GEOLOGICAL SURVEY CIRCULAR 348

RECONNAISSANCE FOR 

RADIOACTIVE DEPOSITS 

IN EASTERN ALASKA 

1952

This report concerns work done on 

behalf of the U. 8. Atomic Energy 

Commission and is published with 

the permission of the Commission.

UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

GEOLOGICAL SURVEY CIRCULAR 348

RECONNAISSANCE FOR RADIOACTIVE DEPOSITS IN EASTERN ALASKA

1952

By Arthur E. Nelson, Walter S. West, and John J. Matzko

This report concerns work done on 

behalf of the U. 8. Atomic Energy 

Commission and is published with 

the permission of the Commission.

Washington, D. C., 1954

Free on application to the Geological Survey, Washington 25, D. C.
1 MINERAL POINT AREA

2 INDIAN GROUP PROSPECT

3 SILVER CREEK PROSPECT

4 ROCK CREEK PROSPECT

5 NABESNA MINE

6 ORANGE HILL

7 CHISANA DISTRICT (we fig. 2)

6 HOPE CREEK AREA (IM fig. 3)

9 MILLER HOUSE-CIRCLE HOT SPRINGS AREA (»e fig. 4)

10 CHANDALAR MINING DISTRICT (we fig. 5)

11 GOLD BENCH

12 FOKTYMILE DISTRICT (ie> fig. 6)

Figure 1. Index map of eastern Alaska showing areas investigated in 1952.

ii
RECONNAISSANCE FOR RADIOACTIVE DEPOSITS IN EASTERN ALASKA

1952

By Arthur E. Nelson, Walter S. West, and John J. Matzko

CONTENTS

Page

Abstract....................................... 1

Eastern Alaska Range, by Arthur E. Nelson........ 2

Geology.................................. 2

Slana-Nabesna district..................... 2

Mineral Point area................... 2

Slana area........................... 2

Indian Group prospect ........... 2

Silver Creek prospect............ 3

Rock Creek prospect.................. 3

Nabesna mine........................ 3

Orange Hill.......................... 4

Chisana district........................... 4

Bonanza Creek....................... 4

Summary and

conclusions............................. 7

Page

Hope Creek and Miller House-Circle Hot Springs

areas, byWalterS. West and John J. Matzko..... 7

Hope Creek area......................... 7

Miller House-Circle Hot Springs area....... 11

Summary and conclusions................. 14

Koyukuk-Chandalar region, by Arthur E. Nelson... 15

Geology and radioactivity studies........... 15

Chandalar mining district............ 16

Gold Bench......................... 16

Summary and conclusions................. 16

Fortymile district, by John J. Matzko........... 19

Wade Creek.............................. 19

Walker Fork............................. 19

Literature cited............................... 21

Unpublished reports........................... 21

Figure 1.

2.

3.

4.

5.

6.

Table 1.

2.

3.

4.

5.

10.

11.

ILLUSTRATIONS

Page

Index map of eastern Alaska showing areas investigated in 1952.................................. ii

Geologic sketch map of the Chisana district showing sample locations ............................ 5

Geologic sketch map of the Hope Creek area showing sample locations............................ 8

Geologic sketch map of the Miller House-Circle Hot Springs area showing sample locations......... 9

Sketch map of the Chandalar mining district showing sample locations............................ 17

Topographic map of part of the Fortymile district, east-central Alaska .......................... 20

TABLES

Page

Radioactivity and mineralogy of rock and ore samples collected in the Slana-Nabesna district, 1952.. . 4

Radioactivity of stream-gravel and placer concentrates collected in the eastern Alaska Range, 1952..... 6

Radioactivity data on rock and ore samples collected in the Chisana district....................... 6

Equivalent-uranium analyses of samples, Hope Creek area, Alaska.............................. 10

Mineralogy of heavy-mineral fractions of selected samples, Hope Creek area, Alaska.............. 11

Equivalent-uranium analyses of samples, Miller House-Circle Hot Springs area, Alaska ........... 12

Analyses of water samples, Miller House-Circle Hot Springs area, Alaska........................ 13

Mineralogy of the heavy-mineral fractions of selected samples from the Miller House-Circle

Hot Springs area, Alaska................................................................... 13

Uranium-bearing minerals in samples from the Miller House-Circle Hot Springs area, Alaska......... 14

Equivalent-uranium analyses and radioactive minerals of stream and placer

concentrate samples from the Koyukuk-Chandalar region, Alaska............................... 18

Radioactivity of rock and ore samples from the Koyukuk-Chandalar region, Alaska................. 19

ABSTRACT

Reconnaissance for radioactive deposits was conducted in selected areas of eastern Alaska during 1952. 

Examination of copper, silver, and molybdenum occurrences and of a reported nickel prospect in the SlanaNabesna and Chisana districts in the eastern Alaska 

Range revealed a maximum radioactivity of about

0.003 percent equivalent uranium. No appreciable 

radioactivity anomalies were indicated by aerial 'and 

foot traverses in the area.

Reconnaissance for possible lode concentrations 

of uranium minerals in the vicinity of reported fluorite 

occurrences in the Hope Creek and Miller House-Circle 

Hot- Springs areas of the Circle quadrangle and in the
Fortymile district revealed a maximum of 0.055 percent equivalent uranium in a float fragment of ferruginous breccia in the Hope Creek area; analysis of samples obtained in the vicinity of the other fluorite occurrences showed a maximum of only 0.005 percent equivalent uranium.

No uraniferous lodes were discovered in the 

Koyukuk-Chandalar region, nor was the source of the 

monazite, previously reported in the placer concentrates 

from the Chandalar mining district, located. The source 

of the uranothorianite in the placers at Gold Bench on 

the South Fork of the Koyukuk River was not found during a brief reconnaissance, but a placer concentrate 

containing 0.18 percent equivalent uranium was obtained. 

This concentrate is about 10 times more radioactive 

than concentrates previously available from the area.

EASTERN ALASKA RANGE 

By Arthur E. Nelson

An appraisal of uranium possibilities in Alaska 

made in 1950-51 (Wedow and others, 1951) indicated 

that certain mineral deposits in several localities in the 

eastern Alaska Range were favorable for the occurrence 

of uranium ores. In the summer of 1952, seven localities (nos. 1-7, fig. 1) in the Slana-Nabesna and Chisana 

districts in the eastern Alaska Range were investigated 

for possible radioactive deposits on behalf of the Division 

of Raw Materials of the U. S. Atomic Energy Commission. The work was done by the writer and 

Richard S. Smith, geologic field assistant. The 

investigation consisted of radioactivity traverses of 

mines and prospects in and around mineralized zones, 

contacts, and aureoles. Specific outcrop tests were 

made at various points along the traverses. Supplemental check samples were collected for radioactivity analysis and mineralogic study. These included channel and 

wall-rock samples of veins and mineralized zones, and 

samples of ore dumps and various rock types. Concentrates were taken of certain stream gravels to determine 

if radioactive minerals were being released from the bedrock within the specific drainage basins. In addition, an 

airborne radioactivity traverse was made over the Orange 

Hill area and other larger mineralized zones that were 

otherwise inaccessible with the equipment available.

Standard commercial portable survey meters adapted for a variety of probes were used to detect radioactivity. Individual outcrop tests were made with a 

6-inch beta-gamma probe; ground traverses were made 

with the survey meter and a 2- x 20-inch gamma probe 

lashed to a packboard; and airborne traverses were made 

with a probe consisting of six 2- x 40-inch gamma tubes, 

connected in parallel, coupled to the survey meter, and 

carried in light, fixed-wing aircraft. (See Wedow, 1951.)

The Slana-Nabesna and Chisana districts lie in 

that part of the eastern Alaska Range known as the Mentasta and Nutzotin Mountains (fig. 1). These mountains 

merge near the Nabesna River, a northeastward flowing 

glacial stream originating in the Wrangell Mountains to 

the southwest. At Mentasta Pass in the Mentasta Mountains the Alaska Range trends southeastward toward the 

international boundary. On the northeast the range is 

bordered by the broad lowlands of the Tanana River and

to the southwest by the Copper River and the Wrangell 

Mountains. The relief in this part of the Alaska Range 

is rugged, the mountains having been intensely glaciated in Recent geologic time. At higher altitudes there 

are numerous small glaciers.

The geology of the Nutzotin Mountains has been 

discussed in detail by Moffit (1943). In summary, a 

series of sedimentary beds, locally metamorphosed 

and ranging in age from Devonian to Quaternary, form 

a major part of the eastern Alaska Range. Shale, argil - 

lite, sandstone, arkose, graywacke, and conglomerate 

are the major bedrock types; minor amounts of limestone 

also occur. These beds have been folded and locally 

faulted.

Igneous rock types are widely distributed throughout the region and occur as both flows and intrusives. 

The flow types are present throughout most of the section 

and in the main are represented by basalts and andesites. 

Intrusive rocks of Paleozoic and Mesozoic age ranging 

from gabbro to granite intrude all the rock types, the 

intrusive rocks of Mesozoic age being more extensively 

developed. Superimposed upon the consolidated sedimentary and igneous rocks are a series of unconsolidated stream and glacial deposits which occur in most 

of the valleys.

Slana-Nabesna district 

Mineral Point area

Thorne (1946, p. 8, 9) reported a nickel occurrence in a shear zone in argillite in the Mineral Point 

area (locality 1, 'fig. 1), which is about 32 miles northeast of Slana on the eastern section of the Glenn Highway. The prospect is on the north side of the road on a 

mountain that has two prominent limestone peaks which 

are separated by a saddle of reddish argillitic rock. 

Some of the rock in the shear zone has been altered to 

a red-yellow material.

Investigations conducted in the area revealed little 

mineralization. Radioactivity traverses were made over 

the entire area, which included the shear zone as well 

as contacts and all rock types outcropping on the mountain. No anomalous radiation was detected during the 

course of the traverses. The radioactivity data on the 

rock specimens collected are shown in table 1.

Slana area

Slana, located near the confluence of the Slana and 

Copper Rivers, is on the south flank of the Alaska Range. 

Deposits of silver-bearing galena and copper minerals 

in quartz veins occur at several prospects located at 

different sites northwest of Slana. Two of these properties the Indian Group and Silver Creek prospects were 

examined for radioactive minerals. (See fig. 1.)

Indian Group prospect. The Indian Group prospect 

(locality 2, fig. 1) is near the top of a ridge separating 

the Indian Creek and Ahtell Creek valleys and is 13 airline miles from the Indian Creek bridge on the eastern 

section of the Glenn Highway. The site of most of the 

open cuts is on the Indian Creek side of the ridge dividing the Indian Creek drainage from that of Ahtell Creek. 

A trail from Indian Creek leads to the property, and the
first of the open cuts is about 400-500 feet below the 

crest of the divide. Little or no development work has 

been done on the Indian Group claims in recent years. 

At the present time there are at least six recognizable 

open cuts, all of which have either caved or have been 

partially filled with slide rock so that none of the mineralized portions of the veins are exposed. Sampling, 

therefore, was confined to the numerous ore dumps and 

float in and around the cuts.

Moffit (1938) gives a detailed account of the geology of the Slana district. Briefly, the country rock at 

the Indian Group claims consists of quartz diorite which 

shows wide variations in texture. Most of the rock has 

a porphyritic texture with large phenocrysts of feldspar 

set in a coarse-granular groundmass. Locally, a series of nearly vertical fracture planes that strike nearly 

east seem to have had some control in the placement of 

the mineralized quartz veins. The ore minerals are 

galena, tetrahedrite, and chalcopyrite, all of which are 

silver bearing.

Radioactivity traverses were conducted over the 

area. These included checks in each of the open cuts 

as well as traverses along the veins and in the areas 

immediately adjacent to the prospect itself. No radioactivity anomalies were discovered. Supplemental check 

samples were collected from the country rock and ore 

dumps, and one concentrate (sample 4531, table 2) was 

collected from the sand and gravel in a stream draining 

the mineralized area. Results of the laboratory studies 

made on the samples collected during these investigations 

are shown in tables 1 and 2.

Silver Creek prospect. The prospect on Silver 

Creek (locality 3, fig. 1) is located on the north side of 

the creek a little more than 1 mile upstream from its 

junction with Ahtell Creek. No work has been done recently on the prospect, but the trail to the property is 

in good condition and the site is easily accessible from 

the highway. The workings consist of two adits, several open cuts and prospect pits, all of which have caved, 

and an inclined shaft slightly more than 15 feet long. The 

site of the caved adit at creek level had been examined 

briefly by Wedow and Matzko in 1946 (Wedow, Killeen, 

and others, 1954, p. 16-18).

The prospect is located in a northwest-trending 

fault zone about 100 feet wide in the quartz diorite country rock. Bedrock in the fault zone has been altered to 

a relatively soft material, in places highly stained with 

iron oxide and with some copper carbonate. Prospecting has been carried out on several steeply dipping mineralized quartz veins which occur in the shear zone 

and have the same northwest trend. Although most 

of the workings were inaccessible, ore containing 

pyrite, galena, chalcopyrite, and a blue copper 

stain in quartz gangue was found on the lower 

dump.

No anomalous radiation was indicated in traverses made across the fault zone and adjacent 

areas, ore dumps, and along exposed parts of the 

veins. Check sampling was confined to ore dumps 

for the most part, but it was possible to take a 

channel sample across the face of the vein in the 

inclined shaft. This channel sample contained galena and chalcopyrite in a gangue of quartz. The 

results of laboratory studies on these samples are 

given in table 1.

Rock Creek prospect

The Rock Creek molybdenite prospect is located 

on the south flank of the Alaska Range (locality 4, fig. 1) 

about 3. 5 miles north of mile 84. 5 (measured from junction of the Richardson and Glenn Highways near Gakona 

see fig. 1) on the Nabesna road. The prospect is near 

the head of the west fork of the east branch of Rock Creek 

at a height of 2, 200 feet above the road. No work has 

been done on the prospect in recent years, but former 

development work consists of an adit 170 feet long and 

one open cut which has caved and is now 30 feet long.

A report by Van Alstine (1945) discusses the molybdenite deposits at Rock Creek. The bedrock at the head 

of Rock Creek is part of a mass of rock mapped by Moffit 

(1938) as undifferentiated granitic rocks of late Paleozoic 

and Mesozic age. Permian lava flows are exposed in the 

middle part of the creek. The prospect site is in a pink 

gneissic syenite which has interlaminations of biotite 

schist. A pegmatite dike as much as 2 feet wide intrudes 

the syenite and schist. The dike crops out 150 feet north 

of the adit and is about 100 feet higher. Molybdenite, the 

only metallic mineral noted, occurs in the pegmatite dike 

as tiny plates and blebs erratically distributed. The pegmatite dike was not found in the adit which was driven in 

the syenite to intersect it.

Radioactivity traverses in the area failed to indicate any significant anomalies. Laboratory studies on 

check samples collected from the prospect are listed in 

table 1.

Nabesna mine

The Nabesna Mining Corporation property (locality 5, fig. 1) is located in the northern part of theWrangell Mountains of the eastern Alaska Range where the 

Wrangell and Nutzotin Mountains merge. The property 

is accessible from Slana by a road which is about 54 miles 

long.

The Nabesna area has been prospected periodically 

since 1899. However, it was not until the fall of 1929 

that a company was formed to mine gold at Nabesna. In 

1931 a mill was in operation, and mining continued until 

about 1947 when most of the ore bodies had been exhausted. At present the several adits and shafts at the main 

property are in such poor condition that access into the 

mine is impossible. At a newer development, about half 

a mile north of the main mine, two adits have been driven 

into an ore body; one of these is caved, but the other is 

open for several hundred feet.

Wayland (Moffit, 1943) gives a detailed account 

of the geology of the Nabesna mine. Briefly, limestone of Triassic age, intruded by stocks and dikes 

of quartz diorite, overlies shale and basaltic lavas 

and is capped by Tertiary lavas. The limestone 

has been recrystallized in part with the development of tactite. Three types of ore bodies occur 

at the Nabesna mine, the most important being 

a series of discontinuous veins of auriferous pyrite and calcite with lesser amounts of chalcopyrite, sphalerite, and galena. These veins occur 

as replacements along fractures and contacts in 

the limestone. The other two types of ore deposits occur as bodies of magnetite and of pyrrhotite.
Minerals occurring at the Nabesna mine are pyrite, chalcopyrite, sphalerite, galena, pyrrhotite, 

arsenopyrite, stibnite, gold, andcalcite with a suite of 

contact minerals including andradite, vesuvianite, epidote, magnetite, specularite, wollastonite, spinel, 

brookite, and others.

Because entrance into the mine was impossible, 

investigations consisted of traverses along contacts 

and ore dumps. At the newer development, half a 

mile north of the main mine, several hundred feet of 

the adit was traversed as well as the ground in the immediate area. At no time during the traverses was any 

radioactivity anomaly detected. Check sampling, of 

necessity, was confined to the ore dumps. The results 

of the laboratory studies of these samples are given in 

table 1.

Orange Hill

Orange Hill (locality 6, fig. 1) is located on the 

east side of the Nabesna River, 12 miles south of the 

Nabesna airfield and half a mile below the foot of 

Nabesna Glacier. It is elliptical in shape with its 

top about 600 feet above the level of the river. Access 

to Orange Hill is from Nabesna where the Nabesna River 

can be crossed in a boat or on horseback; routes across 

the rapidly shifting channels of this glacial stream 

should be selected carefully, and the crossings made 

at low water.

Development work done on the property includes 

adits, shafts, and opencuts as well as some diamonddrill work. Many of the shafts and adits are reported 

to be caved. (See Van Alstine and Black, 1945.) High 

melt waters in the Nabesna River at the time of the

writer's visit made access to Orange Hill impossible. 

However, an airborne radioactivity traverse was flown 

over the mineralized area as well as over larger gossans in the region. No significant radioactivity anomalies were detected.

The oldest rocks of the region are thick lava flows 

and greenstones of Permian age. There is also a metamorphosed limestone of Permian age which is overlain 

and underlain by hornfels. The core of Orange Hill is 

a quartz diorite of probable Jurassic age. Dikes of 

alaskite intrude the quartz diorite as well as the sedimentary rocks, and all of these rocks are intruded by 

dacite and andesite dikes. Veinlets of quartz in the 

quartz diorite and silicic dikes contain pyrite, chalcopyrite, molybdenite, tetrahedrite, sphalerite, magnetite, and gypsum. The limestone has metamorphic deposits composed of magnetite, pyrrhotite, pyrite, chalcopyrite, sphalerite, and molybdenite. This summary 

of the geology and mineralogy at Orange Hill is taken 

from a detailed account by Van Alstine and Black (1945).

Chisana district 

Bonanza Creek

Bonanza Creek in the Chisana district (locality 7, 

fig. 1) is a south-flowing creek in the Nutzotin Mountains emptying into Johnson Creek 7 miles east of the 

settlement of Chisana. (See fig. 2.) In this region 

most of the mining has been confined to placer-gold 

operations. At the time of the writer's visit there were 

three small placer mines in operation. However, some 

lode prospecting has been done recently in several mineralized zones in the district, but at none of these prospects has there been any extensive development work

Table 1. Radioactivity and mineralogy of rock and ore samples collected in the Slana-Nabesna

district, 1952

[Equivalent-uranium analyses by J. J. Matzko and others, U. S. Geological Survey laboratory, College, Alaska]

Sample 

number

4510

4529 

4530

4532

4533 

4534

4535 

4536

4537

4538 

4539 

4540

Location

Mineral Point (nickel prospect )-

Indian Group, Indian Creek 

__________ rin ________ _ ______

Silver Creek ( silver-lead 

prospect) .

. do 

Rock Creek (molybdenite 

prospect) . 

. do 

. do 

__________ r5 n _ ______ _ ______

Type of sample

Rock occurring in 

shear zones.

Quartz diorite country 

rock.

Ore dump 

Vein material 

Wall rock next to 

vein. 

Mafic phase of igneous 

country rock. 

Syenite country rock 

Ore dump 

_______ rtn _____ _____ _

Equivalent 

uranium 

(percent)

< 0.001

.002 

.004

< .001

.001 

< .001

.002 

.003

.003

< .001 

< .001 

< .001

Radioactive 

minerals

Accessory minerals, 

mostly zircon.

Accessory minerals, 

mostly sphene 

and zircon. 

Accessory minerals, 

mostly zircon 

and a trace of 

sphene .
CD 

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MESOZOIC PERMIAN, 

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QUATERNARY TERTIARY CRETACEOUS CRETACEOUS, 

AND JURASSIC 

TRAISSIC
Table 2. Radioactivity (percent equivalent.uranium) of stream-gravel and placer concentrates

collected in the eastern Alaska Range, 1952

[Equivalent-uranium content of original concentrates determined by J. J. Matzko and others, U. S. Geological Survey laboratory, College, Alaska]

Sample 

number

4515 

4522 

4525 

4524

4551

Location

Skookum Creek, Chisana 

district. 

Canyon Creek, Chisana 

district. 

Bonanza Creek, Chisana 

district. 

Johnson Creek, Chisana 

district. 

Unnamed creek near "Slana 

Lake," Slana-Natesna 

district.

Type 

of 

sample

Placer 

Streamgravel. 

 do 

 do 

 do 

For 

original 

concentrate

< 0.001 

< .001 

.001 

.002 

< .001

For heavy mineral 

fraction

Bromoform 1

< 0.001

Methylene 

iodide 2

< 0.001 

< .001 

< .001

.005

For magnetic fraction

1.6 

magnetic

3 0.01

1.6 

nonmagnetic

4 0.09

1 Specific gravity greater than 2.8.

2 Specific gravity greater than 3.3.

3 Radioactive mineral: sphene.

4 Radioactive mineral: zircon.

Table 5* Radioactivity data on rock and ore samples collected in the Chisana district

[Equivalent-uranium analyses by J. J. Matzko and others, U. S. Geological Survey laboratory, College, Alaska]

Sample 

number

4511

4512 

4515 

4514 

4516

4517 

4518

4519 

4520 

4521 

4525

4526 

4527 

4528

Location

Big Eldorado Creek 

On ridge 1 mile north of Little Eldorado 

Creek.

_ _ _ __ __ _ fin-- __ - - __ _ - _ _ _ -- -

_ _ ____ rlo _ ______________ ___ ___

___ _ _ _ _ -rln- __ _ - _ _ -

Right limit of Johnson Creek, 1 mile west 

of Bonanza on hillside. 

_ ____ do

- do 

_ _ __ __ _ rio _ _ _ _ _ _ __

Type of sample

Stained material in fracture 

zone.

Granite country rock 

Sulfide float 

Sulfide vein 

Sulfide vein 

_ _ do - __ _ - __ _ -

\T& ~t n inci 1~ P*~f*^ Q 1

 do 

_ __ _ rln- - ___ _ _ _ _ _

Equivalent 

uranium 

(percent)

< 0.001

.001 

< .001 

< .001 

< .001

< .001 

< .001 

.001 

.005 

< .001 

< .001

.001 

< .001 

.005
done other than a few opencuts. At one prospect two 

adits had been driven into a mineralized zone many 

years ago, but these have caved.

Moffit (1943) gives an account of the geology of , 

this region. Briefly, volcanic and sedimentary rocks 

of Devonian and Permian age have been intruded by 

andesitic dikes and sills and by a large mass of granodiorite of Mesozoic age.

Minerals occurring in the area include galena, 

molybdenite, cinnabar, pyrite, copper, silver, and 

gold. There appears to be a definite structural control in the formation of the mineralized zones in the 

district. The mineralized fissure veins all have the 

same general trend with a strike of west to northwest 

and a northerly dip. The fissures are probably the 

result of the stresses and strains developed during the 

intrusion of the granodiorite into the Devonian and 

Permian rocks.

Investigations consisted of radioactivity traverses 

of the mineralized zones and rock types occurring in 

the district as well as collecting supplementary check 

samples from mineralized zones, outcrops, and stream 

gravels. Figure 2 shows the routes of the radioactivity 

traverses and the location of the samples collected. 

The traverses conducted in the district did not indicate 

any anomalous radioactivity. The results of laboratory 

studies made on samples collected in this district are 

listed in tables 2 and 3.

Summary and conclusions

Results of radioactivity investigations conducted 

in the eastern Alaska Range during the 1952 field 

season showed that no high-grade uranium deposits 

occur in association with the metalliferous lodes previously deemed favorable (Wedow and others, 1951) for 

the occurrence of uranium ores. Only three of the 

samples collected contain 0.003 or more percent equivalent uranium, and the radioactivity of these samples 

is due primarily to the accessory igneous rock minerals, 

sphene and zircon.

Laboratory studies of the stream-gravel and 

placer concentrates indicated the presence of some 

radioactive material in one sample. The radioactivity 

of this sample, also, is due to trace amounts of sphene 

and zircon.

Therefore, the results of the studies made in the 

field and upon the samples collected indicate that there 

is little likelihood of finding high-grade uranium ores 

at the sites and prospects investigated. However, 

there are many other areas in the eastern Alaska 

Range which have not been studied and in which private 

prospecting should be encouraged.

HOPE CREEK AND MILLER HOUSE-CIRCLE HOT

SPRING AREAS 

By Walter S. West and John J. Matzko

The Hope Creek and Miller House-Circle Hot 

Springs areas, Circle quadrangle, Alaska, were investigated for the occurrence of uranium deposits by 

the U. S. Geological Survey in 1952.

The Hope Creek area is located approximately 

55 miles northeast of Fairbanks and about 10 miles 

north of the Steese Highway (fig. 1). The area constitutes the headwaters sources of Hope, American 

Champion, Little Champion, Nome, and Sourdough 

Creeks. The nearest accessible point to Hope Creek 

is 5 miles north of milepost 67 on the Steese Highway. 

This point is at the end of a tractor trail along Sourdough Creek which will accommodate jeeps and trucks. 

(See fig. 3.)

The Miller House-Circle Hot Springs area is 

about 100 miles east-northeast of Fairbanks (fig. 1) 

and is drained by Mammoth, Independence, Bedrock, 

Boulder, Deadwood, Holdem, Ketchem, Hot Springs, 

Portage, and Half Dollar Creeks. Part of the area is 

accessible from the Steese Highway by roads and trails 

up Mammoth, Independence, Boulder, Deadwood, 

Ketchem, Portage, and Half Dollar Creeks. An airfield at Circle Hot Springs will accommodate small 

planes. (See fig. 4.)

Fluorite, suggestive of the possibility of the 

presence of associated uranium minerals, has been 

reported in the Hope Creek area (Prindle, 1910). 

Uraniferous fluorite and several other uranium-bearing 

minerals were found in the Miller House-Circle Hot 

Springs area in 1949 by White and Tolbert (Wedow, 

White, and others, 1954).,

These areas were examined for the possibilities 

of lode concentrations of uranium during the summer 

of 1952 by Walter S. West, geologist, and George M. 

Haselton, geologic field assistant. Part of the work 

in the Miller House-Circle Hot Springs area was done 

by John J. Matzko, geologist, and Fred Freitag, field 

assistant.

Field work in the Hope Creek area consisted of 

radioactivity traverses on foot with standard portable 

survey meters equipped with interchangeable betagamma and gamma probes, and of the collection of 

rock and mineral samples. Helicopter support for 

part of the work was furnished by the Topographic 

Division of the U. S. Geological Survey.

The examination of the Miller House-Circle Hot 

Springs area consisted of radioactivity traverses by 

foot and car, and by the collection of rock, mineral, 

placer, and water samples. The equipment used for 

measuring radioactivity is the same as that described 

in the section on the eastern Alaska Range.

The equivalent-uranium analyses and mineralogic 

determinations were made at the Geological Survey's 

laboratories at College, Alaska, and Washington, D. C.

This work was done on behalf of the Division of 

Raw Materials of the U. S. Atomic Energy Commission.

Hope Creek area

The geology of the Hope Creek area has been 

described by Prindle (1910, 1913a) and Mertie 

(1937).

The bedrock in the area consists of the Birch 

Creek schist of pre-Cambrian age, intruded by granitic 

rocks and dikes of Mesozoic(?) age (fig. 3).
Chiefly congtomerotes, sandstones, and graywaclies, 

with slates and some 

limestones, chert, and 

greenstone

Base modified from Circle quadrangle, Alaska Reconnaissance Topographic Series

I 0

Geology modified from U. S. Geol. Survey Bull. 525, plate 8 

5 Miles

Figure 3. Geologic sketch map of the Hope Creek area showing sample locations.
EXPLANATION

QUATERNARY MESOZOIC (?) PRE-CAMBRIAN

Approximate 

contact

Birch Creek schist

/

G

Base modified from Alaska Map 38 

Figure 4. Geologic sketch map of the Miller House-Circle Hot Springs area showing 
 Erosion has exposed granite at two localities 

within the area: a small exposure consisting entirely 

of granite talus near the headwaters of Sourdough Creek, 

and a larger mass of granite that forms pinnacles and 

talus on the tops and sides of the high ridges at the 

headwaters of Hope, American, Champion, Little 

Champion, and Nome Creeks. The granite at both localities is a biotite -tourmaline variety, and its texture 

ranges from medium-grained equigranular to coarsegrained porphyritic. The accessory minerals include 

zircon, sphene, garnet, andpyrrhotite. Quartz and 

quartz-tourmaline veins occur in the granite. Granitic 

and aplitic dikes ranging from slightly less than 1 inch to 

6 feet in width are of rather common occurrence in the 

granite.

In the Hope Creek area the Birch Creek schist 

consists mostly of quartz-mica schist. The occurrence 

of quartz-pyrite-fluorite veins in the schist adjoining 

the granite has been reported (Prindle, 1910; Mertie, 

1937) but was not confirmed during the 1952 investigation. Pyrite was observed at several places along the 

granite-schist contact.

Radioactivity traverses in the Hope Creek area 

indicated that the granite bedrock and granite talus were 

more radioactive than the adjacent schist bedrock and

schist talus. For this reason sampling was confined 

to the granitic rock localities. Sample locations are 

shown on figure 3. Equivalent-uranium analyses of 

unconcentrated crushed rock samples from the Hope 

Creek area are given in table 4. Laboratory studies 

revealed that most of the radioactivity was confined to 

the minerals present in the heavy-mineral fractions 

(sp gr greater than 3.3) of the samples. The mineralogy 

of the heavy-mineral fractions of selected samples is 

given in table 5.

Sample 4474, containing 0.055 percent equivalent 

uranium, was the most radioactive sample collected 

in the Hope Creek area. The rock occurs as float in 

a small saddle between two large granite pinnacles on 

the high divide between the middle and south headwater 

forks of American Creek (fig. 3). The granite float 

rock in this sample contains such an intricate network 

of hematite-goethite veinlets that it appears to be 

brecciated. No uranium-bearing minerals could be 

identified. An alpha plate made of the sample indicates 

that the radioactivity is probably due to a radioactive 

element or elements occurring as impurities in the 

goethite or in very minute discrete minerals, not 

discernible under the petrographic microscope, mixed 

with the goethite. Zircon probably contributes a small 

amount of radioactivity to the sample.

Table 4. Equivalent-uranium analyses of samples, Hope Creek area, Alaska

[ By U. S. Geological Surrey laboratory, College, Alaska]

Sample 

number

4470 

4471

4472 

4473 

4474

4475 

4476 

4477 

4478

4479 

4480

4481 

4482

4483 

4484 

4485

4486 

4487 

4488 

4489 

4490 

4491

Location

Divide between north headwater fork of 

Hope Creek and south headwater fork 

of American Creek.

Ridge between south and middle headwater 

forks of American Creek.

_ _ __ _ _ r\n _ ___

_ _____ __ -rln- ________ - _ ____ -- __ _ - _

Left limit, north fork of Hope Creek 

Granite-schist contact between the middle 

and north headwater forks of American 

Creek. 

Divide between American and Champion 

Creeks . 

Divide between middle and north headwater 

forks of American Creek. 

 do 

Left limit, north fork of American 

Creek. 

Granite -schist contact at head of north 

fork of American Creek. 

Saddle on divide between north headwater 

fork of Hope Creek and Nome Creek. 

Divide between south headwater fork of 

Hope Creek and Nome Creek.

_____ __ _ ____ H n _____ __ _ ____ _ __ _ __ _ _____ _________ __ _

. do 

__ _ ______ -rln- __ _____ ______ _ _ - _ __ - ___

Type of material

Granite bedrock 

____ _ ____ Hn _ ______________

Granite talus 

fl n~M -M r» r\i Ire* - - __-.-.-.-...

Granitic talus 

Granitic dike talus - 

Granite talus 

Granite bedrock 

Granite talus 

Granite bedrock 

_ ____ _ _ _ _r1n _ _____ ___ _____ _

Equivalent 

uranium 

(percent)

0.003 

.004

.003 

.004 

.055

.003 

.002 

.004 

.002

.003 

.002

.003 

.004

.001 

.003 

.004

.003 

.002 

.003 

.001 

.003 

.003

10
Table 5- Mineralogy of heavy-mineral fractions (sp gr greater than 5-5) of selected samples,

Hope Creek area, Alaska

IX indicates mineral is present but amount not determined]

Minerals

AT "] a n -t -\-f* ( 9 \ __ _ _

Biotite 

Epidote 

Fluorite 

/"J*5 T*nO"f~ __L __L

ri/"\^ ^"hl t'£^^__ u ._,_ __ u _,_

TT^m in "t~ "? "f o

Hornblende 

Ilmenite 

MflT nrl-il i-e> - - _

Molybdenite 

RiTMl^ -

Stlbnlte 

*7 1 TV* f^ilTl _ »____«_ ___ __ __

Estimated volume percent of minerals 

present In samples

4470

2

1

10 

9

1

Tr.

50

Tr.

15 

1

1 

10

4471

2 

Tr.

Tr.

5

Tr.

40

1

50

4

4475

Tr.

1

10

Tr.

1 

80

Tr. 

7

4474

X 

X 

X

 

X 

X

4477

9

10

Tr.

20

60

1

447B

1

2

21

20

1 

25 

50

Tr.

4482

25

50

2

12 

11 

2

4485

Tr.

5

25 

16

4 

11

Tr.

16

 

Tr. 

25

4486

 

7 

Tr.

1

15 

12

Tr.

Tr.

45

Tr.

20

Tr.

4487

8

Tr.

Tr.

 

Tr.

 

Tr.

50

 

40 

2

The radioactivity of the. remaining samples from 

the Hope Creek area is attributed to the presence of 

zircon, sphene, hematite, and allanite( ?). In addition 

to these minerals, fluorite, topaz, limonite, apatite, 

garnet, scheelite, and malachite may contain trace 

amounts of uranium as an impurity, as in the Miller 

House-Circle Hot Springs area. However, none of the 

minerals in samples from the Hope Creek area has been 

subjected to fluorimetric tests for uranium.

Niobium and tantalum have been detected spectroscopically in trace amounts in the heavy-mineral fraction of sample 4473 (fig. 3) and may be present in the 

rutile which constitutes an estimated 80 percent of this 

fraction of the sample (table 5).

Miller House-Circle Hot Springs area

The geology of the Miller House-Circle Hot Springs 

area has been described by Johnson (1910), Prindle 

(1913b), and Mertie (1937, 1938).

Bedrock in the area includes metamorphic and 

igneous rocks consisting of Birch Creek schist of preCambrian age intruded by a granite stock and dikes of 

Mesozoic( ?) age (fig. 4). The exposed part of the igneous stock is composed principally of coarse-grained 

granular-to-porphyritic biotite granite. The common 

accessory minerals are zircon, sphene, allanite, garnet, scheelite, and pyrrhotite. The granite stock has 

a greater area! extent than has been shown on any previous geologic map of the region (Prindle, 1913b, pi. 2; 

Mertie, 1938, pi. 1). The Birch Creek schist is mainly

of the mica and quartz-mica varieties. Feldspathic, 

carbonaceous, and chloritic schists are also present 

in the area. Granitic and aplitic dikes, genetically related to the granite stock, occur in, the granite and adjoining schist. The dikes range in width from a few 

inches to 2 feet. Numerous quartz veins, ranging from 

a fraction of an inch to several feet in width, occur in 

the schist and to a lesser extent in the granite. Most 

of the veins show no signs of mineralization. However, 

pyrite, arsenopyrite, galena, wolframite, and gold have 

been found in a few of these veins.

Stream and bench gravels in the valleys of Porcupine, Bonanza, Miller, Mastodon, Independence, Mammoth, Crooked, Boulder, Deadwood, Switch, Ketchem, 

Portage, and Half Dollar Creeks and the North Fork of 

Harrison Creek have been mined for placer gold. During 

1952 the only active mining in the area was on Independence, Mastodon, Crooked, Deadwood, and Portage Creeks.

Radioactivity traverses by foot and car in the Miller 

House-Circle Hot Springs area disclosed that the granite 

localities are more radioactive than those composed of 

'schist. This conclusion was borne out by the results of 

radioactivity studies of the samples collected in the area. 

The sample locations are shown on figure 4. Equivalenturanium analyses of representative samples are given in 

table 6; with the exception of placer samples, the analyses were made on unconcentrated crushed rock material.

As shown in table 6, the equivalent-uranium content 

ranges from 0.001 to 0.005 percent for the granite samples, 0.002 to 0.004 percent for the dike samples, 0.001 to 

0.002 for the schist samples, and0.001 to0.01 percent for

11
Table 6. Equivalent-uranium analyses of samples, Miller House-Circle Hot Springs area, Alaska

[By U. S. Geological Survey laboratory, College, Alaska]

Sample 

number

4696 

4699 

4698

4697 

4722 

4721 

4720 

4719 

4718 

4717 

4716 

4715 

4714 

4676 

4705 

4704 

4702 

4701 

4706 

4709 

4590 

4690 

4691 

4692 

4693 

4689 

4591 

4587 

4588

4589 

4600 

4596 

4597 

4599 

4598 

4677 

4678

4679 

4680 

4688 

4687

4595 

4685 

4683 

4681 

4592

Location

Mammoth Creek, right limit 

 __ __ do - - __ - - __ __ ______ - -

. _ _ _ _ _ __ _ r\n-~- -

Bedrock Creek^ left limit 

_ _ __ _ ___ _ _ do _ _ ___ _ ___

. _ __ _ rlo - _ _ ___ ___ _

.__ _ _ _ _____ do _ _

.__ _ __ _ ___do _

. _ ________ __ . do _ ___ _ _ _

_ __ _ _ _ _ _ -do- _

Boulder Creek, left limit 

__ _____ _ r] n _ _ _ _ __

__ _ ___ __Hn _

 do - ______ _ __

 _ ___ _ .,_ do- ___________ _______ ________ 

Boulder Creek, stream bed 

Deadwood Creek, 1.5 miles below Svitch Creek _

Deadwood Creek, 0.5 mile below Switch Creek 

 _ _ _ _ ______ do - ___ --

_ __ __ _ _ _ do - - _ __ - -

___ _ _ _r|o -- -__ _

Deadwood Creek, 0.25 mile below Switch Creek -

Discovery Creek, tributary to Deadwood Creek 

_ __ _ --do _ __ _ __ ______ __

_ _ _ _ _ _ do - -

_ __ __ __ _ _ do - _ -

Deadwood Creek, 0.5 mile upstream from road end -

Deadwood Creek, 1 mile upstream from road end 

Deadwood Creek, west tributary below 25 Pup 

Deadwood Creek, 2 miles upstream from road end 

Portage Creek, Carstens 1 mining operation 

_ _ __ _ _ rip, ____

_ __ _ _ __ rlo _ __ _____ _

__ ______________ _ r] n _ ____

Portage Creek, left limit 

 _ _ do- _______ __ __

Divide between Portage and Half Dollar -Creeks 

Half Dollar Greek, right limit 

Type of material

_ ____ -r\n _ __ ____ _ -

do -

_ _ _fl r> _ __ _

Vein in granite 

Granite bedrock 

 do 

Vein in granite 

fVpjQ yi i I" ^ "t~ a "1 1 1 a

. dO 

_ __ do _________

___ _ r] n_ ___ _ _ _

- - do ____ _ ---

 do 

Granite bedrock 

Tin-iron nuggets 

 do 

Equivalent 

uranium 

(percent)

0.001

.004 

.003 

.005 

.005

.004 

.005

.005

.005

.003 

.004 

.001 

.004 

.004 

.004 

.003 

.003 

.004 

.004 

.005 

< .001 

.003 

.005

.003

.004

.005

< .001 

.004 

.001 

.005 

.005 

.002 

.001 

.001 

< .001

.005

.002 

.01 

< .001 

.003 

.003 

.002

.003 

.003

.002

.003

the placer samples. The equivalent-uranium content 

averages 0.004 percent for the granite samples and 

0.003 percent for the dike samples.

A limited number of water samples were taken 

for experimentation in the use of a water-sampling 

technique to locate lode concentrations of uranium in 

an area where radioactivity traversing and rock sampling were of no avail because of the widespread cover 

of disintegrated bedrock, alluvium, and vegetation. The 

analyses are shown in table 7.

Table 7 shows that sample 52AMz 15 from Portage Creek contains a relatively high uranium content 

compared with the average uranium content of fresh waters,

which is IxlO" 8 percent (Irving May, personal communication), and the average uranium content of sea waters, 

which is 3xlO~7 percent (Nakanishi, 1951; and Pietsch 

and Grimaldi, 1954). This may indicate the desirability 

of using a more detailed water sampling technique in 

this and other areas where large expanses of ground 

cover effectively shield radiation that might come from 

the underlying rocks.

Radioactivity and mineraloglc examinations of the 

rock, mineral, and placer samples indicate that most 

of the radioactive minerals are present in the heavymineral fractions (sp gr greater than 3. 3) of these samples 

The minerals found in the heavy-mineral fractions of 

selected samples are listed in table 8.

12
Table 7- Analyses of water samples, Miller House-Circle Hot Springs area, Alaska

[By Ivan Barlow, U. S. Geological Survey laboratory, Washington, D. C., September, 1952]

Sample 

number

52AMz 5 

52AMz 6 

52AMz 10 

52AMz 11 

52AMz 12 

52AMz 15 

52AMz 14 

RPAMy. 1R

Location

Switch Creek, tributary to Deadwood Creek 

___ _ _ -do- _ - -- --- - - --_ ___-._-__ -__

Uranium 

(percent)

0. 33x10 ~ 7 

. 42x10" 7 

1. 56x10 ~ 7 

2.01xlO- 7 

1. 11x10 ~ 7 

1. 74x10 ~ 7 

1. 44x10 ~ 7 

4n_p -x-in-7

Uranium 

(ppb)

0.33

.42 

1.56

2.01 

1.11 

1.74 

1.44 

4n.p

Original sample contained much clay-size material in suspension because of sluicing operation upstream from sample site; therefore, uranium content may 

be high because all solids may not have been removed in subsequent decanting to obtain clear sample, or because more uranium was taken into solution during 

the period of sluicing when more solid material than normal was in suspension and subject to corrosion. Another factor may be that some additional uranium was 

taken into solution from the suspended solids when the sample was acidified prior to decanting.

Table 8. Mineralogy of the heavy-mineral fractions of selected samples from the Miller HouseCircle Hot Springs area, Alaska

Minerals

A~l ~l an1 tp> _ _ ___ __ _

Amphibole 

A -p Q 4* Q oca

Biotite 

Bismuthinite 

PVj~) nr»1 1^> - __ _ - - 

TJ-? f^-rici -i do

Fluorlte 

C*r\e* fh1tp>- - - - 

Gold 

T 1 rrtca v-i -? 4-^

T J^ 1 1 C* f^L"Y"O Tl^

IVf fl cm P* *t~ 1 "t~£*...-. _ _ _ _ _ .

M Q T flr*Vi HT "t~ta _ _

IVIons 7 "i "!"£* m* _ _

P"UT>1 1~P» __ «_ _

P"W~POpViT c\"Y*P* m 1 r*y*oT n "t*ca

PT7~nT>Vioi* n f/#^ _ ._ ^

Rock forming minerals 1 

Rutile 

^r'ViooT ? 4-ci

Sphalerite 

Spinel 

Topaz 

TTv>Q n/^-f- Vi/^yj-i Q n -t -f-ca

WoT "P"PQTT1 "1 "t~ PS

Zircon 

Estimated volume percent of minerals present in samples

4696

Tr.

Tr.

3

Tr.

Tr.

40

Tr.

12

4 

30

2 

2

1 

2 

3

Tr.

1 

Tr.

Tr.

4697

3 

11

Tr.

2

Tr.

Tr.

4

9

Tr.

Tr.

1

50

Tr.

20

4718

 

24

1

10

Tr.

10

 

35

Tr.

5

15

4701

45

25

15

1 

Tr.

1

Tr.

Tr.

Tr.

7

6

4709

50

15

Tr.

 

30

Tr.

5

4691

10

1

2

10

50

5

10

1

Tr.

5

2

2

4689

1

35

40 

22

1

1

4600

1

4

6

1 

5

3

Tr.

 

Tr.

70

2

Tr.

1

4596

 

5 

75

 

10 

4

4

2

4677

Tr.

Tr.

10

Tr.

7

1

1

2 

60 

Tr.

Tr.

4

1

Tr.

1

10

4679

Tr.

1

Tr. 

Tr.

3

Tr. 

3

10

Tr.

5 

50

15

Tr. 

Tr. 

1 

Tr.

1

1 

1 

Tr.

1

Tr.

5

1

4685

25

Tr.

Tr.

 -

1

2

15

 

2

40 

15

Tr.

 

Tr.

4683

20

 

Tr.

3

6

 

10

Tr. 

1

55

Tr.

Tr.

5

1 Mostly quartz and feldspar.

13
Mineralogic studies of the samples revealed that 

fLuorite, which was previously reported in the granite 

bedrock only on Deadwood Creek, also occurs in vugs 

of granitic rock on Portage and Boulder Creeks.

Fluorimetric tests proved that fLuorite, limonite, 

malachite, zircon, sphene, topaz, allanite, garnet, 

uranothorianite, and scheelite contained in some of the 

Miller House-Circle Hot Springs samples were uraniferous. Other minerals listed in table 8, such as 

hematite, goethite, monazite, xenotime, pyrochloremicrolite, and some of the sulfides, may contain impurities or intergrowths of uranium, but none has yet 

been subjected to fLuorimetric examinations. The 

biotite in many of the samples contains pleochroic 

halos. The distribution of the uranium-bearing minerals in samples from the area is summarized in 

table 9.

In addition to the minerals listed in tables 8 

and 9, a nonfLuorescent yellow-green uranium mineral was found in granite bedrock, sample 4677 

(fig. 4), from H. C. Carstens 1 gold-mining operation on Portage Creek. The mineral could not 

be identified because an insufficient quantity was 

available for X-ray determination. Practically all 

of the biotite in this sample contains pleochroic 

halos. The ilmenite contains trace amounts of 

niobium.

The only occurrence of uranothorianite, the most 

important uranium-bearing mineral found in the area, 

was in sample 4679, a sluice-box concentrate also from 

Carstens' mining operation on Portage Creek. The 

uranothorianite occurs as very small black cubes, principally in that fraction of the placer concentrate which 

has a mesh size between minus 100 and plus 200. This 

fraction of the sample contains 0.091 percent equivalent 

uranium. The uranothorianite appears to be responsible 

for most of the radioactivity of the sample. An assay 

made on part of this sluice-box concentrate by the 

Territorial Department of Mines, Fairbanks, Alaska, 

gave 4. 65 percent tungsten trioxide (WO 3 ). Most of the 

tungsten is in the form of wolframite with only minor 

amounts of scheelite.

Although no quantitative analyses for uranium and 

thorium were made on the samples from the Miller HouseCircle Hot Springs area, mineralogic studies indicate 

that most of the radioactivity of these samples is apparently due to uranium rather than thorium.

Summary and conclusions

No lode or placer deposits in the Hope C reek and Miller 

House-Circle Hot Springs areas were found to contain sufficient quantities of uranium-bearing minerals to be of commercial value.

Table 9 Uranium-bearing minerals in samples from the Miller House-Circle Hot Springs area, Alaska

Locality and type of sample

Independence Creek:

Mammoth Creek:

Bedrock Creek:

Boulder Creek: 

Granite 

Deadwood Creek:

"P~I Q(^>OT» 2

Discovery Creek:

Ketchem Creek:

Hot Springs Creek:

Portage Creek: 

Granite 

Half Dollar Creek: 

Granite 

Uranium-bearing minerals

Allanite

X 

X

X

X 

X

X 

X

Apatite

 

X

Pluorite

X

Y1

X

Garnet

X 

X 

X 

X

X 

X

X 

X

X

Limonite

X

X

X

X

Malachite

X 

X

 

Scheelite

X 

X 

X

X 

X 

X

X 

X

X

0

c1CO

X 

X

X 

X

X 

X

N

a0 

EH

X 

X

X

X

Uranothorianite

X

Zircon

X

X 

X 

X

X

X 

X

X

1Mineral present in sample collected by M. G. White and G. E. Tolbert in 1949. 

2Samples collected by M. G. White and G. E. Tolbert in 1949.

14
A wide variety of radioactive minerals were found 

to occur in granite. Certain uranium-bearing minerals 

in the Miller House-Circle Hot Springs area, which are 

also believed to contain uranium in the Hope Creek area, 

appear to be primary accessory minerals in the granite. 

Other minerals, such as fluorite, topaz, and several 

metallic sulfides in both areas, and cassiterite and 

wolframite in the Miller House-Circle Hot Springs area, 

were probably formed as a result of pneumatolytic action 

after the crystallization of the magma or during the late 

stages of crystallization. Some of the minerals in the 

latter group are known to be uranium bearing; therefore, it seems likely that hydrothermal solutions were 

partly responsible for the introduction of uranium during the process of pneumatolysis.

On the basis of present information, the Hope Creek 

area does not appear to be favorable for the occurrence 

of high-grade uranium ores. It should be pointed out, 

however, that the work done in 1952 consisted only of a 

brief reconnaissance primarily intended to locate and 

test reported fluorite occurrences. Prospectors searching the area for other metals should keep in mind the 

possible association of uranium with mineralized zones 

containing hematite of hydrothermal origin, with minerals containing silver, cobalt, nickel, bismuth, and 

fluorine, and to a lesser extent with lode deposits containing copper, tin, lead, molybdenum, and gold.

The investigation conducted by the Geological Survey in 1949 (Wedow, White, and others, 1954) and in 

1952 (this, report) show that there is little hope of discovering commercial concentrations of uranium in the 

Miller House-Circle Hot Springs area by established 

methods of radioactivity traversing with portable survey 

meters, primarily because of the widespread cover of 

vegetation, soil, and disintegrated bedrock. On the 

other hand, this area, particularly the watershed of 

Portage Creek, cannot be ruled as unfavorable for the 

occurrence of uranium in lode deposits, because of the 

relatively high uranium content of water and the presence 

of uranothorianite in concentrates from Portage Creek. 

(See tables 7 and 8.) Prospectors interested in the uranium possibilities of the Miller House-Circle Hot Springs 

area will probably find that geochemical methods of prospecting, such as water, soil, and vegetation sampling, 

would be the best techniques to use in the search for 

uraniferous lodes in the area. Also, the testing of heavymineral concentrates from gravels, slope wash, and 

disintegrated bedrock for radioactivity, in a fashion similar to that used by West (1953) in the Darby Mountains 

of the Seward Peninsula, would aid considerably in localizing the occurrence of the uranothorianite on Portage Creek.

KOYUKUK-CHANDALAR REGION 

By Arthur E. Nelson

The presence of radioactive materials is known in 

two localities in the Koyukuk-Chandalar region (Wedow 

and others, 1951; White, 1952). Accordingly, radioactivity reconnaissance investigations were undertaken 

in the Chandalar mining district and at the Gold Bench 

mining area (fig. 1). Airborne radioactivity traverses 

were conducted over a part of the region while flying 

the party into the region and returning it to Fairbanks.

Radioactivity traverses and outcrop tests were 

made in and around the mines and prospects, mineralized zones, and the country rock at the two localities,

and samples were collected for equivalent-uranium 

determinations and mineralogic studies. Stream gravels were sampled to determine if radioactive minerals 

are being liberated from the bedrock of areas drained 

by the streams.

A standard portable survey meter was modified 

to accept interchangeable 6-inch beta-gamma and 2- by 

20-inch gamma probes, which were used for individual 

outcrop tests and normal ground traverses, respectively. 

For airborne traverses a standard survey meter coupled 

with six 2- by 40-inch gamma probes, connected in parallel, was mounted in a light aircraft (Wedow, 1951).

The field work in this area was conducted in late 

August 1952, by Arthur E. Nelson, geologist, and 

Richard S. Smith, geologic field assistant. This work 

was done on behalf of the Division of Raw Materials of 

the U. S. Atomic Energy Commission.

Geology and radioactivity studies

The Koyukuk-Chandalar Region (fig. 1) lies in the 

southern foothills of the Endicott Mountains which are 

a part of the Brooks Range. The region is drained by 

the south-flowing Koyukuk River on the west and the 

Chandalar River on the east, both of which empty into 

the Yukon River. To the south the area is bounded by 

the Koyukuk flats and the Hodzana highlands; to the 

north, by the crest of the Endicott Mountains.

Maddren (1913) gives an account of the geology of 

the Koyukuk-Chandalar region, and Mertie (1925) gives 

a detailed account of the Chandalar mining district; hence, 

only a summary of the main geologic features is presented herein.

The rocks of the region consist of a series of sedimentary strata which have been folded and faulted and 

range from pre-Cambrian or pre-Ordovician to Cretaceous in age, and of igneous rocks of Paleozoic and 

Mesozoic age. Generally, the oldest sedimentary rocks 

occur in the southernmost extremities of the district 

and are overlain by successively younger sedimentary 

beds to the north.

The southernmost belt of sedimentary rocks, consisting chiefly of quartzite and quartzitic schist of preCambrian or pre-Ordovician age, is folded along a general east-west axis and has a northerly dip. Overlying 

the quartzite and quartzitic schist is a sedimentary sequence of Paleozoic age, now metamorphosed to schist 

and phyllite. These latter rocks have the greatest area! 

distribution in the region and have the same general attitude as the underlying quartzite and quartzitic schist. 

Limestone of Silurian age overlies the metamorphic rocks 

of Paleozoic age and is in turn overlain by Devonian and 

Mississippian slates, sandstones, and limestones. In 

the southern part of the district Cretaceous conglomerates, sandstones, and shales lie unconformably on the 

older rocks. The igneous rocks in the region consist 

of Upper Silurian or Lower Devonian granitic gneiss and 

a granodiorite of possible Mesozoic age. Greenstones 

of late Paleozoic age occur as dikes, sills, and flows 

and are associated with all rocks of Paleozoic and prePaleozoic( ?) age.

No significant radioactivity anomalies were noted 

during any of the airborne traverses conducted in the

15
Koyukuk-Chandalar region. The airborne traverses 

were made over many mineralized zones located in and 

around granitic masses which were not easily accessible 

otherwise. Most of these areas are located in the region 

drained by the North Fork of the Koyukuk River. In general that area drained by the South Fork of the Koyukuk 

River has a heavy cover of overburden, and it was impossible to get effective radioactivity coverage; thus, 

little traversing was done there.

Chandalar mining district

The Chandalar mining district (fig. 5) is located 

about 6 miles east-northeast of the head of Lake Chandalar and comprises an area of about 100 square miles. 

Prospecting for placer- and lode-gold deposits has been 

carried on intermittently in this district since 1900. 

Placer mines have been located on four creeks in the 

district, including Little Squaw, Big Squaw, and Tobin 

Creeks. Development work on numerous quartz veins 

in the district consists of adits, shafts, and opencuts, 

most of which are now inaccessible. Hence, all that 

can be seen of the geological relationships is at the surface outcrops.

Mining activity in recent years has been somewhat 

limited; in 1952 only five men were engaged in either 

prospecting or mining operations. One man was prospecting on a very limited scale, and two men were developing a quartz vein on the divide between Big and 

Little Squaw Creeks. Sluicing at a small placer mine 

on Tobin Creek and at another on Big Creek, each a oneman operation, was considerably hampered because of 

a limited water supply.

Sedimentary and igneous rocks of Paleozoic age 

were the only formations seen in the district besides the 

unconsolidated stream and glacial deposits. The sedimentary rocks are primarily mica schist with minor 

amounts of chlorite schist. The schist is cut by greenstone dikes and locally by small bodies of granitic gneiss, 

Numerous gold-bearing quartz veins occur in the schist 

and are apparently confined to four main zones, all of 

which have a westerly trend, but some dip to the north 

and others to the south. Locally, minor veins are subsidiary to the more persistent ones. These subsidiary 

veins have different trends which are probably the result of local stresses superimposed upon regional 

structure.

Radioactivity traverses were made across and 

along mineralized zones, ore dumps, and adits; specific outcrop tests were made and a general traverse 

conducted in the main drainage systems of the district. 

At no point along any of the traverses was a significant 

anomaly noted. Samples were collected from these 

areas for further study in the laboratory. The results 

of laboratory studies of the samples are summarized 

in tables 10 and 11.

Laboratory studies found traces of monazite, zircon, and uranothorianite in certain stream samples collected during the summer field season of 1952, as indicated in table 10. A few grains of pyrite and galena and 

one grain of molybdenite were found in the sample containing the uranothorianite. This suggests the possibility of sulfide minerals occurring in veins in the drainage basin of Big Squaw Creek, which may be the source 

of the uranothorianite.

Gold Bench

Gold Bench, a high-level deposit of stream gravels, is situated on the northwest side of the South Fork 

of the Koyukuk River (fig. 1). Placer gold has been 

mined from these gravels since about 1899, but no 

mines were being operated in 1952. The gold-bearing 

gravels consist mostly of schist fragments with varying 

amounts of quartz, chert, and igneous rocks, and they 

overlie a thick sequence of wash deposits. The size of 

the unconsolidated sediments (gravel and wash) ranges 

from coarse to fine grained. The deposits are crudely 

stratified and are about 200-300 feet high on the south 

side of the river. Little is known of the geology in the 

vicinity of Gold Bench, and the actual source of the gravels is unknown at the present time. The following minerals have been observed by White (1952, p. 11) in concentrates from Gold Bench: magnetite, garnet, hematite, zircon, olivine, epidote, sphene, pyrite, scheelite, 

galena, chalcopyrite, rutile, cinnabar, cassiterite, 

bismuthinite( ?), and thorianite( ?).

A radioactivity traverse of the entire mining area 

of Gold Bench was made, the stream gravels sampled, 

and a placer concentrate obtained. The traverse indicatedTio radioactivity of any significance above the normal background count. However, a placer concentrate 

obtained contains 0.18 percent equivalent uranium. The 

results of the laboratory studies on the radioactivity of 

the samples are summarized in table 10.

Summary and Conclusions

The results of radioactivity investigations in the 

Koyukuk-Chandalar region during the summer of 1952 

showed that no high-grade radioactive deposits are 

associated with certain metalliferous lode deposits in 

the Chandalar mining district that were previously deemed 

favorable for the occurrence of uranium ores.

Trace amounts of monazite have been found in 

samples from Little Squaw, Big Squaw, and Tobin Creeks 

in the Chandalar mining district, but traverses in the 

area did not locate the bedrock source of the monazite. 

However, Mertie (1925, p. 263) has suggested the source 

of the monazite to be some highly acid granitic rock, 

possibly of pegmatitic character. The results of investigations in the Chandalar mining district indicate that 

there is little possibility of finding commercial quantities of monazite in the stream gravels.

Traces of uranothorianite have been found in the 

stream gravels of the middle fork of Big Squaw Creek in 

the Chandalar mining district. The valley of Big Squaw 

Creek is about 5 miles long, and it divides into west, 

middle, and east forks approximately 1. 5 miles from its 

mouth. Stream-gravel samples were taken from each 

fork, but only the sample from the middle fork contained 

uranothorianite.

A traverse of a part of the ridge at the head of the 

valley of Big Squaw Creek revealed no anomalous radioactivity. Likewise, no prominent zones of oxidation or 

alteration were found in the valley of Big Squaw Creek 

to denote the presence of sulfide-bearing mineral deposits that could be the source of the uranothorianite and 

the other metallic minerals occurring in the placer concentrates. It is highly probable that such mineral deposits exist, but they may not be very extensive because only

16
Base from Chandalar quadrangle, Alaska 

Reconnaissance Topographic Series

0_________I_______2_______3_______4_______5 Miles

Scale

EXPLANATION 

........ Radioactivity traverse Trail

O Rock sample Concentrate 

9? Lode mine X Placer mine 

 Building

Figure 5. Sketch map of the Chandalar mining district showing sample locations.

17
Table 10. Equivalent-uranium analyses and radioactive

[Equivalent-uranium analyses and mineral identifications by J. J. Matzko and A. E. Nelson. X indicates that magnetic fraction cont

minerals of stream and placer concentrate 

region, Alaska

Sample 

number

4652

4655

4657

4658

4659

4640

4641

4642 '

Location

TnVnn P-r>p>p>lr _ 

Little Squaw

Creek. 

East fork of Big

Squaw Creek. 

Middle fork, Big

Squaw Creek. 

West fork, Big

Squaw Creek.

west of Big 

Squaw Creek. 

Gold .Bench,

south fork of 

the Koyukuk 

River.

. __ dn _ _ __ _

rn-rrytrt

of 

sample

__do 

 do 

__do 

__do 

._dn- --

 do 

"P~I 53 f"»OTl

For

original 

concentrate

< 0.001

< .001

< .001

.001

< .001

< .001

< .001

-i D

For heavy

fraction: 

methylene 

iodide 1

0.01

.002

< .001

.018

.005

.005

.015

0.1 amp

For ma£

0.4 amp

jnetic fr«

0.5 amp

2 0.10

2y

action: n

0.7 amp

2 f\ Ar\c

lethylene

1.0 amp

3 5-2

5 .05

1 Heavier than methylene iodide (sp gr 3-3).

2 Monazite. 

3 Uranothorianite.

* Zircon.

5 Sphene and thorite(?).
Table 11. Radioactivity of rock and ore samples from the Koyukuk-Chandalar region, Alaska

[ By U. S. Geological Surrey laboratory, College, Alaska]

Sample 

number

4631 

4633

4634

4636

Location

Mine at the head of Tobin Creek 

Mine on divide between Little Squaw and Big Squaw 

Creeks.

Type of sample

We* In ___ __.._ _- - -

Equivalent 

uranium 

(percent)

< 0.001

.001

< .001

.001

trace amounts of the metallic minerals were found. 

It is thought that these minerals were not deposited 

by glacial action because the upper valley of Big 

Squaw Creek does not appear to have been glaciated, 

nor do the tops of the mountains at its head seem 

to have been overrun by glaciers, as has been 

pointed out by Mertie (1925).

Thus, the traces of uranothorianite and metallic 

sulfides in concentrates from the placers of the valley 

of Big Squaw Creek suggest that this locality may be 

favorable to prospect for a uraniferous lode deposit. It 

should be stressed, however, that the discovery of the 

bedrock source of the uranothorianite at this locality 

would not necessarily lead to commercial production of 

uraniferous ores. The size, extent, and grade of a deposit, insofar as they can be determined by surficial investigations, as well as the remoteness and, hence, accessibility of the district require much consideration 

and study prior to exploration and development.

Uraniferous thorianite has been noted in placer 

concentrates taken from Gold Bench previous to 1952 

(White, 1952, p. 8-12). A placer concentrate obtained 

during the summer of 1952 contains 0.18 percent equivalent uranium that is due primarily to uranothorianite 

and, to a lesser extent, to monazite.

Maddren (1913, p. 106), in discussing the origin 

of the placer gold and, presumably, of the uranothorianite 

occurring at Gold Bench, suggests that the mountains on 

the south side of the South Fork of the Koyukuk River are 

the probable source area, because the rocks there are 

known to contain gold. These mountains are drained by 

tributaries of the South Fork and are formed in part of 

igneous rocks that may have genetically associated metalliferous lode deposits that could be the source of the 

radioactive and metallic minerals in the placers at 

Gold Bench. A reconnaissance consisting of the radioactivity testing of concentrates from the placer gravels 

of minor creeks and slope wash in the mountains south 

of the South Fork might locate the source of the uranothorianite. A similar technique was used in 1947 by 

West and Matzko (Gault, Killeen, West, and others, 

1953, p. 21-27) and in 1948 by West (1953) on the eastern part of the Seward Peninsula, Alaska, where soil 

conditions and sampling problems are about the same 

as in the vicinity of the South Fork of the Koyukuk River.

FORTYMILE DISTRICT 

By John J. Matzko

A sample of fresh fluorite ranging from colorless 

to blue, green, and purple was received by the Territorial Department of Mines in the summer of 1952 from

Mr. George King, Boundary, Alaska. The writer learned 

from Mr. King that the sample came from Mr. George 

Robinson of Jack Wade on Wade Creek; also, that 

Mr. McDonald, who was prospecting in the Fortymile 

district, had uncovered some fluorite along the highway 

east of Chicken, Alaska (figs. 1 and 6).

A party consisting of John J. Matzko, geologist, and 

FredFreitag, field assistant, investigated these occurrences during the latter part of August 1952. This work was 

done on behalf of the Division of Raw Materials of the U. S. 

Atomic Energy Commission.

Wade Creek

Wade Creek heads against Steel- Dome and flows 

almost due southwest to join Walker Fork. The bedrock in Wade Creek includes several varieties of schist 

and some thin-bedded ferruginous limestones, all of 

which are a part of the Birch Creek schist of preCambrian age (Prindle, 1909; Mertie, 1938). Several 

small bodies of granitic rocks intrude schist in the 

valley. A basaltic dike is reported to occur near the 

head of the creek (Prindle, 1909, p. 36).

Mr. Robinson, who had given the fluorite sample 

to Mr. King for identification, was working a small 

gold-placer deposit on Wade Creek. Robinson reported 

that he had found the fluorite in a prospect pit which he 

had dug on a fourth left tributary above the mouth of 

Wade Creek (fig. 6) and that the pit had since caved. 

The source of the fluorite was not determined.

A concentrate of stream-gravel (sample 4626, 

fig. 6) from Wade Creek taken below the mouth of the 

fluorite-bearing tributary has an equivalent-uranium 

content of 0.001 percent. No radioactive minerals were 

found in the sample.

Walker Fork

Mr. George King reported to the writer that 

Mr. McDonald, prospecting in the Fortymile district, 

Eagle quadrangle, had uncovered some fluorite along 

the highway east of Chicken. The fluorite monument, 

which McDonald had set up to mark the location, was 

found east of Chicken and about 2 miles west of the 

Walker Fork bridge on the south side of the road (fig. 6). 

Only a few extra pieces of weathered fluorite besides 

those of the marker were found. A traverse made with 

a Geiger counter did not locate any anomalous radioactivity.

A channel sample, 4627, taken across the zone of 

decomposed rock contains only trace amounts of radioactive minerals 0.003 percent equivalent uranium as

19
Base from Eagle quadrangle, Alaska Reconnaissance Topographic Series

i i 10 15 

Figure 6. Topographic map of part of the Fortymile district, east-central Ala
determined in the laboratory. Mineralogic examination 

of the sample indicates that goethite and hematite are 

the major constituents; colorless fluorite constitutes 

about 5 percent of the sample, and iron-stained mica, 

pyrite, and rutile occur in minor amounts.

Bedrock outcrops alongside the road west of the 

bridge across Walker Fork and on either side of the 

sample fluorite zone consist of fresh-appearing granodioritic rock. Details of the geology of the area have 

been discussed by Prindle (1909) and Mertie (1938).

LITERATURE CITED

Gault, H. R., Killeen, P. L., West, W. S., and 

others, 1953, Reconnaissance for radioactive deposits in the northeastern part of the Seward Peninsula, Alaska, 1945-47 and 1951: U. S. Geol. Survey Circ. 250.

Johnson, B. L., 1910, Occurrence of wolframite and 

cassiterite in the gold placers of Deadwood Creek, 

Birch Creek district (Alaska): U. S. Geol. Survey 

Bull. 442-F, p. 246-250.

Maddren, A. G., 1913, The Koyukuk-Chandalar region, Alaska: U. S. Geol. Survey Bull. 532.

Mertie, J. B., Jr., 1925, Geology and gold placers 

of the Chandalar district, Alaska: U. S. Geol. Survey Bull. 773-E, p. 215-263.

_______1937, The Yukon-Tanana region, Alaska: 

U. S. Geol. Survey Bull. 872.

JL938, Gold placers of the Fortymile, Eagle,

and Circle districts, Alaska: U. S. Geol. Survey 

Bull. 897-C, p. 133-261.

Moffit, F. H., 1938, Geology of the Slana-Tok district, 

Alaska: U. S. Geol. Survey Bull. 904.

_______1943, Geology of the Nutzotin Mountains, 

Alaska, with a section on the igneous rocks and a section 

on gold deposits near Nabesna, by R. G. Wayland: 

U. S. Geol. Survey Bull. 933-B, p. 103-199.

Nakanishi, M., 1951, Uranium content of sea water: 

Chem. Soc. Japan, v. 24, no. 1, p. 36.

Pietsch, Audrey, and Grimaldi, F. S., 1954, The 

fluorimetric determination of uranium in nonsaline 

and saline waters, in Grimaldi, F. S., May, Irving, 

Fletcher^ Mary H., and Titcomb, Jane, Collected 

papers on methods of analysis for uranium and thorium: U. S. Geol. Survey Bull. 1006, pt. 17.

Prindle, L. M., 1909, The Fortymile quadrangle, 

Yukon-Tanana region, Alaska: U. S. Geol. Survey 

Bull. 375.

_______1910, Sketch of the geology of the northeastern part of the Fairbanks quadrangle (Alaska): 

U. S. Geol. Survey Bull. 442-F, p. 203-209.

_1913a, A geologic reconnaissance of the

Fairbanks quadrangle, Alaska: U. S. Geol. Survey 

Bull. 525.

_1913b, A geologic reconnaissance of the

Circle quadrangle, Alaska: U. S. Geol. Survey 

Bull. 538.

Thorne, R. L., 1946, Exploration of argentiferous 

lead-copper deposits of the Slana district, Alaska: 

U. S. Bureau of Mines Kept, of Inv. 3940.

Wedow, Helmuth, Jr., Killeen, P. L., and others, 

1954, Reconnaissance for radioactive deposits in 

eastern interior Alaska, 1946: U. S. Geol. Survey 

Circ. 331.

Wedow, Helmuth, Jr., White, M. G., and others, 

1954, Reconnaissance for radioactive deposits in 

east-central Alaska, 1949: U. S. Geol. Survey 

Circ. 335.

West, W. S., 1953, Reconnaissance for radioactive 

deposits in the Darby Mountains, Seward Peninsula, 

Alaska, 1948: U. S. Geol. Survey Circ. 300.

UNPUBLISHED REPORTS

Van Alstine, R. E., 1945, Report on the molybdenite occurrence at Rock Creek, Alaska: U. S. 

Geol. Survey report for the War Production 

Board.

Van Alstine, R. E., and Black, R. F., 1945, Mineral deposits at Orange Hill, Alaska: U. S. Geol. 

Survey report. (In open files.)

Wedow, Helmuth, Jr., 1951, Adaptation of portable 

survey meters for airborne reconnaissance with 

light planes in Alaska: U. S. Geol. Survey Trace 

Elements Memo. Rept. 323. (In open files released through Technical Information Service, 

U. S. Atomic Energy Commission, Oak Ridge, 

Tennessee.)

Wedow, Helmuth, Jr., and others, 1951, Interim 

report on an appraisal of the uranium possibilities of Alaska: U. S. Geol. Survey Trace 

Elements Memo. Rept. 235. (In open files.)

21 INT.-HIP. SEC.. WASH.. D.C.«»1430



UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

GEOLOGICAL SURVEY CIRCULAR 332

THE KATHLEEN-MARGARET (K-M) COPPER PROSPECT ON THE 

UPPER MACLAREN RIVER, ALASKA

By Robert M. Chapman and Robert H. Saunders

Prepared in cooperation with the 

Department of Mines, Territory of 

Alaska.

Washington, D. C., 1954

Free on application to the Geological Survey, Washington 25, D. C.
146"40' 146° 20' 146° 

COPPER 

PROSPECT,

Adapted from U.S.Geological Survey m

by R.H. Sounders, Department of 

Figure 1. Map of upper Maclaren River, Alaska.
THE KATHLEEN-MARGARET (K-M) COPPER PROSPECT ON THE 

UPPER MACLAREN RIVER, ALASKA

By Robert M. Chapman and Robert H. Saunders

CONTENTS 

Page Page

Abstract..................................... 1

Introduction.................................. 1

Location and accessibility ..................... 1

Physical features

and climate ................................ 2

Property and ownership ....................... 2

Geology and mineral deposits...............'.. 2

Geology................................ 2

Mineral deposits........................ 4

Sampling and assays ......................... 5

Conclusion and recommendations .............. 5

Literature cited............... .............. 5

ILLUSTRATIONS

Page

Figure 1. Map of upper Maclaren River, Alaska............................................. Faces page 1

2. Sketch map of claims showing Albertson-Pettyjohn copper prospect, Maclaren River.............. 3

TABLE

Table 1. Analyses of six samples assayed by the Department of Mines Assay Office at College, Alaska...... 5

ABSTRACT

The Kathleen-Margaret (K-M) prospect is in the 

Mount Hayes quadrangle on the west side of the Maclaren 

Glacier about 25 miles south of the peak of Mount Hayes. 

The proposed route of the Denali Highway is about 

9 miles south of the prospect.

Several veins have been discovered on the prospect, but only one appears to be minable. The vein is 

about 10. 5 feet thick; it strikes N. 3°-4° E. and dips 

70°-90°W. Along its east wall there is a zone of nearly 

barren quartz 1. 5 to 2 feet thick. The richest ore, 

samples from which have assayed 30 to 45 percent 

copper, is confined to a zone about 1. 5 to 2 feet thick 

adjacent to the nearly barren zone. Assays of samples 

from the remainder of the vein, about 7 feet thick, have 

ranged from 3. 5 to 12. 5 percent copper.

INTRODUCTION

In 1950 E. O. Albertson and F. S. Pettyjohn, Jr., 

of Big Delta, Alaska, formed a partnership and prospected the vicinity of Chistochina, a gold-placer 

district on the south slope of the Alaska Range about 

20 miles east of the Richardson Highway. From 

Chistochina they gradually worked westward until they 

reached the Maclaren River drainage. In 1952Pettyjohn 

discovered an outcrop of a copper-bearing vein on the 

west side of the Maclaren Glacier.

From August 11 to 14, 1953, the copper-bearing 

outcrops and adjacent area were examined by 

R. M. Chapman of the U. S. Geological Survey and

R. H. Saunders of the Department of Mines, 

Territory of Alaska. This report is written from notes 

taken during that examination and from information furnished by Albertson and Pettyjohn.

LOCATION AND ACCESSIBILITY

The Kathleen-Margaret (K-M) copper prospect 

is in the Mount Hayes quadrangle at latitude 

63°17' N. and longitude 146°35' W. By U. S. Geological Survey classification, it is in the upper 

Susitna valley district of the Cook Inlet region 

and by the U. S. Bureau of Mines classification, 

the prospect is in the Valdez Creek subdistrict 

of the Cook Inlet-Susitna region. The claims lie 

on the west side of the Maclaren Glacier about 

25 miles south of the peak of Mount Hayes. A 

glacial stream flows along the lower part of the 

west side of the glacier; it is fed by eastwardflowing tributaries that head in icefields on the 

ridge west of the glacier. The main outcrop is 

in the north wall of the gulch that has been 

eroded by Discovery Creek, named by Albertson 

and Pettyjohn, the first tributary upstream from 

the terminus of the glacier. This outcrop is at 

an altitude of 4,100 feet.

The prospect is about 9 miles north of the 

proposed route of the Denali Highway between 

Paxson and Cantwell. The highway is now under construction. The extent of the road at the end of 

the 1953'working season is shown on figure 1. 

By the end of 1954 the road probably will be 

completed as far as the Maclaren River.
An access road from the prospect to the Denali 

Highway would be 9 to 10 miles long. The flood plain 

of the Maclaren River probably would provide the best - 

route for the first 7 or 8 miles of the access road. The' 

flood plain consists mostly of coarse well-drained 

gravel and it appears that the building of a road on the 

gravel would require little more than clearing boulders 

from the roadway. A mile or two south of the prospect 

the road would leave the flats and would be built on the 

lower slopes on the west side of the river. This part 

of the road would be more difficult to build, but there 

are no obstacles that would make the cost of construction prohibitive.

Alter the necessary roads are built, the prospect 

will be 50 miles from Paxson, 245 miles from Valdez, 

and 450 miles from Seward by road. Snipping over the 

Alaska Railroad would require a truck haul of 105 miles 

to Cantwell; the distance by rail from Cantwell to Seward 

is 320 miles.

There are only a few small lakes within 10 miles 

of the copper prospect, and the nearest lake that is 

suitable for use by small pontoon-equipped aircraft is 

situated near the west bank of the Maclaren River about 

2. 5 miles south of the terminus of the Maclaren Glacier 

and about 5 miles south of the prospect. Several large 

lakes, 12 to 20 miles southeast of the prospect area, 

would be suitable for larger pontoon aircraft.

A landing field large enough for multiengine aircraft could be constructed on the braided flood plain of 

the Maclaren River. Many stretches of the alluvial gravel 

between Cottonwood Creek and Maclaren Glacier are 

nearly smooth and clear enough in their natural state 

to serve as a landing strip. If a permanent strip is 

built on the flood plain, it will be necessary to raise 

the level of the runway surface and possibly to build 

protective dikes to prevent flooding during extreme 

high water stages, as channel shifting is frequent in 

the braided channel areas.

The prospect can be reached conveniently by 

small pontoon aircraft from one of the lakes along the 

Richardson Highway to the small lake on the west side 

of the Maclaren River. Pontoon planes are available 

for charter at Summit and Meier Lakes.

PHYSICAL FEATURES AND CLIMATE

The upper Maclaren River area is a part of the 

rugged glaciated south slope of the Alaska Range. The 

altitudes range from about 3, 000 to 8, 000 feet and the 

copper-bearing veins are exposed at altitudes of 

3,800 to 4,100 feet. The mountain slopes are predominantly steep, and the average relief is about 2, 000 feet. 

The main Maclaren River valley and the other large 

valleys are wide, flat floored, typical glacial valleys, 

and the smaller tributary valleys are either small 

glacial valleys with moderate gradients, or small, 

sharp postglacially eroded valleys with gradients steep 

enough to produce cascades and small waterfalls. Many 

of the small glacial hanging valleys are connected to the 

main valley by a postglacial notch in their lip. Discovery Creek is an example of this.

There are several glaciers in the vicinity of the 

copper prospect. The large Maclaren Glacier is about 

10 miles long and occupies the head of the main Maclaren

valley. A number of cirque glaciers and small icefields, remnants of larger tributary glaciers, are 

present at altitudes of 5, 000 feet and higher in the 

peaks between the Maclaren River and the West Fork.

A flow of water adequate for the needs of a camp 

and mining operations is available during the summer 

months from any of the small streams that are fed by 

snowfields and glaciers. In addition to the melt water, 

precipitation is frequent in this area during the summer, 

according to Pettyjohn's report and the writers' experience during the field examination. The Maclaren 

River carries a large volume of water, but much of 

its upper course is braided, and fordings with tractors 

and other equipment can be made in the braided stretches 

if reasonable care is used.

The area within several miles of the copper prospect and the-Maclaren Glacier is devoid of timber. The 

vegetation consists of scrub willows and alders in the 

main valley floor and in a few protected valleys, and 

low brush and small tundra plants, mosses, and lichens 

on the slopes and mountains. Timberline in this part 

of the Alaska Range is at an altitude of 2, 500 to 3, 000 feet. 

It is reported that some spruce timber of usable size 

can be obtained on the Maclaren River about 9 miles 

south of the terminus of the Maclaren Glacier, but 

most of the timber would have to be hauled from greater 

distances.

The climate in this area is moderately severe. 

Weather records for 7 years between 1914 and 1944 

taken at Paxson, about 36 airline miles east-southeast 

of the copper prospect, show 18.36 inches mean annual 

precipitation, most of whichf alls during the period of June 

through September.- The snowfall ranges from about lOto 

22 inches per m onth during the period from October through 

April. Written records, and personal observations indicate that cloudy skies and strong winds are common. The 

mean temperature at Paxson is 25.3° F. The mean maximum temperature during June, July, and August is about 

65°F, and during December and January is about 8 degrees. 

The mean minimum temperature is about 37° Fduring June, 

July, and August, and about -12° Fduring December and 

January.

PROPERTY AND OWNERSHIP

The two owners have staked 10 claims to cover 

the veins that they have discovered. The claims are 

designated Kathleen-Margaret Nos. 1 to 10. The locations of the claims are shown on figure 2. Each 

claim is owned jointly by the two partners. The location certificates are recorded in the records of the 

U. S. Commissioner at Talkeetna, Alaska.

GEOLOGY AND MINERAL DEPOSITS

Little time was available for general study of the 

rock formation during the visit to the copper prospect, 

and only the rock exposed in the immediate area of 

the prospect was examined. The formations have been 

generally defined and mapped by Moffit (1912) and 

distant observations and examination of aerial photographs confirm his reconnaissance mapping.

The country rock in which the copper-bearing 

quartz veins occur is chiefly a green diabasic lava.
Outcrop of copper-bearing vein, 

showing dip

Vertical copper bearing vein

400

I

1200 Feet

_I

From compass survey by R.M.Chapman,U.S.Geological Survey, 

and R.H. Sounders, Deportment of Mines, Territory of Alaska, 

September 1953

Figure 2. Sketch map of claims showing Albertson-Pettyjohn copper prospect, Maclaren River, Alaska.

3
Moffit assigned'a late Carboniferous or early or 

middle Triassic age to this unit, which is exposed in a west-trending range of low mountains 

that lies between Summit Lake and the Susitna 

River. Capps (1940, pi. 2) shows the same unit 

as pre-Cretaceous (Mesozoic). As described by 

Moffit (1912, p. 29-30):

"The rocks consist largely of diabase and locally are 

amygdaloidal. They are associated with argillites, 

tuffs, and tuffaceous conglomerates in a number of 

places and are intruded by diabases and by dikes of 

less basic, light-colored porphyritic rock. Intrusions 

of peridotite have taken place in the Tangle lakes 

vicinity, and probably also in other places, for 

boulders of this character were found in some of the 

younger conglomerates near the glacier at the head of 

the east fork of Maclaren River. The lava flows have 

been deformed in the general folding of the region so 

that steep dips are common, and schistosity is occasionally developed."

Apparently the oldest rocks in the area lie 

east of the Maclaren Glacier and northeast of 

the copper prospect. These rocks, correlated by 

Moffit with the Chisna formation of Mendenhall 

(1905), lie in a west-trending belt on the south 

side of the Alaska Range. This formation extends eastward from the Maclaren Glacier to the 

Summit Lake area, but has not been recognized 

west of the Maclaren valley. The Chisna formation was not examined in the field, but 

Pettyjohn reports that he found no mineralization 

in the parts of it that he prospected. As described by Moffit (1912, p. 27-28), the formation 

consists of quartzite, tuffaceous beds, and metamorphosed limestone containing associated granular 

intrusives. Many of the weathered surfaces of 

this formation have a rusty red color that is 

particularly conspicuous.

Rocks of probable Triassic age include limestone, conglomerate, and thick units of slate 

having intercalated basic igneous flows or intrusives, all of which are cut by granular intrusives 

of dioritic or related compositions. These rocks 

are exposed on the west side of Maclaren valley 

about 2.5 miles north of Discovery Creek, and 

they form an outcrop belt that extends westsouthwestward from this point. Triassic rocks 

apparently are not exposed in the area between 

the Maclaren Rivsr and the Richardson Highway.

The Jurassic rocks, as described by Moffit, 

consist of gray quartz diorite and hornblende 

diorite that in part show well developed cleavage 

and schistosity. They occur as dikes, sills, and 

large, irregular, intrusive masses. Several small 

masses of Jurassic rocks were mapped by Moffit 

(1912, pi. 11) on both sides of the Maclaren valley 

in the area just north of the copper prospect. An 

igneous mass of batholithic size lies in the Susitna 

River drainage about 5 to 12 miles west of the 

Maclaren Glacier.

The geologic mapping of this region is of 

the general reconnaissance type. Additional reconnaissance and semidetailed geologic mapping of 

the south slope of the Alaska Range between the 

Richardson Highway and the Alaska Railroad should 

be done to provide basic geologic and economic 

data.

Mineral deposits

Several quartz veins bearing bornite and chalcopyrite with malachite surface alteration occur in the 

vicinity of Discovery Creek, a western tributary of the 

Maclaren River near the terminus of the Maclaren 

Glacier (fig. 2). The largest and richest vein is located on the steep north slope of Discovery Creek about 

3, 200 feet upstream from the mouth. This vein is 

about 10. 5 feet thick, strikes N. 3°-4° E., and dips 

70°-90°W. Mineralized talus from this vein can be 

traced down the slope to Discovery Creek and 

downstream in the creek gravel. The best exposure 

of the vein is near the top of the slope about 180 feet 

above the bottom of the valley. It is from this outcrop, 

which had been dug out for sampling and examination, 

that the authors obtained samples. The vein crops out 

at several places down the slope within a vertical distance of about 80 feet, and the width and mineralization 

appear to be fairly uniform throughout this distance. 

The richest ore, samples from which have assayed 

30 to 45 percent copper, is confined to a zone about 

1. 5 to 2 feet thick within the vein. Assays of samples 

from an adjacent zone about 7 feet thick have ranged 

from 3.5 to 12. 5 percent copper. Appreciable amounts 

of silver and traces of gold also are present in the 

samples from both zones. The gold content seems 

to be higher in the lower grade copper bearing material 

than in the rich zone.

Two small quartz veins about 30 feet apart containing bornite and chalcopyrite with malachite surface alteration crop out on the south side of Discovery 

Creek about 200 feet downstream from the 10. 5-foot 

thick vein. These veins are 0.75 to 1. 0 foot thick. 

Several barren quartz veinlets associated with them are 

1 to 2 inches thick. One vein strikes N. 35°E. and dips 

60° south. Samples taken from widths of 0.75 foot in 

these veins assayed 1. 58 percent copper (sample 12) and 

2.95 percent copper (sample 13) with only traces of gold 

and silver. The bedrock in this zone is a highly fractured, 

dark grayish-green flow(?) rock and includes light applegreen pods and small dikes that are composed largely of 

epidote(?). Thin, sheared zones of blackish-green serpentine and/or chlorite are associated with the quartz veins. 

Some brick-red iron staining is present in this fractured zone.

A small quartz vein, banded with bornite and 

calcite, crops out on the south side of Discovery Creek 

about 1, 000 feet above the mouth. Chalcocite, chalcopyrite, and epidote have been identified in other 

specimens from this vein. This vein, which is 

0. 4 foot thick, strikes N. 15°-20° E., and is vertical, 

apparently continues northeastward for at least 100 feet 

to another small vein outcrop. Sample 11, taken across 

the width of the vein, assayed 1.33 percent copper, a 

trace of gold, and no silver or nickel. Albertson and 

Pettyjonn reported that their sample from this vein 

showed 2 percent copper and a trace of nickel.

Another small quartz vein is exposed on a rock knob 

on the east side of Spray Creek about 600feet downstream 

from Discovery Creek. This vein strikes N. 30° E. and 

dips 75°-90° southeast. It contains traces of copper 

minerals and has some greenish-black serpentine streaks 

and pockets and some epidote within the quartz.

A quartz vein bearing some chalcopyrite and 

bornite with malachite surface staining is exposed in
a small gully tributary to Discovery Creek about 

600 feet upstream from the 10.5-foot vein. The 

quartz vein is 3 to 5 inches thick and can be 

traced laterally for at least 20 feet. The rock exposed 

in the gully has slumped, but the vein appears to 

strike N. 20° W. and to dip 60° north.

Minor amounts of malachite are found on weathered exposures of the copper-bearing veins, but 

azurite occurs only rarely. Chrysocolla has been 

identified in at least one sample that was collected by 

the owners.

In addition to the above-mentioned veins that 

were examined by the writers, Pettyjohn reports that 

there are several copper-bearing veins about 2. 5 miles 

southwest of Discovery Creek on the slopes of Cottonwood Creek valley. Several specimens from veins 

are reported to assay 0. 5 to 1.5 percent copper, and 

one piece of float assayed 40.85 percent copper. Samples from a 51-inch thick quartz vein near the highgrade float had copper assays ranging from nil to 

1.43 percent. The 51-inch vein reportedly is cut off 

at one end by a fault. Pettyjohn plans further prospecting in the Cottonwood Creek and West Fork 'area. 

Pettyjohn also reports that he found no metallization 

on the east side of the Maclaren valley or on the west 

side north of Spray Creek.

SAMPLING AND ASSAYS

Six samples taken during the field examination 

were assayed by the Department of Mines Assay Office 

at College, Alaska, and the results of the assays are 

shown in table 1. The sampling points are shown on 

figure 2.

Table 1. Analyses of six samples assayed by 

the Department of Mines Assay Office at 

College, Alaska

Sample 

no.

11 

12

13 

14

15 

16

Width 

sampled 

(feet)

0.40 

.75

 75 

2.00

1-75 

7.00

Ounces per ton

gold

(1)

[ij

0,18

silver

U)(1)

jij

2.55 

1.20

Copper 

(percent)

1.33 

1.58

2.95 

.27

30.45 

8.99

'Trace.

2Nil.

Samples 14, 15, and 16 are rough channel 

samples that were taken across the uppermost outcrop 

of the main 10. 5-foot vein. Sample 14 represents a 

band of barren quartz 2 feet wide on the east side of 

the vein. Sample 15 represents a band of "high grade"

adjacent to the barren quartz; it ranges in width from 

1. 5 to 2 feet. The high-grade band consists mostly of 

bornite and contains minor amounts of chalcopyrite 

and quartz probably with a few other minerals. The 

remainder of the vein, represented by sample 16, 

ranges from 6.5 to 7.5 feet in width. It consists of 

quartz impregnated with bornite and chalcopyrite. 

The three bands in the vein appear to be consistent in 

width. The vein is exposed at several points over a 

distance of about 150 feet on the slope.

Samples 11, 12, and 13 were tested for nickel; 

none was present. The owners reported that there 

was a.trace of nickel in a sample that they took from 

the vein from which sample 11 was taken. The owners 

have taken several samples across the high-grade band 

in the main vein. All have assayed more than 40 percent copper. Samples taken by the owners from the 

7-foot band of quartz, bornite, and chalcopyrite on 

the west side of the vein have assayed from 

3.5 to 12.5 percent copper.

CONCLUSION AND RECOMMENDATIONS

The 10. 5-foot bornite-chalcopyrite-quartz vein 

on Discovery Creek is worthy of further exploration. 

The tenor and the apparent downdip continuity of the 

vein indicate a minable deposit if the vein has sufficient continuity along its strike. Unfortunately the 

ridge top to the north of Discovery Creek is completely covered by vegetation, and no surface indications of the vein or bedrock can be found without 

trenching or underground exploration.

In addition to exploration of the 10. 5-foot vein, 

further prospecting is recommended in the Discovery 

Creek area and the westward extension of the outcrop 

belt of basaltic lavas. The headwaters of Cottonwood 

Creek and the West Fork are a virtually unknown area, 

and the basaltic lava formation'continues westward 

to the Susitna River. Moffit (1915, p. 76) points 

out that a vein of chalcopyrite was found on Butte Creek, 

just west of the Susitna River, and that copper-bearing 

minerals have been found in the lava flows between 

Butte and Wachana Creeks and the Susitna River.

LITERATURE CITED

Capps, S. R., 1940, Geology of the Alaska Railroad

region: U. S. Geol. Survey Bull. 907. 

Mendenhall, W. C., 1905, Geology of the central

Copper River region, Alaska: U. S. Geol. Survey

Prof. Paper 41. 

Moffit, Fred H., 1912, Headwaters of the Gulkana and

Susitna Rivers, Alaska: U. S. Geol. Survey Bull. 498. 

_______1915, The Broad Pass region, Alaska:

U. S. Geol. Survey Bull. 608.

INT.-DW. SEC.. WASH.. D.C.