O., Prof. Paper U. §. Geol. Survey No. 35,, 1905, p. 20.
GEOLOGY. 15

with certain of the Silurian rhyolites. The granite apparently was 

not rich in metals, although some of the ore deposits appear to be 

related to it genetically.

Diorite, etc. Diorite, diabase, and gabbro are associated with the 

granite and are believed to be somewhat earlier but essentially contemporaneous differentiations from the same magma. They are dark 

rocks of medium grain and are free from schistosity. At some 

places diorite and granite may be seen grading one into the other, 

and dikes of either rock may cut the other. The Gouldsborough 

lode is a fissure vein in diorite which near by is brecciated and 

cemented by medium-grained granite.

Basic lava flows. In the Perry Basin, near Lubec, in Pembroke, 

and at many other places in Washington County there are great 

flows of basic lavas, including basalts, diabase, and " trap rock." 

In the Perry Basin these are interbedded with sandstone and conglomerate carrying late Devonian fossils, showing that at least some 

of the flows are of late Devonian age.

Basic dikes. The granite and the older rocks are cut by dikes of 

diabase, basalt, and analcite basalt. Some of these are doubtless 

very old, others are believed to be the intrusive equivalents of the 

lavas included in the Perry formation, while others still are probably 

Mesozoic (Triassic?). A basaltic dike cuts across the Robinson lode 

at Concord, Somerset County, and is very clearly later than the ore. 

The basalt at the intersection is so fresh that even the olivines show 

very little of the characteristic alteration to serpentine along cracks.

ORE DEPOSITS.

CLASSIFICATION OF DEPOSITS.

The principal ore deposits of Maine, not including the iron ores 

nor the gem-bearing pegmatites, may be divided into three groups 

(1) deposits formed before the end of the last period of great 

regional metamorphism; (2) deposits associated with the granite intrusions; and (3) deposits associated with eruptions of diabase or 

trap.

DEPOSITS OLDER THAN REGIONAL METAMORPHISM.

Distribution and character. The pre-metamorphic deposits are the 

most important. All the known representatives are in Hancock 

County, in the hilly country between Penobscot and Blue Hill bays. 

They include, stated in order of importance, pyritic copper ores, 

garnetiferous zinc ores, and siliceous zinc-lead-silver ores. All are 

in the Ellsworth schist and the Castine volcanic rocks the Twin Lead, 

Douglas, Blue Hill, Stewart, Mammoth, Owen Copper, Granger, and 

Weil Freddie being in the Ellsworth, and the Tapley, Deer Isle,
16 SOME ORE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

Cape Eozier, Emerson, and Hercules in the Castine. In all the mines 

in which the ore bodies are exposed the sulphides appear disseminated 

through the rock, as lenses approximately parallel to the schistosity, 

or as deformed breccia zones.

The copper deposits near Blue Hill and Brooksville are the most 

important. All of the mines have lain idle for years and their 

underground workings are inaccessible, but the character of the ore 

and its relations to the structure are shown in a number of deep 

open cuts. Except at the Tapley mine, which is in the Castine formation, the Blue Hill and Brooksville' deposits are all in the Ellsworth 

schist. This is a siliceous sedimentary rock which has been metamorphosed at great depths and under pressure. (See p. 11.) The 

minerals of the ore are quartz, chlorite, muscovite, biotite, pyritr, 

chalcopyrite, pyrrhotite, magnetite, arsenopyrite, bornite, chalcocite, 

and a little zinc blende and galena. Near Blue Hill the deposits 

lie approximately parallel to the schistosity, striking from S. 87° E.

to N. 77° E. and dipping 

from 45° S. to vertical.

The lodes are from 5 to 20 

feet wide and are said to persist along the strike for several hundred feet. Their 

central portions are as a rule 

composed of massive pyrite, 

with which some chalcopyrite 

and other sulphides are intergrown. Some quartz is present. Toward the wall thin 

slabs of schistose quartz and 

chloride rock are included 

in tiie pyritic ore. These slabs and their constituent minerals lie 

nearly parallel to the schistosity of the country rock and the trend of 

the deposit. The walls themselves, which are of the same composition 

as the slabs, contain stringers of pyrite. Thus there is a gradation 

from the center of the deposit, which is in the main massive pyrite, 

to the country rock, which carries only a little pyrite. Comb structure and druses with crustified banding are lacking. At some places, 

notably in the Twin Lead and Tapley mines, small veins of the 

sulphides are crumpled parallel to the crumpling of the schist, as 

illustrated by figures 2 and 3.

In the Milan mine, New Hampshire (see p. 50), deposits of the same 

general character occur in two overlapping lenses. These two lenses 

are clearly parts of a single ore body which was torn apart during 

the process of regional metamorphism. At that time the country 

rock was deformed by fiowage and the pyritic deposit by fracture;

.FIGURE 2. Stringer of contorted pyrite in corn 

: torted rhyolite near the Tapley lode.
CLASSIFICATION OF DEPOSITS. 17

that is, the depth was such that the pressure due to the weight of the 

overlying rocks exceeded the crushing strength of the quartz-chlorite 

schist and was inferior to that of the pyrite and quartz. The schistosity of the country rock near by is parallel to the line of separation,

i Foot

FIGURE 3. Quartz-pyrite veinlet leading off from Twin Lead lode. The crumpling of the 

pyrlte shows that it is older than the metainorphism of the inclosing Bllsworth schist.

which "wraps around the broken ends of the ore body. The fault, if 

it be so called, is reverse. The place of separation is a highly siliceous portion of the lode and one where the ore is highly crumpled. 

Perhaps future exploration will show that some of the lodes at Blue 

Hill which are said to be overlapping in the underground workings

FIGURE 4. Plan of part of the 115-foot level, Milan mine, New Hampshire.

are joined at their ends by thin fissures and that the schistosity of the 

country rock along such fissures is parallel to them, as indicated in 

figure 4. 

The wall rock does not show leaching or changes like those commonly resulting from hot-water action of vein-forming solutions, and 

42381° Bull. 432 10 2
18 SOME ORE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

if ever changed by the processes of hydrothermal metamorphism, the 

changes have been obscured by later regional metamorphism. The 

latter process must also have destroyed such features as druses with 

crustified banding and comb structures, if they were ever present.

Metamorphism. The behavior of the sulphides during regional 

metamorphism is noteworthy. Where the ore is nearly pure sulphide, 

composed of pyrite with some chalcopyrite, it is crushed and recemented by pyrite or by chalcopyrite. It then appears massive and 

shows little or no schistosity, and one examining the central part of 

the lode only would not suppose that it had been deformed with the 

metamorphism of the schists. But near the walls, in the lower-grade 

ore composed of pyrite, quartz, chlorite, and mica, there is a welldefined schistosity, as shown in figure 5. From microscopic studies it 

is seen that some of the crushed fragments of pyrite have oriented

FIGURE 5. Ore from Twin Lead mine, Blue Hill, Maine. The schistosity was developed 

after the ore was formed, a, Quartz; I, pyrite; c, chlorite schist. (Compare fig. 8, 

P. 21.)

themselves parallel to the schistosity between the grains of quartz 

and chlorite. The crushing is especially well shown where two 

crystals of pyrite are pressed against each other or against a grain 

of quartz. If the pyrite crystals are surrounded by chlorite or by 

mica, they are protected by these yielding minerals, but where two 

pyrite crystals touch they are shattered and recemented. This feature is illustrated by figure 6, which shows crystals of pyrite that 

appear in hand specimens to be quite homogeneous. Some perfect 

crystals of pyrite are formed, however, from iron sulphide dissolved 

and reprecipitated; such are found mainly in thin crumpled seams 

where movement has been most intense. Under these conditions 

cubes and octahedra are developed rather than pyritohedra or pentagonal dodecahedra. The pyrite was deposited in perfect crystals 

even under the conditions of great pressure and the presence of other
CLASSIFICATION OF DEPOSITS. 19

minerals. The great crystallizing power of pyrite is well known. 

It is so great that when pyrite replaces other minerals exactly enough 

nf their substance is dissolved to make a space for the pyrite. As an 

example may be cited the common case of quartzites in which two or 

more of the rounded grains of quartz are half dissolved and one perfect pyrite crystal fills completely the space left where the parts of 

quartz grains were removed.

It is no easy task to determine the character of these deposits 

before they were metamorphosed, but this may be inferred from 

their present condition and mineralogical character. The diagnostic 

value of the minerals is lessened by the fact that nearly all of them 

may be produced under conditions of regional metamorphism wherever the necessary elements are at hand. 

Before metamorphism

the pyritic copper deposits of Blue Hill and 

Brooksville were presumably fissure veins 

of replacement types 

and disseminated ores 

along fractured zones. 

At the zinc mine at 

Deer Isle, (see p. 37) 

garnet, actinolite, and 

calcite are abundant 

and are all microscopically banded parallel to the schistosity 

of the country rock 

and to the tablets of 

massive sulphides. 

This deposit is believed to be a contact-metamorphic deposit which has been regionally 

metamorphosed. An alternate hypothesis is that the garnet and 

tremolitti Avere developed by processes of regional metamorphism 

when the ore body was subject to the stresses which developed its 

schistosity. The garnet, however, is not in the perfect crystals which 

usually form under such conditions, but occurs in crumpled bands, 

mashed and very highly fractured, alternating Avith the other minerals. (See_fig. 7 and PL I, A.) Further, garnet and actinolite are 

rare or absent in the Blue Hill copper deposits, which, Avith respect 

to regional metamorphism, have had a similar historj^. The silver 

deposits of the Cape Eozier, Hercules, and Emerson mines, Avhich 

from the character of the ore are believed to belong to this very

lldiam.

FIGURE 6. Thin section of ore from Milan mine, New 

Hampshire. The pyrite has been shattered and recemented, p, Pyrite; cp, chalcopyrite; c, chlorite; 

q, quartz.
20 SOME OEE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

old group, are not well exposed and their primary origin is not 

understood.

i Origin. The source of the solutions which deposited the primary 

ores is not known. The youngest rocks of this area which contain 

the schistose ores are the greatly metamorphosed Castine intrusives 

and flows. -All of these ores may have been formed during or at the 

close of the volcanic period of the Castine and North Haven eruptives, and they may have been formed by solutions contributed by 

intrusive rocks such as the North Haven greenstone and the andesites 

associated with the Castine formation. The North Haven, which 

includes diabase, basic trachyte, and albite-augite syenite, occurs at

some places as dikes

b b b an(j sj]|s of approximately the same age as 

the Castine/1 If the 

garnetiferous zinc ores 

of Deer Isle, which 

seem to have been deposited in calcareous 

tuffs of the Castine formation, are contactmetamorphic deposits 

formed near the margin of a North Haven 

greenstone intrusive, 

then the thickness of the Castine above the tuffs must have been 

considerable, for such deposits are not formed at shallow depths.

 DEPOSITS ASSOCIATED WITH GRANITE INTRUSIONS.

The deposits associated with granite intrusions include the Sullivan, 

Gouldsborough, and West Franklin mines, the Owen lead deposit at 

Blue Hill, and the molybdenum mine at Catherine Hill. The deposits 

are (1) fissure veins in schist and diorite near intrusive granite; 

(2) molybdenum sulphide ore associated with the pegmatitic phases 

of the granite magma'; and (3) lead sulphide consolidated with the 

rock-making minerals of the granite.

Fissure veins. The chief metals of the fissure veins are silver and 

zinc. The principal minerals are quartz, zinc blende,.galena, pyrit7e, 

chalcopyrite, and arsenopyrite, but at the Sullivan mines stephanite, 

argentite, native silver, and tetrahedrite are reported to be present. 

Pyrrhotite is lacking. In composition and structural features these 

lodes contrast strongly with the regionally metamorphosed deposits.

FIGURE 7. Thin section of schistose ore from Deer Isle 

mine, showing parallel bands of garnet, sericite, and 

sulphides, a, Chlorite and sericite ; I), fractured garnet ; G, pyrite, blende, and galena. .

"Smith, G. 0., Bastin, E. S., and Brown, C. W., Penobscot Bay folio (No. 149), Geol. 

Atlas U. S., U. S. Geol. Survey, 1907, p. 7.
U. S. GEOLOGICAL SURVEY

A. PHOTOMICROGRAPH OF SCHISTOSE ORE FROM DEER ISLE MINE.

B. PHOTOMICROGRAPH OF THIN SECTION OF ORE FROM OWEN LEAD PROSPECT.
MINEEALOGY. 21

Although some of them are in the quartz-chlorite (Ellsworth) schist 

they cut across the schistosity of that rock and include angular fragments of it. These fragments are slightly rounded by the veinforming solutions and are arranged haphazard with respect to 

schistosity. Drusy cavities with crustified banding and comb structure are common. These features are illustrated by figure 8, which 

is a sketch of the ore at Sullivan. Comparison of this ore with the 

schistose Twin Lead ore illustrated by figure 5 shows many of the 

points of difference between deposits associated with granite intrusions and those of earlier origin.

The Gouldsborough mine is in quartz diorite, a rock-which shows 

no regional metamorphism and is believed to be an earlier differentiation from the granite magma. Its age relations Avith the granite are 

shown near the mine, where broken pieces of the diorite are cemented 

by granite. The lode is a fissure vein or sheeted zone composed

:fe^-:^);^M^:£^

3 Inches

FIGURE 8. Ore from Sullivan mine The schistosity was developed before the ore was 

formed, a, Fragments of schist; fc, vein quartz. (Compare fig. 5, p. 18.)

of banded sulphides and quartz. Near the lode the hot solutions have 

changed the country rock, and much chlorite, some pyrite, epidote, 

and sericite have replaced the minerals of the quartz diorite.

The zinc mine at Concord,...near Bingham, Somerset County, is a 

siliceous deposit occupying the crest of an anticlinal axis. The ore 

is not metamorphosed and may belong to the granite period of mineralization, but the deposit is isolated and the geology of the surrounding area has not been studied with sufficient care to justify an attempt 

to classify it.

Molybdenite and lead deposits. The Catherine Hill molybdenite 

deposit (PL III, B] and the Owen lead deposit (PL I, B) are magmatic segregations which belong to this period of mineralization. The 

galena and the molybdenite inclose well-shaped crystals of feldspar 

rounded on the edges, but clearly idiomorphic, or nearly so. The 

sulphides solidified at the time the rock was formed. A similar
22 SOME ORE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

crystallization of pyrrhotite in peridotite from Knox County has 

been described by E. S. Bastin.0

DEPOSITS ASSOCIATED WITH DIABASE AND TRAP.

The deposits associated with the diabase and trap include those of 

the Lubec lead mine, the Denbow Point mine, and the copper and 

zinc prospects in Pembroke, all of which are in Washington County 

and in the Eastport quadrangle. The country rock is at no place 

greatly metamorphosed by pressure and the ores show no schistosity. 

The galena-blende ores at Lubec are deposited in thin fissures and in 

brecciated zones. The ores at Pembroke are deposited in vesicular 

cavities and in nonpersistent fractures in basic flows, as illustrated by 

figure 9.

The deposits of this group show drusy cavities and crustified banding. The minerals of the ore are quartz, dolomite, calcite, galena, zinc

blende, pyrite, chalcopyrite,

a, <& a, a, a, a- bornite, and arsenopyrite.

The oxidized ore is composed 

of quartz, limonite, and a 

little manganese oxide and 

copper carbonate. The Lubec ores carry some silver. 

No pyrrhotite is present in 

the ores of these deposits and 

no massive magnetite, although the crushed ore yields 

a trace of magnetic dust 

possibly an oxidation product. As a result of the reactions of the vein-forming solutions with 

the wall rock much secondary chlorite and calcite were formed but 

only a little sericite.

MINERALOGY.

The following list includes the most important minerals of the 

deposits, with brief descriptive notes of their occurrence. Only the 

most important of the rock-making minerals are mentioned and no 

attempt is made to list the minerals of the pegmatites, except those 

which are closely related in genesis to some of the ore deposits. The 

pegmatites of Maine are to be treated in a forthcoming paper by 

E. S. Bastin.

Actinolite. Developed by secondary processes in some of the regionally 

metamorphosed schists and intimately associated with the garnetiferous ores at 

the Deer Isle mine.

FIGURE 9. Brecciated diabase cut by quartz and 

sulphides, Pembroke mine, a, Quartz and ore ; 

I), diabase.

0 Pyrrhotitic peridotite from Knox County, Maine a sulphide ore of igneous origin : 

Jour. Geology, vol. 16, 1908, p. 124.
MINERALOGY. " 23

AlMte. A common constituent of the granite and some other igneous rocks. 

Appears as icliomorphic crystals surrounded by galena at the Owen lead mine 

and as crystals surrounded by molybdenite at the Catherine Hill molybdenite 

mine.

Apatite. A common accessory constituent of the granite and other igneous 

rocks. Crystals of apatite are surrounded by galena in the Owen lead prospect.

Argentite. Reported from the silver mines at Sullivan.

Arsenopyrite. Present in the copper mines at Blue Hill and in the silver 

mines at Sullivan, but not abundant at either place.

A'ligite. Abundant in the basic igneous rocks, but not noted in connection 

with any of the ore deposits.

Barite. Not abundant. A little was noted on the dump at the Deer Isle mine 

and at the Sullivan mine.

Biotite. A common constituent of the schist. Is present in the schistose 

copper ores.

Bornite. Not abundant in any of the deposits but appears in some of-those 

. at Blue Hill, at the Lubec lead mine, and at the prospects in Pembroke.

Gttlcito. Rare or absent in the schistose ores at Blue Hill but present in the 

Deer Isle zinc ore, in the Lubec lead ores, and in the wall 1'OCk near the lodes 

along some of the fissure veins.

Cerargyrite. Reported from the silver mines at Sullivan.

Chalcocite. Not abundant in any of the deposits. Sparingly present as 

dark films on chalcopyrite at the copper mines near Blue Hill.

CliMleop'ijrite. Present in nearly all of the deposits. An important ore mineral in the schistose copper ores of Blue Hill.

Chlorito. Abundantly developed in the schist and intimately associated with 

the schistose ores; also the most abundant mineral formed by metasomatic 

processes along the fissure veins in igneous rocks.

Copper, native. An oxidation product of the copper-bearing sulphides. Reported from the Douglas mine and the Owen mine at Blue Hill.

Cuprite. Sparingly present in the zone of oxidation of the copper deposits.

Epidote. Appears with quartz in some small veinlets in Pembroke. Developed with chlorite and sericite in the quartz diorite wall rock of the Gonldsborough lode.

Galena. Sparingly present in nearly all of the deposits. More abundant at 

the Lubec and the Bingham mines. lutergrown with feldspar at the Owen lead 

prospect.

Garnet. Abundantly present in the schistose ores of the Deer Isle mine, 

where it has been regionally metamorphosed. Sparingly developed in intruded 

rocks near intruding granite and pegmatite.

Gold. Sparingly present in the Blue Hill mines and reported in small quantities from most of the other mines visited. Occurs sparingly in some river 

gravels. Not an abundant ore mineral in Maine.

Graphite. Occurs in pegmatite and in metamorphosed schists at several 

localities.

Gypsum. Present in ore of Sullivan mine.

Hematite. Either hematite or the hydrated oxide turgite is usually present 

in the oxidized ore of all groups.

Kaolin. Formed from feldspar and other minerals in the igneous rocks by 

reactions with surface waters.

Limonite. The most abundant mineral in the oxidized ore. Appears near 

the surface of nearly all the deposits.
24 SOME OEE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

Magnetite. Occurs in noticeable quantity in the Blue Hill copper ores and 

in the Deer Isle zinc ore. Minute specks are present in the ore of some of the 

later silver lodes but only as the merest traces.

Malachite. Rare in the copper deposits of Blue Hill. Forms on) the old 

slag dumps, but was not noted in the ore. A little is present in the copper prospects at Pembroke.

Manganese oxide. Present in the oxidized ore at Blue Hill and occurs in the 

Lubec lead ore.

Microcline. See Orthoclase.

Molybdenite. Present in granite and in pegmatite at Catherine Hill.

Muscovite.-^Occurs in the quartz-biotite schist and is associated with the 

ores of that rock. Forms as sericite along the silver lodes by metasomatic replacement, but not abundantly.

Olivine. Fresh olivine is abundant in the later trap rocks and decomposed 

olivine in the greenstones.

 Orthoclase. Orthoclase and microcline are prominent minerals of the granite 

and associated pegmatites.

Pyrite. The most abundant and a ubiquitous mineral of the ores.

Pyroxene. Present in the more basic igneous rocks.

Pyrrhotite. Present in all of the copper ores at Blue Hill and in some of the 

lead and zinc ores near by, and sparingly present in the Bingham zinc ore. 

Not present in the silver lodes associated with the granite.

Quartz. Present in most of the igneous rocks, in all of the sedimentary 

rocks, and in the ore of all groups of deposits. The pegmatitic quartz contains fluid inclusions.

Rhodochrosite. Absent in most deposits; a little noted at the Deer Isle 

zinc mine.

Sericite. See Muscovite.

Siderite. Gangue mineral at the Pembroke copper prospects.

Silver, native. Reported from the Eggemoggin and Sullivan mines.

Specularite. Nowhere abundant. Some was noted at the Stewart copper 

mine and on the Hercules dump.

Stephanite. Reported from the Sullivan mine.

Stil>nite. Reported from the Sullivan mine and from the copper deposits 

near Blue Hill.

Talc. Present in ore of Sullivan mine.

Tetraliedrite. Reported from the Sullivan mine.

Tourmaline. Present in the pegmatite at Mount Mica and at Crocker Hill.

Tremolite. Developed in the wall rock at the Tapley mine.

Wolframite. Dr. Charles T. Jackson 0 found wolframite (iron-manganese 

tungstate) and molybdenite in granite near Blue Hill Falls.

7Anc Uende. Present in deposits of all groups, but sparingly so in the Blue 

Hill copper deposits.

DISTRIBUTION OF OUTCROPS.

In relatively late geologic times the entire State of Maine was 

covered with an immense glacier or ice sheet which had slowly invaded it from the northwest. Much of the territory now under the 

sea was doubtless overlain by this ice sheet, for it is known to have 

extended to far outlying islands. As the climate grew warmer the 

ice gradually receded northwestward, but upon the country it had

0 First report on the geology of the State of Maine, vol. 1, p. 103.
OXIDATION AND SECONDARY ENRICHMENT. 25

covered it left drift of various types which concealed many outcrops 

of rocks and their contained ore deposits. After the ice had gone the 

land slowly rose to higher levels above the sea. At some places seaworn pebbles are found as much as 225 feet above the present coast.0 

The emergence of the land was very slow, however, and at times it 

remained stationary long enough for imperfect bars, spits, and similar coast features to be formed.6

In some places in the region of Penobscot Bay, when the land was 

about 20 or 25 feet below its present position,0' there was a noteworthy halt in the process of elevation, and during this period terraces Avere built by the sea and cliffs were cut in exposed places. 

Doubtless the glacial drift was washed away at many places, laying 

bare the rocks and ore deposits. Subsequently the land rose 20 or 25 

feet. Thus along the ragged seacoast about 25 feet above the present 

shore line was exposed a belt which had at favorable places been 

lately washed by the waves. Along this belt the rocks are well exposed, and in it many of the ore deposits have been discovered. The. 

Deer Isle, Eggemoggin, Hercules, Emerson, Cape Rozier, Sullivan, 

Denbow Point, Lubec, and other'deposits are near the water's edge, 

hot more than a few feet above sea level, and some of them doubtless 

owe their exposed condition to the washing of the waves in this zone 

of delayed emergence. Some of the deposits named were discovered 

beloAv high tide and worked by means of cofferdams, but most of them 

were found some 10 to 20 feet above high tide.

In many regions creeks and brooks which cut through the overlying mantle of soil furnish good exposures of the rocks, and the 

banks along such streams are favorable positions to search for outcrops of ore deposits. In Maine, however, these smaller streams have 

been engaged in removing the glacial material left at the comparatively late recession of the ice sheet and have not had sufficient time 

to do much cutting in the solid rock; consequently, their banks do 

not furnish the customary quota of outcrops. At some places, where 

the glacial ice with its included stones planed off the country rock, 

the latter has not yet disintegrated into soil and still remains bare; 

in such places a few deposits have been discovered, among which are 

the Tapley mine, in Brooksville, and some of the copper prospects in 

Pembroke.

OXIDATION AND SECONDARY ENRICHMENT.

When sulphide ores remain for a long time near the surf ace. of 

the earth the oxygenated surface waters react on their minerals. 

Oxides, carbonates, and other compounds are formed, and the quartz

" Stone, G. H., Mon. U. S. Geol. Survey, vol. 34, 1899, p. 48. 

6 Willis, Bailey, Bull. Geol. Soc. America, vol. 14, 1903, p. 205.

"Smith, George Otis, Bastin, E. S., and Brown, C. W., Penobscot, Bay folio (No. 149), 

Geol. Atlas TJ. S., U. S. Geol. Survey, 1907, p. 13.
26. SOME ORE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

and other difficultly soluble minerals are usually disintegrated. As 

a result of these processes the outcrop of a sulphide ore body appears 

in general as a mass of iron oxide or of quartz stained with iron oxide 

and other oxygen compounds. In cupriferous deposits carbonates 

commonly appear at the outcrop, but such are rare in the oxidized 

copper ores in Maine.

The depth to which the oxides extend is variable and depends 

largely on the shattering or fracturing of the sulphide deposits, 

which makes them more pervious to water, and on the length of time 

they have been exposed to surface waters. In Maine the deposits are 

not greatly fractured, and since glaciation is of relatively recent date 

they have not been long exposed to highly oxygenated surface waters. 

At many places the sulphides appear at the very surface, and mixed 

oxides and sulphides are very common in the outcrops. At the Douglas mine, in the open pit just west of the main shaft, the oxidized 

ore ends abruptly along a fracture which cuts the lode 5 or 10 feet 

below the outcrop. In the Milan mine (New Hampshire) the depth 

of oxidation is greater and the lode is partly oxidized to 40 feet below 

the apex, while oxidation along watercourses extends 100 feet below 

the surface. Compared with-that of deposits in unglaciated region's 

oxidation in northern New England is slight. >

Where the upper portion of^a lode is in the zone of oxygenated 

waters, some of the minerals pass into solution. Pyrite and chalcopyrite on oxidation yield sulphuric acid and iron and copper sulphates. If it happens that a lode is highly shattered below the zone 

of oxidation these sulphates are carried downward in solution, and 

when they reach a zone in which there is relatively little oxygen they 

react with pyrite and chalcopyrite and deposit chalcocite. This process is commonly termed secondary enrichment, for it changes the 

lower-grade sulphides to richer copper ores. In the Milan mine

the process has operated to some extent to enrich shallow chalcopyrite and cupriferous pyrite; and masses of these minerals where 

fractured are commonly coated with a film of black chalcocite. 

Similar ore was observed on the dumps of the Douglas mine, near 

Blue Hill, and at other mines near by, but there is no evidence that 

this process was carried far. The tight condition of the deposits 

and the brief period of exposure to oxygenated waters are unfavorable to much sulphide enrichment or to extensive oxidation, and if the 

deposits extend downward to great depths the copper content will 

not be much lower than it is near the surface.

FUTURE OF THE MINES.

Lead, zinc, and silver. It does not appear likely that any of the 

lead, zinc, and silver deposits which have been examined will become 

important sources of these metals. Possibly some of them could be 

worked in a small way by hand sorting and by the more simple
SUMMARY OP GEOLOGIC RESULTS. 27

methods of mechanical concentration, but the ore is in the main of 

low grade. It is nowhere greatly oxidized and could easily be concentrated mechanically, but no ore body yet developed'is of sufficient 

size to warrant the erection of a plant large enough to work with real 

economy. A presumption against the existence of rich deposits associated with granite is afforded by the chloritic alterations of the walls 

along the veins alterations supposedly due to the ore-depositing 

solutions given off by the granite as it solidified. Chlorite is formed 

extensively by regional dynamometamorphic processes, to some extent in contact metamorphism, and as a secondary mineral by hydrothermal metamorphism of the wall rocks along certain productive 

lodes in diabase and other basic rocks. Where associated with fissure 

veins in acidic rocks, it has generally been formed by the weaker orebearing solutions; and in regions of large and rich deposits it is found 

some distance away from the veins, in places where apparently the 

solutions had already spent too much of their power to change the 

country rock greatly and to deposit ore. Again, near the great vein 

deposits the Avail rock has commonly undergone strong sericitization. 

pyritization, silicification, and other processes; and these were relatively inactive when the lead, zinc, and silver veins associated with 

the intruding granite were formed and Avere not strongly active when 

the ores associated with the trap rocks were deposited.

Copper. The pyritiferous deposits near Blue Hill are not at present sufficiently exposed to warrant an estimate of their.value, but a 

deposit which is in many respects similar is now successfully worked 

at Milan, N. H. (See p. 50.) To judge from the mineral composition at that place, it would seem that somewhat similar methods could 

be applied to the Blue Hill ores. These ores or concentrates from 

them would be rich in sulphur and could without doubt be sold 

advantageously to acid works. If the paper mills of New England 

should ever adopt the practice followed at some European plants, 

they could make their sulphur dioxide at a lower cost for the raw 

material from pyrite than from native sulphur, a large tonnage of 

which is now utilized in paper manufacture. The schistose garnetiferous sulphide ore at Deer Isle has proved refractory to metallurgical 

treatment, but possibly one of the newer methods of oil flotation could 

be successfully employed to separate the garnet from the sulphides 

if the amount of ore exposed is sufficient to warrant an installation.

SUMMARY OF GEOLOGIC EVENTS AS RELATED TO ORE DEPOSITS.

From studies of the geology of the Penobscot Bay quadrangle,* the 

Perry Basin,6 and other areas, and from the observed relations of the 

ore deposits, the geologic events related below are deduced.

"Smith, G. O., Bastin, E: S., and Brown, C. W., Penobscot Bay folio (No. 149), Geol. 

Atlas U. S., U. S. Geol. Survey, 1007.

6 Smith, G. 0., and White, David. Prof. Paper U. S. Geol. Survey No. 35, 1905.
28 SOME ORE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

Pre-Cambrian and Cambrian time. In pre-Cambrian or possibly 

in early Cambrian time a series of siliceous shales and impure sandstones were laid down in extensive beds and were subjected to jregional metamorphism. Later, probably in Cambrian time, the impure sand which now forms the slates of the Islesboro formation was 

deposited. During the deposition of this formation great volcanic 

activity prevailed; the acidic Castine rocks, which included both 

flows and dikes and some calcareous water-laid tuffs, were formed. 

These were followed very closely or perhaps in part were accompanied 

by the North Haven eruptives. These North Haven diabases, basic 

trachytes, and albite-augite syenites included both effusive and intrusive bodies. The garnetiferous zinc ores at the Deer Isle mine, which 

are in a calcareous phase of the Castine near the contact of the North 

Haven greenstone, were probably formed by processes of contact 

metamorphism during North Haven time, and part or all of the Blue 

Hill and Brooksville pyritiferous copper ores are believed to have 

been formed at the same period or in connection with the Castine 

eruptions. Near the close of the period regarded as Cambrian and 

following closely the igneous activity, the Coombs limestone, a member of the Islesboro formation, the Battie quartzite, and the slates of 

the Penobscot formation were successively laid down.

After the eruptions, after the copper and the zinc ores were deposited, and after the Penobscot beds, which later became slates, were 

laid down, the region was subjected to profound dynamic metamorphism. A schistose structure was developed in all of the rocks, but 

is most marked in those containing the most clay. The ore bodies 

also took on a schistose structure. As a result of this, in the Deer Isle 

zinc deposit garnet, amphibole, quartz, sulphides, and magnetite were 

compressed into thin crumpled parallel bands. The copper deposits 

also were greatly affected, but since these were simpler in mineral 

composition the resulting deposits were different. At the center 

of the deposits the large and relatively pure masses of pyrite were 

broken and recemented with pyrite and chalcopyrite. Where there 

was a higher percentage of quartz wifli the pyrite the two minerals were broken into unequidimensional fragments and these 

oriented themselves in lines parallel with the schistosity. Where 

considerable clayey material was present chlorite and the micasformed in great abundance and oriented themselves with their long 

directions nearly parallel with the schistosity and parallel to the 

long dimensions of quartz and pyrite fragments. Where a pyrite 

crystal was protected by a cover of clayey material it did not break, 

but the micaceous minerals formed inclosing spheres around it and 

bent' to accommodate themselves to it; but where such a pyrite 

crystal was pushed through the chlorite against another crystal of 

pyrite, both were shattered. There was much recrystallization and
SUMMARY OF GEOLOGIC RESULTS. 29

some pyrite was redeposited as perfect crystals. Quart/ seems also 

to have been dissolved and reprecipitated to some extent, but not in 

crystal form. During metamorphism some of the ore bodies were 

probably separated by a peculiar kind of faulting, which must have 

taken place at a depth that was in the zone of flow for the wall 

rock and the zone of fracture for the ore. Such a fault, as illustrated 

by the Milan mine (see p. 50), is strikingly sigmoidal and laps 

around both of the ends of the broken ore body, the schistosity following its complexly curving plane, as shown by figure 4. The 

overlapping lenses Avhich are said to constitute some of the Blue Hill 

deposits probably resulted from similar movements. Just when 

these events happened is not known, but they were before the beginning of the deposition of the Arnes Knob formation, which lies unco n form ably above the metamorphosed series. The Ames Knob is 

of Silurian age (Niagaran) and is not metamorphosed, its lowest 

member being a basal conglomerate which contains well-rounded 

pebbles of black and green slates, quartzites, and vein quartz." The 

metamorphosed rocks and ore deposits are therefore older than the 

Silurian, but how much older is not known.

Silurian time. While the Silurian rocks were being deposited 

volcanic forces again became active. The Thorofare andesite was 

erupted and was followed by the Vinalhaven rhyolite. At about this 

'time gentle folding and some faulting took place, accompanied or 

followed by the great intrusions of granite and diorite. The intruded 

rocks were metamorphosed to some extent, though not profoundly, by 

the gases and solutions given off. The granite intrusions all along 

the coast Avere probably formed at about the same time, and.if so 

they are of post-Niagaran or early Devonian age, for pebbles of the 

granite are found in the late Devonian (Perry formation). It seems 

that the granites were in the main poor in metals, but some of their 

pegmatitic phases carried a little molybdenum sulphide, which was 

deposited when the pegmatites solidified. Quartz veins were deposited also by solutions which originated in the granite. Some of 

these veins were barren, but some carried ores of silver, zinc, and 

load. The Sullivan silver veins, which are in the Ellsworth schist, 

were deposited at this time, and the Gouldsborough zinc-silver lode 

in diorite is presumably of the same age. The mineralizing solutions 

altered the wall rock to chlorite, epidote, and sericite, but this action 

was not intense. The galena-feldspar ore in a prospect on the Owen 

farm at Blue Hill appears to have consolidated directly from the 

granite.

Devonian time. After the granite had solidified it was eroded; 

and above it the lower conglomerate member of the Perry formation 

was laid down in late Devonian time. Subsequently basic lavas were

a Smith, Bastin, and Brown, folio 149, 1907, .p. 4.
30 SOME 0KB DEPOSITS IN MAINE AND NEW HAMPSHIRE.

extravasated upon these, and upon the lavas Denovian sandstones were 

deposited, which were in turn overflowed by vesicular basic lavas. 

In connection with the same general period of basic eruptives, and 

probably in late Devonian time, the Lubec, Denbow Point, and Pembroke lead and zinc deposits are believed to have been formed. Still 

later probably in Mesozoic time basaltic dikes cut the various 

formations; at Concord, in Somerset County, an ore deposit which 

in general character most closely resembles those associated with the 

granular intrusives is cut by such a dike.

Quaternary time. Other events that affected the ore deposits in 

Mesozoic or in Tertiary time are not known. If the deposits exposed 

to weathering were deeply oxidized during those periods then the 

oxidized portions were planed off by the great ice sheet which 

covered the country in Pleistocene time. In Recent time, however, 

since the retreat of the ice, the sea has cut cliffs in which many of 

the deposits are exposed, and as a result the seashore has become a 

favorable place for outcrops. The copper lodes, where fractured, 

have been to a very trivial extent leached by descending surface 

waters, which have deposited chalcocite films on the older sulphides, 

but these lodes were presumably so completely recemented during the 

period of regional metamorphism and have been disturbed so little 

since that time that they have not been greatly affected by the 

processes of chalcocitization. Some oxidation has taken place, but' 

as a rule it has extended to only slight depths generally to not more 

than a few feet below the itcrop.

DESCRIPTIONS OF MINES. 

HANCOCK COUNTY.

GENERAL STATEMENT.

The southwestern part of Hancock County has been geologically 

mapped in detail by George Otis Smith, E. S. Bastin, and C. W. 

Brown in the Penobscot Bay folio (No. 149) of the Geologic 

Atlas of the United States, published by the United States Geological Survey. Plate II of the present paper is a reproduction of a part 

of the geologic map of this folio, with the addition of symbols indicating the positions of the mines in the district. Figure 10 is a section 

showing the relations of the rocks, along the line A-A' in the plate, 

but extending beyond it, and figure 11 is a section along the line B-B'.

The principal rocks with which the ores are associated are the 

Ellsworth schist, the schistose volcanic rocks, and the granite and 

closely related diorite. The relatively small area of Ellsworth schist 

at Blue Hill includes nearly all of the schistose deposits of pyritic 

copper ores. A large area of quartzose schist extends northwestward
U. S. GEOLOGICAL SURVEY BULLETIN 432 PLATE II

% ', Bear \\ --- -^4. 

*^ead\ '"" .fir

1) <; W I

^;;>>; '" - Co nary

GEOLOGIC MAP OF THE MINERALIZED AREA OF BLUEHILL, BROOKSVILLE, DEER ISLE,

AND CASTINE, MAINE

Scale i2soop 

i T o i 2 3 & £ Miles.

H.M.Wilson, Geographer in charge. 

Topography by U. S Coast and 

Geodetic Survey, W. H. Lovel I, a nd 

Hersey Munroe. 

Tria ngulation by U.S.Coast and 

Geodetic Survey.

Surveyed in 1900-1903.

SURVEYED IN COOPERATION WITH 

THE STATE OF MAINE.

SEDIMENTARY ROCKS

Coirtortr interval 2O feet. 

Tn&turi: &<*,a,

19O9

Geology by George Otis Srn ith, 

E.S.Bastin,and C.W.Brown.

Surveyed in I902-I904-. 

SURVEYED IN COOPERATION WITH 

THE STATE OF MAINE.

LEGEND

IGNEOUS ROCKS

DEVONIAN ? CAMBRIAN ?

CorttemfiarcuieoTLS witfi iipper* part 

of Islesboj-f fbrwLcition'

Islesbbro formation EUsworth. sclrist Biotite granite Diorite, diabase, Se_i^pentnie

(states and. schists Zoo«ZZv fcnonpled, ffr&erv and, ffin&,med*ian,,and. ooarse- and. dSLblarO

Txrrue'St&n&B) from ifi& gr&nite, magma,)

^oi^li Haven Casime iomiatiorL

- (r7iyotite>, andesite, and, some-

,

. te, dOce-s, and, pvroclaatic 

ana- aMnfe-tzugrte, syentte-, -

,

jyyrooldstic 

rocha)

Mine Quarry & Gravel pit
HANCOCK COUNTY. 31

from Frenchman Bay along Union River far to the 

north of Ellsworth. This area includes the mines at

Sullivan and Franklin. 

The schistose igneous rocks which

belong; to the Castine formation cover

o

extensive areas in the western part of 

the region represented on Plate II. 

The Tapley mine, which in many respects resembles the Blue Hill copper 

deposits, is inclosed in the Castine, and 

the Deer Isle, Eggemoggin, Cape 

Rozier, Hercules, Emerson, and other 

deposits are in the same formation.

The granites and associated diorite 

which are intrusive in the schistose 

rocks cover a large part of the area 

represented on Plate II, but in this 

area the only deposit known which is 

genetically related to the granular 

rocks is at the Owen lead prospect.

In the eastern part of the county, at 

Sullivan and at Franklin, fissure veins 

of silver ore which cut the schist near 

granite contacts have been deposited 

by solutions which are believed to have 

had their origin in the granite. Still 

farther east, the Gouldsborough, a lode 

of argentiferous zinc blende in diorite 

is supposed to have had a similar genesis, and just east of the Hancock 

County line at Cherryfield a zinc deposit is inclosed in schist not far from 

granite to which it may be genetically 

related. The molybdenite deposits of 

Catherine Hill are associated with pegmatite veins which cut the granite.

DOUGLAS MINE.

The Douglas mine, located about 2 

miles southwest of Blue Hill village, 

is owned by interests identified with 

the Pittsburg and Montana Company, of Butte. The 

mine was opened in 1878 and was worked until 1883 

and is said to have produced between two and. three

O

er M
32 SOME QBE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

million pounds of copper which yielded about $300,000. It was 

reopened in 1908 and sampled by its present owners. A two-compartment shaft inclined 47° is sunk 245 feet on the incline. ° A second 

two-compartment shaft, about 150 feet to the east, is sunk to a depth 

of 75 feet. Both were under water when the mine was visited. The 

deep shaft is equipped with steam power and skip. On the surface 

are numerous heaps of roasted ore and the ruins of a concentrator, 

blast furnace, precipitation plant, and refining furnace. The deposit 

is a lode said to be from 12 to 20 feet wide, striking eastward and 

dipping about 45° S.

An analysis of the better grade of ore made for the company by 

S. P. Sharpies, of Boston, is given below:

Analysis of copper ore from the Douglas mine.

SiOa ______ _.

Fe _

CaO

Mn _

Al-Os - - -

S _ _ _ _

On _ _ _ .

- _ _ __. _ _ 35.8

25.9

_ _ _ _ .13

_ _ __ .52

. _ _ _ _ _ _ 3. 11

__ _ _ _ _ 28

H - - - 5. 88

99.34

This ore carries 0.01 ounce gold and 1.17 ounces silver to the ton.

The country rock is a rather siliceous phase of the Ellsworth schist 

and is composed of quartz, muscovite, and biotite, with pyrite scattered liberally through it. Where exposed in an open cut a few feet 

west of the main shaft the lode follows the schistosity of the country 

cock. The ore minerals observed in the pit and on the Odump are 

pyrite, chalcopyrite, pyrrhotite, chalcocite, arsenopyrite, zinc blende, 

magnetite, and cuprite. Stibnite, tennantite, and tetrahedrite have 

also been reported.0 The gangue minerals, which in places are 

banded with the sulphides, are quartz, sericite, biotite, and chlorite. 

A little molybdenite is present, with pyrite and muscovite. Thin 

sheets of native copper are reported to have formed in joint seams of 

the ore. Oxidation in the open pit is nearly complete to a depth of 

5 feet and ends at a prominent joint plane which dips to the south 

at a very low angle.

TWIN LEAD MINE.

The Twin Lead mine is on the Sargentville road about 1-| miles 

southwest of Blue Hill. A three-compartment inclined shaft now 

filled with water is reported to be 200 feet deep. The lode has been

a Smock, J. C., Mineral Resources U. S. for 1882, U. S. Geol. Survey, 1883, p. 687.' 

Bartlett, F. L., Mines of.Maine, p. 23.
HANCOCK COUNTY. 33

stoped out open cast to a depth of 12 feet for about 70 feet along the 

strike. The ruins of a smelter and small slag dump show that some 

ore has been treated. The lode, which is about 10 feet wide, is in the 

Ellsworth formation and parallels the schistosity, striking N. 77° E. 

and dipping about 45° S. The ore minerals are pyrite, pyrrhotite, 

magnetite, chalcopyrite, and a little bornite. The gangue minerals 

 are quartz, sericite, biotite, and chlorite. The sulphides outcrop at 

the surface and oxidation is inconsiderable. The pyrite is disseminated through the rock and in bands parallel to the schistosity, but 

lenses of ore, consisting mainly of pyrite, chalcopyrite, and quartz, 

are found here and there in the lode. A stringer of pyrite, making 

off from the main lode, is shown in figure 3; its associations show 

that the quartz and pyrite are older than the metamorphism of the 

schist, a fact also indicated by the arrangement of the minerals in 

the lower-grade ore.

BLUE HILL MINE.

The Blue Hill mine is located 1,050 feet west of the Twin Lead 

mine, on the opposite side of the road. Large dumps of ore and country rock similar to that of the Twin Lead surround the ruins of a 

shaft, and roasted heaps of ore lie near by. Near the mine are the 

ruins of a concentrating mill, and below this are the ruins of a smelter 

and slag dump. The lode is not accessible above or under ground. 

At the low hill just south of the mine a 75-foot tunnel is driven eastward in pyrite-bearing schist cut by large masses of white quartz. 

Southwest of this tunnel, on the soutlnvest slope of the hill on which 

the Blue Hill mine is situated, a deep open cut about 75 feet long and 

10 to 15 feet wide is driven S. 85° E. into the hillside. The country 

rock is quartzite impregnated with pyrite and cut by numerous 

closely spaced veinlets of pyrite. It carries also some large masses 

of nearly pure pyrite and some chalcopyrite.

STEWART MINE.

The Stewart mine is southeast of Third Pond, between this and 

Second Pond and about 100 yards northeast of the Douglas mine. A 

two-compartment shaft said to be 150 feet deep but now filled with 

water is sunk southward at an inclination of 57° on an eastwardstriking lode. The ore on the dump is similar to that of the Twin 

Lead but is more siliceous. About 150 feet north of the shaft another lode about 10 feet wide strikes S. 87° E. and dips 70° to 80° 

S.; it is opened in a long, deep cut exposing a great mass of pyritiferous rock. The country rock, which is the Ellsworth schist, contains considerable biotite, but is more siliceous than at the Blue Hill 

and Twin Lead. Actinolite, tremolite, biotite, sericite, chlorite, and 

zircon are microscopically visible. Near the lode the quartzose schist 

42381° Bull. 432 10 3
34 SOME OEE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

carries considerable pyrite and some chalcopyrite, magnetite, and 

pyrrhotite. The trend of the deposit agrees with the schistosity of 

the rock, and as at the Blue Hill and the Twin Lead the pyrite bands 

are crumpled like the silicates, showing that the ore was deposited 

before the regional metamorphism of the country.

MAMMOTH MINE.

The Mammoth mine is located on the south shore of Second Pond, 

one-half mile from the Douglas. A vertical shaft, now full of water, 

is said to be 100 feet deep. The country rock is Ellsworth schist, 

here very quartzitic. The gangue is quartz, biotite, muscovite, arid 

actinolite. The ore minerals are pyrite, chalcopyrite, pyrrhotite, and 

specularite, with a very small amount of zinc blende and galena. 

On the dump are several hundred tons of highly pyritiferous rock 

which carries a noticeable amount of the copper sulphides.

OWEN MINE.

The Owen mine is located on the west side of Second Pond, half 

a mile southwest of the Douglas. The country rock is a siliceous 

phase of the Ellsworth schist with a schistosity that strikes S. 82° E. 

and dips 45° S. A pit 25 feet long and 12 feet wide is sunk in sulphide ore and pyritiferous quartzite to a depth of 30 feet. The 

workings do not show the direction of the lode. The minerals are 

quartz, biotite, sericite, pyrite, chalcopyrite, pyrrhotite, and magnetite. According to Mr. Arthur Owen thin sheets of native copper 

have been found in joint planes of the rock. The ore is said to carry 

more than 3 per cent of copper.

OWEN LEAD PROSPECT.

The Owen lead prospect is one-half mile west of the Mammoth 

copper mine and north of the granite batholith which cuts siliceous 

Ellsworth schist near by. In 1909 the small pit 20 feet deep was 

full of water. The Ellsworth here is c'omposed of quartz, biotite, 

muscovite, and other minerals and is cut by .dikes of granite which 

make off from the large mass. There is no pronounced contact metamorphism of the schists; no garnet appears to have been formed; 

actinolite is rather more abundant than elsewhere; magnetite and 

pyrrhotite are developed but are not more abundant than at other 

places in the schist a mile or more aw^ay from the contact, where they 

have formed through dynamometamorphism. In one of the small 

granite dikes there is considerable galena, a, little pyrite, and some 

chalcopyrite, all of the sulphides being intergrown with feldspar, 

quartz, biotite, and muscovite. Magnetite or pyrrhotite, Avhich are 

common in the copper ores, are not present in the lead ore.
HANCOCK COUNTY. 35

While the deposit appears to be small, the genesis of the ore is 

of peculiar interest. The granite near by is medium grained and 

is composed of quartz, feldspar, biotite, and a .little sericite. The 

feldspars are orthoclase, microcline, and .a little albite. The galenabearing granite is not coarse like most pegmatites but is of medium 

grain like all the granite near by. It has the same minerals in the 

same proportion except that albite, a small amount of which is 

present in the granite, is even less abundant in the ore. The galena, 

which in some specimens makes up one-fourth or more of the mass, 

is intergrown with the feldspars and surrounds well-formed idiomorphic feldspar crystals, the sharp corners of which have been 

rounded off before the galena solidified. A little apatite is also 

inclosed in galena and some chalcopyrite is intergrown with galena. 

The structure is the same as in some diabases, where feldspar crystals 

are surrounded by a matrix of augite, but in the granite here galena 

takes the place of augite. A photomicrograph of a thin section 

of this ore is shown in Plate I, B. None of the minerals are highly 

altered, but some chlorite is developed by decomposition of biotite and 

the feldspar is slightly clouded by decomposition to kaolin. The 

white mica present is mainly or altogether primary. The ore is 

clearly the consolidation of a molten magma.

GRANGER MINE.

At the Granger mine, about three-fourths mile south of Blue Hill, 

a shaft, now inaccessible, is sunk in the Ellsworth schist. In the 

ore exposed on the dump the gangue minerals are quartz, biotite, 

chlorite, and sericite. The sulphides noted are pyrite, chalcopyrite, 

and bornite.

WEIL FREDDIE MINE.

The Weil Freddie mine is a few rods east of the village at Blue 

Hill Falls, on the north shore of the bay. An- inaccessible shaft, reported to be 100 feet deep, is sunk in pyritiferous Ellsworth schist 

which carries some copper pyrite.

TAPLEY MINE.

The Tapley mine is on the farm of Charles P. Tapley, about 2£ 

miles southwest of Brooksville. It was opened about thirty years 

ago and a small amount of ore has been shipped for experimental purposes. The mine changed OAvnership in 1907 and some development 

work was then done, but these operations were soon suspended, and in 

1909, when the property was visited, the mine was idle and the underground Avorkings full of Avater. A shaft is sunk on the lode to a 

depth of 80 feet and according to report some 200 feet of drifts.and
36 SOME ORE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

crosscuts are turned from it. The deposit was exposed at several 

places in open cuts.

The country rock is the Castine formation, which is here, in the 

main, a rhyolitic breccia, but which locally includes a dark rock, 

presumably andesite. Both of these rocks are regionally metamorphosed, with the development of secondary biotite, sericite, and 

tremolite. Small colorless garnets are developed also in the andesite. 

Some of the rhyolite contains numerous specks of microscopic magnetite and in hand specimens is as dark as the andesite. The schistosity 

of this rock, which though not pronounced is Avell defined, strikes 

northeastward. The rhyolite is at some places strongly plicated and 

cut by quartz veinlets which cross its schistosity. Northwest of the 

lode a dike of basalt only slightly metamorphosed cuts the Castine.

The deposits outcrop on a glaciated surface. For 500 feet along the 

lode the ground is cleared and open cuts are dug at several places. 

The lode strikes'N. 47° E., parallel to the schistosity, and is a wide 

zone of shattered and altered rhyolite. The sulphides are pyrite and 

chalcopyrite, both of which are found at the very surface; films of 

limonite, hematite, cuprite, and bornite appear in small amount in 

the cracks of the ore, which is not highly shattered.. The ore 

includes fragments of the country rock which are slightly silicified, 

but the lumps of pyrite ore on the dump contain but little quartz. 

These fragments contain much more sericite and chlorite than the 

country rock a few .feet from the vein. Some of the ore in the open 

pits is rhyolite which contains secondary tremolite, sericite, biotite, 

and chlorite, with flakes and specks of pyrite, the latter constituting 

perhaps 10 per cent of the mass. A little magnetite and pyrrhotite 

is present. Some of the ore impregnated with pyrite shows laminated 

sericite and quartz, and some of the chalcopyrite is feebly laminated 

parallel to the micaceous sheen which shows when the ore is held in 

suitable position, suggesting that the sulphides were formed before 

the regional metamorphosing processes had ceased operation. This 

relationship is indicated also by the crumpled stringers of pyrite 

which are found near the lode. One of these is shown in figure 2.

EGGEMOGGIN MINE.

The Eggemoggin mine is at tide water on Byard Point, about a 

mile west of Sargentville. Two shafts, now inaccessible, are sunk in 

devitrified rhyolite breccia of the Castine formation. The lode is 

not exposed, but the dump showed altered rhyolite impregnated with 

sulphide and galena. Some of it is strongly sheeted and cut by parallel stringers of white quartz, which also carries sulphides. The 

principal minerals are quartz, sericite, pyrite, arsenopyrite, chalcopyrite, galena, and zinc blende. The ore is reported to carry good
HANCOCK COUNTY. 37

values in silver. Native silver is said to have been present. According to report, shipments of ore were made in the late eighties, but the 

mine has not been worked for many years. The ruins of an old 

metallurgical plant stand near by.

DEER ISLE MINE.

The Deer Isle mine is located at tide water on Dunham Point, about 

3 miles west of Deer Isle village. This mine was first worked in the 

seventies and was reopened in 1907, since when it has produced about 

900 tons of ore. A shaft is sunk on the lode at an .inclination of 45° 

to a depth of 260 feet, and on the 200-foot level drifts about 100 feet 

long are turned in either direction. Near the shaft stopes are carried 

up within a few feet of the surface. When the mine was visited stopes 

below the 100-foot level were inaccessible.

The mine is in the Castine formation, presumably an altered porphyritic rock with phases which were probably calcareous water-laid 

tuff. The North Haven greenstone outcrops near by and is regarded 

as of approximately the same age as the Castine formation."

The lode follows the schistosity of the country rock, striking from 

N. 22° E. to N. 70° E., and dips from 45° to 65° N. The schist is 

heavily impregnated with sulphides for a width of 1 to 8 feet. 

Sheets of pure sulphide an inch or two wide persist for several feet 

along the dip and strike and are overlapped by similar sheets. The 

rock between these is composed of innumerable paper-thin sheets of 

alternating sulphide and garnet.

The sulphides are steel-colored zinc blende, pyrite, galena, and 

chalcopyrite. Intergrown intimately with them is a considerable 

amount of magnetite. The gangue minerals are garnet, actinolite, 

sericite, calcite, chlorite, quartz, and rhodochrosite; a little barite 

was noted on the dump. Figure 7 is a sketch of a thift section of the 

ore, showing parallel bands of garnet, sericite, and sulphide. Without doubt the deposit has been regionally metamorphosed since it 

was formed, and the highly schistose structure of the lode, which 

parallels that of the country rock, has resulted from the same dynamic forces that developed the schistosity in the country rock. According to George H. Plolden the high-grade ore carries zinc 30 

per cent, lead 16 per cent, silica 12 per cent, copper 2-| per cent, and 

gold v $2.50 a ton. T.he minerals with the exception of barite and 

rhodochrosite are those commonly found in contact-metamorphic 

deposits, but they have been crushed or redeposited by regional metamorphism.

The sulphides have been crushed, recemented, and in part recrystallized. The chlorite and mica seem to have been completely

0 Smith, Bastin, and Brown, folio 149, Geol. Atlas TJ. S., p. 5.
38 SOME ORE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

dissolved and recrystallized with longer axes parallel to the schistosity and to the orientation of the lode. The garnet is so highly 

fractured that in places it is almost opaque in thin section when the 

nicols are not crossed. None of the garnet shows the crystal form. 

Garnet, as is well known, is formed in igneous rocks, in contact-metamorphic deposits in some deep veins, and by regional metamorphism. 

In igneous roc'ks it is nearly always idiomorphic. In contact-metamorphic deposits it is either massive or idiomorphic and very often 

shows such optical anomalies as double refracting rings. It may 

have schistose structure when it replaces schists, but it is not highly 

fractured like the'Deer Isle garnets, and some crystals usually have 

the crystal outline or else show the double refracting rings. In the 

veins of the deep zone it is usually idiomorphic. The garnet of the 

Deer Isle mine is not idiomorphic. is greatly crushed, and does not 

show double refracting rings. Under the microscope it has the color 

and general appearance of andradite and without much doubt is contact-metamorphic garnet which has been regionally metamorphosed 

by pressure. (See fig. 7 and PI. I. A.)

CAPE ROZIER MINE.

. The Cape Eozier mine is at Harborside, across the harbor from 

Castine. The country rock is schistose pyroclastic tuff of the Castine 

formation. This is cut by diorite, which shows no schistosity. 

On the dump are fragments of the Castine formation cut by thin 

sheets of pyrite and chalcopyrite and stained with green copper carbonate. The two shafts are inaccessible. Some ore on the dump of 

upper shaft is composed of calcite, zinc blende, pyrite, and chalcopyrite. The ore observed shows no schistosity.

HERCULES MINE.

The Hercules mine is between Penobscot and Castine, just above 

the Bagaduce Narrows. A shaft sunk at tide water is now submerged. 

The country rock is the Castine formation, which, near the ore body, 

is highly silicified and somewhat sericitized. Some ore on the dump 

shows quartz, serkdte, zinc blende, galena, chalcopyrite, pyrite, pyrrhotite, and specularite. . .

JONES & DODGE MINE.

The Jones & Dodge mine is one-half mile southwest of the Hercules, on the south shore of the Bagaduce Narrows. The country 

rock is the pyroclastic phase of the Castine formation, which at the 

mine shows a schistosity striking northward. In the dark biotitic 

portion of the country rock certain bands carry small amounts of 

pyrite, chalcopyrite, galena, and zinc blende.
HANCOCK COUNTY. 39

EMERSON MINE.

The Emerson mine is near the Castine ferry on the west shore of 

Bagaduce River. A two-compartment shaft, sunk near the shore, 

is under water. The country rock shown on the dump is devitrified 

rhyolite. Some of this is brecciated and has sulphide ore deposited 

between its fragments. The amount of ore on the dump is very small. 

The minerals noted are galena, zinc blende, pyrite, magnetite, and 

pyrrhotite.

SULLIVAN, WAUKEAG, AND PINE TREE MINES.

At West Sullivan, east of Frenchman Bay, several mines are located 

along tide water. These include the Sullivan, Waukeag, and Pine Tree

FIGURE 12. Cross section of the Sullivan mine. (After Kempton.)

mines, all of which, according to report, are on the same lode. The 

Sullivan lode, which was discovered in 1877, outcrops below high tide. 

A cofferdam was built and this and the Waukeag mines were Avorked 

from 1878 to 1884. The Waukeag, which operated a 14-stamp mill 

and smelting furnace, is reported to have produced 25 tons of sih^erlead bullion. All the mines Avere inaccessible in 1909.

The country rock is dark-gray micaceous schist, probably the 

Ellsworth. Near the mines the schistosity strikes S. 75° E. and is 

practically vertical. At places it is cut by a dark rock, presumably 

a diorite. A feAv rods west of the Waukeag shaft are large outcrops 

of medium-grained granite, composed of quartz, feldspar, biotite, and 

rnuscovite. The Wraukeag shaft, Avhich is vertical, is reported to be 

.410 feet deep. A second shaft near by on the same property is 60 feet 

deep. On the Sullivan, about 1.80 feet southeast of the Waukeag, a 

shaft is driven 290 feet on a steep incline to the northeast. A cross 

section of the vein, after C. W. Kempton, is shown in figure 12. The
40 SOME ORE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

Milton shaft, about one-fourth mile down the bay and along the strike 

of the lode, is sunk to a depth reported to be 260 feet. According to 

report the lode was not encountered in a 400-foot crosscut to the 

southwest.

To judge from the ore on the dump the deposit is a clean-cut vein 

filling a fissure in the schist and is not regionally metamorphosed. 

The gangue is quartz, barite, talc, and gypsum; the sulphides, which 

are not abundant in the gangue, include zinc blende, galena, pyrite, 

chalcopyrite, arsenopyrite, and a gray sulphide which is probably brittle silver. Threads of native silver are said to have been found 10 feet 

below the surface. Magnetite, specularite, and pyrrhotite are absent. 

The quartz is usually massive, but is also found as acicular crystals 

pointing to the center of a druse. Brecciated fragments of the 

schistose country rock are included in the ore and the rounded edges 

of these show that they were partly dissolved by the ore-depositing 

solutions. These relations are shown in figure 8. The schist is not 

strongly leached near the lode, but chlorite and sericite have developed through metasomatic processes.

The banded ore is not schistose like the pyritic copper ores in the 

Ellsworth schist and is clearly of later age; it was probably formed 

at the time of the intrusion of the granite.

C. W. Kempton,0 who was engaged as a mining engineer at Sullivan in 1877, gives the following information relating to the Sullivan 

mine:

Proceeding with the shaft, at about 30 feet depth, the vein, composed of 

quartz, with more or less slate highly impregnated with sulphides, was found 

to be 4 feet wide. * * * The ore is essentially silver, sulphides and native, 

in quartz and slaty gangues, with slight amounts of iron, zinc, etc., as sulphides, and also galena. Of the silver minerals, stromeyerite is most plentiful, 

stephanite next, argentite (silver glance), common, native silver in flakes very

plenty, threads frequent, lumps occasional.

Ituby silver is exceedingly rare; antiinonial silver has been found. The 

occasional yellow copper sulphide met with has a peculiar luster and runs 

very rich in silver.

As stated above,, the course of the vein is from northwest to southeast, with 

the strike of the slate running parallel to the line of contact of the granite. 

The vein is in the slate, dipping at an angle of 70° from the horizon, northeasterly, toward the granite, which it probably reaches in less than a thousand 

feet. The slate also dips toward the granite at this place about 37° from 

horizontal, although at some other places not more than 12°.

At the contact of the slate and granite the latter often penetrates the bedding of the slate, in known instances nearly 200 feet. The granite is much 

cut up by dikes of black trap, which also runs into the slate, faulting the vein 

in several places.

GOULDSBOROTJGH MINE.

The Gouldsborough mine is in the town of Gouldsborough, about 

9 miles southeast of West Sullivan. A shaft 150 feet deep is sunk on

"Trans. Am. Inst. Min. Eng., vol. 7. 1878, p. 349.
HANCOCK COUNTY. 41

the lode and a drift is driven northwestward 75 feet from the 100-foot 

level. The mine is now under water. On the surface the vein is 

sloped, underhand, in an open cut 150 feet long, Avhich reaches a 

maximum depth of about 50 feet. In the early eighties some ore was 

shipped. The country rock is dark quartz diorite, which shows no 

sign of contortion or regional metamorphism. One mile to the south 

there are large areas of granite and near the mine the hrecciated 

diorite is cut by granite veinlets. Near the lode the diorite is 

somewhat decomposed and locally it is brecciated and cemented by 

rhodochrosite.

The lode is a fissure vein which strikes N.. 63° E. and is approximately vertical. It varies in width from 6 inches to 2 feet and is 

composed of banded quartz and sulphides, with angular slabs of 

country rock. The metalliferous minerals are galena, chalcopyrite, 

pyrite, zinc blende, and a very small amount of magnetite. The proportion of sulphide to quartz is high and the ore is said to carry 

considerable silver. The hydrotherrnal metamorphism of the wall 

rock is clearly shown. The quartz diorite is a medium-grained rock, 

is very fresh, and is composed of oligoclase, andesine, hornblende, 

biotite, quartz, orthoclase, and pyrite. Within a few feet of the lode 

this is altered to a rock composed of chlorite, sericite, epidote, quartz, 

and pyrite. The chloritization does not extend far from the lode. A 

rod or tAvo away a brecciated quartz diorite is, as already stated, cemented by coarse granite. The quartz diorite is certainly older than 

the granite, and the granite is probably the source of the ores.

The outcrop is partly oxidized, but sulphides appear within a few 

feet of the surface. The banding of the ore, the open clruses parallel 

to bands, the brecciation of diorite and its inclo'sure in ore, the'absence 

of crenulation and foliation in the vein, and the characteristic hydrothermal metamorphism of the wall rock show that the deposit belongs 

to the class which postdates regional metamorphism.

FRANKLIN EXTENSION MINE.

The Franklin Extension mine is 2 miles west of Franklin station 

and one-eighth mile west of West Franklin. The lode is a narrow 

fissure vein in contorted schist, presumably the Ellsworth. It strikes 

N. 18° E. and is approximately vertical. Two shafts, said to be on 

the same lode, are sunk about 300 feet apart. The ore is composed of 

quartz, arsenopyrite, galena, and pyrite. Granite, cutting the Ellsworth schist, is exposed within a feAv feet of the lode. The deposit, 

which is said to carry silver, is banded and shows comb structure. It 

is clearly of later age than the metamorphism of the schist.

COPPEROPOLIS MINE.

The Copperopolis mine is near Egypt, 4 miles west of Franklin 

station. Two hundred yards west of the mine house three pits are
42 SOME ORE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

sunk in the contorted Ellsworth schist, which carries seams of quartz 

and pyrite with stains of copper carbonate. The Harvey Elliott 

prospect is about 300 yards east of the mine house. The shaft was 

under water when visited, but to judge from the dump the country 

rock is the Ellsworth schist intruded by a dark igneous rock which is 

slightly schistose. The ore consists of thin sheets of quartz, calcite, 

rhodochrosite, pyrite, and chalcopyrite.

CATHERINE HILT, MOLYBDENUM MINE.

The Catherine Hill molybdenum mine is at the north end of Tunk 

Pond, near the summit of Catherine Hill. The deposit was described 

by F. L. Hess a in 1908.

The country rock is a medium-grained granite composed of pink 

and white feldspar (orthoclase and albite), quartz, biotite, and muscovite. The granite is cut by aplite dikes from one-half inch to 4 

inches wide, some of which dip about 15° N. It is cut also by numerous pegmatite veins and veinlets which vary from coarse to fine pegmatite, the minerals of the latter being only a little larger than the 

crystals of the granite. The deposits are worked by open cuts on a 

ledge of granite which trends eastward. The principal opening is 75 

feet long and 15 feet wide and has a maximum depth of 20 feet. The 

pegmatite veins carry quartz, feldspar, molybdenite, apatite, biotite, 

chlorite, hornblende, and fluorite. At some places quartz and feldspar are graphically intergrown. Miarolitic cavities are found in 

both the granite and the pegmatite, and in the latter are lined with 

quartz crystals. The molybdenite occurs as scales and flakes from 

one-eighth inch to 1 inch in diameter; some of them are in cracks 

which join the pegmatite veins, others in the pegmatite veins themselves, and still others in the granite in positions which seem to 

have no connection with the pegmatite veins. Most of the molybdenite is in or within a few inches of the pegmatite, yet some of it 

seems to be an original constituent of the granite. There is little or 

no sericitization in the granite that carries molybdenite, and under the 

microscope the molybdenite is seen to inclose well-shaped crystals of 

albite and orthoclase, the corners of which are slightly rounded, indicating that the potash and soda feldspars were floated in the molybdenum sulphide solution and were partly dissolved before it solidified. The structure is much the same as that shown by some diabases where augite incloses idiomorphic feldspar, except that the 

corners of the feldspars in the ore have been rounded by corrasion. A 

photomicrograph of this ore is shown in Plate III, B.

a Bull. U. S. Geol. Survey No. 340, 1908, pp. 234-235.
U. S. GEOLOGICAL SURVEY

A. POLISHED SURFACE OF SCHISTOSE ORE OF MILAN MINE.

B. PHOTOMICROGRAPH OF MOLYBDENITE ORE FROM CATHERINE HILL.
WASHINGTON COUNTY. 43 

WASHINGTON COUNTY. 

GENERAL STATEMENT.

The geology of a portion of Washington County has been described 

by George Otis Smith and David White." The eastern part of the 

county has been mapped by'E. S. Bastin and will be described in a 

folio of the Geologic Atlas of the United States soon to be 

published. The western part of the county is made up in the 

main of slates and argillaceous schists. The zinc lode of Cherryfield 

is inclosed in these rocks, but so far as known there are no schistose 

deposits of pyritic copper ores in Washington County. East of this 

area of slates and schists is a broad belt of intruding granite which 

extends from Jonesport to Calais. Some deposits of molybdenite 

described by F. L. Hess ?' are associated with pegmatitic phases of the

granite. East of this broad belt of granite, and including Pembroke, 

Lubec, and Eastport, is a large area of rhyolite, trap, and other volcanic rocks which are in part later than the granite. The Lubec 

lead mine, the Denbow Point silver deposit, and the copper deposits 

in Pembroke are associated with the basic phases of these volcanic 

rocks.

CHERRYFIELD MINE.

The Cherryfield mine, one-half mile east of Cherryfield, was first 

opened in 1878 and reopened in 1905. In 1909 it was under water. 

G. 0. Smith visited the mine in 1907, and the following description 

is taken chiefly from his notes. The country rock is a dark aphanitic 

diabase, without conspicuous plienocrysts, and is composed of hornblende, feldspar, quartz, and magnetite; under the microscope it is 

seen to have a well-defined schistosity. Near the mine the dark schist 

is cut by unsheared diorite, and granite outcrops about three-fourths 

mile to the northwest. The deposit is a fissure vein which cuts the diabase, strikes N. 85° W., and dips steeply northward. A two-compartment shaft is sunk on the lode to a depth of 260 feet, and three short 

drifts are turned from this shaft. The vein is from 12 to 20 inches 

wide, is banded, and contains fragments of the country rock. The 

minerals are quartz, calcite, zinc blende, galena, pyrite, and chalcopyrite, and the ore is said to carry silver values. Chlorite is developed in 

the Avail rock near the lode, but sericite is not conspicuous. No schistose ore was noted on the dump. A mill, erected in 1907, is equipped 

with crusher, rolls, trommel, jigs, and concentrating table. A high 

percentage of the selected ore is zinc blende.

0 Geology of the Perry Basin : Prof. Paper U. S. Geol. Survey No. 85, 1905. 

6 Bull. U. S. Geol. Survey No. 340, 1908, pp. 231-284.
44 SOME OEE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

LTJBEC LEAD MINE.

The Lubec mine is located about 1 miles by wagon road from Lubec, 

on a shore marked by high, steep cliffs along which the veins outcrop. 

According to report the deposit was discovered in 1828 and has been 

worked in a small way through several short periods. A mill, now in 

ruins, is said to have been in operation for about six years in the late 

sixties and early seventies. A report on the mine by N. S. Manross is 

included in the report upon the natural history and geology- of 

Maine for 1861 (p. 299). At present the mine is idle and the 

deep workings are submerged. A mill built in late years is equipped

* underground * * 

* *******

25 50 Feet

FIGURE 13. Sketch showing position of principal veins in Lubec lead mine.

with jaw crusher, coarse and fine rolls, screens, jigs, a Wilfley table, 

and two Frue vanners. Steam power was used and the milling was 

done with salt water.

The country rock is a dense green trap :an altered surface lava. 

Near the mill the trap is in faulted contact with a dark fissile shale. 

The freshest specimens of the trap contain much secondary calcite, 

chlorite, and a little white mica. Near the lode and in the fragments 

which the ore includes chlorite appears to be more abundant than elsewhere, but 'sericite is not conspicuously developed.
WASHINGTON COUNTY. 45

The deposits are closely spaced intersecting fissure veins, some of 

which are shown in0 figure 13. The ore carries, besides lead and zinc, 

some silver, a little copper, and a trace of gold. The minerals are 

quartz, calcite, galena, zinc blende, pyrite, chalcopyrite, and limonite 

and manganese oxides. At many places the lodes are opened by short 

tunnels, deep cots, ,and underhand stopes. Below the mill a shaft 

is sunk on the -principal lode, but in 1909 this Avas under water. 

Above the mill this vein (No. 8), which strikes Avestward, is well 

exposed in the open cut, and considerable ore has been removed. It 

is a foot or more wide and carries galena. It consists of a number of 

thin, closely spaced, anastomosing fissures, between which are broken 

fragments of trap. Some of the stringers of galena play out 

as they pass into the country rock. The shaft sunk on this vein is 

reported to be 180 feet deep, and drifts are run out 170 feet under 

the bay. Vein No. 9 is east of No. 8, strikes N. 50° W., and would 

intersect No. 8

;>>*

* * * »

' * ' * *jt

<&/*

vC/ S*7 &

* * * *

* * # # * 

* * *

f *

B- *

ff

 rf w

* #

f * *

Trap

* * » 

* » *

* * *

\ * i

* ^^ *

*;>

X

*» * 

* *

f *

* * f

X * *

* * »

* * t

 \ * *

* * N

#

* «

<r

*

t

4

 ^

,;

*

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Ml

* * 

* *

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»*,*,

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- * * '

V * * *

 * * * '

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5 Feet

FIGURE 14. Small vein in Lubec lead mine. The vein 

is later than the fissure in which it ends.

the bay. Not far from 

the shore a 50-foot tunnel is driven in this deposit. Where exposed 

along the cliff the vein 

is a breccia zone 10 

feet Avide, with about 

10 per cent of ore and 

g a n g u e minerals in 

broken country rock. 

No. 5 vein, Avhich 

strikes a feAv degrees 

east of north, crosses 

the other lodes, and for 

80 feet along its strike forms a cliff escarpment 30 feet high. Along 

its face are thin flakes of sulphide ere. As shown by this vein, both 

sets of fractures, which are nearly at right angles to each other, Avere 

formed, before mineralization. This is illustrated also in a small 

vein (No. 2) of quartz and galena, Avhich strikes northeastward and 

ends in a crossing fissiire in a small pit northeast of the mine. The 

galena and quartz follow the fissure for a feAv inches, making a large 

angle Avith their former course, as is indicated in figure 14.

There are said to be thirteen veins in all, but some of those exposed 

at tide Avater to the south of the mill are very small.

DENBOAV POINT MINE.

On Denbow Point a shaft is sunk in basic tuffs, but has been lost 

through caving. The country rock throAvn up on the dump shows 

stringers of ore composed of quartz, zinc blende, galena, and pyrite.
46 SOME ORE DEPOSITS IF MAINE AND NEW HAMPSHIRE.

PROSPECTS IN PEMBROKE.

On the road from West Pembroke to Ay res Junction, about 2.miles 

northwest of West Pembroke., there are several prospects in diabasic 

lavas. The most extensive Avorkings are on the Sinclair farm, where 

the Eastern Exploration Company has recently been prospecting. 

The workings are all open cuts from 5 to 15 feet deep, and some of 

these are extensive. (See fig. 15.) The country rock is vesicular trap 

which, except for a little shearing at pit No. 5, shows no metamorphism. The ore occurs as veinlets filling fractured zones, as disseminations in vesicular lava, and as amygdaloidal fillings in the lava-.

There is some chloritization, but sericitization is not extensive. The minerals present are 

sphalerite, chalcopyrite, pyrite, gaShop lena, arsenopyrite,

300 Feet

and bormte, with a 

little limonite near 

the surface and 

some small stains 

of malachite. The 

gangue is dolomite, 

calcite, and quartz, 

and at some places 

there is a noticeable 

amount of cherty

silica. The dolomite, which is the 

most abundant mineral associated with 

the ore, is presumably ferruginous, since it is nearly everywhere stained with a brown 

film upon the weathered surface.

At pit No. 5, which is 120 yards northwest of the blacksmith shop, 

an excavation about 20 by 40 feet, sunk to a maximum depth of about 

10 feet, has been made on a glaciated surface. The rock here is a 

bluish-gray amygdaloid, bleached white near the surface. Bands of 

dense gray flows alternate with the vesicular phases, the banding of 

the rock striking about southwest. The flows are cut by closely spaced 

parallel fractures which are nearly vertical and strike S. 55° W. 

There is a little shearing along some of these fissures as if they had 

resulted from compressive stresses. The amygdaloids are from oneFIGOKE 15. Sketch showing position of pits of Eastern Exploration Company at Pembroke. By E. S. Bastin.
WASHINGTON COUNTY. 47

eighth to one-half inch in diameter, and many are filled with pure 

white calcite, others are filled with calcite and quartz, and some of 

them are lined with shells of metallic sulphides with crystalline 

quartz inside. Some of the ore is in the sheared fractures and some 

is disseminated in the rock near the fractures. Most of the sulphides 

appear as small bodies not one-half inch in diameter, but some are in 

masses measuring 4 to 5 inches; zinc blende predominates. Fifty 

yards northwest of this pit a small cut shows banded comb quartz 

with zinc blende and galena.

At pit No. 2 the trap is traversed by small irregular fractures 

healed with quartz and sulphides. The relations are shown in figure 15. At pit No. 4, 200 yards southwest of the blacksmith shop, the 

country rock is darker than at pit No. 5 and some is porphyritic, but 

it is presumably a part of the same flow. The rock is cut by many 

thin stringers of metallic sulphides, galena and chalcopyrite beingmore abundant than at other pits. This pit is 125 feet long and 20 

feet wide; its trend is S. 30° E., and most of the small stringers strike 

southwestward across it.

COOPER MINE.

Molybdenum deposits have been opened at Cooper, and the American Molybdenum Company has erected a mill there for treating the 

ore. The deposits have been described by George Otis Smith* and 

the following notes are abstracted from his report:

The country rock is granite, presumably of late Paleozoic age, and 

is cut by pegmatite dikes. In and near the dikes bunches of molybdenite crystals 1 to 2 inches in diameter are intimately mixed or intergrown with the quartz and feldspar of the pegmatite, where they 

were deposited by the pegmatite magma. They also occur in flakes 

and nests disseminated through the granite mass, especially near 

the pegmatite, where they may- have consolidated from the granitic 

magma or may have been brought in by the pegmatite solutions, 

which are regarded as nearly contemporaneous with the granitic 

intrusion. The deposits were visited by F. L. Hess,& who reports 

that the molybdenite-bearing granite in the American Molybdenum 

Company's mine is shown by a trench and crosscut to be at least 300 

feet long and 100 feet wide. Mr. Hess also reports that the Calais 

Molybdenite Mining Company, whose property joins the American 

Molybdenum Company's holdings on the north, has opened up similar 

deposits. Molybdenite has also been found near Sand Cove, Tunk 

Pond, and in the town of Brunswick, Cumberland County at both 

places in the granite.

« Bull. U. S. Geol. Survey No. 260, 1905, p. 17.

6 Molybdenite in Maine, Utah, and California : Bull. U. S. Geol. Survey No. 340, 1908, 

p. 231.
48 SOME ORE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

SOMERSET AND OXFORD COUNTIES.

KOBINSON MINE.

The Robinson mine, in Concord Township, Somerset County, 7 

miles southwest of Bingham and about 1^ miles north of Em den 

Pond, was discovered by W. S. Robinson in 1898 and has been worked 

now and then for several years. It is now owned by the Somerset 

Mining Company, which has erected a concentrator near the mine.

Section along \\r\QA~A

Limestone

\ Open cut \

\ ', Quartzite

\- (fl I hanging wall

\ i. 5"

«M 1 ^05- 

2-foot ore o'T 3-foot ore

20 30 Feet

FIGURE 16. Plan and cross section of the Robinson mine, near Concord, Somerset County.

This mill is equipped with a 12-inch Blake crusher, a set of rolls, a 

trommel, and three jigs. It employs steam power generated by wood 

and has a capacity of 10 tons daily. A small amount of concentrates 

and 8 carloads of ore have been shipped. The property has been idle 

since 1907.
SOMEKSET AND OXFORD COUNTIES. 49

The country is an area of quartzite, limestone, and shales, which 

are somewhat metamorphosed. These rocks are cut by trap dikes 

and probably by other intrusives. The quartzite consists of rounded 

quartz grains which under the microscope are seen to be rimmed with 

secondary silica. Between these grains biotite, chlorite, and hornblende have developed. As shown in figure 16, the deposit is a 

bedding-plane fissure which occupies the axis of an anticlinal fold. 

In thickness it varies from 2 to 8 feet and is thickest at the crest of 

the anticline, where it has been stoped or quarried out for about 60 

feet along the strike of the crest and from 10 to 25 feet across it. At 

the southwest end of the open cut a fault strikes N. 50° W. and dips 

75° SW. South of this fault the hanging wall of the deposit is sandy 

limestone overlain by shale; northeast of the fault it is quartzite. 

The fault is clearly older than 

the lode, for the lode crosses 

it without interruption. (See 

fig. 17.) A trap dike 6 inches 

wide, encountered on the southwest end of the cut, is followed 

in a tunnel some 15 feet. This 

dike rock is a very fresh basalt; 

even its olivines are but slightly 

altered, and it is clearly later 

than the ore body which it 

crosses.

The gangue consists of quartz 

and dolomite. The metallic 

minerals are pyrite, galena, 

zinc blende, chalcopyrite, arsenopyrite, pyrrhotite, and a 

little bornite. The sulphides are said to carry silver. Much of the 

lode is barren white quartz, and the sulphides in the run of mine do 

not constitute more than 4 per cent of the mass, though in selected 

ore they run higher. The lode near the dike is quartz, with no metallic minerals. Just at the contact it is slightly oxidized and any 

metamorphic changes would be obscured, but an inch away it has 

suffered no visible change at the contact Avith the trap.

MOUNT GLJNES.

The deposits at Mount Glines, in Oxford County, have been described in a paper by George Otis Smith," from which are extracted 

the following notes:

At Milton plantation there are quartz veins in a gneissoid granite 

which is probably older than the granite quarried on the Maine coast. 

The principal lode is a well-defined fissure vein, with a maximum 

width of 4£ feet, composed of quartz and wall rock, the latter altered

« Bull. U. S. Geol. Survey No. 225, 1904, p. 81.

42381° Bull. 432 10 4 '

35 Feet

FIGURE 17. Vertical section of wall at open 

cut, Robinson mine, near Concord, Somerset 

County. Faulting is older than ore deposition, a, Shale ; 'b, limestone ; c, quartzite ; 

d, quartz and ore.
50 SOME OEE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

to kaolin and sericite. The ore minerals are pyrite and galena, which 

occur in bunches and bands up to 4 inches wide. The sulphide ores 

cross the structure of the quartz gangue and are presumably of later 

origin than the major portion of the quartz. Assays made by the 

Mount Glines Gold and Silver Mining Company are said to give good 

value in silver, copper, and lead, but these are presumably of picked 

specimens. A sample taken from the upper portion of the 35-foot 

shaft, where the vein is 2^ feet wide, and assayed by Dr. E. T. Alien, 

yielded less than $1 in combined metals.

MILAN MINE, NEW HAMPSHIRE. 

GENERAL STATEMENT.

The Milan mine is in Coos County, northern New Hampshire, in 

the foothills of the Presidential Range, about 8 miles northwest of 

Berlin and one-fourth mile from the Grand Trunk Railway at 

Marston, with which it is connected by tramway. The deposit was 

discovered in the seventies and was worked steadily until 1886. 

According to Herbert J. Davis,0 the monthly production was. 2,600 

tons, and this production was presumably sustained for several years. 

A 60-ton smelter was installed at the mine, but the fumes killed the 

spruce, and, owing to objections of the farmers and the decline in the 

price of copper, this was closed after a small tonnage had been put 

through. The property was opened again in 1895, when lessees 

mined about 1,500 tons of ore. It was acquired in 1907 by J. B. 

Carper, of Portland, who organized the Milan Mining and Milling 

Company, which is now working the mine and making regular shipments of ore and concentrates.

The deposit, first worked by open cuts, is operated through a 

265-foot shaft inclined from 59° to 85° W. Levels are turned TO, 

88,115, and 215 feet (measured on the incline) below the collar; these 

aggregate about 1,500 feet.

The character of the deposit and its situation and accessibility to 

markets for all the products favor low costs both for mining and 

for milling. The stopes are at many places from 10 to 20 feet wide 

and the rock breaks well and runs easily in the chutes. Practically 

no timbering is required to hold the ground even when the large 

stopes are left open. The concentration of the ore is satisfactory 

for the pyrite, but the saving of copper, gold, and silver is low, and 

where these exceed a certain value it is found to be more profitable 

to ship the rock than to mill it. The ore is mined with air drills, 

dumped in a chute, and loaded in buckets of 1,200-pound capacity. 

It is hoisted to the top of the mill, where it falls over a grizzly, the 

fines going to a 1-inch shaking screen, from which they go over an 

elevator to the rolls. The coarse rock from this screen and from 

the grizzly passes over two picking belts on which the ore is washed

0 Mineral Resources U. S. for 1885, U. S. Geol. Survey, 1886, p. 501.
MILAN MINE, NEW HAMPSHIRE. 51

The milling ore goes through a Dodge crusher

by a small stream of water to facilitate cobbing. The waste from the

picking belt is sent to the dump, the low-grade pyrite ore is run

through the mill, and the ore carrying a noticeable amount of copper

is shipped to smelters.

and is elevated to the

ore bin, from which it

passes through coarse

rolls, up an elevator

through an impact

screen of one-eighth

inch mesh. From this

screen the fines go to

a thickening tank and

Shipping

J_

Mne

i

Grizzly

Fine Coarst

~r I

inch screen I 

1 Picking

I

Coarse Shipping ore

Picking belt > 

II .

> 

HSlt

Was

Milling ore

Dodge crusher

Elevator

Bjn

Coarse rolls

Elevator

Undersize 

t Thickening tank

Impact screen l/&

Oversize 

Fine rolls

In.

2 Wilfley and 3 Bartlett tables

Concentrate to to sluice 

bins

FIGURE 18. Plan of ore treatment at Milan mine, 

New Hampshire.

pass to a Richards pulsator classifier, where

they are classified for

the two Wilfley and

three Bartlett tables.

The coarse material

from the screen goes

through fine crushing

rolls and is elevated

back to the shaking

screen. The mill feed

carries about 26.5 per

cent sulphur and 1.35

per cent copper. The

concentration is 2 or

3 to 1 and the concentrates are shipped to acid works, from which

the cinders are sold to smelters and smelted for the copper, gold,

and silver. Analyses of representative concentrates, and cobbed ores

are given below:

Analysis of concentrates from Milan mine.

[Clias. L. Constant, analyst.]

Ounces per ton.

Gold ______________________________________ 0. 21 

Silver ________________ ________________ 1. 50

Per cent. 

Copper _______ _________ ______________ __ 1.58

Arsenic ____________________________ None.

Sulphur_____________________________..___ 41.30 

Silica ________________________________'__ 12. 47 

Alumina 1________________________________ 2. 80 

Iron ___________________________________ 35.00 

Lime ______________________________ Trace.

Magnesia _____________________._________.. 0. 30

Zinc ___________________________________ 6.46
52 SOME ORE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

Analysis of shipping ore co66eeZ from the mine run.

Per cent.

Insoluble_______________________________ 15.40 

Sulphur _________________________________ 39. 84 

Copper________:_________________________ 2.25 

Zinc ___________________________________ 7.26 

Lead ___________________________________ 1.57 

Iron ___________________________________ 32.85

The ore carries about $1.50 in gold and 1 or 2 ounces in silver to the 

ton, and the sulphur, iron, copper, gold, and silver yield from $12 to 

$18 a ton. There is a considerable accumulation of tailings from former operations which carry 36 per cent of sulphur and 1 .per cent of 

copper, and these are now being put through the mill for their pyrite 

content. From the low copper content of the concentrates it appears 

that a high percentage of the copper passes off in the slimes.

GEOLOGY.

The Milan area is included in the great shield of crystalline schists 

which covers most of New England and which is generally regarded 

as of pre-Cambrian age. These schists have been intruded presumably in Paleozoic time by great masses of granitic rocks which show 

little or no deformation by shearing and are therefore later than, the 

regional metamorphism of the schists. To the east and south these 

rocks cover extensive areas, but they are not known to be present 

in the vicinity of the mine.

The geology of New Hampshire has been mapped and the rocks 

described by C. H. Hitchcock.® In the geologic atlas accompanying 

his report the rocks inclosing the copper deposits are mapped as the 

Lyman group, a belt of which 3 or 4 miles wide extends from a point 

2 miles south of the Milan mine northward toward the Canadian 

boundary. A belt of the same rocks separated from the first by 

intruding porphyry extends southwestward 50 miles or more beyond 

Woodville. The latter belt includes the mines of the Ammonoosuc 

district, which have been worked for copper, gold, and silver. The 

deposits of these mines, to judge from the descriptions of the ores, 

have many features in common with the deposits at Milan.

The rocks mapped by Hitchcock as the Lyman group are mainly 

quartzites and siliceous chloritic schists, which were regarded by him 

as upper Huronian. They are in the main siliceous sedimentary 

rocks intensely-metamorphosed. On either side of this belt are areas 

equally long and wider, which Hitchcock mapped as the Lisbon 

group. These two groups of rocks are intimately inter folded and

0 Geology of New Hampshire, vols. 1 to 3,
MILAN MINE, NEW HAMPSHIRE. 53

presumably have about the same age and origin. Southeast of the 

Milan mine, including the area of the Milan Hills and extending 

southward beyond Berlin, is an area mapped by Hitchcock as " Lake 

and Granitic gneiss." The contact relations with the Huronian rocks 

are not given, but this gneiss is presumably in part a regionally 

metamorphosed granite, the age of which is not known.

The top of the Huronian series is the auriferous conglomerate which 

is exposed at many places in New Hampshire. It contains pebbles 

of jasper, schists, and quartz and has been greatly metamorphosed. 

It carries locally from 40 cents to $2 a ton in gold, but it is not clear 

whether the gold is a clastic constituent or was introduced after the 

formation was deposited; the presence of quartz pebbles, however, suggests the possibility of mineralization prior to regional 

metamorphism.

The country rock at the mine is a highly metamorphosed siliceous 

schist. In the underground workings, which do not go far into the 

country rock, it shows neither quartzites, limestones, or conglomerate 

layers, nor grains of grit, bedding planes, or other characteristics of 

sedimentary rocks that would indicate its clastic character. It has 

well-defined planes of schistosity, which near the mine strike northward and dip from 30° W. to 90°. Locally they dip eastward at 

very high angles. The microscope shows the schist to be composed 

of quartz, chlorite, biotite, muscovite, and pyrite. The quartz grains 

are oriented parallel to the mica and chlorite flakes.

On the surface, perhaps one-fourth mile northwest of the mine and 

between the mine and the railroad track, beds of highly siliceous schist 

outcrop at many places. Some of these rocks contain a myriad of 

thin dark actinolite fibers. Where subjected to weathering the 

siliceous schist shows the rounded sand grains of a fine quartzite. 

The wall rock of the mine is less siliceous than the quartzite and 

contains a greater percentage of chlorite, biotite, and muscovite. 

Mineralogically the wall rock is such as may have resulted from the 

intense regional metamorphism .of a quartz-rich shale or clayey 

quartzite, and there is nothing inconsistent with a sedimentary origin 

in its general appearance and mineralogical composition.

J. W. Huntington,0 of the New Hampshire Geological Survey, 

describing the area near Milan, says:

The railway cuts the gray siliceous schist in the east part of Stark, in the 

corner of Dunimer, and at several places for a mile east of West Milan. Easterly dips prevail on the west and westerly dips prevail on the east, so as a 

whole it seems to be a synclinal axis with minor folds near the middle of the 

area. The rocks, except the hard siliceous schists on the west, we have placed 

in the Lyman group, which is the upper member of the Huronian.

<> Hitchcock, C. H., Geology of New Hampshire, vol. 2, 1877, p. 201.
54 SOME ORE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

From these observations it seems that the Milan mine is on the 

east limb of the synclinal axis formed by the schistosity. A cross 

section taken from the New Hampshire atlas is shown as figure 19.

On the 115-foot level of the mine, about 35 feet northwest of the 

shaft, there is about 3 feet of an actinolitic schist which is different 

in appearance and mineralogical composition from the biotite schist 

that constitutes the walls at most places. It consists of a dark, 

fine-grained groundmass containing abundant crystals of hornblende 

about 1 mm. thick and 1 cm. long. Under the microscope the hornWest Milan 

(Percy Pa..^ ' |

Androscoogin. R. 

Lisbon r

Lyman group / / LaKegneiss ~ \ Lisbon group

Jr

epy Str.

Montal gain o- I 

 oup I

jMi

.FIGURE 19. Geologic east-west cross section through West Milan, N. H., north of the 

Milan copper mine. (After Hitchcock, Atlas of New Hampshire, 1878.)

blende shows characteristic cleavage and is surrounded by a groundmass of fine quartz and clouded sericitic bodies, which are probably 

decomposed feldspars. It contains also some chlorite, magnetite, and 

calcite. This rock appears to be more basic than the biotite schist 

and, to judge from its relations with the schist, it is probably the 

metamorphosed product of a dike of diabasic or more acidic composition a dike which cut the siliceous country rock before that rock 

was metamorphosed.

MINERALS OF THE ORE.

The deposits are overlapping pyritic lenses parallel to the schistosity of the country rock. The gangue is quartz, chlorite, black 

mica, and white mica. The sulphides are pyrite, chalcopyrite, zinc

blende, galena, bornite, and chalcocite. 

Little or no magnetite is present and 

pyrrhotite was not 

noted in several tests 

that were made. In 

a list of minerals of 

New Hampshire, 

published in 1886," 

a, Quartz; however, it is mentioned as occurring 

in the ore. The ore carries $1.50 in gold and about 1 ounce of 

silver to the ton. Much of the ore is solid pyrite, which includes 

fragments of the banded schists oriented parallel to the walls. 

Here and there the pyrite is cut by white quartz stringers, as is

0 Mineral Resources U. S. for 1885, U. S. Geol. Survey, 1886, p. 757.

l Foot

FIGURE 20. Pyrite cut by quartz, Milan mine. 

 6, pyrite.
MILAN MINE, NEW HAMPSHIRE. 55

shown in figure 20. Some of the sulphide ore, notably in the 

crosscut to the west at the south end of the 115-foot level, is massive 

zinc blende, carrying well-formed crystals of pyrite 1 mm. in diameter, with here and there small specks of galena. In the stope at the 

north end of the 115-foot level and between the 115-foot level and the 

70-foot level above the main ore body, a mass of white quartz is cut 

by veinlets of galena and pyrite and has specks of those minerals 

scattered through it. Below this ore the vein consists of pyrite and 

chalcopyrite cut by innumerable fracture planes which are filled 

Avith paper-thin films of chalcocite, the whole carrying 12 per cent of 

copper. An oxidized seam with 6 inches of limonitic material is 

above this body of copper ore, and this appears to have been a watercourse which was followed by the downward circulation of sulphate 

waters which deposited chalcocite and bornite films on the chalcopyrite. This ore, which carries more of the primary chalcopyrite than 

the mine run, is also richer in gold. Some of it carries as much as 

one-fourth ounce to the ton. A cross section of the vein at this place

sw

10 Feet

FIGDRE 21. Section of vein at east end of 115-foot level, 40 feet above floor, Milan mine. 

a, Oxidized streak ; l>, schist; c, massive quartz, pyrite, and galena ; d, pyritiferous schist 

or milling ore; e, massive pyrite.

is shown in figure 21. The lode is at no place completely oxidized, 

but in the stopes 40 feet below the surface limonite in seams and 

copper carbonate and. sulphate were noted at many places along narrow fractures. Locally the sulphide ore extends to the grass roots, 

with only a light veneer a fraction of an inch thick where it is 

exposed to the air.

ORE BODIES.

The ore bodies are two overlapping lenses separated by 10 or 15 

feet of biotite schist. They strike a few degrees east of north and 

dip steeply westward. They are not tabular but broadly they approach that form. In detail, however, they are characterized by gentle undulations along both the dip and the strike and at some places
56 SOME OKE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

there are turns of more than 45° along both dip and strike. The south 

ore body outcropped on the present site of the mill and the mine was 

first worked in an open cut from 15 to 25 feet wide, which extends 

200 feet along the strike. At a depth of 70 feet a shaft was sunk 

and stopes in both ore bodies were carried up to that level. The 

south ore body as developed is from 5 to 25 feet wide and like the 

north ore body it dips steeply westward. Near the surface it is 

developed southward for 275 feet along the strike. At its northern 

termination the end of the ore pitches southward at a low angle.

On the 70-foot level it is 45 

feet from the shaft and dips 

toward it from 50° to 70°, 

becoming steeper in depth. 

Near the end of this lens, 

at the pump station below 

the 115-foot level, the ore is 

highly crumpled.

The north ore body is developed northward 550 feet 

along the strike and it is 

approximately 15 feet wide. 

The south end of the north 

ore body on the 115-foot 

level is encountered in a 

short crosscut, 40 feet 

southwest of the shaft. It 

has been followed N. 20° 

E. for a distance of 360 

feet, where it bends to due 

north, keeping the course

for 120 feet. At chute No. 

2 it turns at an angle of 

40°, striking N. 40° E. for

FIGURE 22. Cross section of ore bodies, Milan mine, fg feet A CTOSS Section of

the two ore bodies 35 feet south of the shaft is shown in figure 22, O /

and a plan of the 115-foot level in figure 23.

From a point near the east end of the 115-foot level and about 40 

feet up in the stope the section of the lode, which here dips 40° NW., 

shows 4 feet of massive pyrite above a foot wall of chloritic quartz 

schist. Above this is 6 feet of pyrite and quartz with a little mica, all 

highly schistose, the planes following the orientation of the lode. 

Above the latter is a mass of quartz about 3 feet thick, with seams of 

pyrite aiid galena. Near the center of the 6 feet of pyrite and quartz 

which constitute a milling ore there is a seam of highly oxidized, ore
MILAN MINE, NEW HAMPSHIRE. 57

along a plane of movement. This plane is clearly a postmineral

fissure. A few feet lower this

fissure departs from the ore body,

keeping its regular course while the

ore body turns, striking nearly

northeastward and dipping steeply.

Where noted in a drift below it is

vertical and at one place overturned.

The ore bodies are parallel to the 

schistosity. At some places the 

Avails are intensely crumpled and 

much of the milling ore consists of 

the thin alternating bands of schist 

and pyrite intimately interbanded 

and crenulated. These seams of pyrite and quartz are also parallel to 

the schistosity, and . as shoAvn by 5 

Plate III, A, are clearly metamor- » 

phosed bj the same crumpling move- « 

ments. The ore is undoubtedly ^ 

older than the metamorphism of the g 

schists. At many places it grades 2, 

into the pure massive pyrite ore, but E 

the -latter does not show any schis- g1 

tosity. There is no noticeable seri- ^ 

citization or other hydrothermal 1 

metamorphism of the walls nor any "^ 

leaching of the Avail rock, such as is jr 

characteristic of most ore bodies not B 

regionally metamorphosed, and the g 

ore at no place shoAvs comb structure, crustification, or druses.

The plan of the 115-foot level 

illustrates further the effects on the 

ore body of the regional metamorphism due to intense shearing movements under load Avhich develop the 

schistose structure in the country 

rock. Before shearing the ore body 

Avas probably a single tabular mass, 

but by these movements it was 

thrust endAvise upon itself, so that 

it divided and overlapped. The division can hardly be called a fault 

in the common sense, since it took "/////" 

place in the zone of flow for the schist and was a pulling apart, not
58 SOME OEE DEPOSITS IN MAINE AND- NEW HAMPSHIEE.

by a sharp cleavage, but rather as a somewhat viscous body is divided. 

A tight fissure dipping westward at about the same angle as the two 

ore bodies joins the two ends and wraps around the ore at both terminations. The schistosity likewise wraps around the ends of these ore 

bodies and parallels the fissure Avhich joins them. These features are 

shown in figure 23. This relationship of the schistosity to the line of 

movement which separates the two lenses show's that the ore body has 

been subjected to the same earth movements as the rock. Since it has 

separated in the zone of flow it must have been deposited before regional 

metamorphism. This is further indicated by the gradation of the massive pyrite ore into pyrite containing parallel quartz and mica bands, 

of this into quartz biotite with numerous thin bands of pyrite, and of 

this, again, into schist with only an occasional band of pyrite and this 

into nearly pure schist. Thus the rock shows bands of the schist and 

bands of the pyrite A^arying in .all proportions a]ong the wall, and 

the ore always shows the minutely schistose structure wherever it 

contains quartz and biotite. The main lode of pyrite ore has exactly the same character as the smaller massive layers and must 

have the same origin, but where pure and large it is as free from 

conspicuous marks denoting movement as any ore deposit in unmetamorphosed rock. Some of the crystals of pyrite have perfect 

form when included as the thinnest seams between the quartz-rich 

or biotite-rich layers of the schist. As these pyrite seams increase in 

size and purity they become more massive, and where silica minerals 

are absent the ore does not show any lamination parallel to the schistosity of the country rock, although the ore is, without doubt, older 

than the final metamorphism of the schist and partook in its movements. The aluminous, more or less plastic wall rock was capable of crumpling to gnarly schistose layers, and where the seams 

of pyrite alternate with thin seams of quartz the same schistosity 

is shown; but massive pyrite ore not containing quartz or clayey 

material adjusts itself to conditions of pressure without leaving a 

conspicuous record of the movements. The pure pyrite is at no place 

laminated. The larger pyrite bodies have broken and have been recemented by pyrite and the smaller crystals have completely recryst'allized, mainly into small cubic and octahedral crystals rather than into 

pyritohedrons.

Galena and zinc blende have also recrystallized. Some of the chalcopyrite shows faint lamination, a feature of chalcopyrite noted also 

in the Tapley mine at Brooksville, Me.

The ore bodies are believed to be tabular deposits of sulphide ore 

metamorphosed by the same movements that converted the highly 

quartzose shales into quartz-biotite schists. It is remarkable that 

this lode, like most of the members of the class, should everywhere be approximately parallel with the schistosity of the country
MILAN MINE, NEW HAMPSHIRE. 59

rock. Ore bodies in a given district of immetamorphic rocks very 

often present a great variety of dips and strikes, and in many districts 

there are two vein systems nearly at right angles to each other. The 

movement causing the schistosity is apparently controlled to some 

extent by the ore bodies or else the ore bodies are rotated to conform 

to the general movements as recorded in the structure of the schists. 

Probably the agreement of ore with schistosity is brought about in 

both ways. First, the pyrite bodies are broken and the parts tend 

to orient themselves at right angles to the line of pressure, as, for 

example, the flat or oblong grains of sand in a quartzite or quartz 

schist, or as the mica flake in a mica schist; and, second, the schistosity of the walls is probably controlled locally by the large masses 

of ore if the ore body is too immobile to orient itself to conform with 

new conditions of pressure as do the oblong quartz particles in the 

quartzose shale when it is metamorphosed to biotite schist.

At the south end of the north ore body on .the 115-foot level the ore 

is highly siliceous and consists of intensely crumpled pyrite and 

quartz. At this place, where the ore body pulled apart and became 

two lenses, the ore looks like a surface of gnarled oak or vermicelli. 

Here the schistosity of the walls instead of striking northward 

parallel to the main lode strikes westward parallel to the end of the 

lens. On an intermediate level, just beloAv, near the pump station, 

the same intense crumpling is shown at the north end of the south 

ore body.

These places show that the ore body broke where it was most 

siliceous and most heterogeneous and because of that heterogeneity of composition the movement was best recorded. If it had 

been pure pryite instead of quartz-pyrite-chlorite ore it would not 

have shown the intense crumpling, for the pyrite would have broken 

and recemented into an apparently homogeneous mass. Since the 

broken end of the south ore body pitches toward the south, with the 

ore on the foot wall of the pitch, it should be expected that the broken 

end of the north ore body should also pitch to the south, with the 

ore on the hanging wall of the pitch.

SUMMARY OF THE GENESIS.

The deposit was at one time a large mass of ore contained in impure 

quartzite or slate which if metamorphosed was less intensely metamorphosed than at the present time. The ore may have been deposited at 

the time the granular rocks mapped by Hitchcock as " Lake and Granitic gneiss " were erupted or at the time of the intrusion of a basic 

igneous rock which is now actinolite schist. It was not, however, a 

contact-metamorphic deposit, for it has none of the characteristics of 

such deposits and it does not contain garnet and epidote and other 

lime silicates which are usually found in such deposits. Presumably
60 SOME ORE DEPOSITS IN MAINE AND NEW HAMPSHIRE.

 ^

it was first formed at moderate depth and then consisted of quartz, 

pyrite, zinc blende, galena, chalcopyrite, and some aluminous material either clay or sericite; the walls were presumably replaced by 

pyrite and other minerals. After deposition it was deeply buried 

and was intensely deformed in the zone of .flow at the time when 

the siliceous shales were subjected to regional metamorphism and 

changed to schists, or at the latest before this process had ceased to 

operate. During the process of metamorphism the deposit was deformed by pressure. Certainly it was pulled apart at one place and 

thrust back on itself so that the two ends overlapped some 40 feet. 

The ore body pulled apart where it was most siliceous, where parallel 

sheets of quartz and mica are abundant in the pyrite, and because 

of this circumstance of heterogeneity also a maximum of squeezing 

and crumpling was recorded. The sulphides were crushed, recemented, and at some places dissolved and reprecipitated. Drusy cavities and banded and comb structures, if present, were destroyed. Any 

evidences of hydrothermal metamorphism along the walls of the 

deposit were obscured by the subsequent regional metamorphism of 

the deposit and the country rock. After metamorphism the rock 

above the deposit, probably a considerable thickness, was eroded 

away, and minor movements resulted in fractures and slickensided 

planes, cutting the lode approximately parallel to the dip and strike. 

Ultimately through water and glacial erosion the present outcrop of 

the deposit was exposed. Descending sulphate waters deposited a 

little chalcocite in the later fractures. The lode was partly oxidized 

at the outcrop, but at most places the oxides did not extend more than 

40 feet below the surface and at some places near the surface they 

scarcely formed at all,
INDEX.

Page. 

Acknowledgments to those aiding........... 8

Ames Knob formation, occurrence and character of.......................... 12-13

Bastin, E. S., aid of......................... 8,11

Battic quartzite, occurrence and character of. 12 

Bibliography................................ 8-10

Blue Hill mine, description of............... 33

ores of................................ 16,19,33

vicinity of, geologic map of.............. 30

Brookville, copper near...................... 10

Cape Rozier mine, description of............. 38

ores of................................... 19,38

Castine formation, occurrence and character

of............................... 13

ores in................................... 15-16

Catherine Hill mine, description of.......... 42

ore's of................................... 21,42

figure showing....................... 42

Cherryfield mine, description of............. 43

Coast, outcrops on........................... 25

Concord mine, ores of........................ 21

Cooper mine, ores of......................... 47

Copper ores, age of.......................... 15

deposits of........................... 16-19,22

mining of........ 11,16,27,31-32,34-38,41,4<>47

production of............................ 11

Copperopolis mine, description of............ 41-42

Deer Isle mine, description of................ 37-38

ores of............................. 19,20,27,38

figures showing...................... 20

Denbow Point mine, description of.......... 45

oresin................................... 22,45

Diabase, ores associated with................ 22

Dikes, occurrence and character of........... 15

Diorite, occurrence and character of......... 15

Douglas mine, description of................ 31-32

development at.......................... 11

ores in................................... 26

analysis of........................... 32

Eggemoggin mine, description of............ 36-37

Ellsworth schist, occurrence and character

of............................... 11-12

ores in................................... 15-16

Emerson mine, description of.............. 39

ores of................................... 19,39

Enrichment, secondary, effects of........... 26

Field work, extent of........................ 8

Fissure veins, occurrence and character of... 20-21 

Franklin Extension mine, description of.... 41

Geography, character of..................... 10

Geology, outline of.......................... 11-15

See also particular counties.

Glaciation, effects of......................... 24-25

Gouldsborough mine, description of......... 40-41

ores of.........................j......... 21,41

Granger mine, description of................ 35

Granite, occurrence and character of......... 14-15

ore deposits associated with............. 20-22

Hancock County, geology of................. 30-31

mines in, description of................. 31-42

Hercules mine, description of................ 38

ores of................................... 19,38

Hess, F. L., on Cooper mine................ 47

Hitchock, C. H., on Milan mine............. 52-53

Huntiugton, J. W., on Milan region......... 53

Iron, mining of.............................. 7,10

Islesboro formation, occurrence and character of............................ 12

Jackson, C. T., cited......................... 10

Jewel Island, mining on..................... 10

Jones & Dodge mine, description of......... 38

Keinpton, C. W., on Sullivan mine......... 40

Lava, occurrence and character of........... 15

Lead ores, age of............................ 15

deposits of.............................. 21-22

mining of.......... 10,26-27,32-35,37,41,43-45

Lindgren, Waldemar, aid of................. 8

Literature,list of............................ 8-10

Lubec, lead at.............................. 10

Lubec mine, description of.................. 44-45

ores in............................... 22,44-45

figures showing..................... 44,45

Maine, southern, map of..................... 7

mines in, descriptions of................. 30-50

Mammoth mine, description of.............. 34

Map of southern.Maine....................... 7

Metals, occurrence of........................ 7

production of............................ 11

Metarnorphism, effects of.................... 18-20

occurrence and character of.............. 28

time of, relation of ore deposits and....... 15

Milan mine, New Hampshire, description of.. 8,50

faulting in............................... 29,50

genesis of................................ 59-60

geology of............................ '50,52-54

minerals in.............................. 54-55

ores of.................... 16-17,26,50-52,55-59

analysis of........................... 51,52

figures showing.......... 17,19,42,54,55,56

plan of, figure" showing.................. 57

 section near, figure show ing............. 54

Mineralogy, data of.......................... 22-24

Mines, description of.........:.............. 30-60

future of................................. 26-27

61
62 INDEX.

Page 

Mining development, extent of.............. 10-11

Molybdenite, mine of..................... 42,47-49

occurrence and character of........... J.. 21

 plate showing........................... 42

Mount Glines, description of...............1 .. 49-50

Mount Katahdin, iron on.................... 10

North Haven greenstone, occurrence and

character of...................... 13-14

Ore deposits, age of, relation of, to metamorphism........................... 15

classification of.......................... 15-22

distribution and character of............ 15-18

figures showing.............. 17,18,19,20,21,22

geologic history of....................... 27-30

metamorphism of....................... 18-20

mineralogy of........................... 22-24

origin of................................. 20

outcrops of.............................. 24-25

oxidation of............................. 25-20

See also Metals; Mines. 

Outcrops, distribution of.................... 24-25

Owen lead prospect, description of.......... 34-35

ores of, figure showing................... 20

Owen mine, description of................... 34

ores of................................... 21,34

Oxford County, deposits at.................. 49-50

Oxidation, effects of......................... 25-26

Pembroke, ores of........................ 22,46-47

ores of, figures showing.................. 22,46

Penobscot formation, occurrence and character of.......................... 12

Perry formation, occurrence and character

of............................... 13

Pine Tree mine, location of.................. 39

Production of metals, data on............... 11

Page. 

Pyrite, mining of........................... 10

Robinson, F. C., aid of...................... 8

Robinson mine, description of............... 48-49

ore of.................................... 49

figure showing....................... 49

plan of, figure showing.................. 48

Seacoast, outcrops on........................ 25

Silver ores, age of................... 1........ 15

deposits of............................ 19-20,22

mining of.......... 11,26-27,36-37,39-41,43,45,

production of............................ 11

Smith, G. O., aid of......................... 8,11

Somerset County, mines of, description of.... 48-49

Stewart mine, description of................. 33-34

Stone, quarrying of.......................... 10

Sullivan mine, description of................ 39-40

ores in................................ 20-21,40

figures showing..........;........... 21-39

Tapley mine, description of.................. 35-36

ores at................................... 16,36

figure showing....................... 16

Thorofare andesite, occurrence and character

of............................... 14

Twin Lead mine, description of.............. 32-33

ores in....................:.............. 16,33

figures showing................'...... 17,18

Vinalhaven rhyolite, occurrence and character of.......................... 14

Washington County, geology of............. 43

mines in, descriptions of................ 43-48

Waukeag mine, description of................ 39

Weil Freddie mine, description of........... 35

Zinc ores, age of............................. 15

deposits of............................ 19,20,21

mines of......:.:............ 26-27,34-39,41,43

O