DEPARTMENT OF THE INTERIOR

ALBERT B. FALL, Secretary

UNITED STATES GEOLOGICAL SURVEY

 GEORGE OTIS SMITH, Director 

r Bulletin 742

OHROMITE OF KENAI PENINSULA 

ALASKA

BY

A. C. GILL

WASHINGTON

GOVERNMENT PRINTING OFFICE 

1922
ADDITIONAL COPIES

OF THIS PUBLICATION MAT BE PROCURED FROM

THE SUPERINTENDENT OF DOCUMENTS

GOVERNMENT PRINTING OFFICE

WASHINGTON, D. C.

AT

15 CENTS PER COPY
CONTENTS.

Page.

Introduction_____________ _ _ __ 1

Geographic.relations of the area_____________________ 1

Mining operations _______ _ _ _ 1

Previous investigations____ ____ ___ _____ 1

Investigations made for this report____________________ 2

Acknowledgments________-_____________________ 2

Geology_^____________________________________ 2

General features ________ _ _ _ . 2

The rocks_____________ _______-___________ 4

0 Metamorphic rocks_________ __ ___ 4

Dunite masses_____________ __________________ 4

Port Chatham___________________________ 4

Position, size, and shape__ __________ _ 4

Intrusive relations__________________ __ 4

Deformation___ ____ ____________ _ 5

Weathering __________________________ 6

Red Mountain ___________ __________________ 6

, Position, size, and shape__________________ 6

Intrusive relations ___________________ 6

Deformation___________________________ 7

Weathering __________________________ 9

Petrography _______ __ ________ _ 10

Rock types_____________________________ 10

Dunite _________________________________ 10

Pyroxenite _______________________________ 11

Serpentine _______ ______________________ 12

Ore deposits____________________________________ 13

The ore bodies______ __ ____________________ 13

The ore____________________________________ 13

Mineralogy_____________________________________ 14

Origin of the ore_______________________________ 16

Ore bodies at Port Chatham_______________________ 17

Number__________________________________ 17

Position____________________________________ 18

Dimensions and character of the individual ore bodies______ 18

Relation of the ore bodies to the dunite______________ 26

Structural relations____________________________ 26

Physiographic relations________________________ 26

Composition________________________________ 27

Quantity of minable ore________________________ 28

Mining __ ___ _______________ 29

Shipment _____ _____ _____________________ 29

in
IV CONTENTS.

Ore deposits Continued. Page.

Ore bodies at Red Mountain____________________________ 30

Number__________________________________ 30

Position__________________________________ 30

Dimensions and character of the individual ore bodies______ 30

Deposits indicated by float______________________ 39

Relation to the dunite________________________ 41

Structural relations, _ _________________ 41

Physiographic relations__________________ - 41

Composition_____ _________________________ 42

Quantity of minable ore___________________________ 43

Mining and shipment__________________________ 43

Conclusions ____________________________________ 44

Amount of ore____________-_ ________________ 44

Methods of mining______________________________ 44

Concentrating __ __ _ ________________:___ 45

Transportation to tidewater________________________ 46

Shipment and markets___________________________ 48

Possible occurrence of other valuable minerals_______________ 48

Platinum____________________________________ 48

Nickel_____________________________________ 49

Index________________________________._______ 51

ILLUSTRATIONS.

Page. 

PLATE I. Geologic reconnaissance map of the western part of Kenai

Peninsula ________ ________________ 4

II. A, Banded chromite ore from Kenai Peninsula ; B, Mottled chromite ore from Kenai Peniusula_________________ __ 14

III. Map showing chromite deposits at Claim Point, Port Chatham- 18

IV. Map showing chromite deposits at Red Mountain______ 30
CHROMITE OF KENAI PENINSULA, ALASKA,

By A. C. GILL.

INTRODUCTION.

Geographic relations of the area. The region with which this 

report deals is near the intersection of the sixtieth parallel of north 

latitude with the one hundred and fiftieth meridian of west longitude. So far as is definitely known, the deposits of chromite it 

contains are restricted to two areas of basic igneous rock, chiefly of 

the variety of peridotite known as dunite, near the southwestern extremity of Kenai Peninsula. (See PI. I, p. 4.) One of these areas 

forms a rocky hill called Claim Point, which stands at the entrance 

to Port Chatham, where the town site named Chrome was located 

in 1918, and extends for a short distance on to the adjacent 

mainland of the peninsula. It is thus practically at tidewater. 

The other is 16 miles to the northeast. Its culminating point is Red 

Mountain, the top of which, according to aneroid determination, 

stands at an altitude of 3,450 feet above sea level. The lowest point 

on the boundary of the dunite mass is a little more than 900 

feet above sea level. Here the headwaters of a stream locally 

known as Windy River flow first northward and farther down swing 

eastward about 2| miles north of the dunite area and then flow in 

a moderately direct southerly course into Rocky Bay. At other 

points on its periphery this mass of dunite is accessible at altitudes 

ranging from 1.300 to 2,000 feet by two heads of Fish Creek, which 

flows northwestward to Barabara Point, by two southward-flowing 

tributaries of Seldovia River, or by two short streams that run eastward into the lower reaches of Windy River. The distance from 

this deposit of chromite to tidewater at Tutka Bay, Jakolof Bay, 

Seldovia Bay, Rocky Bay, or Port Dick is 5 to 7 miles.

Mining operations. Chromite has been mined commercially only 

at Claim Point, where nearly a thousand tons was mined in 1917 

and about the same quantity in 1918, forming the entire contribution of Alaska to the chromite industry.

Previous investigations. Grant, who visited both areas in 1909, 

noted the character of the igneous rock and mentioned two of the

1
2 CHBOMITE OF KENAI PENINSULA, ALASKA.

chromite deposits. He reported also an analysis of the richer chromite from Red Mountain. 1

In the summer of 1917 J. B. Mertie, jr., of the United States 

Geological Survey, gathered data, some of which have been published,2 concerning the deposits of chromite at Claim Point and 

Red Mountain. Mr. Mertie very kindly placed his field notes at the 

disposal of the writer of this report.

W. P. Lass, of Whitney & Lass, who own and operate the property at Claim Point, has published a statement showing the quantity, quality, and conditions of shipment of their product for the 

season of 1917.3

Investigations made for this report. During the season of 1918 

the writer, assisted by W. Brooke Graves, made a more detailed 

study of these chromite-bearing areas, spending the period from 

July 2 to August 25 in making investigations of the known deposits, in searching for others in adjacent regions, and in making examinations to determine whether nickel or platinum may occur in 

association with the chromite. These investigations and others suggested by the results of the field work have been by no means finished, but such observations as seem to have a bearing on the quantity, occurrence, and exploitation of the chromite of Kenai Peninsula 

are here presented. A preliminary report on these investigations 

was published in 1920 (U. S. Geol. Survey Bull. 712, pp. 99-129).

Acknowledgments. Acknowledgment should be made of the aid 

in the preparation of this report that has been given by the owners 

of the chromite properties, as well as by several members of the 

United States Geological Survey in Washington and by the writer's 

colleagues at Cornell University. Special aid has been rendered in 

the field by Capt. G. H. Whitney, Mr. W. P. Lass, Mr. F. P. Skeen, 

and Mr. F. A. Rapp.

GEOLOGY.

GENERAL FEATURES.

The country rock in which the chromite is found is here broadly 

called dunite, though some of the local varieties of it might be more 

specifically called by other names, and parts of it have been weathered to serpentine.

The rocks are of igneous origin and are surrounded by more 

or less metamorphosed clastic beds like those which in adjacent regions have been termed by Martin 4 slates and graywackes, and by 

Grant 5 graywacke and slate, with chert, limestone, and volcanic

1 Martin, G. C., Johnson, B. L., and Grant, U. S., Geology and mineral resources of 

Kenai Peninsula, Alaska: U. S. Geol. Survey Bull. 587, p. 237, 1915.

2 Mertie, J. B., jr., U. S. Geol. Survey Bull. 692, pp. 265-267, 1910.

3 Lass, W. P., Chrome deposits of Alaska: Min. and Sci. Press, vol. 115, p. 653, Nov. 3, 

1917.

4 Martin, G. C., and others, op. cit., p. 44. 

'Idem, p. 227.
GEOLOGY. 3

material. Both these investigators regard the age of these sedimentary rocks as somewhat doubtful but as probably Paleozoic or 

early Triassic. No attempt was made by the writer of this report 

to investigate their complicated structure, though observations were 

made as opportunity offered. All such observations, some of which 

were made on outcrops presumably not hitherto visited by geologists, 

confirm the conclusions reached by previous observers that they show 

a general northerly to northeasterly strike and a complex structure.

The relation of the dunite to the inclosing metamorphic rocks 

was repeatedly considered during the field examination, but no absolutely conclusive evidence of their relative ages was found. The 

natural assumption that the dunite was intruded as a magma into 

the graywacke series should be accepted without much doubt, but 

alternative possibilities should be kept in mind. For example, solidified dunite may have been thrust upward through overlying beds or 

may have passed to lower geologic horizons, either by its greater 

specific gravity or by the relative elevation of the surrounding rocks 

by orogenic forces to which the dunite was more resistant. A suggestion that the rock masses now in juxtaposition with the dunite 

did not at all places constitute the inclosing walls while the magma 

was crystallizing may be seen in the lack of dikes or apophyses cutting into the adjacent sediments; in the extreme brecciation and 

slickensiding, which show a differential or slipping motion of the 

outer zone of the igneous masses, though their inner parts consist of 

angular joint blocks; and in the very slight indications of contactmetamorphic action, not necessarily more than might result from 

the heat developed by the mechanical crushing. On account of 

their theoretical interest the questions suggested would repay a 

more detailed study than it was possible to give them in connection 

with other field investigations.

Glacial and alluvial phenomena are widely manifested in this 

region. Their relation to the chromite deposits may be seen in both 

the covering of bedrock at some places and its exposure at others, in 

the transportation of dunite or chromite " float," and in some of the 

topographic features which determine or modify problems,of transportation.

The flat, low land near sea level, partly grassed and partly wooded, 

which lies between Claim Point Hill and the mainland of the peninsula, is doubtless composed of gravel, as waves and tidal currents 

have exposed no hard rock. It is probably a remnant of an alluvial 

fan, the outwash from a vanished glacier which occupied the main 

Port Chatham Valley, to the east. This gravel may be said to cover 

the dunite contact, though the contact probably lies below the water 

level.
4 CHBOMITE OF KENAI PENINSULA, ALASKA.

THE BOCKS. 

METAMORPHIC ROCKS.

The metamorphic rocks have been described by Martin, Johnson, 

and Grant.6 They include black slate, chert containing quartz veinlets, graywacke composed of sand or arkose, and graywacke containing lenticular layers of carbonate, with included shale fragments or 

with a decided aspect of " greenstone."

These rocks are in general but slightly altered near the dunite 

certainly much less than lithologically similar rocks at their contacts 

with the diorite near Point Bede and south of the entrance of Koyuktolik Bay.

DUNITE MASSES.

PORT CHATHAM. 

POSITION, SIZE, AND SHAPE.

The Port Chatham dunite mass is so nearly surrounded by water 

that its exact boundaries and dimensions can not be given. (See 

PL III, p. 18.) It doubtless forms Claim Point Hill, as it is exposed 

around the entire base of the hill, either along the shore or in a low 

bluff rising from the grass flats to the northwest. It probably underlies also these grassy flats, a part of which forms the narrow neck 

connecting Claim Point with the mainland of Kenai Peninsula, 

and it is exposed along the base of the mountain on the mainland at 

many points, the most widely separated of which are three-fourths 

of a mile apart. The dunite is not seen along the base of the main 

ridge west of the neck, though the metamorphism of the rock just 

west of the junction of the gravel neck with the mainland may indicate its proximity. The extreme observed distance between actual 

exposures from east to west is almost a mile. From north to south 

the distance is seven-eighths of a mile. The actual dimensions of the 

dunite area are of course greater than this, perhaps nearly as shown 

on the accompanying map (PI. III).

INTRUSIVE RELATIONS,

No decisive evidence that the dunite was intruded into the graywacke series is observable at Port Chatham, but there are some 

indications of such intrusion. At the angle in the shore line on the 

mainland just west of the neck of timbered gravel flat connecting it 

with Claim Point Hill there is an exposure of considerably metamorphosed greenstone like graywacke, containing many silicified 

lenses, several of which show a cross section 3 or 4 feet long and nearly

6 Geology and mineral resources of Kenai Peninsula: U. S. Geol. Survey Bull. 587, 1915.
£D

Lower Jurassic Eocene

INTRUSIVE ROCKS PALEOZOIC (?) TRIASSIC (?) TRIASSIC JURASSIC TERTIARY QUATERNARY
GEOLOGY. 0

1 foot wide. A few specks of what looks like pyrrhotite appear in 

these rocks. A similar lenticular silicification has occurred in the 

slates and cherts near the eastern edge of the dunite also on the 

mainland of the.peninsula. Here many spots of limonite appear in 

the rock, but no fresh sulphide was observed, though it was sought 

at several rusty exposures. The appearance of these minerals may 

very well be considered evidence of contact metamorphism, which is 

often noted as less intense about dunite areas than about more siliceous intrusive rocks.

The brecciated rock at the base of the mainland ridge just at its 

easterly junction with the Claim Point neck contains angular fragments of chert and graywacke together with dunite. It'may be a 

contact breccia formed by the intrusion of the peridotite.

The lower slopes of the mainland ridge are so densely covered with 

grass and trees that the contact phenomena as well as the location of 

the contact are hidden.

DEFORMATION.

The dunite has doubtless been subjected to most of the orographic 

stresses that have folded, faulted, and tilted the adjacent bedded 

rocks, but the effect produced seems to have been somewhat different 

on account of the greater resistance of the igneous rock to flexure. 

As a result it is almost universally jointed and faulted. Unequivocal 

evidence of faulting may be seen in the small offsets in the stringers 

or bands of chromite, which here have high angles of dip. The 

. amount of lateral displacement ranges from a fraction of an inch to 

30 or 40 feet. The vertical differential movement is usually much 

greater than the horizontal. The direction of striae on slickensided 

surfaces at the Reef mine indicates that it was five to ten times as 

much. In fact, Mertie in his unpublished notes described " some 

faults" at this mine as "slightly displacing the ore and others not 

at all," indicating that the fault throw was nearly or quite parallel 

to the intersection of the fault plane with the layer of chromite. 

Faulting is so widespread that the citation of special localities would 

be too onerous for both writer and reader, but the excellent exposure 

at the high sea wall facing the northeast furnishes an unusually 

striking example. Here a 3 or 4 foot zone of chromite stringers is 

broken into four or five blocks, with lateral displacements of 2 to 10 

feet.

Those who attempt underground work on the chromite at Claim 

Point should remember that practically all observed lateral displacements of the ore are toward the right, although the vertical component 

of the movement is relatively downward on the westerly block.

A more profound fault may account for the shattered and highly 

serpentinized zone that extends northwestward from the base of the
6 CHROMITE OF KENAI PENINSULA, ALASKA.

high sea cliff northeast of Claim Point Hill. The angular outline of 

the dunite area at its northeastern extremity is also possibly due to 

faulting.

WEATHERING.

The frequently observed barrenness of soils derived from highly 

magnesian rocks finds only partial exemplification at Claim Point. 

The higher parts of the northerly slopes are somewhat bare of vegetation, but the lower parts carry an abundant and varied flora. On 

the south side trees grow to the summit. This more luxuriant vegetation is very likely due to the glacial deposition of soil-forming 

detritus from other rocks, as the bare dunite seems to develop a plant 

covering very slowly, and glacial till is actually exposed at several 

points where the vegetation has been removed, notably in excavations 

for the tramway on the lower northwest slope and in the well at the 

Reef mine camp. Other weathering phenomena are better exemplified at Red Mountain.

RED MOUNTAIN. 

SHAPE, SIZE, AND POSITION.

The area of dunite on Red Mountain is somewhat elliptical in 

shape (see PI. IV, p. 30), being about 4 miles long from northwest 

to southeast, and 2 miles wide. Its area is approximately 7 square 

miles. The main summit of Red Mountain, which is near its southeast end, forms part of a dunite ridge that is shaped like a somewhat 

distorted horseshoe opening toward the north through the valley 

of Windy River. The boundaries of the igneous mass may be rather 

closely followed with the utmost readiness, uncertainty arising only 

at the outlets of cirques where former glaciers have deposited their 

load of material torn from the highly jointed dunite. . Except by the 

roundabout course of Windy River, the outer slopes of the horseshoe 

ridge are inaccessible from the inner basin at altitudes less than 

2,150 to 2,700 feet. Transportation to tidewater thus becomes a very 

different problem for the different parts of the area, though the 

distance to be traversed may be nearly the same.

INTETJSIVE RELATIONS.

At Red Mountain, as at Port Chatham, only one possible apophysis of peridotite into the adjoining rocks was found, but there is a 

well-developed contact zone, which lies mainly within the igneous 

area. The actual contact shows a jagged surface, as if both rocks 

were solid at the time of their last differential motion. Brecciation 

and slickensiding have thoroughly comminuted the rock. In the 

field some of the hard brown brecciated material seemed to consist 

of crushed carbonate lenses of the graywacke, but laboratory in-
GEOLOGY. 7

vestigation shows that chromite is one of its constituents, so that it 

is probably shattered dunite which has been carbonated. Qualitative 

chemical examination showed that this material is chiefly a carbonate containing much magnesium and iron and some calcium. This 

zone within the contact and adjacent thereto is much more highly 

serpentinized than the interior of the igneous area. The greater 

alteration seems due partly to the fact that it is greatly crushed and 

partly to the fact that the hydrating waters came from the surrounding rocks. A rather high temperature also probably tended to 

produce rapid serpentinization. The change to serpentine if once 

begun would, by the expansion in volume incident to hydration, undoubtedly accentuate the fracturing and slickensiding.

The wall rock into which the igneous mass was intruded has more 

the appearance of having been changed by mechanical action than by 

high temperature, as the°re is much slickensiding but no megascopic 

recrystallization.

The serpentinized contact zone ranges in width from a few hundred feet, its width in most places, to nearly half a mile, a width it 

reaches between the two heads of Fish Creek. It is found around 

the entire circumference of the dunite Where bedrock is exposed, 

though it is much modified in character where pyroxenite instead of 

dunite is the material involved.

The hypothesis is suggested that explosive forces shattered this 

outer zone, probably before the interior was solidified, and that 

serpentinization and regional pressure, owing to its weakened condition, completed the crushing process and possibly caused differential 

motion on a larger scale. Water from the surrounding sedimentary 

rocks may have aided in the weakening of this zone as well as in its 

hydration.

Q DEFORMATION.

. If the assumption is made that the bands or layers of chromite 

were deposited by gravitation from a molten magma it follows that 

they were originally nearly horizontal except where they may have 

been la id down on a sloping floor. Their present high angles of dip 

may be due either to tilting or folding by regional pressure or to 

magmatic flow. The former explanation appeared at first most probable, and in some places it certainly seems to apply, but the difficulty 

of explaining several successive parallel layers of chromite and 

pyroxenite by gravitative differentiation is so> great that the theory of 

flowage has been generally accepted. Hence the widely prevalent 

steep clips of the chromite bands are not treated as indicating deformation of the dunite, even though they are looked upon as denoting a deformation of the settling layers of chromite by movements 

of the dunite magma.
8 CHROMITE OF KENAI PENINSULA, ALASKA.

Rock pressure is most commonly indicated by joints and step 

faults. Jointing is a striking feature in the region, especially about 

the central amphitheater. The joint surfaces in this region strike 

northwestward and dip 30°-40° NE., and at many places along the 

small streams a single such plane surface is laid bare for 1,000 

square feet or more. The jointing will affect actual mining operations in several ways: it will aid greatly in the removal of rock, it 

will decrease the security of mine roofs where the joints are abundant, and it will permit the circulation of water to an extent which 

can be determined only by experience.

Faulting can be detected with certainty only where the bands 

of chromite have been displaced little enough to render obvious their 

original continuity. In small stringers four or five step faults will 

produce a total displacement of only a foot or less, but in stringers 

2 to 6 feet thick a series of such steps may h&ve throws ranging from 

2 to 20 feet.

Examples of this sort of faulting are best exposed in the cliffs 

that form the outer walls of the dunite ridges. One such cliff stands 

at an altitude of 2,600 to 2,800 feet on the southeast declivity of the 

ridge running northeastward from Eed Mountain, about a quarter of 

a mile from the dunite boundary. Here a 3-foot band of chromite 

shows an offset of about 20 feet just at the top of the talus slope, 

and four more bands that have an offset of equal or less amount are 

visible in a distance of 200 to 300 feet along the inaccessible wall 

above. Similar examples of faulting occur at an altitude of 2,400 

feet on the spur extending southeastward from the high peak on 

the ridge running west-northwest from Eed Mountain, at the same 

altitude on the southwestern side of the pyramidal peak between 

the two low passes to the Seldovia River drainage, and at an altitude, 

of about 2,000 feet at the southerly head of Fish Cre^k. The same 

phenomenon is shown at the Star No. 4, Horseshoe, and Juneau No. 

1 claims. In fact, this condition is so general wherever exposures 

are good that most of the abrupt ends of the chromite deposits are 

believed to be due to faults, even where the continuation of the 

" vein " can not be found or at least can not be positively identified.

Faults of greater magnitude are probably few, as the heavy bands of 

pyroxenite can be traced for long distances without perceptible dislocation. One major fault is thought to cut off a small northern 

segment of the dunite just south of the Juneau No. 4 claim, because 

the dip of the chromite bands here and farther northwest to the 

summit of the ridge is nearly vertical, and their strike is practically 

east and west, whereas the main part of the dunite area to the south 

shows very consistent north-northwest strikes and in most places 

dips of less than 50°. The alternative possibility may be mentioned
GEOLOGY. 9

that the part next to the contact is a portion of an early extrusion 

frozen to the rock wall and not moved by the subsequent outflow, 

which determined the attitude of the chromite and pyroxenite bands 

in the interior basin.

A°niore extended study of this fault or contact surface might lead 

to a satisfactory explanation of the abrupt change in position of 

the ore stringers Avhich is so evident on the two sides of it.

In the main area the fault planes coincide with the most pronounced joint planes in position, striking north-northwest and dipping east at low angles.

This widespread faulting will obviously cause some inconvenience 

in the work of following the bands of chromite beneath the surface.

WEATHERING.

The rusty terra-cotta color that gave the name to Red Mountain, 

or Iron Mountain, as it is still sometim.es called in locating mining 

claims, is due to surface weathering of the dunite. This outer oxidized layer in few places exceeds an eighth of an inch in thickness, 

but it is found nearly everywhere on the mountain, and as the summit is higher than that of most of the surrounding mountains and 

as vegetation is almost wholly absent it is conspicuous at great distances. The converse conclusion that rusty rock is an indication of 

dunite was found, as might be expected, to be entirely misleading, 

because many pyritized masses weather to a color that is indistinguishable from that of the olivine rock.

Rock disintegration is much more advanced in the contact zone 

than in the interior of the dunite area or in the surrounding rocks, 

so that wherever the contact crosses a ridge a saddle is formed. The 

only notable exception to this rule among seven such localities is on 

the ridge between the two heads of Fish Creek, where the saddle and 

the accompanying crushed and slickensided serpentinous rock are 

fully 2,000 feet inside the contact line. The cause of this exception 

was not worked out satisfactorily but is believed to be the presence 

of pyroxenic rock on the ridge, perhaps combined with an overthrust or an originally flat-lying contact. The pyroxenic phase of 

the igneous mass is clearly less readily hydrated than the dunite, 

and its product seems often to be chlorite rather than serpentine, 

which suggests questions as to the amount of alumina in the 

pyroxenite.

Disintegration by frost and glacial action has' been much facilitated by the numerous systems of joints. In the main inner cirque, 

at an altitude of about 2,500 feet, blocks as long as 30 feet have been 

piled in promiscuous heaps. Where the glacial valley heads cross the 

dunite boundary there are usually terminal moraines of igneous 

blocks that quite3 obscure the contact.
10 CHROMITE OF KENAI PENINSULA, ALASKA.

PETROGRAPHY. 

ROCK TYPES.

A study of thin sections shows that the rock masses which inclose 

the chromite are of three general lithologic varieties dunite, pyroxenite, and serpentine. Intermediate forms are found and are especially abundant between dunite and serpentine, but the typical forms 

can be readily recognized even in the field. No exhaustive study 

has yet been made of these rocks, but a few of their features that aredue to the geologic processes which have affected the region may 

be noted.

DUNITE.

Dunite is by far the most abundant type of the igneous mass. it. 

ranges from very light gray or light rusty yellow through gray or 

green to dark gray or dark olive-green. All the varieties present a 

very uniform, smooth limonite-stained surface where they have been 

exposed to the weather. Much of the dunite, especially the darker 

rock, is traversed by a network of fine dark lines, which intersect at 

all angles or more rarely lie parallel. Under the microscope the 

massive light-colored varieties are seen to be composed mostly of 

granular olivine through which a small amount of chromite is disseminated. One specimen, No. 30, which contained the smallest 

amount of chromite observed, has a specific gravity of 3.277. Theshattering of much of the olivine, the " strain shadows " generally 

seen under crossed nicols, and the elongated shape of the larger un~ 

crushed remnants, some of which are ten times as long as they are 

wide, indicate the stresses to which these rocks have been subjected.. 

The olive-green varieties that constitute most of the mass appear toowe their color to partial serpentinization, in some specimens very 

slight and in others nearly complete. The network of dark, fine 

veins that is almost universally seen in the olive-green dunite and the 

rarer parallel dark films seen in some of the lighter-colored varieties 

furnish evidence of the same shearing strains.

As seen under the microscope these veins appear to be composed of 

serpentine darkened by many small grains of ore, which is probably 

magnetite formed in the process of serpentinization, for the finelypowdered substance of the veins is somewhat attracted by a magnet.. 

The cracks in which this vein material is found were probably formed 

largely by the jar of volcanic explosions, for they have no general 

orientation and were produced before the serpentinization, which 

occurred early in the history of the dunite. The parallel dark films,, 

which are similar in texture and mineral composition to the material 

filling the cracks, are looked upon as very thin layers crushed byregional pressure.
GEOLOGY. 11 

PYROXENITE.

In the field the pyroxenite was provisionally identified as websterite, on account of its microscopic resemblance to that rock as found 

at Hebbville, Md. It occurs in layers that range in thickness from a 

few inches to about 100 feet, and the larger masses are traceable for 

great distances, one band west of the head of Windy River being 

approximately a mile long. Three or four such bands are visible at 

each side of the Windy Eiver valley just south of the northern limit 

of the igneous area, where the intercalated dunite is jointed into 

large blocks and the pyroxenite has almost the appearance of a 

heavy-bedded sandstone. The contact of the pyroxenite with the 

dunite is usually rather sharp, but at some places one grades almost 

imperceptibly into the other. The bands of pyroxenite are parallel 

to the stringers of chromite, so that the two probably had a common 

structural origin, but whether they were differentiated by gravitational separation or by magmatic flowage that stretched more equidimensional bodies into layers is not conclusively proved, though the 

latter explanation seems more probable. Typical pyroxenite was not 

observed at Claim Point, but small pyroxenic dikes or veins there 

cut the banded chromite, which may indicate that the pyroxenitic 

magma at Claim Point was much less abundant and perhaps less 

viscous than at Red Mountain. The hypothesis is here suggested that 

at Claim Point the pyroxenite magma may have been developed by 

the resorption of spinel (MgAl2O4 ) from the early formed chromite 

by the hotter (lower) dunite magma in the interstices of the chromite 

settlings. It would be intruded from these interstices rather than 

from a magma basin.

Under the microscope the pyroxenite is seen to consist almost 

wholly of grains of a monoclinic pyroxene 1 to 2 millimeters in diameter. Some of it shows the diallage parting. Yellowish or brownish areas that make up perhaps 3 per cent of the mass are doubtless 

composed of an alteration product from olivine or a rhombic pyroxene. The rounded grains of ore are not translucent but may nevertheless prove on further examination to be chromite. They are not 

so abundant as in the ordinary dunite, and the internal shattering 

is not so marked. It was observed only in the severely crushed outer 

zone.

The specific gravity of the pyroxenite was determined by the Joly 

balance to be 3.31, whereas that of the dunite was slightly below 

3.28. This does not necessarily mean that the magma of the pyroxenite was heavier than that of the dunite. An experimental determination of this point would be instructive.
12 CHROMITE OF KENAI PENINSULA, ALASKA.

SERPENTINE.

Though the change of dunite to serpentine seems in its early stages 

to have imparted to the rock a greenish tinge, the distinctive color 

of the rock in which the alteration to serpentine is complete is a dull 

waxy-lustered chocolate-brown. Less commonly it is almost black. 

In some specimens from Claim Point and Bed Mountain the microscope reveals no cores of olivine. These specimens show clearly and 

strikingly the netted structure that is characteristic of serpentine derived from olivine. The dark-gray and black serpentines seem, paradoxically, to owe their color to the fact that the iron in the original 

olivine of the rocks from which they were derived was all separated 

from the olivine as magnetite or possibly as magnoferrite in the process of alteration, so that no iron appears in the serpentines.

The change of dunite to serpentine appears to have taken place 

long ago. No indications of it appear along the more recent joint 

planes, or along the less recent fault planes, many of which have 

been recemented by hornblendic or feldspathic vein material. The 

most convincing evidence of the early origin of the serpentine is seen 

in an angular lens-shaped black mass measuring about 1 foot by 3 

feet, which was found inclosed in the light-colored massive unaltered 

dunite at the water's edge just southeast of the Reef mine camp at 

Claim Point. This mass was at first thought to be a fragment of 

black slate, for it breaks up readily along lustrous black surfaces, 

but it proved to be a partly serpentinized dunite having a specific 

gravity of 3.13. The bright surfaces are due to slippage along cracks 

filled with serpentine and magnetite. Its occurrence seems to show 

conclusively that serpentinization antedated its inclusion in the 

dunite, as the dunite is neither cracked nor hydrated. It may be a 

part of the first solidification of the dunite, which was afterward 

shattered by explosions or pulsations and serpentinized along the 

resulting cracks by steam and then swept from its original location 

by movements of the magma.

The whole contact zone at Eed Mountain may be a part of this 

early consolidation. The light-green alteration product that is abundant at the periphery of this area is believed to be chlorite derived 

from the pyroxenitic facies. This opinion as to the parent rock of 

the chlorite is based on the common occurrence in the chloritic material of fragments of pyroxenite which have smooth, slickensided 

surfaces and which are thoroughly crushed in the interior. If this 

opinion is correct the pyroxenite is aluminous, and interesting questions therefore arise as to its genetic relations to the nonaluminous 

dunite.
CHROMITE OF KENAI PENINSULA, ALASKA. 13

ORE DEPOSITS.

.THE ORE BODIES.

The outstanding peculiarity of the chromite bodies of Kenai 

Peninsula is their continuity for considerable distances in bands or 

layers, for such bodies elsewhere are generally scattered and "pockety." This continuity in the layers is not so pronounced at Port 

Chatham as in the Red Mountain region, though even here it is unusually well developed. Two typical deposits may be cited in order 

to give definiteness to this statement. A deposit at the Reef mine, 

Claim Point, is about 135 feet long. At its east end this deposit is 

about 3 feet thick; a section near the middle measured 47 feet 5 

inches, and another section farther west measured 23 feet 2 inches. 

The thickness near the middle is thought to be approximately doubled 

by faulting. All these measurements include more or less rocky 

material, which occurs in parallel banding with the chromite.

The longest ore body observed in the Red Mountain district is on 

the Star Chrome No. 4 claim. It extends for a distance of more than 

600 feet as a deposit ranging in width from 6 to 11 feet, and it continues northward for at least 500 feet farther in the form of separate stringers, some of which are as much as 1 foot wide. Smaller 

stringers are numerous at many places where there is no workable 

ore. Some that were noted are a quarter of an inch thick and 2 feet 

long; others are 2 inches thick and 8 or 10 feet long. All show the 

same general layer-like shape.

THE ORE.

The chrome ores of the Port Chatham and Red Mountain districts 

vary greatly in appearance. Two pronounced types are chosen for 

description (see PL II), though intermediate forms are quite as 

abundant as these. One is/the granular black massive rock, with 

lustrous surfaces where freshly broken, becoming dull brown through 

attrition of the fragments. The other is the banded variety, in 

which light and dark layers that lie parallel or nearly parallel present a striking contrast in color. The layers in the banded ore range 

in thickness from less than a twentieth of an inch to several inches, 

though on closer inspection the wider bands usually appear to show 

subsidiary banding with more indistinct boundaries between the 

light and the dark parts. The dark constituent is chromite; the 

lighter part is usually olivine. which doubtless contains a very small 

percentage of iron; or, much more rarely, it is a light-green monoclinic pyroxene, which may prove on further study to be chromiferous and may be similar in origin to the pyroxenite bands in the 

dunite.

10627 22 2
14 CHROMITE OF KENAI PENINSULA, ALASKA.

The banded type in many places passes into the massive type 

through gradual increase in the quantity of chromite in the gray 

bands or through segregation of the two constituents, until the dark 

bands become massive chromite and the lighter material merges 

into the wall rock or forms a horse in the ore body. The lighter 

bands grade into normal dunite through decrease in chromite. The 

distinction between ore and rock is therefore not sharp, the banded 

ore running out, both along the strike of the bands and transverse to 

it, into dunite containing a few stringers of chromite. In the banded 

ores the chromite is at many places of sharp octahedral shape. In 

the massive ores well-formed crystals were not observed, possibly 

because internal motion of the mass or the same jarring forces that 

shattered the dunite may have rubbed away the sharp edges.

Certain mottled ores, seen only in small, loose pieces, appear to be 

banded ores in which the bands of olivine were very thin and have 

been stretched by pressure normal to their flat surfaces into a series of 

separate flakes.

A less lustrous and more porous-looking ore, which was observed 

only in detached blocks near the saddle between the heads of Fish 

Creek, is regarded as of the massive type, perhaps dull and brownish 

because it is more finely powdered than the ordinary bright varieties.

Another variant of the massive ore is a chromite breccia that is 

found in several deposits, which are probably of no considerable 

economic value, at places across the bay north of Claim Point Hill. 

This breccia is composed of angular or subangular fragments, apparently cemented, in part at least, by the silicate magma, and it 

seems to be another result of the forces that have so extensively shattered the outer zone of the dunite.

MINERALOGY.

Most of the chrome ores of Kenai Peninsula are very simple in 

mineral composition. They are mixtures of chromite and olivine in 

varying proportions. Possibly some of the peripheral masses may 

contain serpentine or other products of weathering instead of olivine, 

but no special effort was made to determine this point, especially as 

no large ore bodies in the outer zone are well exposed. The pyroxenic 

dikes in the Claim Point ore are small, but their green color suggests 

that they contain chromium. The purplish-pink chrome chlorites 

were observed at several .places, and a similarly colored harder mineral, which has not been studied, looks like a chrome chloritoid. Thin 

emerald-green films are not rare on the slickensided surfaces of the 

crushed chromite. They may be uvarovite or fuchsite. Finally, a 

peculiar hornblende, which occurs either with recrystallized chromite
17. S. GEOLOGICAL SURVEY BULLETIN 742 PLATE II

A. BANDED CHROMITE ORE FROM KENAI PENINSULA.

B. MOTTLED CHROMITE ORE FROM KENAI PENINSULA.
ORE DEPOSITS. 15

or in bands that at a distance resemble in appearance and in position 

bands of chromite, may possibly be chromiferous.

It may be worth while to note both the practical and the theoretical 

desirability of making a more thorough study of the chemical nature 

and relations of the two principal minerals, chromite and olivine. 

Except the mineral chromitite,7 which needs further investigation, 

the black isometric substance from which the largest percentage of 

chromic oxide (Cr2 03 ) can be obtained has been generally known as 

chromite, and its composition has been represented by a chemical 

formula or formulas of the type of spineK(MgAl2 04 ). It is customary to define chromite " theoretically " as FeCr2O4 , with the explanatory statement that the iron is replaced to a greater or less extent by 

magnesium, and the chromium by an equivalent amount of aluminum 

or ferric oxide. This is a perfectly satisfactory treatment for the systematic mineralogist, who can add magnochromite (MgCr2 O.v ) to his 

list and cover the complete known range of composition of chromite. 

If the constituent molecule FeCr2 04 usually occurred in practical 

purity or were usually predominent in the chrome ores there might 

be no serious objection to the present usage, but in the extensive unpublished list of analyses of chromite compiled by Miss E. F. Bliss 

(Mrs. Adolph Knopf) and kindly submitted to the writer for examination, as well as in the published lists of Wadsworth,8 Cirkel,0 

Clarke,10 and others, only one analysis, and that a very old and doubtful one, showed as much as 61 per cent of chromic oxide (Cr2O3 ), 

Avhereas chromite (FeCr2 04 ) should contain 68 per cent of chromic 

oxide (Cr2 03 ) and magnochromite (MgCr2 04 ) should contain 79 per 

cent.

Moreover, most of the analyses made show a higher percentage of 

MgO than of FeO, especially those of Turkish and Canadian ores. 

To what extent this higher content of magnesia may be due to the 

presence of olivine or serpentine can not be decided from the analyses 

and the facts at hand, especially from analyses containing no determination of silica.

The high content of magnesia renders intelligible the association 

of chromite with olivine and serpentine. If the term chromite may 

be used as a group name like olivine and chlorite, the term ferrochromite may be used for those rare combinations in which the 

molecule FeCr2O4 shoAvs overwhelming predominance over its isomorphous associates.

7 Yovitchitcb, Z., Soc. frang. mineralogie Bull., vol. 35, pp. 511-516, 1912.

8 AVadswortli, M. E., Lithological studies, a description and classification of the rocks of 

the Cordilleras : Harvard Coll. Mus. Comp. Zoology Bull., vol. 11, pt. 1, 1884.

' Cirkel, Fritz, Report on the chrome iron-ore deposits in the eastern townships, Province of Quebec, Canada Dept. Mines, Mines Branch, Ottawa, 1909.

10 Clarke, F. W., The data of geochemistry, 4th ed. : U. S. Geol. Survey Bull,. 695, p. 703. 

1920.
16 CHEOMITE OF KENAI PENINSULA, ALASKA.

The practical value of gaining a more thorough knowledge of the 

minerals of the chromite group may be seen in the varying percentage of chromic oxide in these minerals, in the great significance of 

the associated constituents in deciding the uses to which the material 

may be put, and in the limitations imposed upon processes of concentration either by the chemical nature of the chromite in a particular locality or possibly by its specific gravity.

The answers found to theoretical questions as to the sort of magma 

from which the different varieties of chromite have separated out. 

the ratio of magnesium to^iron in the chromite as compared with or 

affected by the ratio between these components in the accompanying 

olivine, the change in composition of chromite as crystallization progresses, and the part played by silica in the constitution of the mineral as suggested by the substitution of MgSi for A12 in the serpentine-chlorite and other groups may find practical application in 

the exploitation of chrome ores.

ORIGIN OF THE ORE.

The chromite ores of Kenai Peninsula, like those of many other 

localities, seem to have been almost wholly formed by early crystallization from a highly magnesian magma. Gravitational differentiation may have been more complete because of a considerable range 

of temperature and consequently a long time between the beginning 

of the solidification of the chromite and the beginning of the crystallization of the olivine. The massive ores are regarded as grains of 

chromite collected into more solid masses by settling, whereas the 

banded ores were similar granular masses, or at least masses of 

dunite enriched by chromite, which have been swept along by the 

currents of the possibly viscous magma. The sharp contacts between 

ore and rock are thought to be due to rapid flow of very liquid 

magma; the banded ores and contacts are accounted for by the 

interkneading of chromite in viscous dunite. By this interpretation the variable dip and strike of the bands of ore at the Eeef mine, 

as well as at the large deposit on the northwest slope of Claim Point 

Hill, would indicate that the magmatic flow was disturbed by the 

heavy masses of chromite in its course. The fact that many bodies 

of chromite ore are "pockety" may be due to the breaking up of 

such continuous masses. .

Though most of the chromite of Kenai Peninsula appears to be of 

magmatic origin the lustrous massive ore at the Babcock & Martin 

prospect, at the bluff end of Red Mountain ridge, seems to be an 

exception to the rule. The structural and mineralogic relations of 

this ore indicate that it was recrystallized. According to a determination of Chase Palmer in the chemical laboratory of the United 

States Geological Survey, it contains only 32.1 per cent of chromic
POBT CHATHAM. 17

oxide, although its specific gravity is 4.46. This recrystallized ore is 

very slightly magnetic. It would seem that recrystallization greatly 

modified the composition of the chromite and that complete chemical 

analyses might help to determine the typical composition of recrystallized chromite in general. This recrystallized material may, of 

course, have been derived from a part of the chromite deposit that 

originally had a composition different from that of the ordinary run 

of the exposed parts.

More detailed field and laboratory investigation would be required 

to clear up these uncertainties.

QBE BODIES AT PORT CHATHAM.

NUMBER.

What appear to be fourteen separate deposits that under normal 

conditions of the market might profitably yield more or less chromite 

were observed (see PL III), but this number may not represent 

that many distinct deposits. In the high sea wall at the head of 

the cove near the northwest end of Claim Point Hill no less than 

eight separate patches of banded ore Were seen. Three of these show 

plainly that they are faulted parts of what was originally a continuous set of stringers, so that the eight or more separate masses may 

be dislocated parts of two stringer systems. These systems are about 

30 feet apart and are in parallel position, and hence in enumerating 

the fourteen deposits these were counted as two. The deposits on the 

hill to the west are believed to be continuations of the same two 

bands, yet they are counted as three more because there is no definite 

evidence of their continuity, and in any event the connecting parts 

are probably not of workable quality.

A statement of the number of ore bodies is also made difficult by 

the lack of a definite limit showing the quality of the ore. The 

distinction between ore and chromiferous dunite must clearly be 

determined by wages, by methods of mining and concentrating, by 

conditions of transportation, and by the price of chromite. For present purposes it has been assumed that a content of 10 per cent of 

chromic oxide is sufficient to render concentration feasible under ordinary wages and prices. Estimates of quality were made in the field 

to be checked later by analyses and determinations of specific gravity 

in the laboratory. An example of the accuracy of this method 

may be cited. Specimen 26 from Claim Point was estimated to 

contain 15 per cent of chromic oxide on the assumption that onefourth of its volume consisted of chromite. Its specific gravity, 

which was found to be 3.58, appeared to confirm the field estimate, 

for calculation from what seemed to be the most probable indications of value that is, 4.4 as the specific gravity of the chromite,
18 CHROMITE OF KENAI PENINSULA, ALASKA.

55 per cent as its content of chromic oxide, and 3.28 as the specific 

gravity of the olivine (determined on the purest of the neighboring 

olivine rock) would give 17 per cent of chromic oxide. In the 

chemical laboratory of the United States Geological Survey Chase 

Palmer found 28.62 per cent of chromic oxide in a sample taken 

from this specimen. This discrepancy may indicate to a certain extent imperfect sampling of the specimen, but it is more probably due 

to a lower specific gravity and higher content of chromic oxide in 

the chromite than had been assumed. If these were placed at 4.1 

and 65 per cent, respectively, the calculation from a specific gravity 

of 3.58 would give 27.3 per cent of chromic oxide.

This explanation has been introduced here in order to make plain 

the uncertainty as to the exact number of ore bodies visited. Lowgrade stringers that were not regarded as workable may be the 

" tailing out" of richer deposits, or they may be more chromiferous 

than the estimates made would indicate. It is believed that no bodies have been mentioned which contain less than 10 per cent of 

chromic oxide in the ore exposed.

Details as to the number of mining claims located in the Port 

Chatham area were not obtained. It is reported, however, that 

Whitney & Lass, who now control the properties originally staked 

by Philip (" Scotty ") McCray, have filed new claims covering the 

remainder of the chromite at Claim Point.

POSITION.

All the known workable ore bodies at Port Chatham except one 

were either laid bare by wave action at the shore line or were exposed in the naked rock on the upper north slope of Claim Point Hill. 

The exceptional one is the very large mass on the northwest hillside 

to which the tramway leads. This occurs in a wooded region, and 

its magnitude was shown only by partial stripping. There is no 

reason to suppose that the parts of the dunite area covered by forest 

and other vegetation or the parts under water are devoid of chromite, but exploration has thus far uncovered only this one mass in 

the forested area.

DIMENSIONS AND CHARACTER OF THE INDIVIDUAL ORE BODIES.

The masses of chromite occur chiefly in bands or layers or composite series of layers ranging from a fraction of an inch to 40 

feet or more in thickness and from 3 or 4 inches to more than 200 

feet in length. These chromiferous bands are in some places composed of massive granular chromite, in others of more or less disseminated grains and octahedral crystals distributed in maximum 

abundance along parallel roughly plane surfaces. The characteris-
U. S. GEOLOGICAL SURVEY BULLETIN 742 PLATE III

Chromite 

(observed cuicryps, numbered as in text)

500 1000_____|500 FEET

Contour interval 100 feet T C

MAP SHOWING CHROMITE DEPOSITS AT CLAIM POINT, PORT CHATHAM.
POET CHATHAM. 19

tics of these ore bodies may perhaps best be shown by describing 

in some detail each body that seems capable of furnishing marketable ore, even though the quantity may not be large. The numbers 

assigned to the deposits correspond to those used on the map (PL 

III) to indicate their location.

Deposit No. ,1. On a small island that lies southeast of Claim 

Point Hill and at low water is connected with the mainland by a 

narrow rocky neck is the Reef mine, operating on the ore body 

from which most of the chromite thus far shipped from Alaska 

has been taken. The strike of this ore mass is S. 76° W., and. its 

dip is nearly vertical, though the component ore bands show much 

local variation in dip and strike. Its length is about 135 feet, and 

its width ranges from 3 to perhaps 35 feet. A section across the 

main heading at high-tide level was measured on July 9, 1918, as 

follows:

Section at main heading, Reef mine. *

Ft. in.

Dark ore, 40 per cent______________________ 6 

Rock___________ _________________ 1 2 

Mostly black with 5 or 6 inches half silicate________ 2 3 

Mostly waste, containing some chromiferous bands____ 1 7 

Black ore, with 2-inch diagonal " dike "__________ 2 

Massive black ore____ __________________ 2 2

Waste_______________________________ 2 6 

Half and half_________________________ 1 

Waste______________________________ 1 1 

Half chromite in wedge-shaped bands___________ 5 5 

Massive ore, good to medium quality____________ 11 1 

Mostly waste__________________ _______ 6 3 

Shipping ore______- ___ _ _ - _ 1

Waste_______________________________ 2 6 

Good ore, 40 per cent______________________ 1 5 

Scattered stringers, no sharply defined

47 5

Faulting has doubtless increased the apparent thickness along this 

line probably 10 feet or more.

Section 50 feet southwest of main heading, Reef mine.

Ft. in.. 

Ore, 35 per cent____________________ ___ 2 9

Waste_______________________________ 6 6 

Shipping ore, 40 per cent or better_______ ______ 7 11 

Disseminated ore, 15 to 20 per cent_____ _______ 6

23 2

The highest point on the good ore between these two measured 

sections is about 18 feet above mean low tide. Some poor ore southeast of the main lode lies 5 to 10 feet higher. The depth below 

water level, on the assumption that it is half the horizontal length,
20 CHROMITE OF KENAI PENINSULA, ALASKA.

would be 65 to 70 feet. The impression of the mine operators that 

this mass of ore becomes larger at greater depths seems to be corroborated by Mertie's measurement of 20 feet for the maximum 

thickness in 1917 as compared with 23 to 34 feet in 1918, and by a 

divergence of perhaps 5° or 10° in the walls. It was hoped to shov/ 

this divergence in a photograph, but all the photographs taken 

failed to show a contrast of color between the black chromite and 

the associated silicate rock, perhaps, as is suggested by Prof. O. D. 

von Engeln, of Cornell University, because of the relatively strong 

reflection of the blue or even ultra-violet "actinic" light by the 

chromite. It is estimated that the part of the ore below tide at 

the Eeef mine is greater than that above, even without assuming 

that the ore body increases in thickness at the lower levels, as the 

height above the water line is so small a fraction of its length.

The content of chromic oxide in this ore in the output of 1917 

reacheddt6 to 49 per cent. In the season of 1918 the operators found 

it advantageous to ship ore that contained approximately 40 per cent 

of chromic oxide, on account of market conditions, their contracts not 

providing for a higher unit value for richer ores. It is thus no indication of a deterioration in the quality of the ore that the later shipments did not maintain the percentage of chromic oxide reached in 

1917. During both years a certain amount of low-grade ore was 

broken and not used, which will be available for concentration when 

the mill is in operation.

Deposit No. 2. In the low sea wall just east of the miners* 

quarters, which are near the shore about north of the Eeef mine, is 

a small exposure of chromite, 15 to 20 inches thick and about 20 feet 

long. The ore is in part of shipping grade and has been worked to 

a slight extent, chiefly for exploration. The strike is N. 70° E., and 

the dip is nearly vertical. A smaller mass to the east may well be, 

as Mertie has suggested, a faulted part of the same deposit, but it 

seems not to be of workable size.

Deposits Nos. 3 and 4- In the high sea cliff at the head of the 

bight northeast of Claim Point Hill is an inaccessible exposure of 

what seem to be two much disrupted stringer systems of banded 

chromite that were probably originally parallel and about 30 feet 

apart. Their thickness is estimated at 3 or 4 feet, and their vertical 

extent at 50 or 60 feet. The ore appears to be mostly of low grade, 

though some of the fallen fragments appear to contain at least 30 

per cent of chromic oxide. At the base of the cliffs at a distance of 

less than 50 yards in both directions from the main exposure there 

are many stringers of chromite of very low grade. Their original 

continuity with the higher masses is extremely hypothetical, yet as 

the shattered country rock suggests faulting, and as the vertical component of the throw here, as at the Eeef mine, is probably much
PORT CHATHAM. 21

greater than the horizontal component, the change in the character 

of the deposit is not greater than might be expected.

Deposit No. 5. About 75 yards northeast of the high wall just 

mentioned a set of very irregular lenses and stringers of chromite is 

exposed for a height of 25 feet just above the beach. At the bottom 

there are small stringers, but in the middle there is some shipping 

ore, though even in this part of the deposit concentrating ore is much 

more abundant. The maximum thickness is nearly 20 feet, perhaps 

through repetition of a smaller body by slipping and faulting. A 

little of this ore has been shipped.

The associated rock is a brownish serpentine, which appears to be 

thoroughly weathered, on account of its proximity to the fault zone 

to which water had free access.

Deposit No. 6. Fifty yards east of deposit No. 5, below high-tide 

level, a sharply bounded lens of massive chromite is exposed at low 

tide for a length of about 60 feet and a maximum width of 26 inches. 

For only 24 feet, however, is its width above 7 inches. Its strike is N. 

86° W., which would carry it very near to the deposit last mentioned. 

Under the action of wave-driven pebbles and boulders it has proved 

less resistant than the dunite walls, so that it is exposed in the bottom 

of a small gully. This gully continues for some distance under 

water, indicating a greater extent for the deposit than that actually 

exposed. Shifting sand and gravel fill this eroded notch, at times 

completely covering the ore, as was observed on a second visit to the 

locality. This chromite has a specific gravity of 4.37 to 4.44, and 

a sample analyzed by Chase Palmer in the chemical laboratory of 

the United States Geological Survey gave 46.84 per cent of chromic 

oxide. A white mineral in the cracks of this ore appears to be 

aragonite.

Deposit No. 7. On the upper slope of the hill about 150 yards N. 

76° W. from deposits Nos. 3 and 4 is a pit made for the purpose 

of developing one of the banded stringer systems of low-grade 

chromite. This pit, which is about 30 feet long, shoAvs an orebearing width of 118 inches at the east end and 128 inches at the 

west (upper) end. The strike of the bands is N. 69° E., and their dip 

is about 70° SE. The best of this ore for a thickness of 6 feet is 

estimated to carry 25 to 30 per cent of chromic oxide, and the remaining 4 feet or more averages perhaps half as much. The silicate 

constituent is in. part a greenish monoclinic pyroxene, in places 

occurring as dikes, one-third of an inch thick, cutting diagonally 

across the bands of ore, and in part a light-colored olivine that 

weathers rusty yellow.

About 100 feet S. 76° E. from the pit, in a direct line toward 

the exposures in the sea wall, is a natural exposure of many stringers
22 CHROMITE OF KENAI PENINSULA, ALASKA.

of chromite, which may be a continuation of the same deposit, 

faulted and displaced toward the south from the part that is uncovered in the excavation. In order to express the legitimate doubt 

as to the continuity of these exposures, the length of the ore body 

may be reduced one-half, namely, to 65 feet, in estimating its magnitude.

Deposit N-o. 8. In another test pit, 40 feet northwest of deposit 

No. 7, a similar ore body is exposed for a length of 50 feet but is 

less sharply defined in its banding. It maintains the same strike 

and has a dip of about 80° SE. Its cross section shows 80 inches 

of ore, three samples of which had a specific gravity of 3.62 to 

3.7, averaging 3.66. On each side of this ore occurs poorer ore 2 

to 3 feet in thickness. From the specific gravity of this ore, on the 

assumption that 3.3 is the density of the silicate constituent and 4.4 

that of the chromite, somewhat more than 39 per cent of the better 

part of the deposit is chromite carrying approximately 20 per cent 

of chromic oxide. The inferior ore nearer the contacts is judged 

to be about half as rich.

Another development pit about 90 feet to the southwest is believed to be on the same ore body, though slightly offset to the 

right. The strike of the bands is still N. 69° E., and the dip is 

nearly vertical. The exposed cross section measures 25 feet, and 

most of the ore is similar in quality to that just noted, though in 

the southeastern part of the pit the ore bands seem to be more 

sharply segregated from the rock, showing 12 or more bands of 

black, high-grade ore ranging from 1 inch to 2-£ inches in thickness. 

The thicker bands may furnish a small amount of shipping ore. 

The total length of the ore mass is probably much more than that 

indicated by the two excavations that is, 140 feet because a considerable number of rich chromite stringers ranging from half an 

inch to 4 inches in thickness occur nearly on the strike at a distance 

of 125 feet to the northeast. The average width of the ore bands for 

the distance exposed by the two pits may be taken at 18 feet, as it is 

11 feet in one and 25 feet in the other.

Deposit No. 9. On the hillside 60 feet about N. 20° W. from the 

westerly opening on deposit No. 8, is a lens of rich chromite 4 

inches wide and 4 or 5 feet long. It is accompanied by many smaller 

stringers of chromite on both sides. This lens may not be a part of 

a workable deposit, but it is interesting because it is the site of a 

small fault that displaces the ore about 6 inches, indicating the 

presence of fractures in this region. Stringers seem to be scattered 

over, a considerable width here, as a few small ore bands are 

exposed in an opening 60 feet farther down the hillside in a direction N. 20° W. This opening was made with the intention of cross-
PORT CHATHAM. 23

cutting by a tunnel to deposit No. 8. The strike of all these bands 

is about N. 70° E., and the dip is nearly vertical.

Deposit No. JO. What seems to be the largest deposit of chromite 

at Claim Point if, indeed, it is not part of an originally continuous 

mass some 1,200 feet or more long connecting deposits Nos. 3 and 4 

by way of Nos. 7 and 8 with this outcrop is about 500 feet N. 68° W. 

from the west end of deposit No. 8 and a little lower on the hill 

slope. It is thus offset about 250 feet to the right from the line of 

strike of the higher ore. Nothing more definite can now be said 

as to the original continuity of these deposits than that many small 

faults haAre been observed in the region, all with displacement such 

as to indicate continuity if the faults had the proper amount of 

throw, either in small steps or in one or more larger breaks.

This ore body is the central point in the plans for immediate 

future development. The tramway starts from it, and the ore bins, 

mill, and wharf have been placed with reference chiefly to the handling of its output.

The ore body was only very slightly exposed by natural outcrop, 

and even when it was visited to obtain information for this report 

it had not been sufficiently developed to afford a clear idea of its 

size. A partly uncovered cross section at the end of the tramway 

up an irregular slope gave the following figures:

Section at end of tramway on deposit No. 10.

Ft. in.

.15 per cent chromic oxide (?)__ ___________ 5 5 

35 per cent chromic oxide____________________ 4 7 

5 per cent chromic oxide (too rocky to work?)______ 2 2 

35 per cent chromic oxide_____________________ 5 5 

50 per cent chromic oxide_ _ ___ ________ 8 

35 per cent chromic oxide____________________ 10 

Covered by soil and vegetation__.______________ 18 

50 per cent chromic oxide____________________ 1 6

47 9

In this cross section the ore estimated at 35 per cent of chromic 

oxide is by no means homogeneous but is made up of streaks of 

poorer and richer material. Two chips from a specimen collected 

to represent its average quality gave specific gravities of 3.79 and 

4.03, or an average of 3.91. If the specific gravity of the silicate 

constituent is assumed to be 3.28 the specific gravity of the purest 

of the silicate rock, which, however, contained a little chromite 

and if the specific gravity of the chromite is assumed to be 4.4, the 

ore tested would contain 63 per cent of chromite. If the specific 

gravity of either the silicate mineral or the chromite is actually 

lower than has been assumed, the percentage of chromite must be
24 CHROMITE OF KENAI PENINSULA, ALASKA.

greater than the amounts calculated. The specific gravity of either 

may differ from that assumed because, (1) as above noted, the silicate material on which the determination of specific gravity was 

made contained some chromite and the silicate part of the ore appears somewhat dull, as if partly hydrated, and (2) the blackest 

pieces of chromite show a specific gravity of only 4.17, though notmore than 10 per cent of the fragments used appeared to be silicate.

The ore estimated to contain 15 per cent of chromic oxide hasalready been discussed (see pp. 17-18) with referenc'e to the high percentage of chromic oxide shown by analysis, 28.62 per cent.

The bands in this ore body are more irregular in course than those 

in most others. They range in strike from N. 34° E. to N. 59° E.,, 

though most of them strike about N. 54° E. The dip is nearly 

vertical but in some places is northwest.

In order to determine approximately the length of the deposit a 

workman furnished by Whitney & Lass made several small pits along 

a line run southwestward about 100 feet across the ore body. Four 

of these pits reached bedrock, and in all of them ore similar to that 

at the main exposure was found. The extreme width of the ore 

indicated by these pits was about 45 feet, but neither wall was 

uncovered.

Along a line run across the ore body some 75 feet farther southwest he dug two pits, 8 feet apart, to bedrock. Both showed ore that 

appeared to be like specimen 26, the field estimate of which was 15 percent of chromic oxide and the'laboratory determination 28.62 per cent. 

Owing to the soil covering and the irregularity of the bedding it is 

impossible to decide whether this poorer ore indicates a decreasing 

content of chromite along the strike or is simply, as is so frequently 

observed elsewhere, a leaner band interbedded with better ore. Chromite was found 25 feet northeast of the main exposure, though only 

slightly exposed. The total length of the ore body is thus at least 

200 feet, probably more, and the width may be placed tentatively at, 

30 feet.

Deposit No. 11. Along the rocky shore where the low-lying west 

end of Claim Point Hill faces the open ocean there are many stringers 

of chromite in more or less detached exposures for an extreme distance of 500 feet. At the westernmost exposure their strike is S. 86° E.v 

which would carry them, if they continue on this course under the 

covering of vegetation, very near to deposit No. 10, about 1,500 feet 

to the east. Their dip is 60° or 70° S. They are mostly below hightide level. The ore is variable in quality but includes several lenticular bands of high-grade chromite 2 to 6 inches thick and 4 to 8 feet 

long. At three or four points a thickness of 4 feet of fair concentrating ore is reached. The variation in quality along the strike is so>
PORT CHATHAM. 25

0

great that no valuable estimate of the amount of ore rich enough for 

concentration can be made, as the length of the workable parts can 

not be determined. Doubtless considerable ore could be mined above 

low tide, and very likely a larger quantity at greater depth.

Deposit No. 1%. About 600 feet along the shore southeast of the 

east end of the series of deposits last mentioned, there is a set of 

bands of chromite striking N. 52° E. and dipping almost vertically. 

The chromiferous zone appears to be about 30 feet wide, though its 

boundaries are rather indefinite. Single layers of clean chromite 

reach a thickness of about an inch. Some of these layers can be 

traced continuously for 10 to 15 feet. Of this material, 28 inches in 

five or six bands, two of which were about 8 inches thick, was estimated to be half chromite. Perhaps 10 feet or even more might prove 

to be of concentrating grade. Another exposure of similar ore about 

half as wide occurs 50 feet to the east. It is perhaps a part of the 

same bands, offset, as usual, to the right.

Deposit No. 13. On the beach at the base of the cliffs northeast 

of Claim Point Hill there is a considerable amount of chromiferous 

sand, which has been much concentrated by wave action, though it 

still contains a large percentage of what appears to be olivine. 

Whether this material is rich enough for direct shipment or should 

be further concentrated had not been determined at last reports, 

though if a mill were in operation near by its shipment would perhaps be found profitable. The sand has evidently been derived from 

the friable rock by wave action. Its quantity is small compared with 

the deposits that occur in place, yet it and other similar deposits that 

may be found hereafter are worthy of consideration.

Deposit No. H. A deposit of chromite of no considerable economic importance lies in the brecciated zone near the dunite boundary about half a mile north of Claim Point Hill, across the small 

bay from the wharf. It occurs as a chromite breccia in several 

separated masses, the largest about 6 feet in diameter, composed 

chiefly of angular fragments that appear to have been broken from 

larger deposits, perhaps by magmatic pulsation. Some of the interstitial spaces between the brecciated fragments are empty, and 

others are filled with original silicate material or with what looks 

like a talcose alteration product. The open spaces may have been 

caused by removal of the carbonated or otherwise altered silicate 

constituent.

These deposits may indicate that large continuous bodies of 

chromite are not likely to be found in the brecciated outer zone of 

the dunite and that nearly all the originally large bodies have been 

broken into detached masses.
26 CHROMITE OF KENAI PENINSULA, ALASKA.

o

RELATION OF THE ORE BODIES TO THE DTINITE.

The boundaries between ore and country reck are at some places 

sharply defined, as, for example, at deposit No. 6 (p. 21), but far 

more commonly the transition from the larger ore masses to dunite 

is gradual, brought about by the increasing distance between the 

stringers of chromite or by decreasing content of chromite, as in 

the less markedly banded ores. These gradual transitions are extremely variable. At some places 4 or 5 feet of chromiferous rock 

at the contact may be all below workable grade, as at deposit No. 

11, whereas at places in the Reef mine (deposit No. 1) there is a 

gradual transition from very black ore to practically pure olivine 

within 4 inches. The significance of these relations in determining 

possibilities of cobbing and concentration is readily appreciable.

STRUCTURAL RELATIONS.

Some of the structural features o.f the ore bodies are susceptible 

of simple and certain explanation; others present complex problems. 

The bands of ore on opposite sides of many of the smaller faults 

were obviously once continuous, and the fault planes usually show 

slipping. But the larger faults and the phenomena of dip and 

strike are less simple. Practically all strikes are oriented between 

northeast and east, and dips are mostly steep from 70° to 90°. 

Whether the fluctuations are due to curvature of the bands of ore, 

to original discontinuity, or to faulting is all-important in the work 

of following the ore and estimating its quantity. Though the ore 

bodies at some places seem to show curvature, the great abundance 

of small faults and angular jointed blocks with slickensided surfaces suggests that they have been most commonly deformed by a 

series of step faults with displacement to the right. Larger faults 

are indicated by crushed zones. Some of the fissures that cross 

the banded ores are filled with pyroxenic material. These filled 

fissures appear to be dikes rather than veins, but they are nowhere 

abundant enough to modify essentially the character of the ore.

PHYSIOGRAPHIC RELATIONS.

The surface features of the chromite bodies seem to indicate that 

either pure chromite or pure dunite is more resistant to subaerial 

weathering than a mixture of the two, the difference being possibly 

due to difference in coefficient of expansion by heat. One curious 

effect of this difference is to make the lean mixtures of chromite 

and olivine appear to be poorer than they really are, because frost 

and rain have loosened and removed the grains of chromite, leaving 

a surface of almost pure olivine. Several specimens show sharp
POET CHATHAM. 27

triangular depressions where the octahedral crystals of chromite 

have been removed. The high-grade ores, by the same sort of disintegration, seem to lose grains of olivine and appear to be richer 

than they really are. But the abrasive action of ice-moved or waterrolled rock fragments appears to be always greater on the chromite 

than on the country rock. Hence it is well worth while for a 

prospector to investigate elongated depressions such as mark the 

locations of deposits Nos. 6, 7, and 8.

COMPOSITION.

No thorough study has been made of the nature of the chromite' 

constituent of the Port Chatham ores nor of the minerals that form 

their impurities. For the season of 1917 Lass n reports 46 to 49 per 

cent of chromic oxide in the output of the Reef mine. The product 

for 1918 was selected to approximate 40 per cent, as the contract 

conditions made such selection preferable to marketing only the 

richest ore, as had been previously done. The percentage of chromic oxide in the bulk ore has hitherto been the main factor considered in determining quality. For the purpose of checking field 

estimates and of judging the significance of specific gravity in determining the quality of these ores, three determinations were made 

on the Port Chatham material by Chase Palmer in the chemical 

laboratory of the United States Geological Survey, with the following results:

f-.i , Per cent of 

f *' ' "'" chromic oxido.

Deposit No. 6, specific gravity 4.4________________ 46.84

Deposit No. 1 (Reef mine), specific gravity 3.79_______ 34.67

Deposit No. 10, specific gravity 3.58______________ 28.62

The field estimates of these specimens were 50, 35, and 15 per cent 

of chromic oxide, respectively. The discrepancy in the specimen 

from deposit No. 10 has been discussed on pages 17-18.

The need for complete analyses and careful determination of the 

nature of associated minerals will doubtless be more strongly felt 

Avhen concentration is in commercial operation. Enough evidence 

has accumulated to show that olivine and its alteration products are 

by no means the only impurities, although they are the principal 

ones in the banded and lower-grade ores.

The market requirements have not yet placed any limit on the 

quantity of alumina (A12O3 ) that the ore may contain, but the silica 

has been restricted to a maximum of 8 per cent.

As intimated above, the marketing of the concentrates may introduce new methods of determining the value of the ore from its composition, mineral and chemical.

"Lass, W. P., Chrome deposits of Alaska: Min. and Sci. Press, vol. 117, p. 653, 1917.
28 CHROMITE OF KENAI PENINSULA, ALASKA.

QUANTITY OF MINABLE ORE.

The quantity of ore that is minable is computed on the assumptions 

employed by J. B. Mertie, jr., in his preliminary study of the region, 

that extension in depth was originally substantially equal to horizontal length, and that the agencies of erosion which have exposed 

the deposits have, in that process, removed on an average half of each 

ore body. With cumulative evidence that the horizontal extent is 

greater than that shown by the exposures, either on account of faulting or covering by debris, or both, it is difficult to make safe estimates 

as to depth. Assumptions as to continuity have already been discussed. 

(See pp. 20-26.) Deposits that are calculated as containing less 

than 100 tons of ore are not included in the summation, for the probable error in the larger numbers is much greater than this amount. 

An attempt is made to discriminate roughly between shipping ore, 

placed at 40 per cent or more of chromic oxide, and concentrating 

ore, which is arbitrarily defined to include that which runs from 

10 to 40 per cent. Field estimates of quality, in which the judgment 

of those who have worked with these ores was kindly offered and 

freely used, are the basis of calculation. The estimated percentages 

of chromite check reasonably well with determinations ojf specific 

gravity, though it should perhaps be stated that the six chemical 

analyses that were made give an unexpectedly high content in chromic 

oxide for the lean ores and a lower content than was expected for 

the richer specimens. These facts can be explained only by further 

investigation.

In the following table the ore bodies are designated by the numbers 

employed in the detailed descriptions (pp. 19-25):

Estimated quantity of chromite ore at Port Chatham as calculated from the 

observed dimensions, in tons.

No.

1....... ...................................

3,4........................................

5..........................................

7........ ..... . .....................

8..........................................

10.........................................

11.........................................

12.........................................

Shipping ore.

Above 

tide 

level.

. 1, 300

10,000

11, 300

Below 

tide 

level.

10,000

10. 000

Concentrating ore.

Above 

tide 

level.

550 

1,000

300 

2,300

20,000

60,000

84, 150

Below 

tide 

level.

4,800

6.000?

1,000?

11, 800?

Chromite in concentrating ore.

Above 

tide 

level.

300 

350 

100 

750 

6,000 

24,000

31, 500

Below 

tide 

level.

2,500

1,200 

200

3,900

Disregarding the concentrating ore in its crude condition and assuming a recovery of two-thirds in the concentrating process, we find
POET CHATHAM. . 29

that the final estimates of exportable ore would be, above tide level, 

32,300 tons; below tide level, 12,600 tons.

MINING.

At Port Chatham the ore has been mined by open-cut workings, 

chiefly at the Reef mine. A large part of the output has been taken 

from the area that lies between the marks of high and low water, 

and great inconvenience has been experienced from the tides. Any 

considerable additional production from this deposit will necessitate an entire change of method, for a large part of the ore that Jay 

above low water has been removed. It is therefore probable that the 

next deposit to be exploited will be No. 10. (See pp. 23-24.) At this 

deposit relatively light stripping will uncover a large body of ore 

on the hillside in favorable position for removal. A large quantity 

may be mined by open cuts, which may be found practicable to a 

considerable depth, for the width of the deposit is 30 to 50 feet and 

the walls are of solid rock.

The operations on deposits Nos. 2, 5, 7, 8, 9, 10, 13, and 14 have 

been mainly exploratory, though a little ore has been shipped from 

several of them.

SHIPMENT.

The facilities for shipping the ore from Port Chatham were much 

improved during the season of 1918. A new wharf was constructed 

in the bay north of Claim Point Hill, and with the cooperation of 

the United States Coast and Geodetic Survey a wire drag of the 

harbor was carried out.

Notwithstanding these efforts the operators of the chromite mines 

say that they have been unable to get transportation .for their output, so that it was impossible for them to complete the delivery of 

1,000 tons of 40 per cent ore for which they had a contract at $1.50 

a unit. About 200 tons was loaded on a barge July IT and towed 

to Seldovia, where it was left standing at the dock on July 29 by the 

steamer that was expected to take it. Latest advices are to the effect 

that little more than 600 tons was shipped prior to December 31, 

1918, when the contract was canceled. On January 4, 1919, 300 

tons of 42 per cent ore was shipped to Seattle, but the market conditions were such-that it could not be sold at any price. How far 

the uncertainties of Alaskan transportation were a result of war conditions during the season of 1918 and how far they are an'index 

of general shipping conditions in that region the experience of the 

writer does not enable him to judge. It is clear, however, that the 

chromite mines can not be successfully operated unless these matters 

are taken into account. 

10627 22 3
30 CHROMITE OF KENAI PENINSULA, ALASKA.

ORE BODIES AT BED MOUNTAIN. 

NUMBER.

In the Red Mountain area not less than 23 deposits capable of 

furnishing chrome ore under favorable conditions of transportation 

were observed in place. (See PL IV.) In addition to these at least 

10 occurrences of good ore in loose blocks were noted. Some of 

these blocks indicate heavy deposits; others may have been derived 

from bodies too small or too crushed to be workable. Perhaps some 

of the abundant and rich-looking fragments of chromite east of the 

main head of Windy River have been brought by glaciers from the 

great mass to the southeast, on which the Star Chrome No. 4 claim 

is located, but most of them are probably derived from ore bodies 

not seen in place, or, if they were derived from any of those seen, 

they are so located as to indicate an immensely greater extension of 

those bodies than was assumed in the estimates of quantity.

The number of mining claims actually located in this district, as 

nearly as could be ascertained, is 49, of which 14 are held by Whitney 

& Lass, 19 by F. P. Skeen, 10 by Babcock & Martin, 3 by Cramer & 

Martin, and 3 by R. V. Anderson. According to common report, all 

other claims made at earlier dates have been abandoned.

POSITION.

The ore bodies seen in place at Red Mountain occur in the firm 

jointed dunite and not in the crushed and hydrated outer zone. The 

single exception is deposit No. 22, which is in that zone. Most of the 

larger masses of ore seen therefore lie on the inner or outer walls of 

the horseshoe ridge. The fact that they were lound at somewhat 

higher altitudes may be due rather to the concealment of ore by the 

debris that covers the lower slopes than to a less abundant supply 

of chromite in the rocks there. If any part of the area is really 

devoid of workable chromite it would seem to be the southeast slope 

and cliffs of the spur between the drainage basins of Fish Creek and 

the northern fork of Seldovia River.

DIMENSIONS AND CHAEACTER OF THll INDIVIDUAL ORE BODIES.

The ore bodies in the Red Mountain district on the whole seem to 

be longer and thinner than those at Port Chatham and less markedly 

banded but nevertheless strikingly similar in character. The deposits 

will be described in order of location on a line running first around 

the inner basin at the head of Windy River and then around the 

outer slopes of the main ridge. (See PL IV.)

Deposit No. 1.- At the northwest end of the high ridge that divides 

the main amphitheater at the head of Windy River from the valley 

of its small tributary, which runs along the dunite contact parallel
GO

W o

Ifef WO GOGO

o

i so
RED MOUNTAIN. > 31

to this ridge and north of it, there is a chromite deposit on one of 

the Babcock & Martin claims. Its altitude is about 2,300 feet, and 

the descent from it to Windy River, to the northwest, is precipitous. 

This deposit is unique in that it is composed of two parts that appear 

to be of different origin. The larger part is an irregular mass of 

lustrous black chromite with cleavable green hornblende at both 

contacts and at some points in its interior. It has the usual strike 

of the chromite bands of this vicinity about N. 10° W. but its 

dip is at a low angle to the east, instead of about 45° W., which is 

the prevailing dip of the chromite stringers at this locality. A 

sample of the ore has a specific gravity of 4.46 and contains only 

32.10 per cent of chromic oxide. (See p. 42.) This ore was noted 

in the field as probably recrystallized, and its variation in composition from that of the usual type was assumed.

The part of this exposure that conforms to the usual type is more 

uniform in thickness, reaching a maximum of a little more than 2 

feet. It seems to be cut by the recrystallized vein, a part of the outcrop occurring at their intersection. From its bearing on ore genesis 

this deposit would deserve much more careful study. As a source of 

chromite, considering the low tenor of the recrystallized ore, it is 

probably of minor importance, as its thickness decreases to about 1 

foot within 40 or 50 feet.

'Deposit No. 2. The exposure of ore body No. 2 is by far the most 

extensive seen in the district. It is covered mainly by the mining 

claim known as Star Chrome No. 4, located by F. A. Rapp for Whitney & Lass, and is at an altitude of about 2,600 feet on a sort of 

ridge-ribbed plateau in the east angle of the main valley. It strikes 

N. 8° W. and dips 60°-70° W.

A section at the discovery monument was measured as follows:

Section on Star Chrome No. l\ claim at discovery monument.

Ft. in. 

Dark ore, mostly of shipping grade, containing 16 inches of

silicate rock in five bands, the thickest of which is 6 inches. 10 7

Rock ______________ ________________ 1 2

Black ore _____________________________ 4

Rock ______________ ______.-___"____ 5

Ore _________,_______________________ 5

Total thickness (2 feet 11 inches is waste)_____ 12 11

For 500 feet along the strike northward from the discovery monument the ore is in a trench or gully, doubtless excavated by glacial 

action in the less resistant chromite. In spite of the abundant loose 

material, the exposures are numerous enough to leave no doubt of the 

continuity of the ore for the whole distance, probably with only 

gradual variations in cross section. At 500 feet from the monument the section was as follows:
32 CHROMITE OF KENAI PENINSULA, ALASKA.

Section on Star Chrome No. 4 claim north of discovery monument.

' - Ft. in.

20 per cent ore______^_______________ _______ 1 10

Mostly dunite _:_____ __'_________ _________ 10

10 per cent ore______ _ _ 8

40 per cent ore_________________________ 1 5

Rock ________________'._______________ 6

42 per cent ore__ _ _ - ___ 11

Rock ________________________________ 2 2

50 per cent ore_____ __________________________ 1 2

Total thickness (3 feet 6 inches is waste)______ 9 6

For the next 200 feet northward on the ore the stringers get farther 

apart, but one rich band maintains a thickness of 6 to 14 inches for 

a distance of not less than 500 feet.

South of the discovery monument the chromite can be traced 130 

feet, to a point where it is reduced to a thickness of 18 inches of 

good ore. At about 50 feet from the monument an offset of 10 feet 

to the right shows that faulting has occurred in this region.

Estimates of quality are based on the appearance of the ore. They 

seem 'to be corroborated by the specific gravities of 4.16 to 4.25 found 

for the richest specimens. The relative proportion of shipping ore 

here is judged to be unusually high. It may be conservatively placed 

at half the volume of the ore body.

Deposit No. S.-r Ai an altitude-of about 2,950 feet, on the inner wall 

of the main valley, about 200 feet below the summit of the ridge, 

above the upper limit of the talus and nearly south from deposit No. 

2, there are many chromite stringers striking N. 30° W. and dipping 

40° W. Two higher-grade ore bands reach a thickness of 2 feet each. 

The low-grade material is mostly too poor to be considered workable. 

At the top of the ridge the ore was estimated by F. A. Rapp, who 

made the difficult ascent, to have a total thickness of 10 feet, 18 inches 

of which seemed to be of shipping grade and the remainder was' 

rated at 20 per cent of chromic oxide.

Deposit No. 4~ West of north from deposit No. 3, at many points 

on the rough surface of the westward-tilting " plateau," there are 

stringers of both high and low grade chromite, most of which seem 

too small for separate mention, though four lenses south and west 

from deposit No. 1 were noted as of shipping grade, with dimensions 

of 12 to 15 inches in greatest thickness and 10 to 20 feet in length. 

The dip and strike of the ore bodies in this region are in general 

somewhat parallel to the mountain slope, so that in many places a 

1-inch or 2-inch layer of chromite simulates in appearance a heavy 

lens of ore through its exposure as a thin layer on a surface 2 or 3 

by 8 or 10 feet. Of the lower-grade bands observed in this region 

only one seemed of sufficient importance for description. It is ex-'
BED MOUNTAIN. 33

posed at altitudes of about 2,000 to 2,200 feet along the south wall 

of the stream that drains this so-called plateau area. It is probably 

continuous for the whole distance along the wall, though it was actually seen over perhaps only half of the distance on account of the 

roughness of the surface and the necessity of passing close under the 

cliffs along the top of the talus slope, which, of course, obscured the 

view of the ore, if, as is thought probable, it was exposed. This 

layer is somewhat more than a foot thick. It is faulted at several 

places, with displacements of a few inches to 3 feet. The grade of 

this ore is estimated at 15 per cent of chromic oxide.

Deposit No. 5. At an altitude of about 1,700 feet on the rocky spur 

that separates the main stream valley heading against the north 

slope of Red Mountain from the small brook that heads near the 

easterly pass to the Seldovia River drainage basin is a body of 

chromite on which the Horseshoe claim of Whitney & Lass is located. 

It is exposed for about 60 feet with a thickness of 1 foot to 3 feet. 

Fully half of it appears to be of shipping grade. It shows several 

small faults, one with a throw of about 3 feet, and ends so abruptly 

as to suggest faulting as the cause of its termination. To the north, 

diagonally downhill, there are many small chromite stringers in the 

rocky stream beds for a distance of 300 or 400 yards. The largest 

of these, composed of low-grade ore, is about 2 feet thick and is much 

contorted. This deposit, which is at an altitude of about 1,400 feet, 

is accompanied by a crushed zone, so that there is much doubt 

whether it is a faulted continuation of the Horseshoe ore body or not. 

On the whole it seems more probable that this deposit and the many 

intervening layers are in a position underlying the Horseshoe. The 

lower ore bands strike about N. 20° W. and dip 75° SW. Above the 

crushed zone the dips are much flatter, as a rule, though variable.

Deposit No. 6. The rich but small ore lenses that occur near the 

two low divides to the Seldovia River basin lie nearly horizontal. 

The next deposit of sufficient importance to be mentioned is that 

on the Star Chrome No. 2 claim of Whitney & Lass, at an altitude of 

2,300 feet on the northeast slope of the main ridge northwest of the 

western pass toward Seldovia. Good ore is exposed for a distance of 

50 feet with a thickness of 14 to 24 inches. About 200 feet to the 

southeast is a 12-inch exposure of good ore that seems to be connected 

by low-grade stringers with the main mass. The ore here lies nearly 

horizontal.

Deposit No. 7. At an altitude of nearly 2,500 feet on the same 

ridge with deposit No. 6 and in line toward the high dunite point 

on the west ridge is an .exposure of 12 to 15 inches of 40 per cent ore 

with 1 foot of rocky material oh each side of it, which was judged to 

carry only 5 to 10 per cent of chromic oxide. Uphill the width de-
34 CHBOMITE OR KENAI. PENINSULA, ALASKA.

creases to only 6 inches of good ore within a distance of 10 feet. 

If it widens downward under the talus slope at this rate, it may be 

a considerable ore body. The strike is N. 22° W., and the dip about 

45° SW.

Deposit No. 8. On the shelf or narrow plateau, which is seemingly 

a remnant of the old valley floor not removed by the glacier that 

deepened the center, at an altitude of a little more than 2,200 feet, 

about half a mile south of the lowest pass to Fish Creek, is the deposit 

on which the Juneau No. 1 claim is located. Its strike is N. 58° W.r 

and its dip 45° SW. At the southeast end of the natural exposure 

the cross section consists of 18 inches of material that grades regularly from rock to shipping ore, 82 inches of good ore, and 12 inches 

of material that shows gradation back to wall rock. About 100 feet 

southeast of this point a pit dug through 3 feet of surface material 

uncovered 5 feet of banded and disseminated ore, half of which is 

estimated to contain 30 per cent of chromic oxide and the rest to be 

of poorer grade. The covering of the ore contained little or no 

chromite, indicating that it is not a result of weathering in place 

but was brought from less chromiferous localities by glacial action 

or hill creep. About 50 feet northwest of the heavy outcrop mentioned above the ore attains its maximum thickness of 12 feet, and at 

30 feet farther in the same direction it comes to an abrupt end, 

probably at a fault, as there are several small step faults in the 80 

feet of exposure. Until the discovery of deposit No. 2, in July, 

1918, this was considered the best body of chromite in the district.

Deposit No. 9. The series of chromite layers described together 

under No. 9 would probably have been classed as at least three separate deposits, or very likely more than that, if time had been available for carefully working out all details observable in the exposures, 

which appear in the irregular cliffs southeast of deposit No. 8, at 

altitudes of 1,200 to 1,800 feet. None of them showed a thickness of 

more than 3 feet of concentrating ore or 16 inches of high-grade ore 

in a single band. Such bands are locally within a foot or two of each 

other, however, so that if one were worked the other would doubtless 

also be taken.

The highest exposure, at 1,800 feet, consists of two bands, with 

a total thickness of 4 or 5 feet of concentrating ore. They strike 

N. 20°-25° W. and have a westerly dip.

About 150 feet lower on the mountain side is a set of chromite 

stringers in a section of 25 feet, two layers in which attain a thickness of 1 foot each. This series of bands can be traced for a distance 

of at least 250 feet, up to an altitude of 1,900 feet, where they pass 

to inaccessible cliffs in which they can be seen for perhaps 100 yards 

farther. They appear to pass under the Juneau No. 1 lode and are
BED MOUNTAIN. 35

separated from it by a heavy band of pyroxenite, which, like many 

smaller ones observed in this locality, is parallel to the ore. They 

strike N. 6° W. and dip 45° W.

At altitudes of 1,200 to 1,400 feet near the base of the cliffs is a 

series of small bands of high-grade chromite, approximately in parallel position under those just mentioned. The largest of these 

bands maintains a thickness of 8 to 16 inches .for a distance of not 

less than 300 feet. How many of the associated smaller bands would 

pay for working is uncertain, but without question many of them 

would be utilized if the larger mass were mined.

Deposit No. 10. The Juneau No. 4 mining claim of Whitney & 

Lass is at an altitude of 1,600 feet, 100 yards or so southwest of the 

small stream that heads against the Fish Creek basin at the dunite 

contact. The ore body is so near the contact that it is within the 

crushed zone, though not so completely broken up as the silicate 

rock nearer the boundary. Its thickness is somewhat variable, 

mostly 3 to 4| feet, though at one point it pinches down to about 1 

foot. Its length is not less than 250 feet. It ends abruptly at the 

top, doubtless at a fault, with a thickness of 2 feet exposed, and the 

north wall is obscured by debris, so that only this minimum thickness could be determined. At the lower end it passes under talus 

in which there are many fragments of chromite for 100 feet or more. 

These fragments may have fallen from the exposed portion. The 

chromite body strikes N. 82° E. and is practically vertical in dip. 

It seems to be largely of excellent quality, though its crushed condition renders its appearance somewhat abnormal.

Deposit No. 11. A quarter of a mile south of the lowest pass 

between Windy River and Fish Creek a heavy band of chromite 

apparently crosses the main ridge, which is here double for a considerable distance, the two parallel crests being 150 feet apart. At 

the easterly crest excavation by F. A. Rapp in the crumbly chromiferous loose material uncovered the ore at a depth of about 1 foot with 

a cross section, beginning at the north, showing 30 inches nearly 

half of which is chromite, 48 inches consisting mostly of rock, and 

84 inches of good ore, at least two-thirds of which is of shipping 

grade. A hundred feet eastward down the mountain side the ore has 

an easterly strike and nearly vertical southerly dip. Its section at 

this point shows 18 inches of shipping ore and 78 inches estimated 

at half chromite. About 20 feet higher the section revealed 72 inches 

of ore, at least half of it estimated to run 40 per cent or better in 

chromic oxide. This deposit may have been originally a part of 

No. 9, but the intervening area is accessible with difficulty, even 

where it is not covered with talus.
36 CHROMITE OF KENAI PENINSULA, ALASKA.

Toward the west chromiferous float can be traced continuously 

to the top of the west ridge, whence a low-grade band perhaps 3 or 

4 feet thick can be seen in the vertical rock wall with a dip of about 

45° S. . ,

Deposit No. 12. From deposit No. 11 the main dunite ridge runs 

due southwest for 500 or 600 yards to a culminating point that 

appears by aneroid determination to be almost exactly 3,000 feet 

above the sea. About 100 yards northeast of this summit three bands 

of chromite appear, from blocks and fragments not exactly in place, 

to cross the crest of the ridge. They are 50 to Y5 feet apart and 

seem to have a thickness of 2-|, 5, and 2 feet, respectively. The 

largest one is thought to continue along the westerly slope of the 

ridge and to be identical with an ore body located by N. Clarberg 

for Whitney & Lass. He described it as on the back side of this 

mountain, and one of his monuments was seen at an altitude of 

2,700 feet on the spur that runs from this peak and divides the two 

main heads of Fish Creek. The fog was so thick at the time of the 

writer's visit, however, that this identification could not be confirmed. 

The deposit is said to be 3 or 4 feet thick, mostly of rather low grade, 

and to dip south.

Deposit Nos. 13 and 14- Deposits Nos. 13 and 14 are probably 

either parts of the same ore band or different bands in a closely related series. Both nearly follow the 2,000-foot level at the southerly 

head of Fish Creek, strike about N. 20° E., and dip east at a variable 

angle, mostly much less than 45°. No. 13 is north of the main stream 

and can be followed along the mountain side for fully 500 feet. It is 

broken at many points by small faults. Its thickness ranges from 1 

to 2£ feet of fair concentrating ore, with only a little that appears to carry as much as 40 per cent of chromic oxide. Toward the 

north end there are three bands of chromite, each more than a foot 

thick, in a section of 100 feet, and one of them is probably the continuation of this layer, though the continuity is established only by 

the occurrence of chromite of similar rather low grade in the blocks 

fallen from the cliffs. Still farther north, about 500 yards south of 

the 2;100-foot divide between the heads of Fish Creek, a portion of 

one of these ore'bands shows 6 inches of material that is nearly of 

shipping grade underlain by 5 or 6 feet of poor disseminated ore. At 

this point the strike is N. 51° E. and the dip 55° SE. Deposit No. 14 

can be followed for more than 400 feet, from the main stream approximately along the top of the talus slope toward the divide between Fish 

Creek and a branch of Seldovia Kiver. Its' thickness is nowhere less 

tlian 1 foot and in some places reaches 2$ feet. Most of it is only of 

concentrating grade, though in many places there is some high-grade
BED MOUNTAIN. 37

material, which at one point is 1 foot thick. The dip of the ore becomes flatter toward the south.

Deposit No. 15. In the upper cirque at the head of the south branch 

of Fish Creek, at an altitude of about 2,350 feet, southeast of the 

stream, there is a band of chromite from 12 to 24 inches thick, which 

is estimated to carry 35 per cent of chromic oxide. Toward the southwest it is cut off by a fault. About 50 yards distant and 30 feet higher 

than this faulted end there are some low to medium grade stringers 

that are judged to be the continuation of the same ore body. Toward 

the northeast it passes under the talus with a thickness of 2 feet and 

with seemingly increasing magnitude. The main exposure is 50 or 60 

feet in length.

Deposit No. 16. High in the wall of the cirque, about northeast of 

deposit No. 15, occurs a black mass that looks at a distance like very 

rich chromite. This appearance seems to be confirmed by the presence of high-grade float in large blocks at the foot of the inaccessible 

cliffs. The suggestion that this deposit may be a continuation of No. 

15 is supported by the increasing dips of the chromite bands in that 

direction. The presence of a heavy band of pyroxenite below the 

deposit raises the further question whether it may not also be a part 

of the ore stringer on which Juneau No. 1 claim is located (deposit 

No. 8), as that also seems to be underlain by a similar layer of pyroxenite.

Deposit No. 17. In the pyramidal peak between the two low passes 

from the head of Windy River to the Seldovia River drainage basin 

there is at least one body of chromite of considerable size. It is covered by a mining claim of F. P. Skeen. It is not well exposed on the 

north side of the mountain, though its nearly horizontal position and 

the presence of considerable chromite float, part of it very rich in 

appearance, would indicate its probably extension to that slope. On 

the northwest declivity, however, at an altitude of about 2,400 feet, 

just above the talus slope, it shows for a distance of 350 feet. At its 

northern extremity it is cut off by a fault of unknown but probably 

not great magnitude. For 60 feet it maintains an average thickness of 

4 feet, and then it gradually frays out into a series of separate lenses 

to the south. Several small faults, the largest having a displacement 

of about 6 feet, show relative uplift of the southerly block. , The ore contains some high-grade lenses but is chiefly of good concentrating type. Below this ore there is much more chromite in the 

talus blocks down to the 2,000-foot level .than would seem likely to 

have been derived from a single layer of this magnitude, but no other 

was seen in place. . '.

Deposit No. 1$. At an altitude of 2,400 feet, on the southerly spur 

of the high point half a mile west of Red Mountain, is a body of
38 CHROMITE OF KENAI PENINSULA, ALASKA.

chromite ore that strikes N. 24° W. and dips 35° SW. At its upper 

end, Where it shows about 4 feet of fair concentrating ore, it is cut 

off by a fault. Downward, it passes under the talus but reappears 

at a distance of 120 feet with a cross section of 12 inches of rather 

rich concentrating ore, 30 inches of rock, and 20 inches or more (the 

lower wall is not exposed) of rich concentrating ore. Float at lower 

altitudes indicates that the ore body continues down the spur with 

good quality and in considerable size.

Deposit No. 19. On the spur that runs nearly south from the summit of Red Mountain, at an altitude of about 3,000 feet, there is considerable low-grade chromite debris, indicating the locality where a 

very large ore body crosses the spur. The crest of the spur is marked 

by monuments as the dividing line between claims of F. P. Skeen and 

Babcock & Martin, Skeen and Babcock having made the discovery 

in common. The ore was not observed in place, as was expected, on 

account of the lateness of the hour when it was reached, though it 

had previously been seen from a distance near the top of the cliffs 

that constitute the flanks of the spur.

Mr. Skeen stated that it was the largest body of chromite ore he had 

seen at Red Mountain, the next largest being deposit No. 3. (See 

p. 32.)

Deposit No. W. At an altitude of about 2,600 feet on the southeasterly slope of the rugged ridge that runs northeastward from Red 

Mountain, just at the top of the talus and approximately a third of a 

mile from the pass (on the dunite contact) between the upper and 

lower parts of the Windy River valley, lies a body of banded chromite. Its thickness is 3 feet where it passes beneath the talus, and it 

maintains a thickness of approximately 2 feet for 200 feet or more up 

the steep cliffs. It strikes almost exactly north and dips about 70° W. 

Near its lower end is an offset to the right of nearly.20 feet, and in 

the higher portion three or more faults of somewhat less magnitude 

can be seen. The ore was judged in the field to be more than half 

chromite. A sample taken to show its average quality was found to 

have a specific gravity ranging from 3.Y3 to 3.87.

Deposit No. 21. On the ridge that runs S. 16° W. from the pass 

just mentioned, at an altitude of a little more than 2,300 feet, there 

are three small deposits of chromite, covered by a mining claim of 

F. P. Skeen. The largest of these deposits shows a thickness of 2 feet 

of ore that runs about 30 per cent of chromic oxide for a distance of 

8 feet. The smaller deposits, just above this one, are of better grade 

but are only about 1 foot thick. All three are apparently terminated 

by faults.

Deposit No. 2®. In the bed of the small stream that flows near the 

dunite contact 100 yards or so northeast of deposit No. 21, at an 

altitude of about 2,460 feet, is a mass of chromite that lies within the
BED MOUNTAIN. 39

outer crushed zone of the dunite. It is much slickensided and shows 

a thickness of 2 to 4 feet for about 30 feet. The ore is of good quality, 

but it is so much crushed that it can not be profitably compared with 

the ordinary ores. The character and distribution of loose material 

suggest that the ore continues for perhaps 100 feet downstream from 

its lowest outcrop.

Deposit No. 23. At an altitude of 1,100 feet in a shallow gully 

near the smaller (southerly) of two streams that flow northwestward into Windy River through the valley caused by erosion of the 

softer rocks at the dunite contact there are large blocks containing 

at least 7 or 8 tons of excellent chrome ore. In one block the 

cross section showed 16 inches of 40 to 50 per cent ore, 5 inches of 

waste, and 7 inches of ore of the same grade as the thicker layer. 

About 100 feet to the northeast, in the stream bed, there are three 

1-foot stringers of low-grade chromite that strike N. 22° W. and 

dip about 60° SW.. Whether the blocks were derived from the same 

ore body that appears in the outcrop is doubtful, but they are certainly near the same position and indicate either an improvement 

in the quality of the ore along the strike or the presence of a 

second deposit of some value.

DEPOSITS INDICATED BY FLOAT.

Streams, glaciers, ancl frost have moved loose fragments of rock 

so widely that it is doubtful whether an acre of fragmental rock 

in the Red Mountain dunite area could be found that did not bear 

visible stringers of chromite. Yet at many places unusual accumulations leave no doubt that a body of workable chromite ore is near 

at hand. There are also places where fragments of rich ore occur 

in such a manner as to show that the ore extends for a considerable 

distance, though there is no evidence that its thickness is sufficient to 

render it workable. Some of the most promising of these occurrences are described below.

From a point just south of the pass between Windy River and 

Fish Creek down the steep talus slope toward Windy River there 

are numerous flat fragments of chromite, most of them less than 3 

inches long. They extend for at least 200 feet. ,The best of the 

ore is mottled and has the composition shown in analysis No. 

6 (p. 42).

A hundred feet below this pass, on the Fish Creek side, there are 

some scattered blocks and fragments of high-grade, much slickensided chromite in the soft-weathering contact zone. These fragments, the largest about a foot in diameter, continue downward 

for more than 300 yards, in varying abundance.

On the ridge between the two heads of Fish Creek, about 150 

yards west of its lowest point, much brownish porous-looking chro-
40 CHROMITE OF KENAI PENINSULA, ALASKA.

mite (analysis No. 5, p. 42) occurs in blocks up to a foot or more in 

size. The small fragments extend down both slopes of the ridge for 

200 or 300 feet. Their abundance indicates a very large ore body, 

though a little digging in the soft chloritic contact rock failed to 

locate it. On the same ridge, less than 100 yards S. 25° E. from 

the low pass, there are many small fragments of ore, which indicate 

a fair-sized ore body of excellent quality. The fragments continue 

less abundantly and of poorer grade upward along the ridge to the 

southeast for 200 or 300 yards.

Large blocks of high-grade ore occur in the moraine at an altitude 

of some 2,000 feet just north of the main southerly branch of Fish 

Creek. These blocks may have come from deposit No. 16, seen in 

the cirque higher up, but they are so abundant as to suggest a 

much nearer source, for it would seem that they would have become 

more scattered in traveling so far on the ice.

In the pass between Fish Creek and the Seldovia River basin on 

the dunite contact, at an altitude of 200 feet, there are many richlooking fragments of chromite, some as much as 6 inches in diameter. They extend some distance downward along the contact 

on the side toward Seldovia River, but if present on the slope to 

Fish Creek are covered by a large snowbank and talus from above. 

Similar fragments were observed at the dunite contact at several 

points southwest and south of Red Mountain. 

Near the discovery monument of F. P. Skeen's Big Chrome No. 1 

claim, at an altitude of 1,500 feet in the contact valley that slopes 

northwestward to Windy River, there are very abundant fragments 

of chromite 2 or 3 inches in length estimated to contain from 30 to 

45 per cent of chromic oxide. These fragments doubtless mark a 

considerable ore body.

Only three localities at which chromite float occurs in the inner 

basin of the Red Mountain ridge will be mentioned, though less extensive deposits of float were seen at many places. At two of these 

three localities the float was probably derived from ore bodies in place 

that have already been described. They are both on the rough-surfaced plateau on which deposits Nos. 1 and 2 were found. At one of 

them the chromite consists of widely scattered high-grade blocks each 

weighing from a few pounds to half a ton, some lying on bare dunite, 

and some piled with other detritus, seemingly carried northward 

from deposit No. 2 by glacial action. Many tons of excellent ore 

could be gathered from the surface. The other locality is at the 

southwest edge of the plateau along its southerly half, and the float 

consists of immense blocks of dunite, in which occur many stringers 

of banded chromite. One block 25 feet or more in length, perhaps 

from deposit No. 3, was cut by a 3-foot layer of concentrating ore 

estimated to contain 20 per cent of chromic oxide.
BED MOUNTAIN. 41

A mixture of high-grade and low-grade ore in abundant blocks 

occurs at an altitude of 1,600 to 1,700 feet on the slope N. 51° E. 

from the pyramidal mountain between the low passes toward Seldovia. The larger blocks show at least 6 feet of concentrating ore, and 

some of the smaller masses 1 foot of fair shipping ore.

RELATIONS TO THE DUNITE.

The chromite at Ked Mountain shows the same relations to the 

dunite as were observed at Port Chatham. On the whole, very black 

ore with sharp contact against the country rock seems more common 

at Red Mountain.

STRUCTURAL RELATIONS.

One marked feature of the bands of chromite at Red Mountain is 

their parallelism with the layers of pyroxenite. This parallelism 

was observed at many places and characterizes the 2-inch stringers 

of pyroxenite as well as the heavy bands. The importance of this 

fact was recognized very early, but the necessity of visiting so many 

exposures of chromite and the uncertainty as to whether successive 

bands of pyroxenite were faulted parts of the same mass or were 

separate units led to the postponement of a special study of the 

pyroxenite as a means of recognizing layers in which chromite occurs until it was too late to work out this study satisfactorily. There 

are doubtless three or four heavy layers of pyroxenite which would 

by careful study aid in locating major faults, if present, and would 

help in finding the faulted prolongations of ore bodies whose position with reference to pyroxenite may be known.

Both the pyroxenite and the chromite layers are nearly horizontal 

in the region of the Seldovia Pyramid, and the dips become steeper 

toward the north, east, and west, whereas toward the south and southeast only nearly horizontal ore bands were seen. The bands dip 

eastward under the west limb of the main ridge, southward near 

the north end, and southwestward or westward in the interior basin 

and the region to the southeast. The general attitude of the ore 

bands resembles a syncline with a north-northwest axis pitching 

steeply southward at the north end and flattening out toward the 

south. The folding appears to have resulted in repeated step faults 

instead of bending without rupture.

PHYSIOGRAPHIC RELATIONS.

In general, the bodies of chromite have had little influence on the 

topography, hardly showing a notch where they cross a ridge, but 

in deposit No. 2, where the outcrop is roughly horizontal, glacial 

erosion seems to have excavated a trench 500 feet long. The accumulation of snow in this trench caused careful prospectors to 

overlook the most extensive ore body in the region less than two
42 CHEOMITE OF KENAI PENINSULA, ALASKA.

weeks before its discovery. When it was found most of it was still 

covered with snow, but two weeks later it was entirely exposed.

COMPOSITION.

The quality of the Red Mountain chromite has not been thoroughly 

studied, though the specimens collected include much material that is 

available for study. Analyses made by Chase Palmer in the 

chemical laboratory of the United States Geological Survey at the 

writer's request were directed to the determination of chromic oxide 

in the aberrant varieties, as the great similarity to the Port Chatham 

material, combined with the high percentage reported by Grant 12 

(57 per cent chromic oxide) on a chromite from this area (the exact 

locality is not stated), leaves no room for doubt as to the general 

quality of the ore. Mr. Palmer's results, together with field estimates on the same specimens, are as follows:

Analyses of chromite ore from Red Mountain.

No.

4 

5 

6

Porous ore. ............................................:..........

Specific 

gravity.

4.46 

3.93 

3.59

Chromic oxide 

(per cent).

Fouiid.

32.10 

48.89 

41.93

Estimated.

60 

50 

30

Of these specimens No. 4 does not appear to contain any foreign 

material. It is from the recrystallized part of deposit No. 1. It 

shows a great divergence from the magmatic ores in content of chromic oxide, and its slight attraction by the magnet would suggest a 

high percentage of iron. Analysis No. 5 was made on material from 

the pass between the heads of Fish Creek, and No. 6 on a specimen 

from the main ridge at a point 100 yards south of the lowest divide 

between Windy "River and the north branch of Fish Creek. These 

two analyses indicate that a somewhat spongy texture is no indication of inferior ore. The porosity may be due to the removal of some 

of the interstitial silicate. The impurity in the specimen of porous 

mottled ore and in the other specimen of porous ore seems to be 

olivine.

A large number of samples were collected, and it has not been 

possible to make a careful study of their silicate constituent within 

the time available, but many facts indicate that such a study would 

be of great interest and practical value, especially if made in conjunction with similar studies of specimens of ore from other regions.

^ Martin, G. C., Johnson, B. L., and Grant, U. S., Geology and mineral resources of 

Kenai Peninsula, Alaska: TJ. S. Geol. Survey Bull. 587. p. 238, 1915.
BED MOUNTAIN.

QUANTITY OF MINABLE ORE.

The estimates of the quantity of chromite in the ore of the Red 

Mountain deposits were made in the same way as those for the ore 

at Port Chatham. (See p. 28. ) This.method of estimation assigns 

a very large quantity of ore to the deposit on Star No. 4 claim, a 

quantity so much larger than that assigned to any other claim in the 

region that some doubt is felt about its accuracy. However, the 

excellent exposure of this deposit at the surface leaves no doubt as 

to its length, so that it would be quite as reasonable to infer that the 

length of the other deposits has been underestimated on account of 

poor exposure or of faulting as to assume that the depth of the Star 

No. 4 ore body has been overestimated because it is longer at the 

surface. On the whole, the alternative that the estimates are low 

seems more probable, though the uncertainty as to depth should never 

be forgotten in considering the significance of the figures. The 

following table brings together the detailed estimates for the larger 

deposits. It includes only masses that appear to contain more than 

500 tons, because this quantity is within the limit of probable error 

of the larger numbers.

Estimated Quantity of chromite ore, in tons, in certain deposits at Red Mountain as calculated from the observed dimensions.

No.

2..

3..

4..

5.. 

6..

8.. 

9..

10.

11. .

Shipping 

ore.

90.000

5,000

250 

250

10,500 

5,000?

8 (\f\f\

7,000

Concentrating 

ore.

80,000

25,000

5,000

1,500 

2,000

6,000

5,000 

16,000

Chromite in concentrating 

ore.

32,000

10,000

1,500 i

600 

600

 2,500 

5, 000?

3 (\f\f\

8,000 .

No.

12. . . .

13....

14....

17.... 

18....

19.... 

20....

Shipping 

ore.

1,000

1,000

(?)

128,000

Concentrating 

ore.

10,000?

22,000

14,000

16,000 

3,000

30,000? 

6,500

242,000

Chromite in concentrating ore.

4,000?

6,600

4,200

6,400 

1,800

12,000? 

3,200

101,400

On the assumption, as before, that two-thirds of the chromite in 

the concentrating ores can be recovered, the estimate of total exportable ore in the Red Mountain district becomes 195,600 tons.

MINING AND SHIPMENT.

No mining operations other than exploratory work have been carried on at Red Mountain. Even the route of shipment was not decided upon in 1918 by the holders of chromite claims, though Whitney & Lass devoted a good deal of time during that summer to 

searching for a feasible route for the transportation of - loose or 

readily accessible ore.
44 CHBOMITE OF KENAI PENINSULA, ALASKA.

CONCLUSIONS.

AMOUNT OF ORE.

On the assumption that material containing 10 per cent of chromic 

oxide can be profitably concentrated the quantity of ore above sea 

level at Port Chatham has been placed at 32,300 tons. There may 

be a much greater quantity below sea level, as the lower deposits 

are generally richer and heavier than the higher ones, a fact which 

is in accord with the theory that the ore was formed by settling 

in a molten magma. But even by the same process that was used 

to determine the quantity of ore above sea level, an estimate of the 

ore in the exposures examined gives a total of 12,600 tons below 

sea level. The availability of Ore below water level is extremely 

problematic on account of the great prevalence of jointing in the 

dunite. These joints are so open as to constitute a serious menace 

of mine flooding.

The quantity of chromite in sight at Red Mountain is placed at 

195,600 tons. This quantity is a minimum, for no estimate was 

made of the quantity of ore in those deposits of indeterminable size 

whose existence is indicated by very rich float at eight or ten widely 

separated localities, nor has any account been taken of the large 

area covered by talus and morainal detritus, which presumably is as 

rich in chromite as the exposed areas. If this last presumption were 

made a basis for calculation it would at least double the estimate 

of chromite present, for more than half the area of the dunite is 

covered by loose rock.

One notable feature of these deposits that makes all estimates of 

quantity uncertain is their tendency to divide along the strike into 

parallel bands and thus to grade into immense low-grade masses 

in which the dimensions of workable material can not be defined. 

JSuch deposits are either excluded from the computations or are 

assigned only such size as is indicated by the relatively homogeneous 

portions. t

METHODS OF MINING.

The unusual persistence or continuity of the chromite bodies of 

Kenai Peninsula promises to make a deviation from the open-pit 

method of working both feasible and ultimately necessary. Crosscutting at levels much below the outcrop may save hoisting of the 

ore and may reduce the distance from the mouth of the mine to 

the shipping point. One obstacle to underground mining will 

doubtless be the occurrence of numerous faults, though some localities have undergone much less faulting than others. In planning mining it should be borne in mind that in places where the 

strike of the faults nearly coincides with that of the ore bodies, 

as it does near the Star No. 4 prospect at Red Mountain, the ore
CONCLUSIONS. 45

bodies may be much less continuous at depths than at the surface, 

though extension in depth is to be expected when the continuation 

is located.

In an emergency the scattered fragments at the surface in the 

Red Mountain district might furnish several hundred tons of ore.. 

The sands at Claim Point and perhaps some stream gravels near1 

Red Mountain suggest the possibility of washing the ore, though 

only on a relatively small scale.

CONCENTRATING.

So long as chromite containing 40 or 45 per cent of chromic oxide 

is marketable, it will doubtless pay to continue the present hand 

sorting except at the few deposits where the ore is rich enough to 

ship as mined. But there will always be a by-product of low-grade 

ore which must be handled even if it is not utilized. There are also 

large masses that are composed chiefly of low-grade ore which would 

not repay the cost of exploitation if only shipping ore were marketed. 

Much of this material, say that running above 10 per cent of chromic 

oxide, can doubtless be profitably concentrated by washing. Concentration has proved feasible at several of the Canadian deposits, 

where, however, serpentine instead of olivine seems to be the chief 

impurity. At Claim Point a milling plant was being installed in 

1918, after preliminary tests made in one of the mills operating on 

gold ore near Juneau. This milling project has been undertaken at 

Claim Point, though it will be necessary to pump water or to bring it 

across the bay from the creek to the north. At Red Mountain the 

water supply is ample up to an altitude of 1,200 or 1,500 feet. On 

the whole, it may be estimated that one-half to three-fourths of the 

available chromite in this region would require concentration, and 

if ore carrying less than 10 per cent of chromic oxide can be profitably milled the quantity of available chromite will be much greater 

than that indicated by these estimates, though, of course, the percentage suitable for direct shipment would be less than that suggested.

Experiments made to determine the relative behavior of olivine, 

pyroxene, and serpentine under mill tests would be of much practical 

interest. Experience has shown that the economical handling of 

these ores would require the installation of concentrating machinery.

The spongy and friable ores can doubtless be readily crushed, 

though the slimes may prove troublesome, especially in the shattered 

ore.

The recrystallized chromite and, possibly, some of the original minT 

eral can not be brought by concentration to a high content of chromic 

oxide, as even the purest chrome-bearing mineral is a low-grade ore.

10627 22 i
46 CHROMITE OF KENAI PENINSULA, ALASKA. 

TRANSPORTATION TO TIDEWATER.

At Port Chatham the problem of reaching tidewater is simple. 

The new tramway promises to suffice for the large deposit on the 

northwest slope of Claim Point Hill, and an extension of this tramway system may be found satisfactory for the higher deposits on the 

north side of the hill, though the alternative procedure of tunneling 

from a point near tide level and entering the high sea wall at the 

northeast bight is suggested by the possibility that the stringers of 

chromite exposed in this cliff are continuous with those in the higher 

pits. At any rate, the lower ores can be taken out in this way until 

they cease to repay working, when it may be possible to form a more 

definite opinion as to their connection with the upper deposits. All 

other known ore bodies at this locality are practically at sea level or 

below it.

At Bed Mountain the transportation problem is much more difficult. In fact, it is a group of problems, for the chromite occurs at 

both high and low altitudes on the inside of the horseshoe ridge and 

also at many disconnected points on its outer slopes. Concerted 

planning by all the holders of chromite properties in the region 

would probably be in the interest of ultimate economy, though only 

further development of the deposits combined with accurate surveys 

of the possible routes can furnish a really sound basis for a final 

decision as to an outlet. Practical miners who have studied the situation seem to agree that the aerial tramway promises to be the best 

means of making the initial descent from the higher ore bodies 

toward tidewater. It is possible here, however, as was suggested in 

the discussion of Claim Point, that if some of the lower deposits are 

worked first they may furnish underground access to those at greater 

altitudes. Though sufficient data may not be at hand for making 

final decision as to the best approach to water transportation, some 

of the features of the different routes may be compared.

Tutka Bay has deep water and is only 6 miles from the inner basin 

of the Red Mountain ridge. The route to it would lead down the 

open valley of the northward-flowing stretch of Windy River for 2£ 

miles, then over a low divide, estimated to stand at an altitude of 

about 800 or 850 feet, into a canyon-walled head of Jakolof Creek. 

Whether the right wall of this canyon would be as difficult to pass 

as the left is not known, but as seen from below it appears to be 

easier. The route of approach to Tutka Bay from the low flat land 

is also a problem, as the natural opening through the ridge that 

follows the southwest shore of the bay is narrow and steep walled.

Jakolof Bay is about the same distance from the dunite area as 

Tutka Bay. The upper part of the route from both to the deposit 

would be identical except as facility in the lower course might indi-
CONCLUSIONS. 47-

cate a different location higher up. But Jakolof Bay is more rocky 

and shallow, a fact that might necessitate a longer road to navigable 

water.

Fish Creek, whi.ch enters Cook Inlet at Barabara Point, would lead 

to any depth of water that might be desired at the dock terminal. It 

touches the chromiferous rock at two places on the outside of the 

ridge. ^The valley of this stream as seen from above looks passable 

for a road beyond the first steep descent over glacial debris. The 

distance is approximately 8 miles. This route would serve three or 

four good deposits of chromite but is cut off from the inner basin by 

a ridge more than 2^600 feet in altitude, except by the roundabout 

way of the headwaters of Seldovia River, where there are two passes 

at an altitude of less than 2,200 feet.

Seldovia Bay has the advantages of a well-charted harbor and a 

populated town. The route from Seldovia Bay to Red Mountain 

would reach dunite at an altitude of 1,200 to 1,400 feet above sea 

level. Its length would be 8 miles or more. The two passes to the 

inner basin are at an altitude of about 2,150 feet. The lower part of 

this route is said to lie along a very steep, rocky mountain side. Its 

upper end would pass over alternating flats of glacial boulders and 

rather steep rock or talus slopes.

Rocky Bay appears to be excluded from consideration beca'use its 

harbor is extremely dangerous and because Port Dick is equally accessible from the landward side and incomparably safer by water.

Port Dick has deep water to a point within a mile of the head of 

the bay. The configuration of the bay is such that the tidal currents 

are moderate for this region. The valley of Port Dick Creek leads 

to that of Windy River over a flat divide, estimated to rise 100 feet 

above sea level. This estimate is v based on an aneroid reading of 75 

feet at the flat sphagnum meadow near the head of the creek, together with the observation that no dividing elevation was discernible from a height of 400 or 500 feet on the mountain slope north 

of the meadow. The Port Dick route would reach the southeast end 

of the dunite area with a length of about 8 miles, having easy grades 

to the point where an aerial tram might set down ore from the two 

or three outer deposits which it would directly approach. The grades 

by way of the Windy River valley around to the inner basin would 

also be moderate, but the distance would be 7 or 8 miles more, and 

there is said- to be a steep-walled narrow canyon with at least two 

waterfalls in the middle of this route.

The suggestion may finally be made that an ore road at an altitude 

of approximately 2,000 feet around the outer slopes of the dunite 

might connect all the peripheral ores with either Barabara Point, 

Seldovia, or Port Dick, and connection with the inside might be
48 CHBOMITE OF KENAI PENINSULA, ALASKA.

made over one of the 2,150-foot passes to the Seldovia River valley 

or possibly by a tunnel on pay ore at any one of several lower bands 

of chromite. The northerly head of Fish Creek would seem most 

promising for a tunnel if this method were to be considered.

Investigations by Whitney & Lass into the possibility of an inexpensive wagon road for emergency shipment from the inner part of 

the horseshoe ridge, where the best of the known chrome deposits are 

situated, led to an adverse conclusion, on account of the steepness of 

the canyon walls and the occurrence of waterfalls both along the 

course of Windy River and along the small streams that enter Jakolof 

Bay with low divides to the Windy River Jbasin.

SHIPMENT AND MARKETS.

Ocean freight rates will doubtless be a permanent factor in the 

production of chromite in Alaska, as the lack of a local market is 

likely to continue indefinitely. If these rates remain as in 1918 $3.50 

a ton to Seattle it seems probable that the expense of delivering 

ore from Cook Inlet at points on the Pacific coast need not be greater 

than that for ore from many of the deposits in California and 

Oregon. It is impossible to forecast the level of wages in foreign 

countries, but if chromite from New Caledonia, South Africa, Australia, and other countries can be sent to Atlantic seaboard points 

at less cost than from Alaska, there still remain the interior and 

western markets, to which access will be had on practically equal 

terms with California and Oregon. It is even conceivable that the 

production of coal in Alaska may lead to the establishment of metallurgic plants near the mines.

But such hypothetical conditions may be disregarded in view of 

the fact that in 1917 and 1918 Alaska chromite was placed on the 

market by way of Seattle at prices that encouraged the producers to 

invest considerable sums in preparation for more extensive operations.

POSSIBLE OCCURRENCE OP OTHER VALUABLE 

MINERALS.

PLATINUM.

In the search for areas of peridotite other than those already known 

the sands and gravels brought down by many streams whose mouths 

lie between Port Dick and Tutka Bay were examined. Some samples 

were taken without concentration; others were washed in a pan used 

for washing gold. No platinum was found, and as all sands that 

seemed to hold out any special prospect of containing platinum were 

carefully washed, it is very doubtful whether platinum is associated 

with the dunite at Port Chatham or Red Mountain, at least .in the 

eroded parts of the deposits.
OTHER VALUABLE MINERALS. 49

It was reported in 1918 that a sample of beach sand from the 

neighborhood of Anchor Point, Cook Inlet, had been found to contain platinum, but this report has not been verified.

NICKEL.

In the hope that they might contain nickel several specimens of 

what appeared to be pyrrhotite were collected near the hut at the 

head of Port Dick and from the brecciated rock associated with the 

diorite at Koyuktolik Bay and at Point Bede. Samples of these 

specimens were submitted to R. M. Overbeck, of the Geological 

Survey, for such study as his wider experience with Alaskan nickel 

minerals might show was worth while. So far as field observations 

indicated, the rock of both the areas of chromite-bearing dunite 

appears to be free from sulphides or arsenides, though the " acid 

dikes " of the region at many places contain pyrite.

INDEX.

Page.

Acknowledgments for aid 2 

Alluvial deposits, nature and distribution of 3 

Anderson, R. V., claims of 30

Babcock & Martin, claims of 30, 31, 38

Claim Point. See Port Chatham.

Composition of chromite 15 

of the ores at Port Chatham 27 

of the ores at Red Mountain 42

Concentrating, feasibility of 45

Cramer £ Martin, claims of _ 30

Dimensions and character of ore 

bodies, at Port Chatham _____ ___ 18-25 

at Red Mountain_______ 30-39 

Dunite, deformation of___ __ 5-6, 7-9 

intrusion of ____-__ __ 4-5, 6-7 

mass of, at Port Chatham, description of - 4-6 

at Red Mountain, description of _ 6-9 

nature of_ _ 10 

relation of, to metamorphic

rocks __ _ _ _ 2-3

Estimation of ores, method of 17-18 

Extent of ore bodies 13

Faulting, prevalence of, at Port

Chatham __ ___ 5-6 

prevalence of, at Red Mountain- 8-9 

Fish Creek, deposits near heads

of _________35-37, 39-40 

route following _ _ 47

Geology, of the chromite localities 2-12 

reconnaissance map showing, in 

the western part of 

Kenai Peninsula _ 4

Glacial action, evidence of __ 3

Horseshoe claim, description of 33

Intrusion, evidence of______ 4-5, 6-7 

Investigations, record of _ ____ 1-2

Jakolof Bay, route to 46-47 

Jointing, prevalence and effects of_ 5, 8, 9 

Juneau No. 1 claim, description of- 34, 37 

Juneau No. 4 claim, description of_ 35

Lass, W. P., acknowledgment to__ 

Location of the deposits ___

Fag&

2

1

Magnesium, content of, in chromite_ 15-16 

Metamorphic rocks, features of _ 4 

Minerals of the ores__ ____ 14-16 

Mining, methods of _____ 29, 43, 44-45

Nickel, search for _____ _ 49 

Number of ore bodies, at Port Chatham ________ __ 17-18 

 at Red Mountain __ _ 30

Ore, banded, plate showing___ 14 

mottled, plate showing_____ 14 

types and nature of 13-14

Origin of the ore __ _____ 16-17

Palmer, Chase, analyses by 18, 27, 42 

Physiographic relations of the ore 

bodies, at Port Chat- . 

ham ___________ 26-27 

at Reel Mountain____ 41-42

Platinum, absence of ____ 48-49 

Port Chatham, deposits at, description of__________ 19-25 

dunite mass at _ __ 4-6 

map showing chromite deposits

at _ _ ___ 18 

transportation to tidewater at_ 46 

Port Dick, route to__________ 47 

Position of ore bodies, at Port Chatham _______________ 18

at Red Mountain _ __ 30 

Production of ore__________ 1,19, 29 

Pyroxenite, nature of 11

.Quantity of minable ore, at Port

Chatham______ 28-29, 44

at Red Mountain________ 43,44

Rapp, F. A., acknowledgment to___ 2

Recrystallized ore, features of 16-17

Red Mountain, color of 9

deposits at, description of___ 30-39

deposits indicated by float at 39-40

dunite mass at_ _ ___ 6-9

map showing chromite deposits

at _ _ ____ 30 

transportation to tidewater at- 46-48 

Beef mine, Port Chatham, description of__ ___ 19-20 

Rocky Bay, disadvantages of 47

51
52 INDEX.

Page.

Sand, chromiferous beach, deposit of- 26 

Seldovia Bay, route to__- ____ 47 

Seldovia River, deposits near head

of _________ 37-38,40,41

Serpentine, nature of _ ____ 12 

at Red Mountain, origin and extent of_____ ___ 7 

Shipment of ore, facilities and rates

for __________ 29,43,48 

Skeen, F. P., acknowledgment to_- 2 

claims of_______-___ 30, 37, 38 

Star Chrome No. 2 claim, location

and extent of_____ 33 

Star Chrome No. 4 claim, description of_________- 31-32 

length of_______________ 13 

location of _ 30

PageStructural relations of the ore 

bodies, at Port Chatham ___ __ _ 26 

at Red Mountain_________ 41 

Tramway, section of ore body on__ 23 

Transition from ore bodies to

dunite __ ______ 26, 41. 

Transportation' of ore to tidewater,

 means and routes for_ 46-48. 

Tutka Bay, route to__________ 46.

Weathering, results of________ 6, Q> 

Whitney, Capt. G. TL, acknowledgment to_ _ __ 2 

Whitney & Lass, claims of_____ 18,30, 

31-32, 33, 35, 36

Windy River, deposits on or near_ 30-35,

38-39,40.