UNITED STATES DEPARTMENT OF THE INTERIOR 

Harold L. Ickes, Secretary

GEOLOGICAL SURVEY 

W. C. Mendenhall. Director

Bulletin 936-M

NICKEL-COPPER DEPOSIT AT SNIPE BAY 

BARANOF ISLAND, ALASKA

BY

JOHN C. REED AND GEORGE 0. GATES

Strategic Minerals Investigations, 1942

UNITED STATES

GOVERNMENT PRINTING OFFICE 

WASHINGTON : 1942

For sale by the Superintendent of Documents, Washington, D. C. ....... Price 10 cents

CONTENTS

Page

Abstract................................................. 321

Introduction............................................. 321

Geology.................................................. 323

Ore deposit.............................................. 324

Mineralogy........................................... 324

Origin............................................... 326

Localization......................................... 326

Size and grade....................................... 327

Reserves............................................. 329

Economic considerations.............................. 330

ILLUSTRATIONS

Page

Plate 48. Geologic sketch map of the nickel-copper 

deposit at Snipe Bay, Baranof. Island, 

Alaska...................................... 324

Figure 36. Index map of southeastern Alaska showing the 

location of the nickel-copper deposit at 

Snipe Bay, Baranof Island................... 322

37. Diagrammatic section of the nickel-copper

deposit at Snipe Bay, Alaska................ 328

III

NICKEL-COPPER DEPOSIT AT SNIPE BAY, 

BARANOF ISLAND, ALASKA

By John C. Reed and George 0. Gates

ABSTRACT

At Snipe Bay, on the outer coast of Baranof(Island, about 

46 miles southeast of Sitka in southeastern Alaska, is a nickelcopper deposit that consists of a mass of basic rock intruded 

into quartzite and quartz schist. Neither the size nor the 

grade of the deposit is adequately known. Natural exposures and 

those in a few prospect openings indicate that to an assumed 

depth of about 130 feet below the lowest point on the outcrop 

there is a reserve of about 430,000 tons of low-grade nickelbearing material, which, to judge from available assays and from 

comparison with similar material from other places, probably does 

not contain more than 0.3 percent each of nickel and copper. 

The deposit thus appears too small and of too low grade to permit the recovery of the nickel and copper except at a considerable financial loss; but as the location is favorable for largescale, low-cost development, further prospecting may be justified, in the hope that a moderate amount of surface stripping, 

plus a few diamond-drill holes, might indicate that the deposit 

is larger, and possibly of higher grade, than it is safe to infer from the available data.

INTRODUCTION

The nickel-copper deposit discussed in this report is at 

Snipe Bay (see fig. 36), a northeastward-trending indentation 

of the west coast of Baranof Island, southeastern Alaska, about 

20 miles northwest of Cape Ommaney, at the southern tip of the 

island. Snipe Bay is about 46 miles by airline southeast of 

Sitka, the nearest town of considerable size, and not very much 

farther by boat. The deposit lies at an altitude of about 450 

to 600 feet near the head of a small, short stream that empties 

into the first small bight east of the entrance on the north

480161 O - 42 321
322

side of the "bay. Although Snipe Bay is deep and fairly w.ell 

protected, thus making a favored anchorage for small fishing 

boats, the deposit lies too near the entrance of the bay to be

Figure 36. Index map of southeastern Alaska showing the location of the 

nickel-copper deposit at Snipe Bay, Baranof Island.

well sheltered, so that to land nearby is difficult in even moderately rough weather and impossible during bad storms. There 

are no docking facilities. The bay is never entered by steamer, 

although this would be possible, but can be reached by small
NICKEL-COPPER DEPOSIT AT SNIPE BAY, ALASKA 323

"boat, except In times of rough water. The best anchorage is 

said to be in a cove on the south side of the bay about l-j^ miles 

Inside the entrance.

The surrounding slopes are, for the most part, very steep, 

and camp sites near the beach are scarce. An abandoned camp, 

which evidently served as a base headquarters for the prospecting 

work that was done on the deposit In 1941, is located near the 

beach on the west side of the stream near the head of which the 

deposit lies. A steep trail leads from the camp site to the

deposit.

I/ 

According to Buddington, who examined the deposit in 1923,

claims were first staked on the deposit by I. Myre Hofstad in 

1922. Ten claims, including some of Hofstad's old claims, are 

said now to cover the deposit and its vicinity. The claims are 

held by S. H. P. Vevelstad, and all of them except those formerly 

held by Hofstad were staked in 1939. No ore has been shipped 

from the property.

The examination on which this report is based was made on 

June 29 and 30, 1941. P. C. Calkins and H. G. Perguson, of the 

Geological Survey, offered many helpful suggestions during the 

preparation of the report.

GEOLOGY

The principal country rocks in the vicinity of Snipe Bay 

are biotitic quartzite and biotite-quartz schist. These rocks 

are part of a graywacke formation, believed to be of Lower 

Cretaceous age, which is widespread on Chichagof and Baranof 

Islands. The graywacke formation, and the predominantly volcanic formations that underlie it, are cut by a variety of intrusive igneous rocks, which are thoiight to be mainly of Cretaceous 

but possibly in part of Tertiary age«

iy Buddington, A. F. , Mineral resources of Alaska, 1923: U. S. Geol. 

Survey Bull. 773, pp. 106, 107, 1925.
324 STRATEGIC MINERALS INVESTIGATIONS, 1942

The quartzite and schist are cut by a dark, coarse-grained, 

igneous mass whose boundaries are largely concealedj this mass 

constitutes the deposit here described (see pi. 48). The mass 

at the surface is at least 265 feet long and 125 feet wide. The 

rock, which before alteration was probably gabbro or norite, now 

consists mainly of brown hornblende, albite, and magnetite, and 

contains apatite in unusual abundance. The alteration appears 

to have been the product of soda-rich hydrothermal solutions.

The quartzite and quartz schist strike northwestward and dip 

northeast. ^h.e longer surface dimension of the intrusive mass 

appears to be roughly the same as the general strike of the wall 

rocks, but it can be seen in prospect pits that the mass at 

least locally crosscx;ts the stratified rocks 

ORE DEPOSIT

The nickel and copper at Snipe Bay occur in the intrusive 

igneous mass just mentioned. The Igneous rock contains a nickelbearing sulfide mineral, probably pentlandite, and the copperbearing sulfide chalcopyrite. The amounts of these ore minerals 

in the rock differ widely at different places, but so far no 

pattern of their distribution has been recognized, and the whole 

intrusive mass is therefore considered as the deposit. The surface exposures are so poor that the shape and attitude of the 

mass, and hence any estimates of the volume to any specified 

depth, are largely matters of conjecture 0

Mineralogy

The metallic minerals in the deposit include principally the 

iron oxide magnetite, the iron sulfides pyrrhotite and pyrite, 

the iron-copper sulfide chalcopyrite, and the iron-nickel sulfide pentlandite. Of these only the chalcopyrite and the pentlandite are of economic significance. The silicate minerals 

include brown hornblende associated with a pale amphibole derived
UNITED STATES DEPARTMENT OF THE INTERIOR 

GEOLOGICAL SURVEY BULLETIN 936 PLATE 48

Covered with soil and 

vegetation

Mostly covered with soil and vegetation 

Probably underlain by intrusive mass

GEOLOGIC SKETCH MAP OF THE NICKEL-COPPER DEPOSIT AT SNIPE BAY.BARANOF ISLAND, ALASKA
NICKEL-COPPER DEPOSIT AT SNIPE BAY, ALASKA 325

from it, a soda-rich plagioclase feldspar (albite or albiteoligoclase), and a.more calcic plagioclase feldspar (andesine or 

labradorite). Apatite constitutes perhaps 1 or 2 percent of the 

rock.

At most places the brown hornblende or its alteration products make up more than 50 percent of the rock. The next most 

abundant mineral is albite or albite-oligoclase, but locally most 

or even all of the feldspar present may be the more calcic 

plagioclase. The apatite appears to be confined largely to the 

soda-rich feldspar in the rock. The magnetite is distributed as 

small crystals and rounded, sickle-shaped, or irregularly shaped 

grains throughout all the other minerals including the sulfides. 

The magnetite varies widely in abundance but in general probably 

forms between 10 and 25 percent of the rock.

The sulfide minerals are very closely associated. Pyrrhotite

is by far the most abundant. The principal nickel mineral is

2/ 

pentlandite. Buddington mentions the presence of pentlandite

and of a nickel mineral secondary after pentlandite. One polished section of relatively high grade material collected by the 

authors was examined microscopically, but no pentlandite could 

be identified in it. An undetermined metallic mineral occurring 

sparsely in the polished section may be the secondary nickel 

mineral mentioned by Buddington. The few available analytical 

data indicate that in general the chalcopyrlte and the pentlandite are present in roughly equal quantity. Pyrite is very 

scarce. The proportion of the rock made up of the combined sulfides ranges from less than 1 percent to nearly 100 percent. 

Where the proportion of the combined sulfide minerals is high, 

the ratio of pentlandite to chalcopyrite, and hence of nickel to 

copper, appears to be high also (see table p. 329),

£/ Baddington, A. 7., op. cit., p. 107.
326 STRATEGIC MINERALS INVESTIGATIONS, 1942

Origin

The deposit has many features in common with other nickelcopper deposits farther north, on the west coast of Chichagof

3/ 4/ 

Island and on Yakobi Island. Prom examination of those

deposits and from a brief petrologic study of the deposit at 

Snipe Bay the following origin has been inferred:

The quartzite and quartz schist were invaded by an igneous 

mass of unknown shape which crystallized probably as norite or 

as gabbro. The rock of the mass probably was a basic differentiate of a more silicic magma. The sulfides of the rock were, 

for the most part, among the latest minerals to crystallize. 

Later, soda-rich emanations from less basic parts of the magma 

apparently permeated the norite and converted the original 

pyroxene to the brown hornblende and, still later, partially 

converted the brown hornblende to pale amphlbole with the release 

of some iron as magnetite. The same emanations have replaced 

the original moderately calcic plagioclase with albite or albiteoligoclase. The sulfides apparently were moved about to a minor 

extent by late fluids to form tiny veinlets and fracture-fillings 

in the igneous mass and, more rarely, in the adjacent wall rocks.

Localization

Some parts of the igneous mass appear to be entirely barren 

of sulfide minerals and therefore do not contain appreciable 

quantities of either nickel or copper. Other parts are relatively rich in sulfides, disseminated in irregular blebs interstitial to the other minerals. One body is made up almost 

entirely of sulfides.

The intrusive mass is poorly exposed and has been so little 

prospected that the general distribution of the sulfides in it 

is not known.

}/ Pecora, W. T., Nickel-copper deposits on the weet coast of Chichagof 

Island, Alaska: U. S. Oeol. Survey Bull. 93^-1 (in press). -

U/ Reed, J. C., and Dorr, J. 7. N., 2d, Nickel deposits of Bohemia Basin 

and"~vicinity, Yakobi Island, Alaska: U. S. Oeol. Survey Bull. 931-?.
NICKEL-COPPER DEPOSIT AT SNIPE BAY, ALASKA 327 

Size and grade

The greatest observed length of the deposit, on the surface, 

is about 265 feet, and its greatest observed width about 125 

feet (see pi. 48). The figure for the length is somewhat, and 

perhaps a great deal, too small, for at the north end the rock 

disappears beneath a cover of vegetation and soil. The shape 

of the body in depth is of course even more uncertain. The mass 

may extend to a considerable depth, have nearly vertical walls 

and a horizontal section similar to its surface plan, or the 

attitude of the walls and the form of the horizontal section 

may change markedly with depth.

In view of all these uncertainties, any estimate of tonnage 

is hazardous. An estimate is offered, however, that is based 

on certain assumptions. Figure 37 is a rough longitudinal section of the deposit showing inferred continuation to a considerable depth. In figure 37 and in the following calculations, the 

deposit, for convenience, has been considered as extending vertically downward. It seems more likely that it actually extends 

downward more or less parallel to the dip of the graywacke. It 

is further assumed that the deposit extends to a depth equal to 

half the outcrop length below the lowest point on the outcrop 

with the same area (22,000 sq. ft.) as indicated on plate 48. 

If this were true, the volume of the deposit would be that above 

the lowest point on the outcrop plus the product of the measured 

area of outcrop and half the outcrop length, or

22,000 x 125 =

feet

1,375,000 + (22,000 x 132 )= approximately 4,300,000 cubic

feet,

where 22,000 square feet is the measured area of outcrop, 125 

feet the difference in altitude between the highest and lowest 

known points on the outcrop, and 132 feet half the outcrop 

length.
328 STRATEGIC MINERALS INVESTIGATIONS, 1942

Assuming that the specific gravity of the rock is such that 

it would take about 10 cubic feet to make a ton, 4,300,000 cubic 

feet would equal 430,000 tons to the depth assumed, which is 

about 300 feet above sea level. But the above estimates can 

hardly be too large and may be much too small; much more than

430,000 tons may be available at depths greater than 132 feet.

SE.

Section along lineA^A'on plate 48 

Horizontal and vertical scale

eoFeet

Figure 37» Diagrammatic section of the nickel-copper deposit at

Snipe Bay, Alaska. 

The one small body composed almost entirely of sulfldes is

about 12 feet long by 4 feet wide and is roughly elliptical. 

If it extends in depth a distance equal to half its longer 

dimension, it contains about 30 tons of relatively high grade 

material.

The grade of the deposit is not known. Only a few analyses 

have "been made of material from it and only three, of which two 

were collected by Buddington and one by the authors, were both 

collected and analyzed by the Geological Survey. Two of these
NICKEL-COPPER DEPOSIT AT SNIPE BAY, ALASKA 329

three samples were from the small, high-grade body, and the 

other, which was collected by Buddington to represent the 

metallized rock, contained much more copper than is thought to 

be present in the average rock.

Nickel and copper in samples from the deposit at 

Snipe Bay, Alaska

Sample

Prom body of massive sulfides. 

Do ........................

Collector

Buddington 

Reed and

Gates. 

Buddington

Nickel 

(percent)

3.67 

4.08

.43

Copper 

(percent)

2.87 

.79

3 A A

At best, the deposit as a whole seems unlikely to yield more 

than about 0.3 percent each of nickel and of copper. This estimate is based partly on the very inadequate analytical data but 

mostly on comparison of the material with similar material from 

the deposits on Yakobi and on Chichagof Island, the metal content of which is better known. Channel samples, cut in each of 

the three principal pits, might be expected to indicate the content of nickel and copper in the rocks close to these pits, but 

in order to make a reliable estimate for the entire deposit, it 

would be necessary to assay many samples from additional pits 

or from diamond-drill cores or from both.

Reserves

The foregoing discussion indicates that the nickel-copper 

deposit at Snipe Bay contains reserves of possibly a few hundreds of thousands of tons of material that may contain a few 

tenths of a percent each of nickel and copper. Within this 

larger mass is at least one body of a few tons which probably 

carries about 4 percent of nickel. Practically no ore is actually in sight, and the nickel and copper tenor of the material 

exposed is largely inferred.
330 STRATEGIC MINERALS INVESTIGATIONS, 1942 

Economic considerations

At an assumed price of 35 cents per. pound for nickel and 12 

cents per pound for copper, the material may contain values in 

these metals of about $2.80 per ton. It seems doubtful that 

such material could be mined, milled, shipped, and smelted at a 

profit even if it were present in much larger quantity than is 

now indicated.

Systematic stripping of the surface of the deposit, or test 

pitting where the cover is too deep for stripping, would determine the size and the shape of the outcrop. Adequate sampling 

should be carried on along with the stripping, in order to 

determine the average grade of the deposit and its range in 

grade. If the results indicated a promising deposit, a moderate 

amount of carefully planned diamond drilling would furnish the 

information necessary to indicate the general shape and attitude 

of the deposit below the surface, and assays of core samples 

would indicate "the tenor.

Mining conditions are such, on the whole, that operations 

could be carried on at low cost if a sufficiently large tonnage 

is available. A good mill site could be found between the 

deposit and the nearby beach, but lack of harbor and docking 

facilities would present a considerable, but by no means insurmountable, obstacle. There is no local supply of labor with 

mining experience, but to bring in such a supply for a projected 

operation would not be unusually difficult.

O
CORRECTIONS for Geological Survey Bulletin 936-N

Page 340, Figure 39.

On the bar scale the small divisions should be 7^ feet and 

the large divisions 37y2 feet, instead of 5 feet and 25 feet 

as shown. 

Page 343, Figure 40.

The scale is incorrect and should be canceled. 

Page 344, Last paragraph, 2d line.

Change "40-foot drift" to "50-foot drift."