GEOLOGICAL SURVEY CIRCULAR 207 

RECONNAISSANCE FOR 

RADIOACTIVE DEPOSITS IN THE 

SOUTHERN COOK INLET REGION 

ALASKA, 1949 

By Robert M. Moxham and Arthur E. Nelson 

UNITED STATES DEPARTMENT OF THE INTERIOR 

Oscar L. Chapman, Secretary 

GEOLOGICAL SURVEY 

W. E. Wrather, Director 

GEOLOGICAL SURVEY CIRCULAR 'JJJ7 

RECONNAISSANCE FOR RADIOACTIVE DEPOSITS IN THE 

SOUTHERN COOK INLET REGION ALASKA, 1949 

By Robert M. Moxham and Arthur E. Nelson 

This report concerns work done on behalf of the 

U. S. Atomic Energy Commission and is published 

with the permission of the Commission. 

Washington, D. C., 1952 

Free on application to the Geologieal Survey, Washington 25, D. C. 

CONTENTS 

Page 

Part 1. --Iliamna Lake-Lake Clark region 

Abstract ........•••.•...•...•••....... 1 

Introduction. . . . • . . . . . . . . . . . . . . . . . . . . . . 1 

Geography . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Geology .............................. 1 

Radioactivity investigations ............. 2 

Copper prospects .........•...•... 2 

McNeil claims .............. 2 

Dutton claims . . . . . . . . . . . . . . 2 

Copper King claims. . . . . . . .. .. 2 

Millet claims . . . . . . . . . . . . . . . 2 

Copper-iron prospect ............. 4 

Kasna Creek claims. . . . . . . . . 4 

Silver-lead prospects . . . . . . . . . . . .. 4 

Duryea claims .............. 4 

Part 1. --Iliamna Lake-Lake Clark 

region--Continued 

Page 

Radioactivity investigations--Continued 

Silver-lead prospects--Continued 

Thompson claims . . . • . . . . . . . 4 

Molybdenite prospect. ... · •.•...•... 4 

Thompson claim ..........•.. 4 

Placers and nonmetalliferous 

rocks ..•....•...••.•...•....... 4 

Summary and conclusioP. ............... 4 

Part 2. --Jakolof Bay area 

Abstract ..............•.......•....... 5 

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

Geology and mining. ..................... 5 

Radioactivity investigations ............. 5 

Conclusion ............................ 5 

ILLUSTRATIONS 

Page 

Plate 1. Geologic map of the Iliamna Lake-Lake Clark region, showing sample localities 

and radiometric traverses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Inside back cover 

Figure 1. Geologic map of Jakolof Bay area, Alaska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

TABLES 

Page 

Table 1. Data on rock and ore samples from the Iliamna Lake-Lake Clark region ...•.......••......•..... 3 

2. Data on concentrates obtained from gravels of streams in the Iliamna Lake-Lake Clark region ..... 3 

3. Data on samples collected in the Jakolof Bay area ............................................. 7 

iii 

RECONNAISSANCE FOR RADIOACTIVE DEPOSITS IN THE 

SOUTHERN COOK INLET REGION ALASKA, 1949 

PART 1. --ILIAJVINA LAKE-LAKE CLARK REGION 

ABSTRACT 

Reconnaissance for radioactive deposits in the 

Iliamna Lake-Lake Clark region undertaken in 1949 

included the examination of two silver-lead occurrences 

and five copper deposits, one of which had been reported earlier to contain uranium; the radiometric 

testing of numerous concentrates from gravels of 

streams draining the more inaccessible areas; and 

about 310 miles of radiometric traversing with portable survey meters. The maximum equivalent uranium content of any material tested did not exceed 

0. 009 percent. 

INTRODUCTION 

One of the principal mineralized areas in southwestern Alaska is in the Alaska Range south of Lake 

Clark. Mining exploration and development flourished 

until about 1925 but gradually dwindled chiefly because 

of transportation difficulties. However, in recent years, 

roads connecting Iliamna Lake with tidewater and with 

Lake Clark have been built and two new airfields constructed. The improved transportation facilities have 

resulted in renewed interest in mining in this area. 

Exploration and development are being undertaken at 

several prospects by both private interests and the 

U. S. Bureau of Mines. 

Most of the mining properties in this 

region are valued for their copper content 

although some contain silver, lead, gold, or 

hematite, or combinaticms of these metals in 

potential commercial quantities. A yellow mineral, identified as a possible uranium compound, 

was reported some years ago to occur at the 

McNeil prospect, 30 miles south of Iliamna Lake. 

The information concerning the McNeil property and the occurrence of silver, lead, and 

hematite at other prospects in this region seemed 

to warrant a field investigation of the metalliferous deposits of the Iliamna Lake-Lake Clark 

region. The party, consisting of R. M. Moxham 

and A. E. Nelson, geologists, and J. C. Whitaker 

and Henry Bender, camp assistants, was in the 

field from mid-July through August 1949. This 

investigation was done on behalf of the Division 

of Raw Materials of the U. S. Atomic Energy 

Commission. 

1 

GEOGRAPHY 

The Iliamna Lake-Lake Clark region of southwestern Alaska is situated at the northern extremity 

of the Alaska Peninsula (pl. 1).- The center of the 

area is about 200 miles southwest of Anchorage. 

Iliamna, on the north shore of Iliamna Lake near the 

mouth of the Newhalen River (pl. 1), is the principal 

center of population and source of supplies. Transportation is chiefly by air. One bush pilot, located 

at Tanalian Point on Lake Clark, has a permanent 

base in the area, and transient planes are usually 

available for local transportation from Iliamna. Three 

commercial airlines offer service to Iliamna from 

Anchorage and the Bristol Bay area. Most light 

freight is brought in by air; heavier items are either 

transported by barge from Bristol Bay or shipped to 

Iliamna Bay and trucked across the mountains to Pile 

Bay at the east end of Iliamna Lake. Two airstrips 

are located in the region, one at Iliamna, the other 

at Tanalian Point. Both will accommodate multiengine 

aircraft. 

GEOLOGY 

The brief description of the geology of the Iliamna 

Lake-Lake Clark region given below has been summarized from a report by Capps. 1 

A group of highly metamorphosed gneisses, 

schists, and quartzites that crop out east of Pile Bay 

and near the north end of Lake Clark are thought to 

be the oldest rocks in this region. They are llildoubtedly 

pre-Triassic and probably are mainly early Paleozoic 

and in part pre-Cambrian in age. Crystalline limestone and calcareous schists overlie the early Paleozoic 

rocks, and, although they are nonfossiliferous, they 

are probably of Paleozoic age. Late Paleozoic or 

Mesozoic slates, locally interbedded with chert, crop 

out at the head of Iliamna Bay and northeast of Lake 

Clark. Late Paleozoic or Triassic greenstones occur 

in the area extending from the east end of Iliamna 

Lake to the head of Lake Clark. The greenstones include tuff, porphyry, banded aphanitic rock, amphibolite, 

and pyroxenite. Limestones of Late Triassic age crop 

out in two small areas: one on the north short of Iliamna 

Lake at Chekok Bay, the other east of Pile Bay. A 

group of lavas, tuffs, and associated sedimentary rocks 

probably of Early Jurassic age occur throughout the 

1Capps, S. R., 1935, The southern Alaska range: u. S. Geol. 

Survey Bull. 862, pp. 35-97. 
Iliamna Lake-Lake C~ark region. The composition 

of the lavas ranges from basalt to rhyolite. They 

are interbedded with tuffs and a few beds of argillite, 

graywacke, and limestone. A narrow belt of argillite, 

slate, and graywacke, probably of Cretaceous age, 

crops out in the vicinity of Kontrashibuna Lake. Lava 

flows and tuffs of Tertiary age occur along the south 

shores of Iliamna Lake and near the south end of Lake 

Clark. Mesozoic granitic rocks of the Coast Range 

batholith form the core of the Aleutian Range. They 

crop out in a belt trending southwestward and lying 

between Lakes Iliamna and Clark and Cook Inlet to 

the east. In general the rock is a gray coarse-grained 

granite; in some localities a gneissic character is 

exhibited. Vast areas, particularly in the western 

part of the region, are covered by Pleistocene and 

Recent glacial deposits and outwash and alluvial deposits of present streams. 

RADIOACTIVITY INVESTIGATIONS 

The field studies made during 1949 included the 

investigation of four copper prospects, one copperiron prospect, two silver-lead prospects, ore from a 

molybdenum prospect, and one placer-gold mine; 14 

placer samples were collected; and about 240 miles 

of radiometric surveys were made by boat, 40 miles 

by truck, and 30 miles on foot. 

A standard make of a portable survey meter, 

modified to accept a probe consisting of four 1- by 

18-inch gamma tubes connected in parallel, was used 

in all radiometric traversing. Individual tests at 

outcrops were made with a 6-inch beta tube. At some 

localities rock and ore samples were taken for laboratory checks against field observations. Concentrates were collected from surface gravels of streams 

draining several different areas to determine if radioactive minerals are being eroded from the different 

rock types known to occur in the more inaccessible 

parts of watersheds, for which time was not available 

to permit direct observation. 

The rock and ore samples were crushed, and the 

equivalent uranium content of the unconcentrated material determined in the laboratory; the equivalent uranium. content of the heavy mineral fractions (those 

greater than 3. 3 specific gravity) of both rock and 

placer samples was also determined. Results of 

these studies are shown in tables 1 and 2: table 1 

gives the data on rock and ore samples collected; 

table 2 gives the data on concentrates from surface 

gravels of streams draining the relatively more inaccessible areas of the region. 

Copper prospects 

McNeil claims. --Claims staked by Charles 

McNeil are located near the mouth of Crevice Creek, 

a western tributary of the middle fork of Paint River 

(sample locality 15, pl. 1). The prospect is about 

15 miles west of McNeil Cove on Kamfshak Bay and 

was accessible by wagon road in former years. Copper 

sulfides with a calcite and e·pidote gangue have been 

deposited along the contact between the Paleozoic 

gneiss and schist and granitic intrusive rocks. 

A few prospect pits and a tunnel were dug but 

they are insufficient to determine the size of the ore 

2 

body. About 1922, approximately 10 tons of ore was 

shipped to the Tacoma smelter. According to Mather, 2 

assay returns gave $2. 50 in gold, 15 ounces of silver, 

and 17. 55 percent copper per ton. 

Three mineralized zones on the McNeil property 

in the valley of Crevice Creek were examined. No 

radiation anomalies were noted. The yellow color 

of the altered limestones, which apparently was the 

material McNeil thought to be uranium bearing, is 

due to epidote. Two representative samples of the 

mineralized rock from the northernmost (sample 15) 

a.nd so_uthernmost (sample 16) outcrops contain 0. 001 

and 0. 002 percent equivalent uranium, respectively. 

The heavy mineral fraction in sample 16 contains 

0. 009 percent equivalent uranium; as sodium fluoride 

bead tests for uranium were negative, this radioactivity 

is ascribed to thorium. 

Dutton claims. --The claims of the Dutton Mining 

and Development Co. are located in the valley of Silver 

Creek (sample location 28, pl. 1), about 8 miles southwest of the village of Pile Bay. The veins have been 

injected along the contact between the Triassic limestone and a greenstone. The mineralized zone, about 

200 feet in width, consists of an aggregate of epidote 

and calcite interlaced with quartz veinlets. Chalcopyrite 

was the only copper mineral observed. Extensive 

development work was carried out from 1902 to 1905, 

but no ore is known to have been shipped, and no development work has been undertaken since that time. 

Only 30 feet of the adit at the Dutton copper 

property was accessible, but dump material from the 

underground workings was examined. No radioactivity 

was detected. A caved tunnel a short distance north 

and prospect pits south of the Dutton adit were also 

checked, with negative results. 

Copper King claims. --Another area of copper 

deposits has been found near the head of Iliamna Bay. 

Several trenches and pits have been excavated on the 

Copper King claim, located a few hundred yards south 

of the Iliamna Bay-Pile Bay road, about 1! miles 

west of the head of Iliamna Bay. (See pl. 1. ) Small 

masses of garnet- and magnetite-bearing rock impregnated with chalcopyrite occur along the contact 

between the granite and greenstone. The claims have 

been abandoned for many years. No radiation anomalies 

were detected at or in the immediate vicinity of the 

Copper King claims. 

Millet claims. --The Millet copper claims (sample 

location 14, pl. 1) are located on the north shore of 

Iliamna Lake, 13 miles east of Iliamna. Copper sulfides and calcite gangue have recemented a shattered 

limestone in a zone about 20 to 40 feet wide, which 

has been traced some 3, 500 feet horizontally. Development has been carried on sporadically since the 

discovery of the lode about 1902, but no ore has been 

shipped. During 1949 a drilling and trenching program 

was being conducted by the U. S. Bureau of Mines. 

The prospect trenches of the Bureau of Mines 

and dump material at the head of a flooded shaft were 

examined radiometrically. A traverse also was made 

along the strike of the mineralized zone. No 

2Mather, K. F.,_ 1925, Mineral resources of the Kamishaic Bay 

region (Alaska): U.S. Geol. Survey Bull. 773-D, p. 174. . 
Table 1.--Data on rock and ore samples from the Iliamna Lake-Lake Clark region 

Sample no. Percent equivalent uranium 

Unconcen- Heavy-mineral Concentration Description and location 

Field File trated fraction ratio 

49AMx7 3773-L 0.002 0.001 2:1 Thompson claims, Kijik River, south prospect; vein material, arsenopyrite, 

galena, sphalerite. 

8 3773-L .000 .000 1:1 Thompson claims, Kijik River, north prospect; vein material, arsenopyrite, 

galena, sphalerite. 

9 3774-L .001 . 003 60:1 South shore Iliamna Lake; tuff . 

14 3779-L .000 .000 5:1 Millet claims, north shore Iliamna Lake; copper ore. 

15 3780-L .001 .003 400:1 McNeil claims, Paint River; copper ore. 

16 3781-L . 002 .009 6,100:.1 Do . 

20 3785 .ooo .000 2:1 -' Kasna Creek; copper ore, float. 

21 3786-L .ooo . 000 2:1 Do . 

22 3787-L .000 .000 1:1 Do. 

25 3790-L . 002 .003 45:1 Thompson claims, Kijik River, upper prospect; molybdenite-bearing granite . 

27 3792-L .000 .000 1:1 Duryea claims, Silver Creek; silver ore. 

28 3793-L .ooo .000 1:1 Dutton claims, Silver Creek; copper ore. 

lthat greater than 3.3 specific gravity. 

c..:> 

Table 2.--Data on concentrates obtained from gravels of streams in the Iliamna Lake-Lake Clark region 

Sample no. Percent equivalent uranium 

Field File Heavy-mineral fractionl Location 

49AMxl0 3775 0.001 Dennis Creek. 

11 3776 .000 Pile Bay tributary. 

12 3777 .002 Pile River. 

13 3778 . 001 Pile Bay tributary • 

17 3782 . 007 East shore, Lake Clark . 

18 3783 .004 Kijik River. 

19 3784 . 001 Lake Clark tributary near Tanalian Point . 

26 3791 . 001 Tanalian River . 

29 3794 .001 Little Lake Clark, south tributary. 

30 3795 . 003 Do • 

31 3796 . 005 Chokotonk River • 

32 3797 .ooo Hatchet Creek. 

33 3798 . 003 Portage Creek . 

1that greater than 3.3 specific gravity. 
anomalous radiation was noted at any locality on this 

property. 

Copper-iron prospect 

Kasna Creek claims. --A group of claims has 

been staked on the east s1de of Kasna Creek, about 

2 miles from its mouth on Kontrashibuna Lake (sample 

locations 20-22, pl. 1). Several parallel mineralized 

zones carrying hematite, chalcopyrite, and gangue 

minerals have been found in the limestone country rock. 

Very little development work had been done before 

1949, at which time the U. S. Bureau of Mines began 

an exploration program. The trenches made by the 

Bureau on the westernmost of three parallel zones of 

mineralization provided excellent exposures, and 

numerous outcrops of ore occur in the tw6 more 

easterly zones. Radiometric tests gave negative results. 

Silver-lead prospects 

Duryea claims. --The Duryea claims (sample 

location 27, pl. 1) are about 1 mile north of the Dutton 

prospect. The ore body, valued chiefly for its silver 

content, is located along the same contact between 

limestone and greenstone as the Dutton copper deposit. 

Silver-bearing galena occurs with sphalerite and pyrit~ 

as fracture fillings in the brecciated limestone. Capps 3 

states that in 1909 the owner reported assays up to 

196 ounces of silver, $20 in gold, ~5 to 50 percent 

lead, and 15 to 20 percent zinc per ton. Extensive 

underground and surface development work has been 

done in the past, but no ore is known to have been 

shipped. As underground workings are now caved and 

flooded, only dump material was tested. No radioactive 

m8.terial was found. 

Thompson claims. --Recently a silver-lead prospect has been staked m the valleys of two parallel 

western tributaries of the Kijik River, about 7 miles 

northwest of Kijik (sample locations 7, 8, pl. 1). 

Arsenopyrite and a little galena, chalcopyrite, and 

pyrite in a gangue of calcite and rhodochrosite have 

been deposited in a shear zone in the granite country 

rock. Very thin veinlets carrying pyrite and a few 

grains of chalcopyrite have been injected along numerous 

parallel joints in a ZOI).e about 200 yards wide. Radio3

Capps, S. R., op. cit., pp. 93·94. 

4 

metric tests were made at several prospect pits on the 

silver-lead claims, and radiometric surveys were made 

throughout the general area in which these claims are 

located. The radioactivity at this locality averages 

about double the normal background for the region. 

The detailed examination, however, of the silver-lead 

showings and other sulfide-bearing veinlets in the 

mineralized zone revealed no concentration of radioactive material. The higher readings are thought to 

have been caused by radioactive minerals sparsely 

distributed through a large mass of granite country 

rock rather than from local concentrations of radioactive minerals. 

Molybdenite prospect 

Thompson claim. --Samples of molybdenitebearing granitic float from a claim near the top of the 

Kijik Mountain (sample location 25, pl. 1) above the 

silver-lead prospect were donated by Mr. Joe Thompson, 

the owner. None gave any indication of radioactivity. 

Placers and nonmetalliferous rocks 

With the exception of the Upper Cretaceous 

argillites and slates, some lithologic variety of every 

unit described under "Geology" (p. 1) was found at 

some point during the 310 miles of radiometric traversing. None is significantly radioactive, and the 

placer samples in this area contain no radioactive 

minerals of interest. 

SUMMARY AND CONCLUSION 

In the course of the 1949 reconnaissance in the 

Iliamna Lake-Lake Clark region all the accessible 

lode prospects in the area were examined. These included five copper prospects, one of which contains 

considerable amounts of hematite, and two silver-lead 

prospects. No concentration of radioactive material 

was found at any of the prospects. In addition, samples 

of molybdenite-bearing granitic rock were tested radiometrically, with negative results. Concentrates from 

gravels of streams draining the more inaccessible areas 

of the region were also tested and showed no appreciable 

radioactivity. From the data gathered in the course 

of this reconnaissance it seems unlikely that deposits 

of high-grade uranium ores occur in association with 

the metalliferous lodes of the Iliamna Lake-Lake Clark 

region. 
PART 2. --JAKOLOF BAY AREA 

ABSTRACT 

As a result of inqu],ries by prospectors in 1948 

concerning radioactive ores in the vicinity of Jakolof 

Bay on the Kenai Peninsula in southern Alaska, the 

Geological Survey conducted a brief investigation there 

during 1949. No radioactive material was found. Possibly a chromite stock pile in this locality was mistaken 

for pitchblende. 

INTRODUCTION 

During the summer of 1948 prospectors were 

reported to have made inquiries at the Fairbanks 

Office of the Territorial Department of Mines concerning the legality of staking claims for radioactive 

ores on a "government reserve" at Jakolof Bay, on 

the Kenai Peninsula, 6 miles east of Seldovia. 

The Survey party conducting investigations in 

the Iliamna Lake-Lake Clark region. (see part 1 of this 

report) spent about one week making a radiometric 

reconnaissance of the Jakolof Bay area (fig. 1) in late 

June and early July 1949. 

GEOLOGY AND MINING 

The geology of the Jakolof Bay area· has been 

described in a general way in reports by Martin, Johnson, 

and Grant, 4 Gill, 5 and Guild. 6 

~rtin, G. C., Johnson, B. L.,. and Grant, U. S.,. 1915, Geology and 

mineral resources of Kenai Peninsula, Alaska: U. S. Geol. Survey 

Bull. 587. 

5

Gill, A. C., 1922, Chromite of Kenai Peninsula, Alaska: U. S. 

Geol; Survey Bull. 742. 

~uild,P. W., 1942, Chromite deposits of Kenai Peninsula, Alaska: 

U.S. Geol. Survey Bull. 931-G, pp. 139-175. 

5 

The rocks in the vicinity of Jakolof Bay consist 

chiefly of highly metamorphosed graywacke and slate, 

an.d minor amounts of limestone and basic igneous 

material. These strata are probably Triassic in age. 

Many small acidic dikes, probably late Mesozoic in 

age, intrude the Triassic rocks. 

According to Rutledge, 7 the only mining in the 

vicinity of Jakolof Bay has been at the chromite deposits on Red Mountain where some chrome ore was 

produced during 1942-44. 

RADIOACTIVITY INVESTIGATIONS 

Detailed radiometric traverses were made on 

foot on the Government-owned mill site on Jakolof 

Bay, where tests included examination of a stock pile 

of chromite from the deposits at Red Mountain. No 

radiation anomalies were detected. Additional traverses were made by boat along the shores of Jakolof 

Bay and the southwest shore of Tutka Bay (fig. 1), 

also with negative results. 

Samples of the Mesozoic graywacke and an 

acidic dike were co~lected; and four placer concentrates 

were panned from the gravels of streams draining 

the mountain on the southwest side of Jakolof Bay. 

No significant amount of radioactive minerais was 

found in any of the samples. Results of the laboratory 

studies of the samples are shown in table 3. 

CONCLUSION 

No radioactive materials of any consequence 

occur in the immediate vicinity of Jakolof Bay. 

'Rutledge, F. A., 1946, Exploration of Red Mountain chromite 

deposits, Kenai Peninsula, Alaska: U. S. Bur. Mines Rept. Inv. 3885. 
YUKONI4 

~ 

Figure 1. --Geologic map of Jakolof Bay area, Alaska. 

6 

Contact 

)... 

Airfield 

.j.. 

Seaplane bose 

ED 

Placer sample 

() 

Bedrock sample 

G-M counter traverse 
....;] 

~ 

~ 

~ 

-

1:1 

~ 

--· "' ...

.. 

. 

Sample no. 

Field ATE file 

l 3766-L 

2 3767 

3 3768-L 

4 3769 

5 3770 

6 ?771 

~----- ~--~ 

Table 3.--Data on samples collected in the Jakolof Bay area 

Percent equivalent uranium 

Unconcen t rated Heavy-mineral fraction Concentration Description and location 

sample (greater than 3.3 sp.gr) ratio 

0.000 0.002 23:1 Graywacke, south shore of Jakolof Bay. 

--- .001 -- Concentrate from surface gravel, first stream west of Jakolo f 

Bay. 

. 001 .oo6 374:1 Acidic dike west of location of sample 2 . 

--- .007 --- Concentrate from surface gravel, west tributary of Jakolof 

Bay . 

--- . Opl --- Do. 

--- .003 --- Do. 

-- C. ------ ' - ~--