GEOLOGICAL SURVEY CIRCULAR 319 

RECONNAISSANCE FOR URANIUM 

IN THE LOST RIVER AREA 

SEWARD PENINSULA, ALASKA, 1951 

This report concerns work done on 

behalf of the U. S. 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 319 

RECONNAISSANCE FOR URANIUM IN THE LOST RIVER AREA 

SEWARD PENINSULA, ALASKA, 1951 

By Max G. White and Walter 8. West 

This report concerns work done on 

behalf of the U.S. Atomic Energy 

Commission and is published with 

the permission of the Commission. 

Washington, D. C., 1953 

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

RECONNAISSANCE FOR URANIUM IN THE LOST RIVER AREA 

SEWARD PENINSULA, ALASKA, 1951 

By Max G. White and WalterS. West 

CONTENTS 

Abstract ..................•............. 

Introduction. . . . . . . . . . . . . . . . . . • • . . • . . . . • 

Geology ...•...•......•..•..•........•.• 

Radioactivity investigations ..........•... 

Page 

1 

1 

3 

3 

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

Literature cited ......................... . 

Unpublished 

report .............................•... 

Page 

4 

4 

4 

ILLUSTRATION 

Figure 1. Geologic map of Lost River area, Teller quadrangle, Seward Peninsula, Alaska............. . 2 

TABLE 

Table 1. Equivalent uranium .analyses of selected samples from the Lost River area . . . . . . . . . . . . . . . . . . . 3 

ABSTRACT 

Reconnaissance for uranium in the Lost River 

area, Seward Peninsula, Alaska, during the 1951 

field season revealed the presence of minor 

amounts of radioactive material in mineralized 

parts of rhyolitic dikes and in a small ironenriched zone in limestone. The dikes contain 

as much as 0. 01 percent equivalent uranium locally 

and average 0. 005 percent equivalent uranium. The 

radioactive material occurs as a secondary hematitic coating of the dike rock. The iron-enriched 

zone has an average content of about 0. 06 percent 

equivalent uranium with the radioactive material 

occurring in limonite, hematite, goethite, and 

mimetite. The radioactivity of these minerals is 

due to the presence of uranium ·as an impurity. 

No uranium deposits of economic importance 

were found. 

INTRODUCTION 

The Lost River area comprises the drainage 

basin of Lost River and Rapid River, the major 

tributary from the west. Lost River heads on 

the southwest slope of Brooks Mountain and 

drains into the Bering Sea about 30 miles southeast from Cape Prince of Wales and 80 miles 

northwest from Nome (fig. 1). Transportation to 

the area is chiefly by air. Small planes may 

land on three airstrips, one at the beach, one at 

the mouth of Cassiterite Creek, and one near 

the head of Lost River (fig. 1). Supplies may 

be landed at the beach by tug and barge. 

The only mining operation in the area is 

at the Lost River mine on Cassiterite Creek 

where development work preparatory to mining 

tin and tungsten is being done by the United States 

Tin Corporation. 

A number of studies have been made of 

the Lost River area by the Geological Survey 

(Collier, 1902, p. 13, 25, 38, 46; 1904a, p. ~54-167; 

1904b, p. 9-41; 1905, p. 120-127; Hess, 1906, p. 145-

150; Knopf, 1908; Eakin, 1915, p. 81-89; Harrington, 

1919, p. 353-361; and Steidtmann and Cathcart, 1922). 

However, no field investigations for radioactive 

materials had been made in this area by the 

Geological Survey before the present investigation. 
N 

l EXPLANATION 

CJ 

Sand and arovel }I ~ 

Basaltic dike 

-

0 

~ 0 

N 

0 

(/) 

Rhyol\t1c dike UJ 

:::E 

Ell] + 

Granite 

~ 

Basalt 

0 

::! ·ct [==:=J zct z 

~~ z r E>a:~o Part C Iorence limestone o :::>' [;'j ~go 

0 

B~ie od~Pted- from unPublished t'"opogrophlc. 

map by J.B. Mertle, Jr. 1940 

,.fie 

~-~···· 

/!'. 

f ,c 

PENINSULA ALASKA 

50 Miles 

Geology by J B-Mertie,Jr. and R.R. Coats, 1g4(j 

Figure 1. -Geologic map of Lost River area, Teller quadrangle, Seward Peninsula, Alaska. 

2 

---.!::· 

Fault 

.- ... --..... . • 

Vehicle trail 

<¢ 

Airfield 

• Sample location 

~ 

Mihe 

• 

Building 
Scanning of rock and ore specimens in. the Survey 

collections for radioactivity revealed a few samples 

containing radioactive material (Wedow, White, and 

Moxham, 1951, p. 25), On the basis of these results 

and because the mineral assemblages of certain known 

mineral deposits suggested the presence of uranium, 

an investigation for radioactive materials.,in the 

Lost River area was made in conjunction with the investigation of zeunerite occurrences at Brooks Mountain, 

which are described in a separate report ~West and 

White, 1952). The investigation was made during the 

latter part of July and in August 1951 by Max G. White 

and WalterS. West, geologists, and Fred Freitag, 

Arthur E. Nessett, and Eugene A. Hainze, field assistants. This work was done on behalf of the Division of 

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

GEOLOGY 

The bedrock in the Lost River area is a white to 

light-gray and-in places-red llmestone of Ordovician, 

Silurian, and Devonian age, called the Port Clarence 

limestone (Collier, 1902) which has been intruded by 

granite of Mesozoic(?) age and rhyolitic and basaltic 

dikes of an age sliglltly younger than the granite (fig. 1). 

The limestone is almost barren of any mineralization 

except adjacent to altered parts of the dikes. A lightgray medium-grained granite is exposed on Tin Creek, 

an east tributary to Lost River. A buried granite mass 

has been found in drill holes at the Lost River mine on 

Cassiterite Creek. The dikes, which were intruded 

shortly after the granite, trend northeast to east and 

range in width from 2i to 35 feet, averaging about 5 feet. 

The emplacement of the igneous rocks was followed 

by the injection of high temperature tin-tungsten-fluorinebearing solutions that mineralized parts of the dikes 

and some of the granite. The center of tb,is mineralization is on Cassiterite Creek. At this locality 

potentially commercial deposits of cassiterite, wolframite, and possibly fluorite have been found in a rhyolite 

dike and in part of the bUPied granite cupola. A wide 

variety of base metals have been found in minor 

or trace amounts in association with the cassiterite, 

wolframite, and fluorite. 

RADIOACTIVITY INVESTIGATIONS 

Radioactivity traverses were made on foot over 

most of the rocks of the area, in many prospect pits 

and tunnels, and through the accessible part of the 

U. S. Tin Corporation mine. The instrum~nts used 

were 2- by 20-inch gamma tubes connected to standard 

portable survey meters mounted on packboards. 

Equivalent uranium determinations on selected samples 

representative of some of the mineralized source 

material in the area are given in table 1; the locations 

of these samples are shown on figure 1. 

Field and laboratory radioactivity determinations 

and mineralogic studies show that minor amounts of 

radioactive material occur in hematitic coatings in the 

mineralized parts of the rhyolitic dikes and in an ironenriched or replacement zone in limestone on the west 

side of Lost River, opposite the mouth of Tin Creek 

(sample 4193, fig. 1). 

The dike rocks average about 0. 005 percent 

equivalent uranium having a maximum of 0. 01 percent equivalent uranium at one locality on Rust 

dike (sample 4080). 

A series of samples were taken of the 

Ida Belle dike, a mineralized rhyolitic dike in 

the north-central part of the area, to obtain a 

pattern in a relationship between radioactivity 

and mineral content of the dike as it passes through 

the center of mineralization on Cassiterite Creek. 

No significant variation in radioactivity was found 

in the samples. The average value obtained is 

0. 005 percent equivalent uranium. 

In the 3-foot wide iron-enriched zone or pocket 

in limestone on the west side of Lost River (sample 4193) 

a value of 0. 06 percent equivalent uranium was obtained. 

The radioactivity is due to the presence of uranium in 

limonite, h,ematite, goethite, and mimetite. The 

source of the uranium was not found. It is possible 

that the uranium could have been deposited from 

solution in relatively cold circulating waters. The 

deposit could be traced no more than a few feet 

in any direction. 

Table 1.--Equiv~lent uranium analyses of selected samples from the Lost River area, 1951 

Sample 

no. 

4o8o 

4167 

4181 

4190 

4191 

4168 

4169 

4170 

4171 

4172 

4173 

4174 

4175 

Location 

Rust dike ----------------- --~--do---------------------

Cassiterite dike-----------

Ida Belle dike ------------ -----do----------------------

-----do---------------------

-----do----------------------

-----do---------------------

-----do---------------------

-----do---------------------

-----do---------------------

-----do---------------------

-----do----------------------

Percent 

equivalent 

uranium 

0.01 

.oo6 

.004 

.005 

.003 

.005 

.004 

.005 

.006 

.006 

.005 

.004 

.005 

3 

Sample 

no. 

4176 

4177 

4178 

4179 

4180 

4184 

4193 

4189 

4099 

Location 

Ida Belle dike-------------

-----do---------------------

-----do---------------------

-----do---------------------

-----do---------------------

Crystal Creek, pegmatite 

dike. 

Iron-enriched deposit 

in limestone, on the 

west side of 

Lost River. 

Dolcoath tunnel------------

Bessie and Maple tunnel----

Percent 

equivalent 

uranium 

0.005 

.005 

.006 

.005 

.006 

.004 

.06 

.004 

.00~ 
SUMMARY AND CONCLUSIONS 

No uranium deposits of commercial importance 

were found in the Lost River area. Minor amounts of 

radioactivity were found in tin-tungsten-fluorinebearing rhyolitic dikes and in an iron-enriched pocket 

in limestone. The di:Kes contain an average of 0. 005 percent equivalent uranium, restricted to hematitic coatings in the fractured rock. The iron- enriched zone 

cohtains about 0. 06 percent equivalent uranium, apparently as impurity in the iron minerals in the limestone; 

this is a very localized deposit. 

Routine radioactivity tests will be made underground at the Lost River mine as exploration of the tin 

deposits exposes mineralized granite and dikes at depth 

to determine whether the radioactivity of these rocks 

increases with depth or whether other types of radioactive deposits are associated with the tin at depth. 

LITERATURE CITED 

Collier, A. J., 1902, A reconnaissance of the northwest 

portion of Seward Peninsula, Alaska: U. S. Geol. 

Survey Prof. Paper 2, 70 p. 

--::-::---;-'---:1904a, Tin deposits of the York region, 

Alaska, in Emmons, S. F., and Hayes, C. W., 

Contributions to economic geology: U. S. Geol. Survey 

Bull. 225, p. 154-167. 

4 

Collier, A. J., 1904b, The tin deposits of the York 

region, Alaska: U. · S. Geol. Survey Bull. 229, 61 p. 

1905, Recent development of Alaskan tin 

-d.,-e-p-os-=i..,...ts-: U. S. Geol. Survey Bull. 259, p. 120-127. 

Hess, F. L., 1906, TheYorktinregion,inBrooks, A. H., 

and others, Report on progress of investigations of 

mineral resources of Alaska: U. S. Geol. Survey 

Bull. 284, p. 145-157. 

Knopf, Adolph, 1908, Geology of the Seward Peninsula 

tin deposits, Alaska: U. S. Geol. Survey Bull. 358, 

71 p. 

Eakin, H. M., 1915, Tin mining in Alaska: U. S. Geol. 

Survey Bull. 622-B, p. 81-94. 

Harrington, G. L., 1919, Tin mining in Seward Peninsula, 

Alaska: U. S. Geol. Survey Bull. 692-G, p. 353-361. 

Steidtmann, Edward, and Cathcart, S. H. , 1922, Geology 

of the York tin deposits, Alaska: U. S. Geol. Survey 

Bull. 733, 130.p. 

West, W. S., and White, M. G., 1952, The occurrence 

of zeunerite at Brooks Mountain, Seward Peninsula, 

Alaska: U. S. Geol. Survey Circ. 214. 

UNPUBLISHED REPORT 

Wedow, Helmuth, White, M. G. , and Moxham, R. M. , 

1951, Interim report on an appraisal of 

the uranium possibilities of Alaska: U. S. Geol. 

Survey Trace Elements Memo. Rept. 235. 

[In open files. ] 

INT.-OOP. SEC., WASH., D.C. 52 ~QJ