TIN-LODE INVESTIGATIONS,

CAPE MOUNTAIN AREA,

SEWARD PENINSULA, ALASKA

By John J. Mulligan

With Section on Petrography by Walter L. Gnagy

0 + + + + + + + + + + report of investigations 6737

UNITED STATES DEPARTMENT OF THE INTERIOR

Stewart L. Udall, Secretary

* BUREAU OF MINES

Walter R. Hibbard, Jr., Director
This publication has been cataloged as follows:

Mulligan, John J

Tin-lode investigations, Cape Mountain area, Seward Peninsula, Alaska; with a section on petrography by Walter L.

Gnagy. [Washington] U. S. Dept. of the Interior, Bureau of

Mines [19661

43 p. illus., tables. (U. S. Bureau of Mines. Report of investigations 6737)

Includes bibliography.

1. Tin-Seward Peninsula. 2. Petrology-Alaska-Seward Peninsula.

I. Gnagy, Walter L. II. Title. (Series)

TN23.U7 no. 6737 622.06173

U. S. Dept. of the Int. Library
CONTENTS

Page

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

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

Acknowledgments .......................................................... 3

Location and access ...................................................... 3

Labor .................................................................... 5

Living conditions ........................................................ 5

Property and ownership ................................................... 5

History .................................................................. 7

Physical features ........................................................ 9

Topography and vegetation ........................................... 9

Climate ............................................................. 10

Water supply........................................................ 10

Permafrost .......................................................... 11

Detrital cover..................................................... 11

General geology.......................................................... 13

Work by the Bureau of Mines .15

Nature and extent....................................... 15

Placer investigations... .................................... 15

Detrital-cover sampling. ...................................... 15

Sampling method....................................... 15

Sample evaluation ..................... ................. 16

Lode sampling............................................... 17

Bulldozer trenching ............................................ 17

Diamond drilling.............................................. 17

Sampling underground workings .................................. 17

Description of the deposits............................................ 17

Tin-placer deposits................................................. 17

The detrital cover.................................................. 21

First Chance Creek ............................................. 21

Cape Creek ......... . . . . . . ................ 22

Goodwin Gulch .................................................. 23

Boulder Creek .................................................. 23

Summary of detrital-cover sampling results ..................... 23

Tin-lode deposits ................................................... 23

Bartels mine area .............................................. 23

Granite-limestone contact deposit ......................... 25

Tin veins in granite ...................................... 29

Summary of lode sampling results, Bartels mine area ....... 29

Miscellaneous lode prospects ................................... 31

Mineralized dike, First Chance Creek valley ............... 31

Mineralized granodiorite outcrop, Cape Creek valley ....... 31

Limestone-shale contact, Goodwin Gulch .................... 32

North fork, Goodwin Gulch ................................. 32

Canoe prospect ............................................ 32

Percy prospect......................................... 32 0 Headwaters, Boulder Creek .32

Dieter prospect ...................................... 33

Northwest ridge, Cape Mountain .33
CONTENTS--Continued

Page

The Potato Creek-Lynx Creek area .......................... 33

Associated minerals and metals ................................. 34

Beryllium ................................................. 34

Radioactive minerals ...................................... 34

Gold ...................................................... 35

Magnetite ................................................. 36

Fluorite .................................................. 36

Petrography by Walter L. Gnagy ........................................... 37

Bibliography ............................................................. 42

ILLUSTRATIONS

Fig_

1. Seward Peninsula, Alaska .......................................... 2

2. Cape Mountain area ................................................. 4

3. Lode claims, Cape Mountain area .................................... 7

4. Frostbreaking and transport of material from a typical outcrop

in a permafrost area ............................................. 13

5. General geology, Cape Mountain area ................................ 14

6. Detrital cover sampling, Cape Mountain area ........................ 22

7. Bartels mine area, Cape Mountain ................................... 24

8. Potato Creek-Lynx Creek area ....................................... 33

9. Beryllium specimens, Cape Mountain ................................. 35

TABLES

1. Population of the western part of the Seward Peninsula ............. 5

2. Patented lode claims, Cape Mountain area ........................... 6

3. Recorded tin production, Cape Mountain area ........................ 8

4. Investigations of tin deposits in the Cape Mountain area ........... 9

5. Weather statistics ................................................. 10

6. Relative abundance of tin in the placer deposits of the Cape

Mountain area ..................................................... 19

7. Discontinuous cassiterite-bearing lenticular pods in limestone

near the granite contact, Bartels mine area ...................... 25

8. Trench samples, granite-limestone contact zone ..................... 26

9. Diamond-drill holes, granite-limestone contact, Bartels mine area.. 28

10. Spectrographic analyses, granite-limestone contact, diamond-drill

hole 4, Bartels mine area ........................................ 29

11. Trench samples, mineralized zone within granite, Bartels mine area. 30

12. Trench FC-1, right limit First Chance Creek ........................ 31

13. Trench CC-1, Cape Creek ............................................ 32

14. Principal minerals in some placer concentrates ..................... 37

15. Principal minerals in detrital cover panned concentrates ........... 38

16. Principal minerals and rocks in typical specimens from the

lode-tin zone, Cape Mountain ..................................... 39

17. Principal minerals and rocks, granite-limestone contact zone,

Cape Mountain .................................................... 40

18. Principal minerals and rocks, beryllium-bearing specimens,

Cape Mountain .................................................... 41
TIN-LODE INVESTIGATIONS, CAPE MOUNTAIN AREA,

SEWARD PENINSULA, ALASKA

by

John J. Mul I igan 1

With Section on Petrography by Walter L. Gnagy

ABSTRACT

The Bureau of Mines investigated the tin deposits of the Cape Mountain

area during July and August 1962 to test the effectiveness of detrital-cover

sampling in permafrost areas as a relatively cheap and simple means of guiding

mine development and exploration. Results indicate that systematic detritalcover sampling can be used effectively to delineate obscure deposits with

sufficient accuracy to permit sampling with a minimum of trenching or drilling.

Extensions of known outcroppings were traced in sufficient detail to guide

lode sampling and several previously unknown tin-bearing lodes were found and

sampled. Lode sampling was limited to the minimum needed to establish the

reliability of detrital-cover sampling results. The results of previous lode

and placer investigations are summarized and detrital-cover sampling methods

and results are described in detail.

INTRODUCTION

The Bureau of Mines has been investigating the lode- and placer-tin

resources of the western part of the Seward Peninsula, Alaska, intermittently

since 1942 (fig. 1). The various investigations are described in Bureau of

Mines publications listed chronologically in the bibliography at the end of

this report.

This report describes an investigation made in the Cape Mountain area

July and August 1962. Primarily, this was a research project to test the

effectiveness of detrital-cover sampling as a method for delineating and

evaluating tin lodes buried under frozen detritus in permanently frozen areas.

Detrital-cover sampling methods were developed during investigations in the

Potato Mountain area (27) ;2 this was the first use of these methods in another

area. The principal lode deposits of the Cape Mountain area and an outlying

'Mine examination and exploration engineer, Area VIII Mineral Resource Office,

Bureau of Mines, Juneau, Alaska. W 2 Underlined numbers in parentheses refer to items in the bibliography at the

end of this report.

Work on manuscript completed June 1965.
2

66' 6 4 6

FIGURE 1 X Seward 4. Peninsul. 10 20 3

Re Lb o t i m t e n t s

66. ~ ~ ~ ~ ~ FGR 1.-SwadPnisl, r a s to t i l e ad d o t lsa U D

Thine dfetrts-oer sampling meeethods uscaed. durin thislinvestiatio armiedt

sipesadptti theiratte potsato onhs Mt ofnwell-kntown at adevlpthe method ithavdet inloesshoul be usfulwi wevaluasyting

the numerous other tin occurrences reported in northern and central Alaska.

The evaluation of these tin deposits is a matter of both national and local

concern; therefore, the sampling theory, methods, and results are described

in detail.
* ~~~~~~~~~~~~~~

ACKNOWLEDGMENTS

The Bureau of Mines Area VIII Mineral Resource Office at Juneau, Alaska,

administered and coordinated the investigation of Seward Peninsula tin deposits. Chemical and petrographic analyses were made in the Bureau of Mines

laboratories in Juneau. A list of claims in the Cape Mountain area was furnished by the Alaska Division of Mines and Minerals, Department of Natural

Resources; additional data on ownership was furnished by the Division of

Lands. Historical notes and general geological data were compiled principally

from Bureau of Mines and Geological Survey publications listed in the

bibliography.

The United States Air Force, Alaskan Air Command, has an installation in

the Cape Mountain area; both the military and civilian personnel materially

assisted the Bureau field party. Particular thanks are due to Major Albert L.

Seaver, the Air Force commander, and to Mr. Ernest M. Garner, station supervisor, Radio Corporation of America. The U.S. Army Corps of Engineers, Office

of the Alaska District, furnished a detailed map of the area that was most

helpful to the field party. This map includes current records of property

included in the military reservations.

Geographical nomenclature in this report follows usage on the Geological

Survey maps available when the work was done. Therefore, names of minor

geographic features may differ from those appearing in older reports. Two

"Village Creeks" in the area have been designated No. 1 and No. 2 (fig. 2).

Village Creek No. 1 flows into the Bering Sea at Wales Village. Village Creek

No. 2 flows into the Lopp Lagoon at Rock Island. If a feature was not named

on the Geological Survey maps, local usage was followed, if known; if local

usage was not known, the feature was designated by a letter. Nomenclature

has not been reviewed by the Board on Geographic Names.

Base maps were adapted principally from Army Map Service maps distributed

by the Geological Survey. Figure 1 is adapted from the 1:1,000,000 scale map

entitled "Nome." Figures 2, 6, 8, and 9 are modified from the Teller (C-6 and

C-7) quadrangle maps. Figure 3 includes data from the plats of patent surveys,

and figure 5 was adapted from a geologic map by J. B. Mertie and Robert F.

Lyman of the Geological Survey; in both cases details not pertinent to this

report have been omitted. Figure 7 was mapped during this project, but claim

locations were taken from maps in Bureau of Mines Report of Investigations

3978 (18).

LOCATION AND ACCESS

Cape Mountain (latitude 65°35' N, longitude 168°00' W) is on the east

side of the Bering Strait, 65 miles south of the Arctic Circle and 105 miles

N 450 W of Nome, Seward Peninsula, Alaska (fig. 1). The village of Wales,

on the west side of Cape Mountain, is the only nearby permanent settlement.

Tin City, on the east side of Cape Mountain, is the site of a small military

installation (fig. 2). There are no permanent inhabitants in the roughly

triangular area included between Tin City, Shishmaref (70 miles northeast),

and Teller (50 miles southeast).
4

ales~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Sae ie

FIGURE 2. - Cape Mountain Area.

The Cape Mountain area is readily accessible by air from Nome, the center

of air traffic for the Seward Peninsula. Nome is served by daily scheduled

flights from Anchorage and Fairbanks. The Tin City military installation

maintains an airfield suitable for large commercial and military cargo planes.

Two small airfields at Wales are used by bush planes carrying 1,000 to 2,000

pounds of cargo.

Freight too heavy or bulky for air transport can be landed from ships at

Tin City beach. No docks or freight handling facilities are available; vessels are beached and unloaded on the sand. Eskimo skin boats capable of

carrying up to a few tons, ordinary barges of 50 to 200 tons burden, and

various military-type landing craft have been used successfully.

Persons visiting the Tin City area or planning to work near the militarya

installations should make prior arrangements with the commanding officer,

710 AC and W (Aircraft Control and Warning) Squadron, U.S. Forces, Alaska.
* ~~~~~~~~~~~~~

LABOR

The population of the western part of the Seward Peninsula (fig. 1) is

listed in table 1. A high percentage of the population is available for

hiring because of the lack of industrial development. The Eskimo and white

residents include unskilled, semiskilled, and many types of skilled labor.

TABLE 1. - Population of the western part

of the Seward Peninsula'

1950 21960

Diomede ................................. 103 88

Igloo ................................... 64 (3)

Nome ..................................... 1,876 2,316

Shishmaref .............................. 194 217

Teller .................................. 160 217

Teller Mission .......................... 109 109

Wales ................................... 141 128

Total ................................. 2,647 3,075

'Settlements are shown on figure 1, except Diomede which

is on Little Diomede Island, about 25 miles N 650 W of

Wales.

2 There is a continuing tendency for the people to move to

the larger communities to take advantage of schools and

other community services.

3 Settlement abandoned.

LIVING CONDITIONS

Modern communications and transport facilities have practically eliminated the isolation of the Arctic and sub-Arctic areas. Small communities and

field parties in the western Seward Peninsula communicate with Alaska Communication System (ACS) stations in Nome and Teller by radiotelephone. Food,

clothing, and hardware are stocked by stores in Nome or Teller; both Wales and

Shishmaref have small general stores. Supplies, repair parts, and perishable

food can be delivered by plane as required. Items not available locally can

be ordered by telephone or telegram and obtained by air in a few days from

distributors in the larger cities or from the factory.

Sturdy, insulated, and heated houses are essential during the winter, but

tents or light uninsulated houses are adequate for summer use. A common expedient is to mount a light cabin on skids (locally termed a wanigan) and tow it

about with a tractor as needed. Ordinarily, dwellings are heated by oil

stoves, and cooking is done with either oil, bottled gas, or gasoline stoves.

PROPERTY AND OWNERSHIP

Three groups of patented lode claims are listed in table 2 and the approximate locations are shown on figure 3. No unpatented lode claims were known

to be in force but one, the Percy claim, has been included on the map. Claim

ownership is listed, if known, but a detailed title search was not made. The
6

placer claims in the area are described in Bureau of Mines Information

Circular 7878 (24).

TABLE 2. - Patented lode claims, Cape Mountain areal

Mineral Company2 Patent Patent Lode Millsite

survey number date claims claims

336 A&B ...I. Bartels Tin Mining Co . .198,633 5/17/11 28 1

337 A&B ... Bartels Tin Mining C 4 . .292,826 9/20/12 7 1

409 A&B ..... U.S. Alaska Tin Mining Co 5 ... 301,775 11/23/12 3 1

Total .. ............................. - - 38 3

lNo unpatented lode claims were known to be in force in 1962.

2 The patents were granted to the companies listed. The United States Government has since acquired title or right of access to a large number of

claims or portions of claims occupied by various military installations

and access roads. The Corps of Engineers, Office of the Alaska District

Engineer, maintains a current real estate map of the Tin City military

reservation.

3 Deed, Bartels Tin Mining Co. to John F. Downey recorded v. 85, p. 296, Port

Clarence recording district records; Deed, John F. Downey to Empire Tin

Mining Co. recorded v. 90, p. 36. A Declaration of Ownership filed by the

Empire Tin Mining Co. on June 26, 1946, lists claims included in Survey

336 A and B in the following order:

Champion Elgin

North Star Fraction Washington

North Star Adams

Lucky Queen Jefferson

Tremont Madison

Bronx Monroe

Daisy Planet

Birthday Fourth of July

Venus Martha

Mars Mispickel

Jupiter Noble

Saturn Tin Quartz

Excelsior Rusty Lode Mining

Aurora Northwestern Millsite.

4 Declaration of Ownership for the Comstock, Canoe, and Sun Drum claims filed

Aug. 12, 1947, by Empire Tin Mining Co.; no record of ownership of remaining claims of Survey 337 A and B: The Aspen, Arctic, Fairview, and Sunrise

lode claims and the Bartels millsite claim.

5A11 claims included in Mineral Survey 409 A and B (Dieter No. 1, Dieter No. 2

and Dieter No. 3) were foreclosed by the State of Alaska, Nov. 10, 1959.

The United States Government has acquired either title or right of access

to various land areas occupied by military installations on Cape Mountain and

in the vicinity of Tin City. Purchase or access agreements were negotiated

with the owners if these areas were included in lode or placer claims.

Because of the ever-changing nature of active military installations, this

report does not include a description of the areas covered. However, it is
* 7

> ~~~~Goodwin.

Cape Mtn \ summit~~~Ysze L U SL M No. 336 \

0 2000 4000 \ /2oOo

Scale,f te |/ Tin Cit y Do

B E R / N G S E A

FIGURE 3. - Lode Claims, Cape Mountain Area.

apparent that an agreement with the military command should be made before

starting any work in the Cape Mountain area.

The western slopes of Cape Mountain are in the Wales Village native reservation. The eastern boundary of this reservation is a north-south line

(longitude 1680 W) that passes through the summit of Cape Mountain and extends

from the Bering Sea to Lopp Lagoon.

HISTORY

Lode tin was discovered on Cape Mountain in 1902 by W. C. J. Bartels.

Active exploration and development continued for about 10 years. A camp named
8

"Tin City" was built, numerous pits, trenches, shafts, and adits were dug, and

two stamp mills were erected. Thirty-eight lode claims and three millsite

claims were granted patents in 1911 and 1912 (fig. 3). Records indicate that

about 6 tons of tin were produced.

Placer tin was first reported in 1918; placer-tin mining started about

1924 and continued until 1941. Over 640 tons of tin were recovered from the

gravels of Cape Creek and Goodwin Gulch (table 3). No tin has been produced

since 1941.

TABLE 3. - Recorded tin production, Cape Mountain area

Lode Placer

Year Tin, Dollar Tin, Dollar Remarks

short tons value short tons value

1906 ....... 6.0 6,819 - - Bartels lode mine.

1924 ....... _ 4.34 4,357 Goodwin Gulch.

1925 ....... _ - 9.75 11,290 Do.

1926 ....... _ - 7.05 9,165 Do.

1927 ....... _ 14.48 31,516 Do.

1928 ....... _ 38.83 38,830 Goodwin Gulch and Cape Creek.

1929 ....... _ - 36.65 32,985 Do.

1930 ....... _ - 10.87 8,718 Do.

1931 ........ - 3.66 1,464 Goodwin Gulch.

1933 ....... _ - 2.90 2,300 Goodwin Gulch (?).

1934 ....... _ - 4.14 4,300 Do.

1935 ....... _ - 46.25 46,250 Cape Creek and Goodwin Gulch.

1936 ....... _ - 99.00 91,080 Do.

1937 ....... - - 154.02 166,341 Do.

1938 ....... _ - 105.00 88,200 Cape Creek.

1939 ....... _ - 25.84 25,840 Cape Creek and Goodwin Gulch.

1940 ....... _ - 43.29 43,289 Cape Creek.

1941 ....... _ - 49.63 51,615 Do.

Total ... E 6.0 6,819 655.70 657,540 1

The Cape Mountain area tin deposits have been examined and studied by

many geologists and mining engineers both in government and private employment. Table 4 lists examinations or investigations that have been described

in reports widely available to the public.
* ~~~~~~~~~~~~~~

TABLE 4. - Investigations of tin deposits in the Cape Mountain areal

Date of Person or Reference

work Organization persons Scope of work numbers in

bibliography

1900 ...... Geological Brooks .... Discovered tin in York area.. 1, 2

Survey.

1901 ...... do ...... Collier .... Geologic and geographic 3

reconnaissance.

1903 ...... do ...... do .... Brief reconnaissance ......... 5

1905 ...... do ...... Hess .... do ...................... 8

1907 ...... do ...... Knopf .... Geologic study of the tin- 11

bearing area.

1920 ...... do ...... Steidtmann Geologic study of the western 16

and Seward Peninsula tin-bearing

Cathcart. area including Cape Mountain

area.

1936 ...... do . Smith ... Description of placer mining 17

methods.

1942-44-48 Bureau of Heide and Lode and placer sampling ..... 18, 19

Mines Rutledge.

1952-53., do . Mulligan Churn-drill placer sampling 24

___________ I and Thorne I

'Includes only investigations described in reports generally available to the

public.

PHYSICAL FEATURES

Topography and Vegetation

Cape Mountain is an isolated peak that rises 2,289 feet from sea level to

form a prominent landmark on the east side of Bering Strait (fig. 1). The

mountain is drained by a number of short creeks that flow a few miles to the

Bering Sea or Lopp Lagoon (fig. 2). A region of low rounded hills extends 8

or 10 miles eastward from Cape Mountain to Potato Mountain and the York

Mountains.

Frostbroken rock detritus covers the hills and mountains. Patches of

bedrock are exposed at scattered locations, usually on streambanks, steep

hillsides, or near the tops of ridges. A picturesque and noteworthy feature

of the ridges and upper slopes of Cape Mountain are granite pinnacles or

"spires," that rise 20 to 50 feet or more above the surrounding rock debris

and may be up to 20 or more feet in diameter. The spires are unfractured

remnants of the granite bedrock left by the frost wedging that removed the

surrounding rock.

Tundra and alpine-type vegetation thrive from sea level to about 800 feet

altitude and a gradually thinning growth extends many hundreds of feet higher.

There are no trees, but sparse groups of willow bushes may grow to a height of

3 or 4 feet in some of the valleys. A dense blanket of vegetation covers the

low hills east of Cape Mountain, but the soil derived from the limestones and

granites of Cape Mountain supports a noticeably sparser growth.
10

Climate

The climate of the Cape Mountain area is sub-Arctic modified by the position between the Chukchi Sea and the Bering Sea (fig. 1). During the summer the

temperature at sea level usually ranges from 330 to 50° F. The wind blows

persistently; often it is accompanied by fog or drizzling rain, although the

total annual rainfall is low. During the winter the weather is windy but

proximity to the sea prevents the extremely low temperatures characteristic

of inland locations at the same latitude. The weather statistics for Wales

are summarized in table 5.

TABLE 5. - Weather statistics'

Wales

Average annual temperature ................... 21.80 F

Months when average temperature is above 32° F .................. 4 months

Average annual precipitation .................................... 11.98 inches

Average annual snowfall ......................................... 51.7 inches

Prevailing wind direction ....................................... North

Highest recorded temperature .................................... 750 F

Lowest recorded temperature ..................................... -410 F

'Data from Federal Weather Bureau, Anchorage, Alaska:

Average breakup:

Bering Strait ............ June 7

Port Clarence ............ June 12

Arctic Ocean ............. June 18

Shishmaref Inlet ......... June 20

Average freezeup:

Arctic Ocean ............. November 6

Port Clarence ............ November 7

Shishmaref Inlet ......... November 9

Bering Strait ............ November 29

Water Supply

A dependable supply of fresh water is difficult to obtain in the Cape

Mountain area. Rain and melt water from snow drain rapidly; no evidences of

water channels in the permanently frozen bedrock were noted. Streamflow fluctuates rapidly and widely, but the streams draining the rolling tundra-covered

hills east of Cape Mountain do not fluctuate as much as the streams draining

the steep rocky slopes of Cape Mountain. Streamflow in winter was not investigated; probably, all streams dry up shortly after freezeup and do not flow

again until spring. At the Tin City military installation water is collected

during the summer and stored in heated tanks for winter use. Residents usually obtain household water from ponds or streams; snow and ice are melted

when such sources are not available.

During the summer, water for a small camp or for limited exploratory

drilling can be obtained on the slopes of Cape Mountain almost to the summit.

The water usually is not visible on the surface but trickles through the frostbroken detritus in the bottom of gulches and gullies. To obtain water, a pit
1 to 5 feet deep (to permafrost or bedrock) is dug by hand or bulldozer to

expose the water; a small dam is erected to impede the flow; and a pipe or

trough is used to carry the water to where it is needed. During the investigation, water for panning and for camp use was obtained in this manner. One

such water collector, about 300 feet northwest of the Lucky Queen adit, was

observed for 2 weeks in August. On a sunny day with a temperature of about

450 F, the flow averaged about 10 gallons per minute; the flow increased

greatly during rains and decreased when the average temperature dropped.

Except during rains, the water appeared to derive from the melting of ice and

snow in the interstices of the frostbroken rubble cover. Drifting snow

refills the voids every winter. Undoubtedly, flow ceases when the daily

average temperature drops below freezing.

The lack of water forced miners who worked the Cape Creek and Goodwin

Gulch tin placers to transport the gravel to stationary recovery plants. The

principal recovery plant, on the beach at Tin City 500 feet east of the mouth

of Cape Creek, utilized salt water pumped from the Bering Sea. A smaller

plant on Goodwin Creek at the mouth of Goodwin Gulch used water from Goodwin

Creek.

Permafrost

The bedrock and the detrital cover throughout the Cape Mountain area

remain permanently frozen, except for the top few feet that thaw during the

summer. Surface waters that penetrate to great depths, or other less obvious

sources of heat, may produce thawed zones within permafrost areas, but no such

thawed zones were recognized at Cape Mountain. In the absence of percolating

surface waters or other sources of heat, the ground temperature 30 to 50 feet

below the earth's surface remains almost constant throughout the year and

about equals the average annual surface temperature. The average annual surface temperature probably is reasonably close to the average annual air temperature, about 220 F (table 5). The geothermal gradient varies considerably,

but the worldwide average is about a 10 F increase in temperature for a depth

of 70 feet. Therefore, freezing temperatures can be expected to extend about

700 feet below the earth's surface. This rough estimate of the depth of

permafrost could not be verified.

Detrital Cover

The principal primary agent of erosion is frostbreaking which takes place

where thawing and freezing occur. The depth of summer thaw varies widely; it

may penetrate to great depths where surface water percolates through porous

strata, but on flat, well-drained, or impervious surfaces, the thaw may not

penetrate more than 1 or 2 feet. A cover of vegetation that insulates the

surface from the sun's heat tends to inhibit thawing. No exact measurements

were made, but in August the average depth of thawed ground in sample pits was

. estimated to be about 2.5 feet.

The nature of the frostbroken detrital material depends on the composition of the source rock. Water enters all available openings; it freezes,

expands, and breaks the rock; the resultant debris may vary in size from
12

blocky fragments many feet in diameter to individual crystals or fragments of

crystals. Most igneous rocks and many sedimentary rocks break into coarse

angular fragments that can support little plant life. The debris derived from

most shales and schists forms a firm soil that can support a vigorous growth

of plants and mosses. Where vegetation is abundant, a layer of peat, varying

in thickness from a few inches to a few feet, may form on the surface. Calcareous rock debris, even if it breaks down into a soil, tends to inhibit the

growth of tundra plants, which apparently thrive best in an acidic environment.

The surface evidences of a rock outcropping depend on the nature of the

rock. A rock that resists frostbreaking may protrude through the overlying

mantle or may be marked by large angular fragments. Rocks of moderate resistance to frostbreaking ordinarily do not form protruding outcroppings, but the

outcroppings may be indicated by fragments in the overburden. Relatively soft

or foliated rocks normally are eroded slightly below the nearby more resistant

rocks. The material derived from the softer outcrop usually breaks down into

small fragments that mix with larger fragments of the more resistant rocks to

form an indistinguishable cover. Deposits containing tin minerals usually are

less resistant than surrounding rocks; tin-bearing deposits are rarely visible.

The frostbroken material moves downhill as an earthflow that follows

regular paths (float lines) perpendicular to the elevation contour lines.

Practically all movement of material takes place in a near-surface "zone of

movement" (fig. 4) that develops because the ground thaws downward nearly to

an equilibrium point early in the summer. A narrow transitional zone, that

thaws gradually as the summer advances, underlies the zone of movement. The

transitional zone merges into an underlying zone of broken but normally frozen

material that remains essentially in place except for some downhill creep

resembling glacial flow. This broken zone in turn merges gradually into

unbroken permanently frozen bedrock.

The lighter material is more readily carried off in the zone of movement

than the heavier material. Thus a residual concentration of heavier minerals

develops on outcroppings. Ultimately, however, much of the heavy material

also is removed. The heavy material is carried along with the lighter material in the zone of movement; there appears to be a churning or mixing action

that prevents heavy material from sinking but results in some lateral dispersal. The mass flows into the stream valleys. Stream action carries off the

smaller particles and lighter materials, and a stream placer deposit develops.

A residual concentration of the heavy minerals was found on the frostbroken tin outcroppings in every case that could be checked. The concentration was directly over the outcrop and extended slightly downslope. The ratio

of concentration varied widely; the broken material might contain up to 10

times as much tin as the unweathered lode. The weathered material could not

always be distinguished from unweathered bedrock, particularly where clay

alteration was extensive.
13

Tundra vegetation and peat 0 to I foot thick

Heavy minerals tend to form a

concentrate over the outcrop

\> \ ~~~~~~~~Float lines flow downhill

°c00o>K4S 'is SS \ perpendicular to contour lines.

)_ /0,> 4ss<, oS Practically all movement of

material occurs within upper

zone. Mixing and lateral dispersal gradually lower grade

SKETCH SECTION

Not to scale

FIGURE 4. - Frostbreaking and Transport of Material From a Typical Outcrop in a

Permafrost Area.

GENERAL GEOLOGY

The oldest rocks in the Cape Mountain area are a metasedimentary series

of early Paleozoic or pre-Paleozoic shales, phyllites, schists, quartzites,

and limy shales locally referred to collectively as "black slates" (fig. 5).

The black slates are overlain by a series of generally gray middle to late

Paleozoic metalimestones and marbles that either include or are overlain by

relatively thin schist and quartzite beds.

Three distinct periods of igneous activity are evident. The first is

represented by mafic dikes, sills, and stocks, locally termed "greenstones"

that intrude the black slates but apparently do not intrude the limestones.

The greenstones are abundant a few miles east of Cape Mountain but were not

. recognized on Cape Mountain. The second period of igneous activity is represented by granitic stocks, sills, and dikes that intruded both the slates and

the limestones. Being more resistant to erosion than the surrounding rocks,

the granitic stocks and the associated halo of dikes, sills, and contactmetamorphosed sediments tend to form mountains with an exposed granitic core;
14

,k-R

Mesozoic V V GnV \V VVand a i rocIs ' VVVt / V V V VmX-. VV 

Upper ~V V \ \V V VVVV/VV V V V '-VV EV\V\VI, M//////M////

Quppternr [ mestoneoi and sdomitentschs an \urt

Paesozoic |v) vY/ v Slar~te, phdllite, sandstoneU roh 2 ,.// orTr4rr V V I V , t /

Lisisipi J and/// impur quartziteh 1 | ^ * Vf/ 7 Slt phlie sodte OV 12

Scale, miles

FIGURE 5. - General Geology, Cape Mountain Area.

Gape Mountain is a prominent and typical example. The third period of igneous

activity is represented by hard black mafic dikes, up to 10 feet in width,

that cut both the limestone and the granite near the head of Cape Greek.

These mnafic dikes do not appear to be either abundant or of great linear

extent; however, they were not traced or studied because they have no discernible connection with the tin minerals except proximity.
15

The general distribution of the granite and the metasediments is shown

on figure 5 but the figure shows neither the late mafic dikes nor the many

granitic dikes and sills that protrude from the granite mass into the metasediments. More detailed descriptions of the geologic features of the area

can be found in the Geological Survey reports listed in the bibliography.

WORK BY THE BUREAU OF MINES

Nature and Extent

The investigation was made to delineate tin-bearing lodes that normally

have no visible surface expression. The mineralized lodes were outlined by

sampling first the placer gravels and then the detrital cover. Sampling the

placer gravels indicated the general location and extent of the tin-bearing

area. Sampling the detrital cover delimited the tin-bearing zones within this

area. Limited specimens and samples from outcroppings in the tin-bearing

zones roughly indicate the general tenor. Data from previous investigations

were used whenever possible.

The sampling procedures are described as they pertain to the succeeding

steps in the investigation. Many placer samples and all detrital-cover samples were roughly evaluated in the field. Some placer samples, and all lode

samples having quantitative value, were analyzed in the Bureau of Mines laboratory at Juneau, Alaska. Tin analyses data are included with the descriptions of the various deposits. Selected typical specimens and samples were

analyzed petrographically. Petrographic descriptions and analyses for metals

other than tin are in special sections following the descriptions of the tin

deposits. Sketches and maps supplement the descriptions.

Placer Investigations

The first stage of this investigation was to estimate the relative abundance of tin in the stream placer deposits. Most of the estimates were based

on data abstracted from the publications listed in the bibliography. If no

data were available, the gravels were sampled by digging test pits at sites

favorable for the accumulation of a placer deposit. The pits were dug in or

near the stream channels, preferably with a bulldozer, but often by hand. The

pits were in thawed gravels; samples were taken close to bedrock whenever possible; and evaluation was limited to roughly estimating the grade. This was

adequate for the purpose. Obviously, the resultant estimates are not a measure of the minable tin in the placers because the estimates include mined-out

tin and both sampling method and sample spacing have been disregarded.

Detrital-Cover Sampling

Sampling Method

Samples of the detrital cover were taken from pits dug by hand or by

gasoline-powered posthole auger. The usual practice was to drill down to

permafrost or bedrock (usually 2 to 3 feet) with a 6-inch posthole auger, stop

the machine, and pull up the auger. About one 16-inch gold pan of material
16 0

could be obtained from the scroll; this was the sample. On steep rocky hillsides or where boulders were abundant, a sample of the same size could be

obtained more rapidly from hand-dug pits.

The samples were concentrated by panning. The panning water was in two

No. 3 washtubs. The sample was first washed and screened through a gold pan

in which a close pattern of 3/8-inch round holes had been drilled. The oversize was inspected for "nuggets" and discarded. Clay, soil, ice, and vegetable matter were washed from the undersize and decanted off; then the heavy

minerals were concentrated by the usual panning techniques.

The sampling was done by two samplers using a tractor and sled to haul

equipment and panning water. If terrain made it possible to bring the tractor

and equipment close to the sample sites, two skilled men could drill, sample,

concentrate, evaluate, and mark 30 to 40 holes during an 8-hour day. Cleaning

and concentrating the samples is hard, tedious labor that requires more than

half the total time. Mechanical concentration of the samples was considered

but was found to be impractical with any available equipment because of the

great variation in the size range and the condition of the sampled material.

Sample Evaluation

The objective of detrital-cover sampling was to find the lode sources of

the tin placer deposits. The first step was to sample the detrital cover

along the streambanks in areas from which the placer deposits could have been

derived. Sample pits were dug on the sides of the valleys, 5 to 50 or more

feet above the valley floor (high enough on the hillside to make reasonably

certain that any material found had come from the hill above rather than being

transported by stream action). The line of sample pits roughly paralleled the

stream at intervals that ranged from 30 to more than 100 feet. The longer

intervals were used until some tin was found, then shorter intervals were

used. Sampling was continued on both sides of a valley to the headwaters.

The grade of the panned samples was estimated visually. The results were

recorded as: 0--no tin; 1 or x--trace of tin-bearing concentrate; 2 or xx--

more than a trace but less than an ounce of tin concentrate; 3 or xxx--more

than an ounce of tin concentrate. A more exact evaluation was found to be

unnecessary. Sample sites and sample maps were marked in a manner that indicated the amount of tin found. Obviously, the only tin detectable by this

means occurs as cassiterite in crystals large enough to be visible. The

identity of cassiterite was verified by placing crystals in hydrochloric acid

in the presence of zinc; then a tin plate formed on the cassiterite crystals.

The sampling results indicated where the cassiterite-bearing float lines

enter the placers. Normally, an area of interest along a streambank would be

indicated by tin minerals in practically every sample for at least several

hundred feet. Nothing more was done in areas that contained no tin or only

an occasional trace.

The sampling process was repeated a couple of hundred feet up the slope

from any areas of interest encountered. The second row of holes roughly
* 17

paralleled the first and was continued until no cassiterite was found at

either end. Additional lines of holes were put in at successively higher

elevations until no more tin minerals were found or the summit was reached.

This procedure outlined an area in which the detrital material contained tin.

Within the tin-bearing area, intermediate lines of samples were taken to form

an irregular grid pattern. Zones of higher-than-normal concentrations within

this grid roughly delineated the lode deposits. If no zones of concentration

were found, it was considered to indicate that the tin was derived from lowgrade disseminations or scattered veinlets.

Lode Sampling

Lode sampling was limited to the minimum required to indicate the probable grade of typical outcroppings in the mineralized zones delineated by

detrital-cover sampling. A more accurate evaluation of the Cape Mountain tin

lodes presented complex problems beyond the scope of this investigation. Some

data from previous investigations has been included.

Bulldozer Trenching

Bulldozer trenches exposed typical outcroppings delineated by detrital-

. cover sampling. The thawed material on the surface was scraped off. This

exposed frozen material which would thaw from an inch or two to a foot or

more per day. The process was repeated about once a day until bedrock was

exposed. The outcrop was cleaned and sampled after it had thawed. Uniform

channels were cut in the clay-quartz and into other soft deposits with a prospector's pick and an iron spoon. Harder rocks required the use of a hammer

and moil. Chip samples were taken across obviously low-grade deposits.

Diamond Drilling

No diamond drilling was done during this investigation, but results of

some drilling by the Bureau of Mines in 1948 are included. During the 1948

investigation, five EX (1.5 inches) holes were drilled to depths ranging from

40 to 68.5 feet in the granite-limestone contact zone. Sludge samples were

not taken.

Sampling Underground Workings

None of the underground workings were reopened during this project. The

Lucky Queen, North Star, and lowest adit of the Bartels mine have been

described in Bureau of Mines Report of Investigations 3978 (18). Some of the

other prospects are described briefly in this report.

DESCRIPTION OF THE DEPOSITS

Tin-Placer Deposits

EThe alluvial tin concentrations in the Cape Mountain area are stream

placers. The deposits appear to have developed under present-day conditions,

and present erosion continues to add tin to the placer deposits. There is
18

evidence that one or more advance and retreat of the sea may have displaced

placer accumulations in the lower sections of the streams. A relatively

recent elevated beach deposit (24, pp. 17, 45, and 54) that may be contemporaneous with the intermediate beach at Nome, 3 has been identified on Boulder

Creek at an altitude of about 80 feet. Beach gravels and shells also have

been reported from Village Creek4 at an altitude of 43 feet. No similar beach

gravels were recognized on Cape Creek or on other streams in the area. However, gravel and overburden over 100 feet deep at the East Fork-Cape Creek

intersection (24) suggest that some radical change in erosional conditions

caused the channel to fill more rapidly than the stream could remove the

material.

The placer sampling data (fig. 2 and table 6) indicates that, although

traces of tin are widely distributed, only seven streams contain 0.1 pound of

tin or more per cubic yard of gravel. Of these seven streams, all except one

drain Cape Mountain. Of the streams draining Cape Mountain, only four (First

Chance Creek, Cape Creek, Goodwin Creek-Goodwin Gulch, and Boulder Creek) contain one pound or more of tin per cubic yard in the placer gravels. The

remaining work was confined to the drainage basin of these four streams.

The tin in the First Chance Creek placers and the Cape Creek placers

could have been derived from either bank of the streams upstream from the

mouth of First Chance Creek. However, on First Chance Creek the grade of the

placer gravels dropped to a trace 1,500 to 2,000 feet upstream from the mouth.

Therefore, all of First Chance Creek valley except the lower 2,000 feet was

eliminated from further consideration. The placer deposits of Cape Creek

extend to the extreme head, but the East Fork drainage contains comparatively

little tin. Therefore, it was assumed that tin could have been derived from

either bank of Cape Creek from the mouth of First Chance Creek to the extreme

head but not from East Fork valley.

The Goodwin Creek-Goodwin Gulch placers were considered as a single unit.

On Goodwin Creek, a narrow placer-tin deposit extends from the mouth of

Goodwin Gulch downstream and grades down to a trace a short distance below

Wales Creek. Only traces of tin occur in Wales Creek or in Goodwin Creek

upstream from Goodwin Gulch; therefore, most of the tin in Goodwin Creek must

have been derived from Goodwin Gulch. Goodwin Gulch was mined from the mouth

upstream to the headwaters forks. It was assumed that tin might have been

derived from either bank of Goodwin Gulch above the intersection with Goodwin

Creek.

The tin-bearing placer gravels on Boulder Creek form an alluvial fan

where the stream debouches on the coastal plain. It was assumed that the tin

could have been derived from either bank upstream from this fan.

3 Hopkins, Dave (geologist, Geological Survey). Letter dated Nov. 12, 1959,

available on request from Area VIII Mineral Resource Office, Bureau of

Mines, Juneau, Alaska. No published reference is known.

4 No published reference is known but shells and beach sands were noted in

original churn-drill logs signed by Otto Worm and William Bourgault, churndrill operators, who drilled on Village Creek in 1943. Copies of logs

available on request from Area VIII Mineral Resource Office, Bureau of

Mines, Juneau, Alaska.
* 19

TABLE 6. - Relative abundance of tin in the placer deposits

of the Cape Mountain areal

Tin, Number and Source

Creek average type of of Remarks

lb per samples data3

cu yd 2

Village 0.1 8 churn-drill RI 4345 This Village Creek flows into the

No. 1. holes. Bering Sea at Wales Village. The

placer tin occurs where the stream

debouches from steep mountain gorge

onto flats. Only occasional scant

traces above or below this point.

Boulder.. 1.0 22 churn-drill IC 7878 This average includes only holes in

holes. the downstream end of the restricted

valley.

Boulder4 . .5 54 churn-dr ill do ... This average inc ludes only holes

holes. where the stream gravels spread out

on the coastal plain downstream from

the restricted valley.

Granite Trace 21 churn-drill RI 4345 Check panning revealed only an occaholes. sional scant trace of very fine

cassiterite.

Wales 5... Trace 6 shovel p it s. - Shov el pits along the channel contained scant traces of tin.

Goodwin 2 to 5 Estimated ..... - This creek was mined from the juncGulch. tion with Goodwin Creek upstream to

the headwaters forks. Panning

during this project revealed abundant tin in the south headwaters

tributary from the upstream end of

the placer pits to the extreme head.

Only traces of tin were found in the

north headwater tributary.

Goodwin.. 4.0 2 churn-drill RI 4345 Apparently a narrow pay streak

holes. extended about 1,000 feet down

Goodwin Creek from the mouth of

Goodwin Gulch. Only scant traces of

tin were found above Goodwin Gulch.

Goodwin 5 1.0 3 churn-drill do... This placer tin deposit extends abou t

holes. 1,000 feet downstream from the mouth

of Wales Creek.

Village 0 1 bulldozer - This creek flows into Lopp Lagoon.

No. 2. trench.

Prince of Trace 2 bulldozer - About 0.01 lb tin per cu yd.

Wales. trenches.

Manna ... 0 2 bulldozer - One trench on each principal

trenches. tributary.

Lynx . Trace _ - - About 0.03 lb tin per cu yd.

See footnotes at end of table.
20

TABLE 6. - Relative abundance of tin in the placer deposits

of the Cape Mountain area--Continued'

Tin, Number and Source

Creek average type of of Remarks

lb per samples data3

Cu yd 2

Gulch "J" 0.2 1 bulldozer - Tributary Potato Creek.

trench.

Gulch "H" Trace do ....... - Do.

Gulch "G" 0 do ....... - Do.

Potato ... 0 5 churn-drill RI 4418 Headwaters of Potato Creek.

holes.

Do Trace 1 bulldozer - Left limit above gulch "H," below

trench. gulch "G."

Do .2 15 churn-drill RI 4418 Below gulches "H" and "J." Apparholes. ently the principal source of tin in

Potato Creek is the drainage basin

of gulch "J." The tin in this tributary, in Lynx Creek, and gulch "H"

indicates a lode source on the ridge

between Potato Creek and Lynx Creek.

Creek "E" 0 1 shovel pit.. - First creek east of Ocean Creek (not

on fig. 2).

Ocean .... Trace do ...-.... Very scant trace.

Lagoon ... Trace 2 shovel pits. - Do.

East Fork .1 15 churn-drill IC 7878 East fork of Cape Creek.

holes.

Cape . 4.5 48 churn-drill do... Cape Creek above the valley of First

holes. Chance Creek (above drill-hole line

3A). The placer deposit starts at

extreme head of Cape Creek and

extends down to a point between

churn-drill hole lines 3A and 4.

Very little tin occurs in the gravels between this point and line 3.

The tin in Cape Creek between lines

2 and IA is considered to be, at

least in large part, derived from

First Chance Creek valley and is

averaged with the First Chance Creek

samples.

First 1.0 20 churn-drill do... Includes the lower 1,500 feet of

Chance. holes. First Chance Creek and lines 2

through 1A on Cape Creek.

Do Trace 5 pits ........ - Both hand-dug and bulldozer pits put

down on First Chance Creek at intervals from 2,000 feet above mouth to

headwaters revealed only scant

traces to very minor amounts of

cassiterite.

See footnotes at end of table.
21

TABLE 6. - Relative abundance of tin in the placer deposits

of the Cape Mountain area--Continued'

Tin, Number and Source

Creek average type of of Remarks

lb per samples data3

Cape ..... 0.2 32 churn-drill IC 7878 Deltalike deposit in the beach gravholes. els at the mouth of Cape Creek.

Sarah7 ... 0 1 bulldozer - One bulldozer trench across the chantrench. nel near the base of Cape Mountain.

Steep .... 0 6 shovel pits. -

Paulina.. Trace 4 shovel pits. - Barely perceptible trace.

"A" Creek .1 do.

"B" Creek Trace do _ "A" through "D" Creeks are on the

"C" Creek do. do _ southwest slopes of Cape Mountain.

"D" Creek do. do .... _ _ l

'Includes mined-out tin and is not indicative of recoverable tin.

2 Estimated average grade of pay streak.

3 Work was performed during this project if no publication or other references

are cited.

. 4 Boulder Creek was churn drilled in 1938 by the Molybdenum Corporation of

America from the deposits described in IC 7878 (24) downstream to the

mouth. Also five holes were drilled through the ice along the edge of Lopp

Lagoon. Reportedly, very little tin was found at any place. Letter from

W. R. VanCampen, former American Tinfields, Inc., Tin City, Alaska, supervisor, Nov. 31, 1942. Available upon request from Area VIII Mineral

Resource Office, Bureau of Mines, Juneau, Alaska.

5 George Waldhelm, a miner who formerly worked in this area, reported that

several hundred pounds of tin concentrate had been recovered from a small

basin-like depression at the headwaters forks.

GA section of Goodwin Creek extending about 15,000 feet downstream from the

mouth of Wales Creek was sampled by 28 churn-drill holes in 13 lines by

Pacific States Mining and Development Co. and Bering Straits Tin Mines,

Inc., in 1935. Results are not known. No additional work was done and the

claims have since reverted to the public domain. (Data from maps originally collected by T. C. Christensen.)

7 Five churn-drill holes were drilled across the channel where Sarah Creek

enters the beach gravels. No tin was found. Data from conversation with

Jack Thiessen, churn driller. No written records were kept.

The Detrital Cover

First Chance Creek

Widespread traces of tin were found in the detrital cover bordering First

Chance Creek in the area where the grade of the stream placer deposits dropped

(fig. 6). The tin in the placer gravels must have been derived from this area.

Additional sampling did not reveal any large concentrations in the detrital

cover but one float line more prominent than the others was traced to the outcropping of an acidic dike (trench FC-1).
22

\° Canoe prospect

/0 00;/ Bartels mine area

m a)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I.~~ :1'".- ~ 

I.~~~~~~~~~~~~~C I.

'oo . .i . . .

S cample pit-no ftin

Trace to moderate amount v' e * p c Area. of tin in samples Acidice ;~ m

_=__ Bulldozer trench 2

o iooo 2000/ , ,

Scale, feet /

FIGURE 6. - Detrital Cover Sampling, Cape Mountain Area.

Cape Creek

Sampling both banks of Cape Creek indicated that practically all the tin

in the placer deposits came from the general vicinity of the Bartels mine at
* 23

the extreme headwaters (fig. 6). A small amount of tin also was derived from

a previously unknown outcropping on the north (left limit) bank, 3,750 feet

upstream from the mouth of East Fork (trench CC-1). No tin was found on

either bank below this point.

Goodwin Gulch

Detrital-cover sampling revealed that the tin placer deposit in Goodwin

Gulch was derived from a very small area at the extreme head of the south

headwaters fork (fig. 6). A placer deposit of unknown grade extends from the

mining pit upstream to the head of this fork. Typical cassiterite specimens

including "nuggets" that exceed 1 inch in diameter were traced from the placer

deposit to the granite-limestone contact downslope from the Lucky Queen adit.

Careful observation while sampling did not reveal any evidence of tin deposits

in the limestone downslope from the mineralized contact zone.

Boulder Creek

The detrital cover on both banks of Boulder Creek, including tributaries,

were sampled from the coastal plain to the headwaters. Results were negative

except at the extreme headwaters (fig. 6) where widespread traces were found.

. The amount of tin in the detrital cover left no doubt that this was the source

of the Boulder Creek placer deposits, but the dispersed traces indicated that

the tin minerals were derived from many scattered sources. Some of the numerous prospects in this valley are described briefly in the section on miscellaneous lode prospects.

Summary of Detrital-Cover Sampling Results

The detrital-cover sampling (fig. 6) indicated that a mineralized zone at

the head of the Cape Creek and Goodwin Gulch drainage basins is the source of

practically all placer tin in both drainages. This zone will be referred to

hereafter in this report as the Bartels mine area. The Boulder Creek drainage

basin extends to the margin of the Bartels mine area; apparently the placer

tin in this drainage basin is derived from scattered and relatively minor tin

occurrences in the margins of the Bartels mine area. The tin in the First

Chance Creek placers is derived from a group of acidic dikes in First Chance

Creek valley about 2,000 feet from the mouth.

Tin-Lode Deposits

Bartels Mine Area

Practically all the tin outcroppings at the head of Cape Creek and

Goodwin Gulch are in an area about 2,000 feet from north to south and 800 feet

from west to east that includes the Bartels mine (fig. 7). Within this miner- O alized area investigations were limited to two centers of abundance: A

granite-limestone contact zone centered about 200 feet north of the Lucky

Queen adit and a zone of fracturing and clay alteration in granite about 1,100

feet south of the Lucky Queen adit. A third zone in the vicinity of the North

Star and lower adit has been described in Bureau of Mines Report of
24

* 4* ,- - Hendwoters Goodwin Gulch

4 j.iS' .,*

44

.4

4~~~~~

- 4 4 

x N xO4t (^> user .I 

" 4 X.' tf ,@ ^ O t.

* ';: ,:, ', :. Sample pit - no tin'

4 \ .'tt.4* x* T . .. ./s Trae of tin ,'t' ~x.4. at °/.g<' X Moderarte amount of tin X 4 t o t °t. XXX Abundont tin

* * 4.~~~~~~~~~~~~~~6u ,. - Trench

' X ,,t /X 0 X Diamond-drill hole

4 *)\\t j*4 t o |O x. -o-- Claim cornerr

t* 44 t °>. l. *.C XX,

.t 0 .\ E x.

I x 0 Scale, fpt

FIGURE 7. - Bartels Mine Area, Cape Mountain.
* 25

Investigations 3978 (18). During the present investigation work was limited

to a few trenches to indicate the nature of the occurrences and the approximate grade.

Granite-Limestone Contact Deposit

Tin occurs as cassiterite along the granite-limestone contact north of

the Lucky Queen adit (fig. 7). The contact is an irregular zone of mixed

granite offshoots and limestone blocks. Most of the cassiterite occurs as

spectacularly high-grade discontinuous lenticular pods within the limestones

near the contact. Obviously, the value of this deposit depends on the size

and number of high-grade pods present; however, the intensive sampling necessary to determine the value was beyond the scope of this project. Clay alteration is common in the adjacent granite, but only minor amounts of cassiterite

were found in the granite or on the actual contacts. Descriptions and analyses of the material in the high-grade veins are in table 7. Trenches 1

through 11 were excavated in the same area and sampled to determine the grade

of the intervening material. Results are in table 8. Records of five short

diamond-drill holes drilled during a previous investigation also are in tables

9 and 10. The drill holes locations shown are approximate only because hole

collars and nearby reference marks had been excavated for road fill.

TABLE 7. - Discontinuous cassiterite-bearing lenticular pods in limestone near the granite contact, Bartels mine area

Sample Tin,

width, Engineer's field description' percent

feet

0.8 Quartz, muscovite, cassiterite, some limestone .14.57

1.0 Quartz, sericite, some limestone and cassiterite. .4.14

1.0 Quartz, muscovite, brown cassiterite, and limestone .14.44

1.0 Limestone, some quartz and cassiterite .1.99

1.0 Tremolite, muscovite, and limestone .. 05

.5 Limestone, quartz, and sericite .. 05

.5 Quartz, sericite and some quartz porphyry .. 12

1.0 Limestone, quartz, sericite, and some cassiterite. .1.12

1.0 Limestone, muscovite, quartz, and some cassiterite. .1.47

1.0 Limestone, sericite, quartz, with some cassiterite. .3.58

1.0 Quartz, sericite, and cassiterite .32.93

1.0 Gray limestone, calcite, quartz, sericite and some

cassiterite .3.28

5.5 Granite, limestone, actinolite, quartz, and cassiterite.... 5.12

1.0 Gray limestone with some cassiterite .3.73

2.8 Gray limestone......................................24

1.8 Limestone and quartz .. 12

2.0 Quartz, sericite, granite, and cassiterite .14.86

2.0 Granite, tremolite, quartz, sericite, and abundant

_______ cream-colored cassiterite .25.02

'Rutledge, F. A. Unpublished report by former Bureau of Mines mining engineer

containing descriptions and analyses, 1960. Available on request from Area

VIII Mineral Resource Office, Bureau of Mines, Juneau, Alaska.
26

TABLE 8. - Trench samples, granite-limestone contact zone

Footage Engineer's field description | Tin,

From | To I I percent

Trench 1, measured from southwest end

0 5 Dark gray to sooty black limestone ....................... ()

10 15 }Yellow clay, quartz grains, and granite fragments .... {o. 06

15 38 Gray limestone with few calcite veinlets. Partly (l)

altered to fine-grained marble.

38 41 Yellow clay, quartz grains, and granite fragments ........ 06

41 58 5 Yof(1)

58 59 Dominantly granite ....................................... 09

59 63 Dark gray limestone ......................................

Trench 2, measured from southwest end

0 12 Gray limestone with few calcite veinlets................. ()

126 20 Dark gray limestone with some altered granite and clay 0.09

20 25 along bedding and fractures. .03

25 28 Yellow clay, quartz grains, cassiterite, and limestone .11

fragments.

28 40.5 Broken dark gray limestone with few calcite veinlets..... ()

40.5 46.5 Iron-stained limestone, calcite, yellow to red clay, a .11

little quartz.

46.5 56.5 Light gray limestone with many calcite veinlets..........(l )

Trench 3, measured from southwest end

0 1.5 Overburden. (1)

1.5 5 Broken dark gray limestone and red brown clay, quartz 0.06

grains.

5 10 Metalimestone with calcite veinlets and about one-fourth .07

15 20 brown clay. .01

20 25 'Dark brownish green clay with fragments of granite and f .01

25 30 I limestone l .01

30 35 Dark brownish green clay grading into dark gray lime- .12

stone with 3 inches of granite at 33 feet.

35 53 Dark gray metalimestone with many calcite veinlets....... (1)

Trench 4, measured from southwest end

0 3 Dark gray metalimestone. (1)

3 7 Quartz, calcite, and cassiterite in limestone .2.29

7 20 Dark gray metalimestone with calcite veinlets............ (1)

20 29 Clay, chlorite, and granite in an elliptical pod .. 05

Trench 5, measured from west end

0 49 Gray much broken limestone with calcite veinlets......... (1)

49 49.4 White igneous dike (Alaskite?) ........................... (1)

49.4 80 Contorted dark to light gray limestone with calcite (1)

veinlets (strikes S 550 E, dip 450 SW at 70').

80 84 Limestone with much calcite and chlorite (?) and some 0.01

quartz vein material.

84 141 Limestone similar to 49.4 to 80. (1)

!No analyses.
27

TABLE 8. - Trench samples, granite-limestone contact zone--Continued

Footage Engineer's field description Tin,

From | To I percent

_____ ____ Trench 6, measured from south end

0 7 Overburden ............................................... (1)

7 20 Granite altered to white, yellow, and brick red clay (1)

and quartz grains.

20 22 Gray-green unaltered granitic dike--apparent strike N to (1)

S, dip not evident.

22 29 Granite altered to reddish yellow clay and quartz grains. (l)

29 35 Gray less completely altered granite . . (l)

35 39 do ......................... 0.09

39 44 Dark gray silicified limestone ............... .01

544 6524 Dark gray marble with few calcite veinlets . ........ .01

62 92 Overburden ...................................................... (l

Trench 7, measured from southwest end

O 55 Overburden ................................................ (1)

55 60 ( 0.18

60 65 (Mixed blocky metalimestone and granite with feldspars.12

W 65 70 altered to clay but much quartz. 1.02~~70 75 I.21

75 80 ' .22

80 85 Granite-limestone contact intergrades . ........... .02

85 90 .01

90 95 .02

95 100 Broken metalimestone with siliceous veinlets and some .05

100 105 iron stain. Much mud in cracks--possibly a residual .04

105 110 concentration of tin in this material. .07

110 115 .03

115 120 .01

120 125 .01

125 135 .01

125 145 Similar less altered metalimestone ....................... .06

145 155 1

155 165 o6

165 195 Slightly altered metalimestone with calcite veinlets..... (l)

Trench 8, measured from southwest end

0 12 Overburden, dominantly limestone debris and clay. . (1)

12 17 Red iron-stained clay, some white clay, and altered 0.02

17 22 J fragments of limestone. .01

22 27 JWhite clay, grains of quartz, some fragments of 02

27 32 J limestone and some red clay. .01

32 7 }Granite with most of feldspars altered to clay .{ .33

37 40 3L.04

40 69 Overburden........................

_____ ____ Trench 9, measured from south end

* _9 +2 Overburden.... (l)

2 12 }Siliceous limestone and sandy clay--poorly exposed {° 025

'No analyses.
28

TABLE 8. - Trench samples, granite-limestone contact zone--Continued

Footage Engineer's field description Tin,

From To IPercent

Trench_9,_measured from south end--Continued ___

12 17 Siliceous limestone with quartz veins and granitic dikes 0.23

17 22 1 up to about 6 inches normal width. .17

22 32 Broken siliceous metalimestone with tiny quartz .04

32 42 f veinlets.L .01

42 50 Less altered metalimestone ....................... (1)

50 63 Overburden ...............................................

Trench 10, measured from southwest end

0 5 Overburden ............................................... ()

5 10 Granite with quartz grains intact, feldspars altered to 0.01

10 15 clay dominantly yellow with some red-brown, brown, and 01

white.

15 46 Buried in mud and water ................... ()

456 60 }Similar granite except clay yellow to white . ......... 01

60 68 Silicified limestone and dark brown clay . ......... .01

68 73 White clay and quartz grains; some red stain . ....... .04

73 78 }Siliceous limestone with quartz veins . {. 01 78 90 J f .01

90 106 Overburden ...............................................

Trench 11, measured from south end

0 3 Overburden .......................... ()

3 57 Blue-gray schistose metalimestone with few small calcite (l)

veinlets. Apparent bedding and schistosity strikes

N 250 W., dips 10° W.

57 166 Overburden ...............................................

TNo analyses.

TABLE 9. - Diamond-drill holes, granite-limestone contact, Bartels mine area'

Angle, Feet Core Tin,

Hole Bearing degrees From To recovery, Description percent

I _ percent

DD1 250 W -45 0.0 47.0 76 Limestone ............ ..... (2)

DD 1 S 250 W -45 47.0 58.5 90 Granite .............. (2)

DD 2 S 250 W -45 0.0 42.5 72 Limestone ................... (2)

DD 2 S250 W -45 42.5 52.0 86 Granite ..................... (2)

DD 3 S 580 W -45 0.0 40.2 81 Limestone ................... (2)

DD 3 S 580 W -45 40.2 41.0 95 Granite ..................... (2)

DD 4 S 250 W -45 0.0 20.0 62 Limestone ................... (2)

DD 4 S 250 W -45 20.0 21.0 90 Limestone, mica, cassiterite 9.13

DD 4 S 250 W -45 21.0 60.0 92 Limestone ................... (2)

DD 4 S 250 W -45 60.0 68.6 95 Granite ..................... (2)

DD 5 S 630 W -45 0.0 35.0 81 Limestone ........... (2)

DD 5 S 63° W -45 35.0 40.0 100 Granite ............ I (2)

1Data from field notes of F. A. Rutledge, former Bureau of Mines mining

engineer.

2 No analyses.
* 29

TABLE 10. - Spectrographic analyses, granite-limestone contact,

diamond-drill hole 4, Bartels mine area

Letters indicate estimates from qualitative analyses:

A more than 10 percent E 0.01 to 0.1 percent

B 5 to 10 percent F 0.001 to 0.01 percent

C 1 to 5 percent G less than 0.001 percent

D 0.1 to 1 percent - not detected'

Sample2 DD4-1 DD4-2 Sample2 DD4-1 DD4-2

Aluminum ........... C A Manganese .E E

Beryllium .......... _ F Molybdenum ......... - E

Boron .............. E D Nickel ............. E E

Calcium ............ A C Silicon .C A

Chromium ........... E E Silver ............. G G

Copper ............. F F Strontium .......... E

Iron ............... D C Tin ................ E E

Lead ............... E E Titanium .E E

Magnesium .......... B C __

'Additional elements sought but not detected: As, Au, Ba, Bi, Cd, Co, Ga, Ge,

Hf, Hg, In, Ir, Li, Mb, Os, P, Pd, Pt, Re, Rh, Ru, Sb, Ta, Te, TI, V, W,

Zn, Zr, Sc, and Y.

* 2 DD4-1, diamond-drill hole 4, 54.6 - 59.6, limestone.

DD4-2, diamond-drill hole 4, 59.6 - 64.5, granite.

See table 9 and figure 7.

Tin Veins in Granite

Trenches 13 through 15 (fig. 7) expose a zone of clay alteration and

quartz-cassiterite veins within the granite mass. It is not evident whether

the clay alteration is a surface weathering effect or extends to depth. Sample descriptions are in table 11. The tin apparently occurs along fractures

as cassiterite, in veinlets associated with quartz and also in the granite

adjacent to the fractures. Some fluorite was noted in the excavated material

but none was recognized in the samples.

Summary of Lode-Sampling Results, Bartels Mine Area

Sampling in the Bartels mine area revealed lode-tin deposits of adequate

size and grade to have produced the Cape Creek and Goodwin Gulch placers. The

resemblance between the large "nuggets" characteristic of the Goodwin Gulch

tin-placer deposit and the cassiterite-bearing lenticular pods in limestone

near granite contacts (table 7) is particularly striking. There is, however,

no way to know how much material was eroded and concentrated to form the tinplacer deposits.

O The relative scarcity of tin minerals in the Boulder Creek drainage andthe fact that they are found only at the extreme head of the valley indicates

that the western margins of the lode-tin zone extend only a slight distance

into the Boulder Creek drainage basin. The eastern and southern margins of

the lode-tin outcroppings coincide with the granite-limestone contact. The
30

mineralizing solutions rising along fracture zones in granite apparently were

unable to penetrate the limestones. Therefore, the mineralized granite and

contact zone in the Bartels mine area could extend eastward and southward

under the limestones without producing any surface evidence.

TABLE 11. - Trench samples, mineralized zone within granite,

Bartels mine area

Footage | Engineer's field description | Tin,

From To I percent

Trench 12, measured from southeast end

0 10 Overburden .................................. (1)

10 15 Iron-stained gray granite ................. (......... (l)

15 20 Clay, quartz grains, and granite fragments, gray to dull r.18

20 24 f red-brown. l .50

24 34 iGray granite fragments and yellow-brown clay ................ 02 34 44 7 ray01

44 52 Clay .............................. .01

52 57 White to dull red-brown clay .................. .02

657 767 }Broken gray granite with some iron-stained clay .. . 01

77 82 Overburden ................... . . . . .

Trench 13, measured from southeast end W

0 31 Coarse-grained gray granite, poorly exposed . .......... ()

31 54 Similar granite with some iron stain .............. ()

54 59 Gray clay and granite fragments ................. 0.04

59 63 Yellow, brown, and white clay with a few rounded iron- .06

stained fragments of gray granite.

63 68 Yellow to brick red clay with some vein quartz . ........ .14

68 72 Light gray clay and granite fragments ............. .01

72 98 Gray granite.....................................1)

98 101 Granite fragments with some clay ................ 1.34

101 106 Yellow, brick red, and gray clay with some vein quartz ...... .38

106 111 Yellow and gray clay with rounded granite boulders to .05

12-inch diameter.

111 115 Yellow clay with some vein quartz and granite fragments ..... .04

115 120 Gray and yellow clay ...................... .08

120 125 Light yellow clay with much granite and granite fragments ... .03

125 130 Gray granite ......................................

Trench 15, measured from southeast end2

0 20 Overburden ........................... ()

20 25 ) 0.01

25 30 Broken iron-stained gray granite. Quartz-cassiterite in .02

30 35 overburden; source may be up hill. .03

35 40 ) .06

40 53 Gray granite; less stain ........... ()

53 84 Overburden ..........................................

!No analyses.

2Trench 14, no bedrock, no samples.
31

Miscellaneous Lode Prospects

Mineralized Dike, First Chance Creek Valley

Tin minerals in First Chance Creek apparently are derived from a group of

acidic dikes that cross the valley (fig. 6). Three prominent dike outcroppings are shown but float indicates that others are present. The dikes are

not uniformly mineralized and the tin minerals are sparsely but widely scattered in the detrital cover. Trench FC-1 (fig. 6) exposes a dike outcrop of

about 100 feet in width that appeared to be one of the principal sources of

tin. Descriptions and analyses of samples from this trench are in table 12.

Note that tin and clay minerals are more abundant near the contacts on both

sides suggesting that the tin was introduced by mineralizing solutions that

followed these contacts. Occasional cassiterite crystals up to one-half inch

in longest dimension were found in the detrital cover downslope from trench

FC-1 and in the placer gravels of First Chance Creek. Apparently none were

included in the lode samples.

TABLE 12. - Trench FC-1, right limit First Chance Creek

Foot ae Engineer's field description Tin,

* From To percent

0 40 Light gray marble... ....................................... o (1)

40 47 Clay, quartz grains, white to light-gray granite fragments. 0.03

Clay iron-stained cream, yellow to brownish red.

47 52 Cream to light yellow clay with much quartz and granite 05

52 58 J fragments. l .01

658 762 ranite with yellow-red clay and quartz grains ... { 1

72 77 Cream to yellow clay with light gray granite fragments and .01

quartz grains.

77 82 Light gray granite with some clay .. 01

82 125 .01

125 135 Gray granite, strike east-west, dip (?), with some clay .10

135 145 .06

145 152 Granite and marble rubble with mud and water. ()

152 154 White sandy clay .. 01

154 156 White to light gray marble .()

156 175 Overburden. (l

'No analyses.

Mineralized Granodiorite Outcrop, Cape Creek Valley

Tin associated with a small granodiorite intrusive was discovered on the

left limit of Cape Creek and exposed in trench CC-1 (fig. 6). Intensive clay

alteration affected both the granodiorite and the adjacent limestone. The tin

appeared to occur as cassiterite principally in segregations at the limestone-

. granodiorite contact. Sample descriptions are in table 13.
32 4

TABLE 13. - Trench CC-1, Cape Creek

Footage Engineer's field description' Tin,

From To Ipercent

Measured from northwest end

0 25 Blocky gray limestone ....................................... (2)

25 35 Mixed clay and limestone rubble .(2)

Clay and granitic fragments .0.01

35 55 Green segregations in clay .. 69

Granitic fragments in clay .. 01

55 145 Blocky gray limestone ...............................- (2)

'Orientation of granodiorite body not determined.

2No analyses.

Limestone-Shale Contact, Goodwin Gulch

An iron-stained limestone-shale contact is prominently exposed on the

north bank of Goodwin Gulch about 2,000 feet upstream from the mouth (fig. 5).

A typical specimen from this contact consisted essentially of quartz with

minor amounts of pyrite, limonite, and clay as well as very small amounts of

calcite and chlorite. Several stages of silicification were apparent. Typical frostbroken material from the outcropping and detrital material directly

overlying the outcropping were panned; no tin minerals were recognized.

North Fork, Goodwin Gulch

Traces of tin were found in the detrital cover near the extreme head of

the north fork of Goodwin Gulch (fig. 6) directly downhill from a group of

prospect pits. The amount of tin found was considered to be too small to

warrant additional work.

Canoe Prospect

A shallow shaft and a series of pits near the southwest corner of the

Canoe lode claim (fig. 3) explores one or more pegmatitic sills in limestone.

Panning downslope from the openings (fig. 6) revealed scant traces of tin.

No additional work was done.

Percy Prospect

A caved adit near the center of the Percy claim (fig. 3) explores a zone

of metamorphism at the contact between the granitic core of Cape Mountain and

the surrounding metalimestones. Specimens from this zone contained some beryllium (see sections on beryllium and petrography) associated with tourmaline,

but a series of detrital-cover samples taken directly downslope from the prospect openings (fig. 6) revealed no cassiterite. No additional work was done.

Headwaters, Boulder Creek

A roughly circular limestone mass is centered about 2,000 feet southwest

of the Bartels mine on the divide between Boulder Creek and First Chance Creek
0 ~~~~~~~~~~

(fig. 5). Numerous pits, shafts, and adits explore the contact between the

limestone and the underlying granite. Placer sampling on First Chance Creek

and detrital-cover sampling in Boulder Creek valley (fig. 6) revealed only

scattered traces of tin derived from this area. Work during this investigation, therefore, was limited to the collection of typical specimens from the

contact zone (see section on petrography).

Dieter Prospect

A tunnel on Dieter No. 2 lode claim (fig. 3) at an altitude of about

1,700 feet extends 418 feet S 720 W (data from patent survey). Previous investigators report finding a single tin-bearing boulder of vein quartz on this

dump (16, p. 99). Detrital-cover sampling revealed no tin on the banks of

Boulder Creek below this prospect; additional sampling below the tunnel

revealed no tin. A sample of the tunnel dump weighing about 50 pounds was

panned; some quartz vein material was seen but no tin minerals were

recognized.

Northwest Ridge, Cape Mountain

The presence of 0.1 pound of tin per cubic yard in Village No. 1 Creek

and in "A" Creek (fig. 2 and table 6) suggests that tin outcroppings occur on

the ridge that extends northwestward from the peak of Cape Mountain towards

Wales. Reports by local residents that cassiterite crystals are occasionally

found in or near the village of Wales tend to substantiate this theory.

However, the amount of tin in the streams draining this area was considered

to be too small to justify

additional investigations.

The Potato Creek-Lynx

Creek Area

Potato Creek (fig. 2) is

65Gi40s / the only stream not draining > 65040 + 3~ < q0 - Cape Mountain that contains

more than traces of tin (table

/ 6). The deposit of placer tin

in Potato Creek extends up

gulch "J" rather than into the

headwater tributaries (fig. 8).

This suggests that the lode

source is on the ridge between

gulch "J" and Lynx Creek (fig.

8). The ridge is about 10

55 <\\ 0o U miles N 600 E of the tinAn I\\ Tbearing zone at Cape Mountain

and about 2 miles west of the

LEGEND l previously known lode-tin 0 * Sample location Scale miles deposits at Potato Mountain

(fig. 1). The bedrock in the

FIGURE 8. - Potato Creek-Lynx Creek Area. Potato Creek-Lynx Creek area
34

is similar to the bedrock in the Potato Mountain area where clusters of tinbearing veinlets occur adjacent to faults in shaly metasediments. The relatively low grade of the placer deposits of Potato Creek and Lynx Creek did not

appear to justify additional work in this area.

Associated Minerals and Metals

Beryllium

During this investigation no samples were taken specifically for beryllium, but stream concentrates, detrital-cover concentrates, and typical outcrop specimens were checked with a laboratory berylometer. Results were

negative with one exception; this was a beryllium-bearing specimen (B 809-3,

fig. 9) from the granite-limestone contact zone on the Percy prospect.

Examination revealed the following:5

The specimens contain many small (less than 1/8-inch) prisms

of white beryl. They check by both optics and X-ray diffraction.

The refractive index is rather low so the alkali content probably

is also low.

Chemical and spectroscopic checks of a number of generally similar specimens

yielded other beryllium-bearing specimens that are described in the section on

petrography and are shown on figure 9. v

This limited investigation did not reveal any large beryllium deposits

but did not eliminate the possibility that large deposits may be present. The

minimum amount of beryllium detectable with the instrument used was 100 to 200

parts per million, which is well below the minable limit. However, such an

instrument is not sensitive enough for reconnaissance sampling; 50 to 100

parts per million or even less beryllium in stream sediments or detritus may

indicate the presence of valuable beryllium lodes (26). Also, all stream

sediment and detrital-cover samples were panned concentrates. The relatively

light beryllium minerals may have been discarded.

Radioactive Minerals

Samples and specimens submitted for petrographic analyses were checked

for radioactivity as a matter of routine; composite samples that included all

the detrital-cover concentrates also were checked. Results were negative.

A field Geiger counter indicated a minor increase in radioactivity when carried across the contact from metasediments to massive granitic rocks. A

larger increase in radioactivity was noted when the instrument was taken into

underground openings in granite. However, radioactivity could not be detected

in specimens small enough to be carried in the hands. Evidently the increase

in radioactivity was due to the mass effect of a minor radioactive component

5 Griffitts, Wallace R. Personal communication by geologist, Branch of Exploration Research, Geological Survey, Denver, Colo., 1965. Available on

request from Area VIII Mineral Research Office, Bureau of Mines, Juneau,

Alaska.
35

C,

f . * BA4B

* Sample lot80 -32 G\odwin GT

*9 Samp loctio

FIGURE 9. - Beryllium Specimens, Cape Mountain.

of the granite. The isolation and identification of minor elements that have

no evident relationship to the tin deposits was beyond the scope of this

project.

Gold

Gold is very scarce in the Cape Mountain area. According to a conversation with Glen Adams, a churn driller, a minor amount of gold is reported to

have been found in one of a large number of churn-drill holes drilled on

Goodwin Creek by private interests about 1935. However, during the extensive

churn-drill sampling programs on Cape Creek and Boulder Creek in 1952 and

1953 (24) no gold was found. During the present investigation only a barely O perceptible trace of gold was found in one pan taken in a gulch that drains

the southwest slopes of Cape Mountain (fig. 2 and table 6). The heavy mineral

concentrates from creeks draining the area between Cape Mountain and Potato

Mountain (figs. 1 and 2) contained no gold; however, a more intensive
36

investigation of this area probably would have revealed occasional traces of

gold as reported by early prospectors.

Magnetite

Magnetite was found in all detrital-cover samples on the north side (left

limit) of Cape Creek from 2,400 to 2,800 feet upstream from the mouth of East

Fork (fig. 6). This was the only place in the area where magnetite was a

notable part of the heavy mineral concentrates. The source of the magnetite

was not investigated but undoubtedly is within 200 feet of the upper line of

sample pits. The magnetic concentrates are described in the section of this

report entitled petrography.

Fluorite

Fluorite occurs in granite as veinlets associated with cassiterite and is

also a com=on constituent of contact metamorphic rocks. A specimen of a veinlet in granite found above the North Star adit contained goethite, quartz,

fluorite, and cassiterite. Occasional similar specimens were found overlying

the tin-bearing granite south of this adit. Samples that contain fluorite are

described in the section on petrography.
37

PETROGRAPHY

by

Walter L. Gnagy6

Petrographic studies were made on specimens of the placer gravels, the detrital

cover, and the rocks associated with the lode-tin deposits of the Cape Mountain area.

The placer specimens, the detrital-cover specimens, and the various lode specimens have

been grouped in separate tables for convenience and clarity. The field descriptions of

the specimens are in the footnotes of the various tables.

TABLE 14. - Principal minerals in some placer concentratesI

Sample No. 2. B815-A B815-B B815-C B815-D B815-E B822-FI B822-J B822-KL B822-MN B822-0

Minerals:

Albite ...... A A A A A S F _ S S

Apatite ..... _ _ T T T _ - _ -_ 

Biotite ..... F F M T _ A A A S S

Cassiterite M - _ _ _ M _ _ T -

Chlorite .... M F F F _ A A A A A

Diopside - - T? F? F? _ - _ _ _

Epidote ..... _ _ T _ T _ _ _ _ _ 

. ~~Garnet .... - - S - - ---

Gold .T? -_ _ _ S _ _ _ _ 

Ilmenite*... M -_ _ _ _ _ _ _ _ 

Potassiumfeldspar A A A A A _ _ _ _ _ 

Limonite ... T - F T _ S F F F F

Muscovite... F F _ T _ S A S S S

Pyrite ...... _ T

Quartz ...... A A A A A S S A A A

Scheelite f T T T T T _ _ _ _ _

Tourmaline. _ _ _ _ T _ _ _ _

Zircon f T T T T T _ _ - _ _

1p - Predominant More than 50 percent

A - Abundant 10 - 50 percent

S - Subordinate 2 - 10 percent

M - Minor 0.5 - 2 percent

F - Few 0.1 - 0.5 percent

T - Trace Less than 0.1 percent

f - Fluorescent 2 B815-A, "A" Creek (see fig. 2).

B815-B, "B" Creek (see fig. 2).

B815-C, "C" Creek (see fig. 2).

B815-D, "D" Creek (see fig. 2).

B815-E, Paulina Creek (see fig. 2).

B822-FI, Potato Creek (see figs. 2 and 8).

B822-J, Lynx Creek (see figs. 2 and 8).

B822-KL, Manna Creek (see fig. 2).

B822-MN, Prince of Wales Creek (see fig. 2).

. B822-0, Village No. 2 Creek (see fig. 2).

6 Petrographer, Area VIII Mineral Resource Office, Bureau of Mines, Juneau, Alaska.
38

TABLE 15. - Principal minerals in detrital cover

panned concentrates1

Sample No.L ........... | B625-1 B625-2 B626-1 B627-1 B627-2 B706-1 B810-5

Minerals:

Albite .............. S S

Biotite ............. T _ T _

Calcite ............. T S P S P M F

Cassiterite ......... M F M _ A

Diopside ............ M

Dolomite ............ T P A A A M P

Epidote ............. T T

Goethite-limonite ... F S S M S M M

Hornblende .......... T

Potassium-feldspar .. _ A _ _ _ 

Magnetite ........... P

Olivine ............. M

Quartz .............. T M S A M P S

Rutile .............. _ T

Scheelite f...... - T T T T T F

Sphene .............. T

Tourmaline .......... _ T _ S _ T A

Zircon .............. T

'P - Predominant More than 50 percent

A - Abundant 10 - 50 percent

S - Subordinate 2 - 10 percent

M - Minor 0.5 - 2 percent

F - Few 0.1 - 0.5 percent

T - Trace Less than 0.1 percent

f - Fluorescent

2B625-1, left limit Cape Creek below trench CC-1, magnetic fraction.

B625-2, left limit Cape Creek below trench CC-1, nonmagnetic fraction.

B626-1, left limit Cape Creek near headwaters.

B627-1, headwaters of Cape Creek.

B627-2, right limit of Cape Creek.

B706-1, First Chance Creek.

B810-5, extreme head of south fork of Goodwin Gulch.
* 39

TABLE 16. - Principal minerals and rocks in typical specimens

from the lode-tin zone. Cape Mountainl

Sample No. 2 . .......... .B704-3 B704-4 B704-5 B802-1 B802-2 B809-2 B810-1 B810-3 829-14

Rocks:

Altered granite .... - - _ C

Granite-pegmatite.. - _ C _ _ -

Granodiorite . . - C C _ C

Quartz vein ........ - C C C _

Quartzite . ...... C? _ C _ _ _ _ _ _ 

Tourmaline vein .... C C _ -_ _ 

Minerals:

Albite............. - P A

Albite-oligoclase.. - - _ A

Biotite ............ - - S

Calcite ............ - - S _ S _ A -

Cassiterite ........ - - T P P _ - A T

Chlorite ........... - - M

Dolomite ........... - - M _ _ _ 

Goethite-limonite.. M - _ T _ T

Graphite ........... S -

Potassium-feldspar. - - - _ _ A _ A

Mica, biotite ...... - - - S _ _ -

Mica, muscovite.... - - - S M _ S _ T

Mica, unidentified. - - - _ _ _ S -

Microcline . - - - _ _ P _ _

Oligoclase. . _ _ _ _ _ _ S _

Quartz .P A P M T A A A P

Scheelite f . . . . _ T _ _ _

Tourmaline.. _ _ A A _ _ A T

Vanadium oxide.... X _ _ _ _ _

Zircon (altered) - _ _ _ _ _ _ _ T

C - Rock classification

P - Predominant More than 50 percent

A - Abundant 10 - 50 percent

S - Subordinate 2 - 10 percent

M - Minor 0.5 - 2 percent

F - Few 0.1 - 0.5 percent

T - Trace Less than 0.1 percent

f - Fluorescent

X - Detected in sample.

2 Field description of samples:

B704-3, graphitic metasedimentary rock adjacent to igneous intrusive, trench CC-1,

Cape Creek (fig. 6).

B704-4, igneous intrusive, trench CC-1, Cape Creek (fig. 6).

B704-5, complex vein in limestone near trench CC-1, Cape Creek (fig. 6).

B802-1, vein outcrop, trench 4, Bartels mine area (fig. 7).

B802-2, vein outcrop, trench 3, Bartels mine area (fig. 7).

B809-2, coarse-grained granite, Bronx claim (fig. 7).

B810-1, 1-inch-wide quartz vein in granite, Tremont claim (fig. 7). Panning indicates that some cassiterite was derived from this vein but none was seen in

specimen.

B810-3, quartz vein in limestone block east of Bronx claim (fig. 7).

829-14, mineralized granite, trench 13, Bartels mine area (fig. 7).

3Sample B704-3 was rechecked for radioactivity because of the presence of a vanadium

mineral and graphite. Results were negative.
40

TABLE 17. - Principal minerals and rocks, granite-limestone

contact zone, Cape Mountain'

Sample No.2 .. B803-71 B803-72 B803-73 B803-74 B803-75 B803-76 B803-77 B809-33

Rocks:

Dolomite .... C _ _

Granodiorite - C _ _ _ _ _ _ Limestone ... - - - _ C

Skarn ....... - - C C

Tourmaline

vein ....... - - C C

Quartz vein. - - _ _ C _ _

Minerals:

Albite ...... _ P _ _ _ _ _ _ 

Calcite ..... _ A P

Diopside .... _ P P _ _ _ 

Dolomite .... P - _

Goethitelimonite ... - - A _ A A A _

Potassiumfeldspar ... _ A -_

Lepidolite.. - _ M

Mica,

biotite .... _ T _

Quartz ...... _ A S T _ P A _

Scheelite f - _ _ T T _ T F

Tourmaline.. - P A _ M P _

Tremoliteactinolite. - _ _ A _ _ _

'C - rock classification

P - Predominant More than 50 percent

A - Abundant 10 - 50 percent

S - Subordinate 2 - 10 percent

M - Minor 0.5 - 2 percent

F - Few 0.1 - 0.5 percent

T - Trace Less than 0.1 percent

f - Fluorescent

2 B803-71

B803-72 This is a suite of seven typical specimens from the contact zone of

B803-73 a metalimestone block entirely surrounded by granite on the

B803-75 Boulder Creek-First Chance Creek divide (fig. 5).

B803-76

B803-77

B809-33, typical specimen from the contact zone, Percy lode (figs. 3 and 5).
. 42

BIBLIOGRAPHY

1. Schrader, F. C., and A. H. Brooks. Preliminary Report on the Cape Nome

Gold Region, Alaska. U.S. Geol. Survey Special Pub., 1900, pp. 25-26.

2. Brooks, A. H. An Occurrence of Stream Tin in the York Region, Alaska,

Ch. in U.S. Geol. Survey Mineral Resources of the United States,

Calendar Year 1900. U.S. Geol. Survey, 1901, p. 270.

3. Collier, A. J. A Reconnaissance of the Northwestern Portion of Seward

Peninsula, Alaska. U.S. Geol. Survey Prof. Paper 2, 1902, 70 pp.

4. . Tin Deposits of the York Region, Alaska. Ch. in Contributions to

Economic Geology. U.S. Geol. Survey Bull. 225, 1903, pp. 154-167.

5. . Tin Deposits of the York Region, Alaska. U.S. Geol. Survey Bull.

229, 1904, 61 pp.

6. . Recent Development of Alaskan Tin Deposits. Ch. in Report on

Progress of Investigations of Mineral Resources of Alaska in 1904.

U.S. Geol. Survey Bull. 259, 1905, pp. 124-125.

. 7. Graton, L. C., and F. L. Hess. The Occurrence and Distribution of Tin.

Ch. in Contributions to Economic Geology. U.S. Geol. Survey Bull. 260,

1904, pp. 161-187.

8. Hess, F. L. The York Tin Region. Ch. in Report on Progress of Investigations of Mineral Resources of Alaska in 1905. U.S. Geol. Survey

Bull. 284, 1906, pp. 145-157.

9. Brooks, A. H. The Mining Industry in 1906. Ch. in Report on Progress of

Investigations of Mineral Resources of Alaska in 1906. U.S. Geol.

Survey Bull. 314, 1907, pp. 28-29.

10. Knopf, Adolph. The Seward Peninsula Tin Deposits. Ch. in Mineral

Resources of Alaska, Report on Progress of Investigations in 1907.

U.S. Geol. Survey Bull. 345, 1907, pp. 257-261.

11. . Geology of the Seward Peninsula Tin Deposits, Alaska. U.S. Geol.

Survey Bull. 358, 1908, 71 pp.

12. Brooks, A. H. The Mining Industry in 1909. Ch. in Mineral Resources of

Alaska, Report on Progress of Investigations in 1909. U.S. Geol.

Survey Bull. 442, 1910, p. 39.

13. . Geologic Features of Alaskan Metalliferous Lodes. Ch. in Mineral

Resources of Alaska, Report on Progress of Investigations in 1910.

* U.S. Geol. Survey Bull. 480, 1911, pp. 88-90.
41@

TABLE 18. - Principal minerals and rocks, beryllium-bearing specimens, Cape Mountaini

Sample No.3 ............. BA2 BA3 BA4B BA5A BA5B BA5C BA7 BAB B809-31 B809-32

Rocks:

Cassiterite vein ......... - _ _ _ _ _ _ C

Greisenized limestone.... -_ _ _ _ _ C

Skarn . ......... - C C C C -_ _ -

Tourmaline schist ........ C

Tourmaline soda syenite.. - _ C

Tourmaline vein .......... C

Vein quartz .............. C _ _

Chemical:

Be (Morin) ............... T X T T T X T T (4) (4)

Minerals:

Actinolite ... _ S _

Albite . ..................T P S

Beryl . ................... S A

Biotite .................. - S

Calcite . . .... - S A S S _ A _ _ A

Cassiterite .............. -_ _ P

Chlorite . . A - - M _ S M F M _

Diopside ..... _ P A P A _ _ _ _ _ 

Epidote . . .... - T S - A T _ _ _ _ 

Fluorite . . .... _ A A A S _ M _ _ 

Potassium-feldspar .. T _ _ _ _ _ _ _ T

Lepidolite . .............. A S _ _ 

Limonite . ................ T A _ _ 

Mica, unidentified ....... - M

Quartz . ........... P - A _ F P A T _ _ 

Scapolite ... _ A _ F P

Scheelite f ........... _ T F F F T M _ T _

Sphene ...................- - T -_ _ _ 

Tourmaline ............... A - T S - S A P

Vesuvianite ................ T

'P - Predominant More than 50 percent

A - Abundant 10 - 50 percent

S - Subordinate 2 - 10 percent

M - Minor 0.5 - 2 percent

F - Few 0.1 - 0.5 percent

T - Trace Less than 0.1 percent

X - Detected in sample

f - Fluorescent

R - Radioactive

C - Rock classification

Numerals - percent 2 Sample locations shown on figure 9:

BA2, float specimen from trench 30 feet east of Percy adit.

BA3, float specimen from trench at head of Boulder Creek; most trench material is granite;

surrounding float is limestone.

BA4B, float specimen, altered limestone; granite-limestone contact, Village Creek.

BA5A

BA5B | Specimens from adit dump; limestone bedrock at portal; dump mostly granite with

BA5C some pegmatitic granite and altered metalimestones.

BA7A I Specimens from shaft dump; shaft was sunk in metalimestone about 25 feet south of

BA7B granite-limestone contact; no granite on dump.

B809 31 }Specimens from adit dump, Percy adit; see section on beryllium. e

3 Specimens BA2 through BA7B collected by R. V. Berryhill, former Bureau of Mines mine examination and exploration engineer, during a reconnaissance examination made in 1961.

4 Not tested.
* 43

14. Hess, F. L. Tin Resources of Alaska. Ch. in Mineral Resources of

Alaska, Report on Progress of Investigations in 1911. U.S. Geol.

Survey Bull. 520, 1912, pp. 89-92.

15. Harrington, G. L. Tin Mining in Seward Peninsula. Ch. in Mineral

Resources of Alaska, Report on Progress of Investigations in 1917.

U.S. Geol. Survey Bull. 692, 1919, p. 358.

16. Steidtmann, E., and S. H. Cathcart. Geology of the York Tin Deposits,

Alaska. U.S. Geol. Survey Bull. 733, 1922, 130 pp.

17. Smith, Philip S. The Mineral Industry of Alaska in 1936. U.S. Geol.

Survey Bull. 897-A, 1938, pp. 84-87.

18. Heide, H. E., Wilford S. Wright, and Robert S. Sanford. Exploration of

Cape Mountain Lode-Tin Deposits, Seward Peninsula, Alaska. BuMines

Report of Investigations 3978, 1946, 16 pp.

19. Heide, H. E., and Robert S. Sanford. Churn Drilling at Cape Mountain Tin

Placer Deposits, Seward Peninsula, Alaska. BuMines Report of Investigations 4345, 1948, 14 pp.

. 20. Heide, H. E., and F. A. Rutledge. Investigation of Potato Mountain Tin

Placer Deposits, Seward Peninsula, Northwestern Alaska. BuMines Report

of Investigations 4418, 1949, 21 pp.

21. Lorain, S. H., and R. R. Wells, Miro Mihelich, J. J. Mulligan, R. L.

Thorne, and J. A. Herdlick. Lode-Tin Mining at Lost River, Seward

Peninsula, Alaska. BuMines Inf. Circ. 7871, 1958, 76 pp.

22. Mulligan, John J. Tin Placer and Lode Investigations, Ear Mountain Area,

Seward Peninsula, Alaska. BuMines Report of Investigations 5493,

1959, 53 pp.

23. . Sampling Stream Gravels for Tin, Near York, Seward Peninsula,

Alaska. BuMines Report of Investigations 5520, 1959, 25 pp.

24. Mulligan, John J., and Robert L. Thorne. Tin-Placer Sampling Methods

and Results, Cape Mountain District, Seward Peninsula, Alaska.

BuMines Inf. Circ. 7878, 1959, 69 pp.

25. Hopkins, David M. Cenozoic History of the Bering Land Bridge. Science,

v. 129, No. 3363, June 5, 1959, pp. 1519-1528.

26. Sainsbury, C. L. Beryllium Deposits of the Western Seward Peninsula,

Alaska. U.S. Geol. Survey Circ. 479, 1963, 18 pp.

27. Mulligan, John J. Tin-Lode Investigations, Potato Mountain Area, Seward W Peninsula, Alaska. BuMines Report of Investigations 6587, 1965, 85 pp.

INT.-BU.OF MINES,PGH.,PA. 9164