R. . 4174

#

JUNE 1948

UNITED STATES

DEPARTMENT OF THE INTERIOR

J. A. KRUG, SECRETARY

BUREAU OF MINES

JAMES BOYD, DIRECTOR

REPORT OF INVESTIGATIONS

TUNGSTEN DEPOSITS IN ALASKA

BY

ROBERT L. THORNE, NEAL M. MUIR, ANER W. ERICKSON,

BRUCE I. THOMAS, HAROLD E. HEIDE, AND WILFORD S. WRIGHT
--- -.r-r-.-n.  *r---- -· r

R. I. 4174,

June 1948.

REPORT OF INVESTIGATIONS

UNITED STATES DEPAEMENT OF THE INTEIOR - BUREAU OF MINES

* *A . * * -

-TUNGSTEN DEPOSITS IN ALISKAI/

By Robert L. Thorne,/ Neal M. Mlir2/ Aner Wirickson4'o

Bruce I. Thomas.,.l Harold E. Re9de..-

A and Wilford, S. Wright-/,

- . CONTENTS

Page

Introduction .... . .............. 3

Acknowledgments . . . . .... .. . . . . . . 5

Gilmore Domoedepositts . . . . . . . . . . . * * 5

Location and accessibility . . . . . . . . 5

Physical features and climate . . . . . . . . 7

History and prodiution . .... ..... . * * *. 7

Property and ownership .. . . .... . . . . 9

General-geology-.. .. ... .... .... * ,

OccUrrence of deposits . . . . . . .. . 10

Character of the ere ................... 11

Bureau of Mines- work at Stepovich deposit . . . . . . . 12

Bureau of Mines work at Colbert prospect . . ..... . 13

Bureau of- M4ines work at. Yellow Pup prospect . . . . . 14

Sampling end analyss . . . . . . . . . ... 15

Development 16

B'eneficlation tests by Bureau of Mines . . . . . . 17

Beneficiati-on tbets by Cleary. .ill Mine.s Co . . . . . 22

Lode deposits in the Steele Creak-First Chance area . ... 23

Tanana group . . . . . , . * . . 23

Spruce .Hen -group . -.. - ., . . 24

Colunibia -group. ,.. . . ........ , 25

Tungsten -Hill group . . ... . 25

Andorson claim. . , . . . * * * 26

Blossom group j . . . . 26

Old Glory prospect . . . . . . , . . . . . . 26

Location . . . . . . . 26

Generai information , ............... 27

Other'tungsten occurrences in interior Alaska . . . . .. . 27

Placer tungsten ^ *. , . . ., 27

The Bureau of Mines will welcome reprinting of this paper provided the

following footnote acknowledgment is used: "Reprinted from Bureau of

Mines Report of Investigations 4174."

2/ Mining engineer, Bureau of Mines, Juneau, Alaska.

1955
Geologic features 

. .. . ...

Lode deposits of the Nome area 

..

...

.Sophie .. .. 

.......

Miscellaneous localities .... ..

Lost River .. ... .. ..

Placer deposits of the Nome area 

.

Location .............

History 

. ... 

Physical features * 

......

...

Ore deposits ..........

The ore ..... ...... 

...

Willow Creek District .........

Independence mine .. ...... ..

Gold Cord mine 

..

. ....

Fern mine .... * * 

...

Hyder district in Southeatern Alaska. .

Location and accessibility 

. ....

Physical featureb and climate 

...

History and production 

. ......

Riverside mine 

. ......

Property and ownership. 

..

..

General geology .... ,... ,,

Occurrence of deposits .. 

.., .

Work done'by the Bureau of Mines 

..

Sampling dnd an aalysis- 

. .. 

..

Development ....... 

....

Beneficiation by the Scott Co. ...

Mountain View inine ..

. .. - .. .. .

Property and ownership .-. 

*

General geology ... 

.

Occurrence of the deposits 

. .....

Character of the ore ..... ..

Development .' .' .'. .. .,

Work done by the Bureau of Mines

Samplinrg 'aid analysis , 

.

,, ...

Beneficiation ...

......

Apex-il Nido mine .. * * 

.

.

to6ation 

.. ... ....

History 

.

.

..

... , 

.

.

Physical features and climate 

...

Description of the deposits 

.

.

Bibliograpkh 

...... .. 

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R. I. 4174

CONTENTS (Cont'd.)

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Fig.

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4B.

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15A.

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Cleary Hill and Colbert scheelite zones .

Sample locations and analyses . ......

Claim map of tungsten properties on Gilmore

Cleary Hill'mine, 1942 . .. . ... .

Cleary Hill tungsten mine, 1946 . . .

Cleary Hill mine, section A1 -A . .....

Cleary Hill mine, section B1-B 2 ......

Cleary Hill mine, section C1-C2 . . . . .

Cleary Hill mine, section D1-D2 . ... ..

Cleary Hill mine, section E1 -E2 . . .

Flow sheet, Cleary Hill stamp mill, 1943 .

R. I. 4174

TABLES

1. Results of flotation tests, Mountain View mine, Hyder, Alaska . .

ILLUSTRATIONS

Page

49

Index map of Alaska showing location of tungsten deposits

Location and geology, Fairbanks tungsten area . . . . .

Surface map of Bureau of Mines exploration work on

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Do. me

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Yellow Pup surface and exploratory work . . . . . . .

Map of Nome area showing stream location of placer and

lode scheelite ." . ... . .

Hyder and vicinity .. . . . . . . . .

Plan map of Riverside mine .............

Vertical projection, Riverside mine .... . ....

Section A-A, East ore body, Riverside mine . . . . . .

Section B-B, East ore body, Riverside mine . . . . .

Section C-C, East ore body, Riverside mine . . . . .

Section E-E, sublevel ore extension . . . . . . . . .

Analyses, underground stopc, mill tunnel . . . . . .

Analyses btopes 1, 2, 3, and cast raise . . . . . ...

Section on plane of vein East ore body . . . . .

*Flow sheet, Riverside tungsten mill, July 942 ....

Mountain View mine and vicinity . . . . . . . . . ...

Workings, topography, and assay map of surface sampling

Plan showing structural control of ore shoots , . . . .

Assay map, lower drift . . . . . . .. . . . . .

Assay map, upper drift Mountain View mine * . . ...

Location of Apex-El Nido mine ...... . . . . . .

Map of part of El Nido mino, Chichagof Island . . ...

Following

page

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INTRODUCTION

For many years the domestic production of tungsten has: been too small

to meet requirements of the United States, and it has been necessary to import about 2 pounds of the metal for every pound produced in this country,

The Bureau of Mines and the Federal Goological Survy, 'cooperating in a

1935 - 3-
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R. I. 4174

program of investigation of strategic and critical minerals, began in 1940

to examine and develop tungsten occurrences in western United States and

Alaska. During the years in which the nation was at war, this work was

given special impetus to stimulate domestic production. This report is a

compilation of results of the tungsten investigations in Alaska supplemented

by certain data made available by the Territorial Department of Mines and

is designed to include in its scope descriptions of all known tungsten occurrences in the Territory. Two areas in Alaska warranted special investigation - one at Gilmore Dome, 16 miles northeast of Fairbanks, and the other

in the Hyder District, at the head of Portland Canal.

Three tungsten properties - the Stepovich, Colbort, and Yellow Pup -

are at GTlmore Dome. The Stepovich property, referred to sometimes as the

Cleary Hill tungsten deposit, was worked by the Cleary Hill Mines Co. from

April 1942' uhtil May 1944 and was first examined by Robert S. Sanford and

Norman Ebbley,' Jr., engineers of the Bureau of Minos, in September 1942.

The Cleary' Hill Mines Co. by that time had explored an 800-foot strike length

of the ore zono with 10 bulldozer trenches and was sinking an inclined shaft

on ore in the cehtral portion of the explored zone. In January 19435, the

senior author, in company with' Ebbloy and Larry C. Doheny, supervising

engineer of R.F.C., examined the pioperty. Preliminary work by the Bureau

of Mines' began' in May 1945, but actual exploration did not commence until

late in June' and' continued until the end of October 1943.

The deposit was examined by John B. Mertie, Jr., and William C.

Overstreet, of the Fedbral' Gbological Survey, n' 1942, and this study was

continued in 1943 by' Frank' Byers, whb also assisted the Bureau's engineers

on geologic problems; A magnetometer survey of this area was undertaken in

1942 by Henry Joesting and' Eskl Anderson, engineers of the Territorial

Department' of Mines, and' was completed with Bureau of Mines assistance in

1943.

During 1943 the Bureau completed exploratory projects on the Cleary

Hill mine and ad-jacent Colbort prospect. The field work on the Colbert'

property was begun' early' in July 1943 and continued intermittently until the

end of October' 1943,'when It was recessed because of subzero weather.

During September 1944, the.Bureau of Mines established (by means of a few

surface trenches) continuity between the Colbert mineralized zone, high on

the dome' and the Yellow Pup vein, the lowest known tungsten mineralization

in the area.' Itis generally recognized that any extensive program to

develop the arba as a whole logically would be carried out from the lower

horizon.'

A. F.'Bldditgton, of the Geological Survey, first mentioned the presence

of scheelite in the Hyder district at the Riverside, Mountain View, and

Monarch properties in 1924. Special attention was called to the district

in 1941 by John C. Reed after a reconnaissance examination by the Geological

Survey. During the summer of 1942, Noal M. Muir investigated tungsten

deposits in the district and in the fall of 1942 and winter of 1942-43

directed a diamond-drilling and underground development program at the

1935 - 4 -
74. 7 - .. 1/-2 ' / ° ¢

N -

--. ,

x,4 , C, 1 M 0 00

Miiiii-a - -

Figure 1. - Index map of Alaska showing location of tungsten deposits.
£ EA'END

I V V V

rancd/ior/ife

A/tCredY Oron,/fe Dzkes

LIIZ

C/ndifferenf/tafed

Scheeitfe

65°00'

o0 2

Sc/e in Miles

Note: Geoloqy ond

Topography offer

Oeo/og/ca/ Survey

and Terriforab/

Dcpcarfmen f of Mtnes

Figure 2. - Location and geology, Fairbanks tungsten area.
- -

R. I, 4174

Riverside mine. Diamond-drill cores were logged and interpreted by F. M.

Byers, Jr., and Clyde Wahrhaftig, Jr., of the Geological Survey. The

Geological Survey field party furnished geological, underground, and crosssection maps, which assisted the Bureau's engineers in the diamond-drilling

program.

The Bureau of Mines, encouraged by the report of the 1942 preliminary

examination of the Mountain View mine, proposed a drifting and sampling

project. Work was begun at the property under the direction of Aner W.

Erickson May 22, 1944, and. was completed October 24, 1944.

In the summer of 1942, Harold E. Heide investigated occurrences of

scheelite in placer gravels in the tributaries of Snake River in the Nome

area on Seward Peninsula.

Tungsten depositg in the Fairbanks mining district were examined in the

winter of 1942 by Henry R. Joesting, mining engineer of the Territorial

Department of Mines. The Old Glory prospect at Seattle Creek was examined

by Bruce I. Thomas in July 1944.

Tungsten minerals have been found in varying amounts in the concentrates

obtained from gold-placer operations in many parts of Alaska. The Apex-El

Nido mine on Chichagof Island was examined for scheelite by W. M. Traver, a

Bureau engineer, in October 1942.

ACKNOWLEDGMENTS

Special acknowledgment is due the following: Robert S. Sanford, acting

chief of :the Alaska division of the Bureau of Mines, under whose direction

all investigative work was done; Norman E. Ebbley, Jr. who directed exploratory work at the Yellow Pup prospect; Dr. Henry R. Joesting, for his

geophysical study of Gilmore Dome deposits; J. S. Kennedy and C. H. Gorski,

of the Metallurgical Branch who conducted beneficiation tests on ores from

Cleary Hill and Mountain View mines.

Acknowledgment also is extended R. E. Wyer, manager, Cleary Hill Mines

Co., for submitting claim maps and other data; to L. D. Colbert for rendering valuable assistance in the investigation of his property; to Arthur 0.

Moa for contributing historical and production data pertaining to the

Mountain View mine, and to Austin H. Merrill, superintendent of the J. H.

Scott Co., for imparting general information regarding the Riverside mine.

GIL3DRE DOME DEPOSIT

Location and Accessibility

Gilmore Dome is in central Alaska at latitude 64° 59' N. and longitude

147° 22' W., 16 airline miles northeast of Fairbanks, as shown in figure 1.

The summit elevation of Gilmore Dome is 2,400 feet. The tungsten area,

shown in figure 2, is reached from Fairbanks by 24 miles of fair road, part

of which is graveled and part unsurfaced. The road is muddy during seasonal

thaws and heavy rains.

1935 - 5 -
R. I. 4174

Fairbanks, a city of about 5,000 population and a major transportation

terminal, is the placer-gold mining center of Alaska, The Alaska Railroad,

468 miles in length, links Fairbanks with its Pacific Ocean terminals at

Seward and Whittier, Alaska. Alaska Steamship Co. vessels make regular

trips at frequent intervals between these ports and Seattle, Wash. Other

freight routes to Fairbanks are the Richardson Highway from Valdez and the

Alaska Highway from Dawson Creek in Canada.

Pan American World Airways and Canadian Pacific Air Lines make Fairbanks a regular stop, and numerous small air-transportation services have

headquarters there. When emergency shipments from Seattle are necessary,

they can be sent via air express at approximately $1 a pound. Airplane

fare from Seattle to Fairbanks is $149.50, including tax. The steamship

fare from Seattle to Seward is $93.58. The railroad fare from Seward to

Fairbanks is $32.44, which does not include the cost of an overnight stop at

Curry and possible step-overs in Anchorage or Seward.

Through freight rates from Seattle to Fairbanks by way of the Alaska

Steamship Co. and the Alaska Railroad range from $45 a ton to $70 a ton,

depending on the nature of the freight. This has been the standard means

of transportation and requires from two weeks to more than a month.

A local transportation problem developed when the Cleary Hill Mines Co.

decided to use the gold-mine camp and mill rather than construct a new camp

and mill at the tungsten mine. Originally the tungsten mine was 19 miles

by road from the gold mine, but a new route only 8 miles long was established

during the summer of 1943 by constructing 6 miles of new road. The final

mile and a half of the new cut-off to the mill has a stoop grade. Chains

are required during 7 or 8 months of the year when winter conditions prevail. It is estimated that tho'truck haul costs $2 a ton.

The lack of a permanent camp at the tungsten mine made it necessary

to haul most of the workmen to and from the Cleary Hill camp during the

winter months. During the summer months two camps were maintained, but

these were discontinued toward the end of October. A bus provided transportation for the men. There is telephone communication between the gold

mine and Fairbanks.

Three properties are at Gilmore Dome. The Stepovich claims along the

strike of the Cleary Hill ore Zone extend 5,000 feet southwest and more

than 5,900 feet northeast of the summit. Five Stepovich claims are on

the north side of Gilmore Dome.

The Colbert prospect is 1,200 feet south of and parallel to the Cleary

Hill ore zone.

The Yellow Pup mine property is on the west side of Gilmore Dome near

the headwaters of Yellow Pup, a tributary of Fish Creek. The claims are

contiguous with the east end line of the Colbert claims and join the south

side of the Lucky, Chippowan, and Schoolite No. 5 claims of the Stepovich

property.

1955 6 -

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R. I. 4174

Physical Features and Climate.

Gilmore Dome is one of .many nearly flat-topped hills with the .ounded

contours of mature topography that form the irregular ridge. pattern of t'he

country. Most' of the mountain tops are..about 2,400 'feat above. sec level,'i

though some are higher or lower by a few hundred feet. Saddles are only

slightly lower than summits, except where the ridge.-chain..-:t'errina.ted by

a drainage system. Valley floors range in altitude from r 700 .to 1S00 feet.

In places trees grow 'upbn the entire' slope of the hills, but tonly on

the lower slope do they reach a size-a.dequate for mine timber,'fire wood,

or lagging. Sprudo, birch, poplar, and tamarack grow in the region 'but ..

only spruce and birch are found -near the mine large enough to be used commercially. Alder, willow, dwarf birch, and huckleberry brush obstruct 'the

work of the prospector. Moss and grass grow on the slopes, but the':rounded

tops of the domes are carpeted with mossy tundra and several types of berry

bushes and vines.

Farm and garden crops mature rapidly -in summer, when the sun shines

nearly 24 hours a day. Most of the year's procipitation, which is slight,

enters the soil during the growing season after the spring thaw. Agricultural land, already productive of farm andi.truck garden crops, could be made

to yield an adequate supply for the local population.

The climate in the Fairbanks area is semi-arctic, with 'long, cold

winters and short, hot summers. The mean temperatures for the 3-winter

months is -7° F. and for the 3 summer months 57° F. The temperature is frequently -40° to -60° F. during December, January, and February. The mild

months of winter (March, April, and early May) are spent in cross country

freighting, placer drilling, and general preparation for the summer's work.

The mature topography of central Alaska, with its many ox-bow lakes,

sloughs, and low gradient rivers, plus the water-retaining qualities of the

tundra and frozen ground, gives the impression of plentiful precipitation,

though this is belied'by. an average annual rainfall of less.than 12 inches,

comparable to a semi-arid climate. Average annual snowfall in the area is

49.4 inches. Most of the soil,' ravel, and bedrockin the region is perpetually frozen. The seasonal thaw ranges from a few inches where the ground

is blanketed by moss to several feet in areas where the moss has been removed.

Histor and Production -

The first work was done on Gilmore Dome in 1915- / and consisted of handdug pits; After the vein had been traced for a -strike length of 200 feet .on

what--is'now the Stepovich'property, an inclined shaft was sunk 40 feet on

the voin.

3/7 Brooks, Alfred:H.· and other4y-iMinral Resburcos of Alaska, 1915: Geol.

Strv. Bull. 642, pp. 61-62.

1935 7
R. I. 4174

. In 1916,4/ two inclined shafts, 75 and 80 feet deep, were sunk on the

vein. In 1917, the 75-foot .shat on the Scheelite claim was continued to

a depth of 180 feet. Mike Stepovich, the owner, reports that prior to

1918, when operations ceased) production amounted to about 10 tons of concentrate (65 percent WO ) and 500 tons of sorted mine-run ore averaging 8

percent tungsten trioxide, all of which was shipped to Tacoma, Wash.

A new inclined shaft midway between the two old shafts was begun in

1942. Two levels were driven from the shaft, one 55 feet long at the 50-

foot slope level and one 356 feet long at the 150-foot slope level. A

tunnel started at a point about 750 feet east of the shaft was driven on

the vein for 448 feet towards the shaft. In 1942, 60 tons of mine-run ore

averaging 4.55 percent WO was recovered from development work and sold to

Metals Reserve Co. at Faibanks. From October 1943 to May 1944, about 800

tons of ore was concentrated at the Cleary Hill mill, from which 38.5 tons

containing 49.7 percent W03 was recovered and sold at the Fairbanks depot.

(See figs. 3 and 3A.)

The mining at this property from April .1942 until May 1944 was done by

the Cleary Hill Mines Co. under lease from Stepovich. The lease was terminated shortly after the operation ceased.

The Colbert discovery was located during the summer of 1941 by L. D.

Colbert of Fairbanks. The mineralized structure has a strike parallel to

the Stepovich vein system and is 1,200 feet to the south. Colbert sank

three test pits indicating a mineralized zone over 1,000 feet in lengths

Subsequent geophysical exploration by the Territorial Department of Mines

indicated a continuous vein structure for over 3,000 feet.

From July until October 1945 the Bureau of Mines explored a 2,000-

foot section of the Colbert mineralized zone by excavating 20 bulldozer

trenches and 55 hand-dug pits. There has been no production from this

property.

The Yellow Pup tungsten property, owned by the Alaska Metals Mining

Co. of Fairbanks, was discovoroe in 1942. By July 1944, several pits

designed to trace the mineralization up the hill west of the discovery had

been dug without success. A short tunnel from the creek level has been

driven on the vein a distance of 12 feet where the vein is cut off by a

fault. About 55 tons of ore obtained from the tunnel operation is stockpiled near the portal. An experimental milling operation has produced

about 225 pounds of 70 percent tungsten trioxide.

Bulldozer trenches excavated by the Bureau of Mines in September 1944

fulfilled two objectives - first, to locate the continuation of the mineralized zone on the west side of the fault encountered in the tunnel, and,

second, to establish continuity between the Colbert mineralized zone and

the Yellow Pup vein.

4/ Mertio, J. B. Jr., Mineral Resources of Alaska, 916: Geol. Surv. Bull,

662, pp. 418-421.

I

1935 - 8 -

i
Figure 3. - Surface map of Bureau of Mines exploration work on Cleary Hill and Colbert scheelite zones.
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A

Figure 3-A. - Sample locations and analyses.
R. I. 4174

Property and Ownership

Figure 4 is a claim map of the Gilmore Dome locality and shows the

Stepovich, Colbert, and Yellow Pup properties.

The Stepovich property consists of seven patented and six unpatented

claims. The patented claims, covering the apex of the mineralized zone,

are, from west to east, the Scheelite, Scheelite No. 2, Slav, Caucasian,

Lucky, Chippewan, and Scheelite No. 3. The unpatented claims are on the

north slope of Gilmore Dome contiguous to the Scheelite No. 2, Slav, and east

half of the Caucasian claims.

Since the death of Mike Stepovich in October 1944, the property has been

owned by his two sons.

The 14 unpatented claims covering the Colbert property are on the south

slope of Gilmoro Dome between the headwaters of Gilmore, Yellow Pup, and

Smallwood Creeks. The claims, staked three deep parallel to the patented

Stopovich claims, begin at the west end of the Scheelite claim and extend for

5,800 feet easterly. The property is owned by L. D. Colbert of. Fairbanks,

Alaska.

The Yellow Pup mine property, consisting of six unpatentoed claims, is

owned by the Alaska Metals Mining Co,, a partnership formed by M. S. Anderson,

William Birklid, and Elmer Stohl, all of Fairbanks.

General Geology

Quartz-mica schist, quartzite schist, and othor metamorphic rocks

originating mostly from ancient sediments form the country rock of the Fairbanks district.

Small crystalline limestone bodies crop out in two local zones, one on

the north side of the Pedro Dome gold belt and the other along the north side

of a granite intrusive in the Gilmoro bolt. Only the limestone of the Gilmoro belt appears to have influenced the localization of scheelite.

Two main intrusives have invaded the metamorphic rocks of the area.

An elongated body of granodiorite extends from the head of Dome Creek to a

point beyond Pedro Dome. The intrusive mass if 3-1/2 miles long and ranges

In width from 0.2 mile at its western end to 0.6 mile at its eastern end.

In the Gilmorc belt, porphyritic granite extends from the head of

Engineer Creek to the head of Pearl Creek, a distance of 7-1/2 miles.

According to a magnetometer surveyS/ the porphyritic granite underlying Gilmore Dome schist is 600 to 1,000 feet beneath the surface. The

scheelite mineralization, which generally parallels the cleavage in the

schist, has also been found in small amounts disseminated through parts of

the granite. No scheelite of commercial grade has been found in the granite.

5/ By Henry R. Joosting, Territorial Department of Mines.

1955 - 9 -
R. I. 4174

Occurrence of Deposits

The Gilmore Dome scheelite deposits are of the contact metamorphic

type. The ore occurs with vein quartz in some places, but more commonly

it is found in calcareous zones in the schist. The ore shoots are small,

irregular, and discontinuous.

The ore lenses occupy portions of a.thin limestone bed that is one

member of the Birch Creek schist. The maximum width of the limestone is

probably 20 feet.. The.general strike of the ore zone is N. 67° E., and

the average dip is 35° 40' N.

Exploration indicates the existence of a number of small, rich lenses

of scheelite ore. The individual lens usually has a downward rake of about

45 degrees to the northeast. The remaining evidence of past and present

underground development and surface exploration on the summit of the dome

indicates a strong belt of mineralization extending 60 to 90 feet below tho

outcrops. By the end of October 1943, development on the 150-foot level

from the shaft had encountered ore along 204 feet of its 265-foot length.

The ore averaged 5.54 percent WO3 over a 1.4-foot width.

The first four raises started from the 150-foot level and went through

the ore into barren rock 15 to 30 feet above the drift. The plan and

longitudinal section of the mine are illustrated in figure. 4A. This evidence suggests a narrow barren zone between the surface ore horizon and

the one partly developed on the 150-foot level, although several partly

developed lenses may continue through to the surface ore horizon.

Strike faulting parallel to the limestone beds and having a slightly

steeper dip has been observed. A number of quartz veins follow both the

cross faults and the strike' faults. These quartz veins have a direct

relationship to the scheelito mineralization. Scheelito lenses are often

found at the intersection of the quartz veins and limestone beds.

Development has indicated that tho maximum dip and strike length of

any lens does not greatly exceed 50 foot and that the average ore width is

only slightly more than 1 foot. Ore lenses of the maximum sizes thus far

encountered may possibly contain 200 ton of minablo ore. Ore lenses range

from this size down to some containing loss than 10 tons of ore. Ore bodies

thus far encountered have contained 1.5 to 20.0 percent tungsten trioxide.

The Colbert mineralized zone lies roughly parallel to and 1,200 to

1,500 feet north of the contact of the schist with the granite mass.

Scheelite mineralization partly replaces a narrow limestone bed that dips

north into Gilmore Dome at a 40-degree angle. The Colbert and the Cleary

Hill deposits, both in thin beds of altered limestone, are parallel in

strike but appear to diverge slightly in northerly dip.

1935 - 10 -
R. I. 4174

The limestone bed, possibly 30 feet thick, apparently has been subjected

to two periods of silicification. Although both periods may have resulted

in some scheelite mineralization, the last period appears to have had the

greatest effect upon mineral deposition.

The Colbert, like most deposits occurring in a highly metamorphosed

sedimentary bed, has various strikes and dips. Along the partly explored

2,000 feet of vein exposure the average strike is N. 75° E., but local

variations were recorded from N. 48° E. to N. 80° E.* Individual sections

explored by lontitudinal trenching strike a few degrees north of the average.

This condition may be a result of a series of faults disclosed by exploration of the parallel Cleary Hill ore zone, which offsets the ore zone to

tho southeast. A fault was encountered in trench 14 on the Colbert mineralized zone, but thO amount and trend of the movement has not been determined.

Narrow veinlets of quartz and thin fractures carrying scheelite

mineralization are found across the replacement zone. The larger mineralized zones are usually found on the hanging-wall side parallel to the strike

of the main zone. Specks or traces of schcolite mineralization occur in

trench 9 over a 40-foot horizontal width, and parallel lenses were noted in

other places within the zone of replacement. (See fig. 3.)

In trench 2, a narrow lens of schoclite mineralization was -uncovered

130 feet north of the Colbert mineralized zone. Trench 1, 80 feet west of

trench 2 and also north of the Colbort, uncovered three barren replacement

zones 6 inches to l foot wide.

The scheelite lenses along the main Colbert replacement zone range

in length from a few feet to 100 feet and in width from 0.5 to 1.2 feet.

The WO content, of the several lenses is 1.2 to 2.5 percent. The lenses

are iregular in shape and distribution.

Although the Yellow Pup vein has been explored intermittently for about

500 feet along the surfact, it appears to conform in occurrence with the two

mineralized zones described above. The faulting condition that was observed

in the exploration of the Stcpovich and the Colbert ore zones apparently is

present in the Yellow Pup area, also figure 5 shows the various strikes and

dips of the separate vion segments, which is characteristic of the highly

metamorphosed schist.

Character of the Ore

The only mineral of commercial value in the three tungsten properties

on Gilmorg Domo is scheelite (GaW04), the tungstate of lime. According to

Joesting.:/ "Gangue minerals, in the approximate order of their abundance,

are quartz, calcito, pyroxene (chiefly diopside and hedenbergite), hornblend,

/7 Joesting, Henry R., associate mining engineer, Torritorial Dopt. of

Minos, Tests Run on Ore of the Cleary Hill Tungsten mine, 1943.

Unpublished report, Copy on file in office of Territorial Dept. of

Mines, Juneau, Alaska.

1935 - 11 -
R. I. 4174

garnet, titanite, and apatite. Of those, the first four comprise the bulk

of the gangue, although garnet is occasionally found in significant

amounts, titanito and apatite are relatively scarce. Pyrite, pyrrhotite

and molybdenite are present but are. so rare that only a few grains were

found in hundreds of specimens of ore."

The gangue minerals in a representative sample of the shaft development

ore were separated.-/ A f 6 .5-pound sample was crushed to minus 1/4 inch

and cut to 470 grams. The sample was then ground to minus 55 mesh, and the

low specific gravity gangue minerals quartz and calcite, representing 58.2

percent of the sample, were separated in bromoform (specific gravity 2.89).

The removal of 34.6 percent of the sample in a gangue containing chiefly

hedenbergite, diopside, hornblende, and garnet was effected with a small

electromagnet fitted with polo pieces. The remaining 7.2 percent of the

sample consisted chiefly of scheelite and assayed 60 percent tungsten

trioxide.

Qualitative spectrographic analysis by the Bureau of Mines on representative samples of. thB'ore and concentrate indicated the following

elements:

Iron-high plus plus Titanium-high plus Tin-trace in concentrate::;

Magnesium-high plus plus Manganese-high plus Molybdenum-trace

Calcium-high plus plus Sodium-high Vanadium-trace

:Silicon-high plus plus Bismuth-low in conct. Copper-trace

Tungsten-high plus Strontium-very low' Nickel-trace

Aluminum-high plus Barium-very low Chromium-trace

Lithium-trace

Bureau of Minos Work at Stopovich Deposit..

The Bureau of Mines excavated and sampled 24 trenches with an aggregate

length of 1 mile. Trenches I to VIII, inclusive, shown on figure 5, were

excavated by Cleary Hill Mines Co. East of the new shaft the Bureau of

Mines. continued to explore from trench VIII.

The first 180 feet explored along the strike contained some weak

schoelite mineralization but no ore. The Cleary Hill Mines Co. started an

adit on ore 750 feet east of the shaft. The site was selected at an elevation suitable for a connection with the 150-foot lovol. The next 80 feet

east, along the strike, was not trenched, as it would have interfered with

work on the adit.

Exploration indicates that the ore zone for the first 400 feet east of

the adit contains two lenses worthy of underground development as well as

several other mineralized sections. The first lens was exposed for a

length of 57 feet. It is limited on the east by a fault, but the western

limit has not boon determined. .Tho explored length averages 1.08 feet in

width and contains 1.62 porcent'tungsten trioxidc. The second lens, slightly over 100 feet east, is 60 feet long and averages 3.31 percent tungsten

1955 - 12 -

I
R. I. 4174

trioxide over a width of 2.3 feet. A fault zone separating the two lenses

displaces the eastern section 50 feet to the south. A test pit revealed a

fault plane dipping 45 degrees to the east with striations normal to the

strike. The southern displacement of a vein dipping to the north indicates

that the fault is normal. (See fig. 5A)

The next 250-foot section to the, east contains weak mineralization.

East of sample 22, the vein has been faulted and offset 100 feet to the south,

as indicated by the location of samples 47, 48, and 49 and as shown on

figure 3A. The mine access road prevented exploration for the next 120 feet.

Trenches 19 to 24, inclusive, covering 350 feet, completed the exploration

to the east. Five samples cut across a vein 0.68 foot wide averaged 3.78

percent tungsten trioxide. Exploration to the east was discontinued after

failure to discover additional ore in trenches 23 and 24.

Bureau trenches 12 to 18, inclusive, continued the exploration 1,000

feet west of trench I. All excavations were examined for scheelite with a

mineral light. Samples 23 and 24 were cut at the only two schoelite outcrops.

Strike faults parallel to (mnd slightly steeper than the limestone beds

have been observed. A number of quartz veins, genetically related to the

scheelite mineralization, follow both the cross faults and the strike faults.

Schoelite lenses are often found at the intersection of the quartz veins and.

limestone beds.

Bureau of Mines Work at Colbert Prospect

The Bureau of Mines excavated and sampled 20 trenches with an aggregate

length of 3,000 feet. Throe nearly equal lenses of schoelite mineralization

totaling 500 feet in length wore exposed. Figure 3 shows trench locations,

and figure 3A shows location of samples,and sample analyses for each lens.

These lenses are confined to 1,500 foot of the total 2,000-foot strike

length prospected. A 600-foot section included in this distance cannot be

considered explored.

The original discovery cut exposed a pocket in a small mineralized vein.

A sample across its maximum width of 24 inches contained 1.56 percent tungsten trioxide. In trench 3, which is 150 feet cast of the Colbort discovery,

a band of scheelito mineralization was uncovered containing 1.09 percent

tungsten trioxide over a 0.7-foot width. This minoralized band persisted

diagonally 15-feet across the trench, its strike of N. 480 E. indicating a

projection south of the discovery. A hand-dug trench extending south from

the discovery, crossed a replacement zone containing much garnet and scatterod grains of scheelite, though it failed to reveal the mineralized band.

Trench 20, which, because of the topography, was excavated diagonally to the

general strike of the Colbort mineralized zone, exposed for 20 feet two narrow lenses containing scheelite mineralization. These lenses, when projected

across the intervening 70 feet, make a reasonable connection with the vein

exposed in the discovery cut.

1935 - 13 -
R. I. 4174

Between trench 5 and the next known lens, which appears in trench 5,

800 feet east, are three trenches that inadequately explore the area.

Trench 17 uncovered the replacement zone 200 feet east of trench 3. Trench

19 was excavated obliquely from the hanging wall of the replacement zone in

trench 3 to the footwall of the zone in trench 17. Trench 18, on the projected strike 220 feet west of trench 5, exposed a 100-foot section of bedrock but did'not encounter the replacement zone, Criteria established by

exploratory work on the parallel Cleary Hill replacement zone suggest the

possibility that the Colbert replacement zone may be displaced by fault

action, between trench 17 and trench 5.

The lens of mineralization: crosscut by trenches 4, 5, and 7 and followed

by trench 6 has been limited to'a length of 108 feet.

The replacement zone was uncovered along all but 70 feet of the intervoning 220 feet between trench 7 and the next mineralized lens to the east.

The section disclosed a zone of intense replacement containing short, narrow

seams of scheelite mineralization.

Cross trenches 9 and 10 cut fairly strong scheelito mineralization, and

trench 14 uncovered the vein along the strike. Trench 14 was excavated along

the replacement zone from trench 8 to a point where the third lens was

encountered just west of trench 9. The third lens was exposed from there

to a point 15 feet beyond cross trench 10, where it was lost by faulting,

Cross trenches 11 and 12 were bulldozed before the fault had been

discovered in trench 14. Each uncovered a 200-foot section of the bedrock

but did not encounter the replacement zone. Trench 13 exposed a narrow

replacement band'containing a thin seam of scheolite. Very similar

mineralization was found in trench 2, one hundred thirty foot north of the

main mineralized zone cut by trenches 4, 5, 6, end '7. The similarity of the

two zones indicates that originally they formed a continuous band. The

mineralized zone found in trench 2 could have been faulted to its present

position, as indicated by the trend and displacement of ,faults along the

east end of the Cleary Hill zone.

Bureau of Minos Work at the Yl1low Pup Prospect

During September 1944, the Bureau of Mines conducted a limited program

of bulldozer trenching to establish the continuity between the Colbert

mineralized zone high ,on the dome and the Yellow Pup vein near its base.

The vein was explored for about 300 feet by three short trenches near the

southwest corner of the Marie claim, as shown in figure 5.

Combined exploration by the Bureau of Mines and local operators on the

Gilmore Dome ore zone has disclosed that the tungsten mineralization forms

a series of' irregular lenses and is erractically distributed horizontally

and vertically. In certain areas those scheelite-enriched lenses may comprise

a large enough percentage of the replacement, zone to be considered cnmorcial.

In other areas where the lenses aro widely scattered, they could not be

considered ore unless found along the course of access or development workings

1955 - 14 -
I

Figure i. - Claim map of tungsten properties on Gilmore Dome.
R. I. 4174

The length of the individual lens or the total length of any one zone

of deposition has little relation to its depth. The distance to the underlying granite, estimated by magnetometer survey to be 600 to 1,000 feet, is

the probable limit of deposition, but irregularities caused by various

degrees of resistance to rising magmas along sedimentary beds may have

altered this limit.

Sampling and Analysis

Figures 3, 3A, 4A, and 5 show the location and results -f 56 surface

channel and 26 mine channel samples taken by the Bureau of Mines, 7 surface

and 14 mine samples taken by Cloary Hill Mines Co., and 4 mine samples taken

by the R.F.C.

The Bureau of Mines channel samples were cut as nearly normal to the

dip and strike of the ore lens as possible. All Cleary Hill-and R.F.C.

samples were reported to be channel cuts.

Surface samples were cut near the bottom of hand-dug pits excavated

on veins exposed by bulldozer trenches. Surface samples were cut 5 to 7

foot below the bedrock surface and as muich as 15 feet below ground level.

The rock in the ore zone has been weathered for a considerable distance below

the surface, and in some sections this weathering has continued to an inclined

depth of 150 feet.

Samples from this property have been analyzed in the Territorial'

Department of Mines Assay Office at College, Alaska, and used in this report.

Check samples were sent to a commercial analyst in Los. Angeles, Calif.. The

results of duplicates of a number of samples sent to' a commercial analyst

were generally higher in tungsten trioxide content.

The miheral light was used to determine the limits of individual

samples as well as to estimate the content of tungsten trioxido in each

sample. In actual practice, the mineral light has proved to be reasonably

accurate in estimating the value of the ore in the Cloary Hill mine. Although the estimates of surface samples are usually high, this may be due

to the tendency of the scheelito crystals to shatter in the altered surface

exposure. Minute particles show distinctly in the fluorescent light. This

property undoubtedly increased the orrr in quantitative comparisons with.ores

containing large crystals.

Samples 201 to 227, ihclusive, were cut from the vein exposros .of the

Colbert property. In each case the entire channel sample, weighing 10 to

50 pounds, was taken to tho Territorial 'Assay Office at Fairbanks-, where it

was crushed to approximately 3/16-inch, out in a r'ffle divider, and then

put through a Braun pulverizer. One cut of' ach sample was analyzed there,

four check samples wore sent to a commercial'analyst, and one cut of each

sample was stored in Fairbanks.

Of the four chock analyses, one was identical and the other three were

higher in percentage of tungsten trioxido than determined by the Territorial

Assay Office.

1935 - 15 -
__ __

R. I. 4174

Figure 5 shows the location and analyses of six samples collected from

Bureau trenches on the Yellow Pup property.

Development

A total of 1,262 feet of underground development has been completed at

the Stepovich property by the Cleary Hill Mines Co. since 1942. In the shaft

area, development along the mineralized zone totals 670 feet. Of this advance, 357 feet were in ore averaging 1.58 feet wide and 5 percent tungsten

trioxide. The lower 112 foot of the shaft and 520-foot crosscut were outside

the ore zone and are not included in the above figures.

The new inclined shaft was begun in 1942 for exploration and development

purposes. It is midway between the two old caved shafts situated 300 foot

apart on the summit of Gilmore Dome. The shaft is the present means of access to the two mine working levels which are named for their slope distance

below the apex of the vein. The 50-foot level is 55 feet long, and the 150-

foot level is 556 feot long. (Soe fig. 4-B.)

The new adit is 448 feet long and now is 184 feet short of a connection

with the shaft 150-foot level. Several small patches of mineralization have

been found, but very little ore has been developed.

Alteration of the rocks in the ore zone and lateral postmineral movements

parallel to the strike of the zone have resulted in a weak or shattered condition in much of the vein material. For this reason, possibly 80 percent of

the underground workings in the ore zone would require timbering if -the mine

was, reopened. The zone of weakness usually extends beyond normal mining

widths, and it is doubtful whether.much open stoping could be done. The

rocks outside of the ore zone consist of tough metamorphosed schist, which

,does not require support.

The development in the shaft area has encountered several solution

cavities in the ore zone. The largest cavity encountered was 20 by 20 feet

and had a maximum width of 4 foot. When this cavity was first found,

scheolite on its walls could boseen through a 2-inch coating of Ice with

the aid of a mineral light. In somo cavities, ochoalite on the walls is

covered with a crust of calcite up to 1/4 inch thick. The.usual cavity is

about 5 by 10 feet in the slope of the vein and about 1 foot in width.

In the fall of 1945, the accessible mine workings were lamped with an

ultra-violet light, and the only mineralized portion of the mine is shown

in section E1-E2, figure 4t-G. The assays and thickness of this mineralized

segment are shown on the 1946 mine map (fig. 4-B)t- Between raise 3 and the

west heading on the 150-foot level, ore has been included with waste fill

and can be seen with the aid of an ultra-violet lamp. Sectional views of

the lower workings are shown in figures 4-C, 4-D, 4-E, and 4-F.

1935 - 16 -
I M

Figure 4-A. - Cleary Hill mine 1942.
CH. PIT 6

a

C.H. PIT 2

»*

PROJECTfON ON PLANE OF VEIN

LEGEND

STOD AmCA

m CAVED AREA

0* - a00

WALE Or EIT

«

Figure 4-B. - Cleary Hill tungsten mine 1946.
Leve/ 50 LJ0 25 50

Figure 4-C. - Section AI-A 2.

Leve/ /50

Scc7/e /r7 Fee7

fuausf /945

Figure 4-D. - Section Bi-B 2.
O5op

rl j

0 5 /0

ScAuq/ i' 19ee

A4ugust 1945

Figure 4-E. - Section Ci-C 2.

I
stop s .

Vt

0 5 /0

Sc q/e ,n /r ee t

Auy'stf 1945

Figure 4-F. - Section DI-D 2.
S,G'i, a/Ei d

5 c/res fo

Limes t-one-

, - -

I /-..

e .0/7/S Quc r / z

MuPck

P1/Q

0 5 /0

5ca/e /in-ee/

Au usi /945

Sarnpl//rg by Bureau of /ines

6eo/Ogy tOy GCeo/og/C/ 5urvey

.Sche&/ re,

Figure L-G. - Section EI-E 2.
P. I. 4174

The entire mine is in the permafrost zone, and surface water seeping

through the old workings in the northeast portion of the mine are icing up

the main drift on the 150-foot level. The timbers in the extreme west end

of the 150-foot level are ruptured, and it is quite likely that the ore

pictured in section E -E2 will be blocked by caves within a short time.

There are no underground workings on the Colbert property.

The nearest source of water for mining and camp use is 2,000 feet west

and at an elevation 200 feet below the discovery cut.

Beneficiation Tests by Bureau of Minos

A metallurgical sample was submitted to the Rolla Laboratory by Norman

Ebbley, Jr., an engineer of the Bureau of Mines, on October 29, 1942. The

report of the metallurgical tests on this ore follows:

"Ore Dressing Report on Scheelite ore from Cloary

Hill Mines Co., Nada Gulch Tungsten Prospect. Fairbanks,

Alaska.

"The second sample was from a 30-foot shaft on the property, whereas the first sample, which has been reported

previously, was a grab sample from the dump on the property.

After having demonstrated that the ore was amenable to concentration, the second sample was submitted to determine

the most suitable flowsheet for the ore.

"Physical character

"The tungsten.ore consists of scheelito in a gangue of

quartz, calcite, and hornblonde. Minor amounts of olivine,

and biotite and sparing amounts of chlorite and epidote are

also present.

'' "In the highly weathorod portions of the.rock, the calcite has been removed, and the hornblende has.been altered,

leaving only a skeleton of limonite with crystals of scheelite.

"A study of the screen size showed that at 48-mesh about

20 percent of the scheelite was locked, whereas at 65-mesh

only 2 percent was locked, and all of the schoolito was freed

in the minus 65-mesh product.

"Chemical character:

"Analysis of ore, percent

W03 S P As

5.91 0.05 0.08 0.07

1935 - 17 -
R. I. 4174

"Treatment procedure:

1. Classification and tabling

2. Flotation of table concentrate

3. Flotation of crude ore

4. Tabling of unclassified feed

"Classification and Tabling

"Although the petrographic eXamination indicated that grinding through 65-mesh was required to liberate the scheelite completely, table.concentration at a coarser size was attempted.

The purpose was to reject the bulk of the gangue without excessive slime losses of the scheelite and to recover a low-grade

scheelite concentrate for further concentration by flotation.

"Treatment

"The'ore was crushed through 10 mesh and classified into

four spigot products and an overflow. The four spigot products

were tabled separately, and the middling from each tabling

operation was crushed, classified, aid added to the finer spigot products. The tailings from tabling the two coarsest spigot products also were crushed, classified, and added to the

finer spigot products. The combined slime was tabled separately.

"Similar products from each table operation were combined

for analysis.

"Results of Classification and Tabling

Percent

Weight, Analysis, percent i of total

Products percent W0O3 S i P ] As ! WO

Concentrate 9.7 55.90 0.18 1 0.04 I 0.05 1 94.7

Middling .. 4.6 4.0 1 ! I 5.2

Tailing ... 85.7 0.14 2.1

Heads, cal. 100.0 i 5.74 . i 100.0

"Remarks

"The concentrate, containing 55.90 percent tungstic oxide,

was 9.7 percent of the ore, and the recovery of tungstic oxide

was 94.7 percent.

"Flotation of Table Concentrate

"Treatment

"A sample of the table concentrate from the classificiation and tabling test was wet-ground through 65-mesh in two

1935 - 18 -
R. I. 41.74

5-minute stages. A scheelite rougher concentrate was floated,

and the ro:.gher concentrate was cleaned once. Zeolite-softened

water was '-sed.in both the grinding and flotation. The flotation pulp Tras 25.0 percent solids and had pH of 8.0.

'Results tf Flotation of Table' Concentrate

Percent

Weight, Analysis, percent of total

Products percent 03 S P As I W03

Concentrate 7. 3. 7 3.96 0.06 0.04 0.O 98.5

Middling .. 4.0 12.73 i 0.9

Tailing ... 199 1.80 0.6

Heads,

calculated i 100.0 57.10 1 100.0 -i

Reagent Data -- ·

Pounds reagents per ton of feed

Reagents Conditioner Rougher Cleaner

"" sodium silicate ... .

Soda ash ............. 0.8

Oleic acid ...... 2.16 0.72

"B-23" Frotherl/ . 1 o0.36 O.l8'

Time, minutes .. 

.. .

.' .-.. I 

10 : ,= j-jZ

' 77

/ E. I. DuPont de Nemours & Co., Inc.

"Remarks

"The rtc..vr , was 98.5 'prcelnt o-' the t'.,lgst;ic oxide contained in tho flotation food, and the concentrate contained

73.96 porco1;:- t-;n,' f-S-ic oxiedo.

"Sunrary of tabling and flotation

of table concentrates

Weight, Analysis percen't ''Percent Prt .... pe , -r WO " Product percent W03 SI P ' As of total

Flotation .

Concentrate .... 7.38 '3.96 .6 0.04 0.0 93.2

Flotation '

Middlig ....... 0.39 12.73 . .9

Flotation i

Tailing ......... 1.93 1.80 0.6

Table Middling .. 4.60 4.01 3.2

Table Tailing ... 85.70 0.14 .i 2.1

Heads, calculated 7 100.00 5.85 100.0

Heads, analysis . I - , , 7 i*.,v , --- - -* I'-.I , 5- ! ' - -- .-t.

1935 - 19 -
B. I. 4174

"Remarks

"The recovery was 93.2 percent of the total tungstic oxide

contained in the crude ore. The concentrate was 7.38 percent

of the ore and contained 75.96 percent tungstic oxide, 0.18

percent sulfur, 0.04 percent phosphorous, 0.0 percent arsenic.

"Flotation of Crude Ore

"Treatment

"A sample of the ore, crushed through 10-mesh, was wetground through 65-mesh in three 5-minute stages and floated.

The rougher scheelite concentrate was cleaned twice. Zeolitesoftened water was used in grinding and flotation. The pulp

was 25 percent solids and had a pH of 8.

"Results of Flotation of Crude Ore

Weight, nalysis, percent Percent

Product percent WO3 S P As of total

Concentrate ..... 7.0 5 0.0990 0'4 o.o 85

Middling ........ 5.5 6.85 7.1

Tailing ......... 87.5 0.45 7

Heads calculated. 100.0 37 _ __100.0

"Reagent Data

Pounds reagents per ton of feed

Cleaner

_____Conditioner Rougher 1 2

"P' sodium silicate 3.2

Soda ash .......... 0.8

Quebracho ......... o.6

Oleic acid ........ 0.72

Frother B-23 ...... _6 .18

Time, minutes ;;...; 10 5 .4 5 

t

"Remarks

"The recovery of tungstic

concentrate was 7.0 percent of

percent tungstic oxide.

oxide was 85.6 percent. The

the ore and contained 65.90

"Tabling (Unclassified Feed)

"At the suggestion of the-examining engineer, table tests

were made on unclassified samples of the ore crushed through

10-mesh and 48-mesh. These tests were made-to determine the

1935 - 20 -
R. i. 4174

recovery of a marketable scheelite concentrate that might be

expected if the limited equipment available on the property

necessitated a simplified flowsheet. Stamps, tables and flotation cells are the only equipment available*

"Results of tabling minus 10-mesh unclassified ore-

- I--I

I ' Analysis,. Percent

I Weight, percent,. of total,

Product percent W03 wo0

Concentrate ......... 5.4 69.90 - 69.4

Middling ............. 35.0 4.39 28.3

Tailing ..... *.......... 59.6 i 0.21 2.,

Heads calculated ....... 100.0100

"Results of tabling minus 48-mesh unclassified ore

Analysis, I Percent

Weight, pardent, ! of total,

Product percent WO W0O

Concentrate .............. 5.1 738 54.5

Middling ................ 7.7 32.26 36.2

Sand, tailing .;........ 85.0 0.68 1 8.4

Slime, tailing ......... 2.2 2.94 0.9

Hoads, calculated ...... 100. 0 .... 100.0

"Remarks

"Tabling of the unclassified crushed ore is not recommended,

because the recovery of tungsten trioxide was lower than.that

obtained by the tabling classified sands and slimo.

"Flotation of the table middling would be necessary to increase the recovery 'of'tungsten trioxide.

"The scheelite ore from the Nada Gulch Tungsten Prospect

of the Cleary Hills Mines Co., Fairbanks, Alaska, was amenable

to concentration by the combined treatment of classification

and tabling and flotation of the table concentrate.

"By classification and tabling, 94.7 percent of the total

tungsten was recovered. The concentrate was 9.7 percent of the

original ore and contained 55.90 percent tungston oxide.

"In the classification and tabling followed by flotation

of the table concentrate 93.2 percent of the tqtal tungsten

was recovered as a product that contained 73.96 percent

tungstic oxide, 0.06 percent sulfur, 0.04 percent phosphorous,

and 0.0 percent arsenic and was 7.38 percent of the ore.

1935 - 21 -
R .I. 4174

"By flotation of the crude ore, 85.6 percent of the tungstic

oxide was recovered in a concentrate that contained 65.90 percent

tungstic oxide, 0.09 percent sulfur, 0.04 percent phosphorous,

0.0 percent arsonic, and represented 7.0 percent of the weight

of the ore.

"The recovery obtained by tabling the unclassified ore

crushed through 10-mesh was-69,4 percent, and the concentrate,

which was 5.4 percent of the ore, contained 69.98 percent

tungsten trioxide."

Behoficiation Tests by the Cleary Hill Minos Co,

The operators were unable to take full advantage Qf the Bureau's beneficiation tests because, owing to war demands, very little equipmont was

available.

Ore was hauled 8.miles from the tungsten mine to the stamp mill at the

Cleary Hill gold mine.. No provision was made for storage of the crude ore.

Upon arrival at the mill the ore was shoveled from the truck onto a sloping

grizzly equipped with 2 inch openings. The oversize was shovel-fed to a

jaw crusher and was joined by the undersize in the stamp mill feed bin, as

shown in flow sheet 1 (fig. 4-Hi.

The standard five-stamp mill received a feed ranging from fines to ore

having a dimension up to 3 inches. The great difference in feed size coming from a bin that holds only slightly more than 10 tons caused the feed

for the mill to vary constantly and resulted in the mill being underloaded

or overloaded a large part of the time.

The increase in the screen size from 45-mesh to 20-mesh on the stampmill discharge screen made necessary a large increase in the water to the

stamp battery. Because of an inadequate water supply, low water-to-ore

ratio was adopted, which contributed to excessive sliming.

Sources of water are available and could be utilized with additional

pumping equipment and approximately 200 feet of winterized pipeline. From

May 1 until the middle of October an abundance of creek water is carried

to the mill by a long ditch. During the winter months approximately 50

percent of the water used in the mill could be recirculated. A dewatering

cone in tho tailing circuit and a small centrifugal pump would be required

to return the excess water to the mill storage tank.

The crushed minus 20-mesh product of the stamp mill went directly to

a three-compartment, rising water classifier. The first two spigot products

of the classifier constituted the feed for the Wilfley sand table. In the

last arrangement seen in use, the third spigot and the classifier overflow

made up the highly diluted feed for the Wilfloy slime table. The two

rougher tables produced a high-grade (60 percent or better) concentrate,

a middling feed, and a final tailing. The middling feed was handled on

the Wilfley middling table, which produced a high-grade concentrate, a

lower-grade concentrate, and a final tailing.

I

1935 - 22 -
Cc

Grizzly

Jaw crusher

Fine ore bin

I

5-stamp mill

Hydraulic

classifier

- L

Sand table

Cone.

Sand table

-

t

Tails

1

Tails

Mi dds.

it

Slime table

Con e.

Tails

w ,

Midds.

1 B

Figure 4-H. - Flow sheet I, Cleary Hill stamp mill, 1943.
.. . 4174

The combined tailing usually contained 0.6 percent to 0.8 percent

tungsten trioxide. Probably two-thirds of the loss came in the tailing

derived from the unclassified feed of the middling table. The major portion of the tailing loss was in free scheelite 200- to 300-mesh in size.

Very little scheelite contained in the coarser particles was lost.

LODE DEPOSITS IN THE STEELE CREEK-FIRST CHANCE AREA

Other tungsten deposits in the Fairbanks area were discovered in 1915,

and by the summer of 1916 five groups of claims at the heads of First

Chance, Steele, and Engineer Creeks had been located. Prospecting continued

on them for 2 or 3 years, but the sudden decline in the market price of

tungsten ores at the end of 1918 caused a cessation of development. Little

more than assessment work has been done since. In 1916, the Geological

SurveyS/ reported upon these deposits as follows: (See fig. 2)

Tanana Group

"The Tanana group consists of five lode claims along the

northeast side of Tungsten Gulch, a headwater tributary of First

Chance Creek. The claims are owned by Grant and Hirsoiberger,

and during the summer of 1916 were being actively prospected for

scheelite. Six scheelite lodes have been discovered on these

five claims, and others are probably present.

"The principal work has been done on the Tanana No. 1

claim. The country rock on this claim is a quartzite schist,

the cleavage of which strikes N. 30° E. and dips 35° NW.

The lode consists of a mineralized zone 3 feet thick, which

lies parallel with the major structure of the country rock.

It is the structure of the schist, in fact, which has determined the site of the ore deposition. The scheelite occurs

in stringers of soft, decomposed, iron-stained schist 2 to

6 inches wide. Many of these stringers contain little quartzscheelite veinlets, which are very rich in tungsten and carry

also some gold. The stringers of decomposed schist are said

to carry both scheelite and gold. The country rock separating the schist stringers in the lode also carries a little

scheelite, possibly as much as 1 percent. A specimen of

sche&lite-bearing pegmatite taken from the bottom of the incline shows the intimate genetic connection of the deposit

with granitic rocks.

7/ Mertie, J. B., Jr., Lode Mining in the Fairbanks District. In Mineral

Resources of Alaska - Report on Progress of Investigations in 1916:

U. S. Geol. Surv. Bull. 662, pp. 422-424.

1935 - 23 -
R. I. 4174

"A gold quartz vein striking N. 8° W. and dipping 60° E.

cuts the schist and the scheelite lode above described. This

vein carries gold in about the same amount as the scheelite ,

lode. In view of the fact that gold and scheelite do not appear to have been deposited synchronously at the other properties visited, it is probable that the gold in this scheelite

lode is a result of local enrichment by the gold quartz vein.

Both structural and mineralogic data, therefore, point to the

conclusion that the scheelite mineralization took place before

the formation of the gold quartz veins, at least at this particular locality.

"The Discovery lode on the Tanana No. 1 claim consists

of 8 feet of scheelite-bearing schist exposed in an open

trench. The hanging wall at this place is porphyritic granite.

"The Tanana group of claims, as well as the other claims

in this vicinity, including the Spruce Hen group, the Columbia

group, the Tungsten Hill group, and the Blossom claim, lie

along the western periphery of a large intrusive mass of porphyritic granite. This is the same body of granite that lies

north of the Tungsten and Scheelite claims, above described.

The granite is intimately associated with the scheelite lodes,

being present at the different claims as transverse dikes or

wall rock, and in the Tanana No. 1 lode a scheelite-bearing

pegmatite occurs. It is quite evident, therefore, that the

scheelite deposits at the west end of this intrusive mass

are disseminated stringer lodes, much like the lodes at the

Scheelite and Tungsten claims. Differences in the form of

the deposits are due largely to the differences in the

character of the country rock.

Spruce Hen Group

"The Spruce Hen group consists of three claims on the

divide between First Chance and Steele creeks. These claims

are being prospected by J. F. Zimmerman.

"Five lodes are said to be present on the Spruc-e Hen

claim. These are being prospected by open trenches. One

trench has revealed a uniformly mineralized body of schist

and metamorphosed basic intrusive rock, without any stringers

or veinlets, 3 to 4 feet wide, averaging perhaps 1 to 2

percent of scheelite. This lode carries no gold.

"At another trench, on the same claim, is exposed a 4-

foot lode of similar character,*which strikes N. 33° E. and

dips 40° NW. This strike is conformable with that of the

country rock on the Tanana No. 1 claim, and it is not

improbable that this trend of the country rock has been

1935 - 24 -
R. I. 4174

determined to some extent by the intrusion of the neighboring

granite mass, one tongue of which extehds from the main mass in

a northeasterly direction along the ridge.

Columbia Group

"The Columbia group, comprising three claims, is at the

head of Steele Creek, southeast of the Spruce Hen group. These

claims are owned by J. Meier, J. Hoffman, and W. Wallace. At

the. time of the writer's visit to this property.,.development

work consisted of a short tunnel at one locality and an open

cut at another. Since that time, however, the tunnel has been

driven 130 feet, and in midwinter the owners were installing a

small mining plant.

"The open cut is on the Columbia claim and has exposed a

scheelite lode similar to the others.previously :described, cut

by a 1-foot vein of quartz. Considerable wad is associated

with the quartz, showing that the vein is to be classed with

the gold quartz veins.

"In the tunnel a 3-foot zone of scheelite-bearing rock

'was exposed. ' Te hanging wall is a porphyritic granite, and

the lode material consists of decayed stringers of country

rock, rich in scheelite, similar to those at the Tannaa No. 1

lode. The strike of the lode system is N. 20° W. and the dip

is 30° E.

- Tungsten Hill Group

"A group of eight claims, owned by Martin Harrais and

known as the Tungsten Hill group, lies on the southwest side

of Tungsten Gulch, a tributary to First Chance Croek.

"Four scheolite lodes had been discovered on these claims

by August 1916, and it is likely that others -are present. On

the Grand Duke Nikolas claim a scheelite lode in the schist

country rock had boon exposed in an open cut. This deposit

consists of 6 to 8 foot of decayed schist, carrying schoelite.

Vein quartz containing a little gold'is also present, cutting

the mineralized zone..

"On the Tungsten No. 1 claim another open cut had been made

in a country rock of mica schist and quartzite schist. A zone

mineralized by scheelite is present, but the width of the lode

was not apparent from the work done.

"On the General Joffre claim, a scheelite lode 14 feet

wide has been exposed. The lode as a whole was considered

low-grade ore, but it contains in the central part an 18-inch

stringer of decayed schist, which is of considerably higher

grade.

1955 - 25 -
R. I. 4174

"These claims certainly deserve further prospecting, for

they are as advantageously situated with regard to the granite

as other scheelite claims in the district on which workable

lodes have been developed.

Anderson Claim

"'A lode claim adjoining the General Joffre claim, of the

Tungsten Hill group, is owned by Charles Anderson. On this

claim a quartz stringer striking N. 50° E. and dipping 55° NW.

has boon exposed in an open cut. The foliation of the country

rock, which is largely a mica schist, strikes N. 60° E. and

dips 20° NW. Schoelite is reported to be present along the

outer edges of this quartz vein, but none is reported either

inside the vein or in the adjoining country rock. It is likely that this quartz vein was formed first, and that at some

later time the scheelite-bearing solutions percolated upward

along the sides of the quartz and-deposited scheelite in its

present position.

Blossom Group

"The Blossom group consists of several claims belonging

to Victor Lundbled and Charles Anderson at the extreme head

of Engineer Creek.

"A shaft on the Blossom claim is said to have exposed

a rich stringer of schoelito, but this was not visible on account of timbering in the shaft. A granite porphyry dike is

present in the bottom of the shaft.

"At another claim of the Blossom group a shaft 20 feet

deep has been sunk, opening a scheolite lode 5 to 4 feet in

thickness. This is another lode of the stringer typo, but a

thin quartz veinlot a short distance from the shaft was

reported to carry 40 percent of tungsten,"

Interest in these claims was revived in 1942, but little was done other

than staking new claims. The present (1947) ownership of the groups of

claims is not known; however, in 1942, L. D. Colbert, Roy Maddock and Al

Goodwin of Fairbanks are reported to have made claim locations in the area.

OLD GLORY PROSPECT

Location

The Old Glory tungsten prospect is in Interior Alaska at latitude 65°

01' 08" north and longitude 147° 34' 36" west as shown on figure 2. It is

near the head of Seattle Crook, a headwater tributary of Domo Creek in the

Fairbanks Mining District, and it is approximately 15 miles north of

1955 

1935 26] - 26 -

0I
_ ___ 1____1 _ · ·_

R. I. 4174

Fairbanks and 2 miles from Elliot Highway. A trail paralleling the U. S.

Smelting, Refining & Mining Co., power line, which passes by the head of

Seattle Creek, lies within 1,000 feet of the prospect.

The Old Glory Lode claim, which is approximately 600 feet by 1,500

feet, was staked and is held by Robert Leslie of Fairbanks, Alaska.

General Information

The Old Glory prospect is exposed at one place.along its strike. A

trench has been bulldozed through 7 feet of overburden and into weathered

schist bedrock; a small pit sunk at the bottom of the trench exposed a 3-

foot zone of finely disseminate scheclite. This zone strikes N. 44° E.

and dips 45° to the southeast.

Considerable trenching would be necessary to expose the mineralized

zone along the strike. Inasmuch as the mineralized,zone was exposed at

only one place, sampling was confined to this pit and trench. Three

channel samples normal to the strike and dip were cut across tho 'mineralized

zone, and two channel samples were cut from the foot and hanging-wall rock.

A chemical analysis was not made of the samples, but after an examination

with a minoralite'it is estimated the zone.contains about 0.5 percent tungsten trioxide.

OTHER TUNGSTEN OCCURRENCES IN tNTEOR ALASKA

In 1942 and 1943 the Alaska Department of Mines prepared reports§/'n

strategic mineral occurrences in Interior Alaska. Mention is made of tungston occurrences as follows:

"Placer Tungsten

"Schoolite probably occurs more commonly in Interior Alaska

placers than is generally supposed.-----About a third of the

samples of placer concentrates collected during 1942 contained

scheelite, as listed in the following table. The terms abundant,

common, scarce, and rare indicate the relative amounts of

scheelite found in the concentrates and not in the original

placers.

"Occurrences of placer scheelite 'in Interior Alaska

I Relative j Source of

District Location of occurrence abundance i information

Bonnifiold Little Moose Crook Scarce IDopt. of Mines

Lower Eva Creok Scarce Dept. of Mines

Circle ... Half Dollar Creek Common !Dept. of Mines

Fairbanks. Cleary Crook, above

Bedrock Creek Abundant !Dept. of Mines

87 Joesting, Henry R,- Strategic Mineral Occurrences in.Interior Alaska,

March 1943: Territorial Dept. of Mines, Pamphlot 2, pp. 19-24.

1935 - 27-
Relative Source of

District I Location of occurrence abundance! information

Dome Creek, above i

Seattle Creek Abundant i Dept. of Mines

Upper Fox Creek Abundant Dept. of Mines

Willow Creek Abundant i Dept. of Mines

Fortymile. Fortyfive Pup, trib',

Buckskin Creek Common j Dept. of Mines

Jack Wade Creek Scarce ! Dept. of Mines

Chicken Creek Scarce i Fred Purdy

Meyers Fork, Scarce j Fred Purdy

Stonehouse Creek Scarce Fred Purdy

Koyukuk .. I Lake Creek Bare | Dept. of Mines

Ruby..... Midnight Creek Rare i Dept. of Mines

Trail Creek Toivo Rae

Talkeetna. Dutch Creek Common Kenneth Wier

"A sample of Jig concentrates submitted by Don Gustafson

from the Red Top mine in the Kantishna district consisted mainly

of scheelite. Placer scheelite is said to occur in creek

gravels in the vicinity.

"Considerable wolframite was found by William Burns, former Territorial assayer, in a sample of placer concentrates

from Steele Creek, in the Livengood.district. The. identification was madc a number of years ago."

In describing tungsten lode occurrences in the Fairbanks district

Joesting states:

"Tungsten lodes in which schoclite is the chief ore mineral

have been found in throe areas in the Fairbanks district. They

are: .(1) The area at the head of Gilmore and Yellow Pup Creeks

known locally as Gilmore Dome; (2) the area at the heads of

First Chance, Engineer, and Stoole Creeks, generally called

Tungsten Hill (shown on fig. 2 as the Spruce oHn, Columbia,

Tanana and Blossom groups); and (3) the Pedro Dome area.

"Little prospecting has boon done in the Tungsten Hill

area since about 1918, when a larger number'of pits and shafts

wore sunk. Several years ago a small draglino cut was mado

by Robert Heath and Louis Colbert, but this has now caved.

All of the old pits and shafts are inaccbssible, but the

locations of mineralized zones may be inferred from material

remaining on the dumps. A number of specimens of high-gradoe

ore - one containing 8 percent WO3 - wore found on some of

the old dumps. Several shafts wore apparently sunk on small

quartz veins. Some of those veins carry considerable

schoolite, but they are apparently too small to be of

R. . '4174

1935 - 28 -
I W

Figure 5. - Yellow Pup surface and underground exploratory work.
R. I. 4174

commercial importance. Possibly the veins intersedt calcareous

beds and form larger ore shoots by replacement, as on Gilmore

Dome.

"In the Pedro Dome area, several scheelite prospects

were found during 1942. One was found by Dan Eagan and associates on the west side of Twen Creek at Mile 18 on the

Steese Highway. Scheelite occurs here in several small stockworks of quartz stringers cutting fine-grained quartz diorite.

It is also found sparingly in the quartz diorite near the

quartz stringers. Some surface work was done during the fall

of 1942£ and a tunnel'was run 30 feet into the hillside during the following winter. Where exposed, the ore in the stockworks is below commercial grade.

'A second prospect was found by Bob Leslie and Frank Hawks

at the head of Seattle Creek, and some work was done by Duane

Franklin and partner. A trench was bulldozed through several

feet of overburden and into the weathered schist bedrock. A

small pit was then sunk in the bottom of the trench to a total

depth of 8 feet below the surface.. Exposed in the trench was

a 3-foot zone of finely disseminated scheelite containing a

few small, high-grade spots, and with an estimated average WO3

content of 0.5 to 1 percent. Fine-grained quartz diorite was

also exposed in the bottom of the pit. Because it was made

when.the ground was covered with snow, a thorough examination

of the prospect was not possible.

"A third prospect is reported to have been found by Ed

Vordin in a placer cut at the bead of Fox Creek. It has not

been examined by the writer. Bedrock is said to'be badly

weathered, so that relations are obscure. A sample of placer

concentrates obtained from a cut nearby consisted mainly of

scheelite of the variety that fluoresces pale yellow, thereby

indicating that an appreciable amount of molybdenum is present.

"Geologic Features

"Most of the schoolitc deposits of the Fairbanks district

are found in calcareous beds in the schist, which is the predominant country rock. Mineralization was apparently effected

by tungsten-bearing solutions expelled from underlying

grapitic rocks; these solutions reacted with the calcareous

rocks, replaced much of the calcite, and deposited scheelito

and associated gangue minerals. Noncalcareous schists adjacent

to'the ore were unaffected by the mineralizing solutions, although occasional small scheelite-bearing quartz veins are

found in them.

1935 - 29 -
R I. . 4174

"Several granitic intrusions are known, around which

scheelite deposition has taken place. One is the mass of

porphyritic granite that outcrops in a 2 by 8 mile area between Pearl Creek on the east and upper First Chance Creek on

the west. Near the east end of the granite are the Gilmore.

Dome deposits, whereas at the west end are those of Tungsten

Hill. Other instrusions near which scheelite deposits have

been found are in the Pedro Dome area. Quartz diorite is

the chief intrusive rock type in this area, but there are

also several smaller intrusions of porphyritic granite, as

well as a number of granitic dikes. Most of the intrusions

are elongated east-west parallel to the regional strike of

the schist.

"Although many of the higher-grade deposits are found

some distance from the nearest known granitic contacts, the

genetic relationship between the scheolite and igneous rock

is indicated by the frequent occurrence of sparse disseminations of schoelito in sills and dikes that are offshoots

of the main intrusion. Scheelite has also been found in

small quartz stringers in the igneous rock."

LODE DEPOSITS OF THE NOME AREA

In 1916, J. B. Mertie, Jr., of the Geological Survcy,2/ examined tungston lode deposits-on Seward Peninsula and reported as follows:

Sophie

"The property known as the Sophie lode, on Sophie

Gulch, a tributary of Rock Crook, consists of one patented

placer claim and two lode claims. Residually weathered

tungsten ore was mined here by placer operations in 1916---."

"The country rock at this place is an iron-stained,

thin-cleavirig, foliated mica schist, the cleavage of which,

measured at one place in the pit, strikes north and dips

23° E. It shows, also, a vertical jointing trending N. 35° W.

Many well-developed fissures are present, striking N. 45° E.

and nearly vertical or dipping steeply to the northwest.

These are filled with iron-stained, shattered quartz. Such

veins range in thickness from a fraction of an inch to a

foot or more. There is great irregularity in these quartz

stringers, most of them thickening in places and'thinning

in-others; also, stringers run out into the country rock.

Iron-stained fault planes striking N. 18° W. and dipping

54°'E. cut both the country rock and the quartz stringers,

and along those there is little or no quartz but considerable iron-stained gouge material.

27 Mertie, J. B. Jr., Lode Mining and Prospecting on Soward Peninsula:

U. S. Geol. Surv. Bull. 662, 1918, pp. 436-437.

19355 - 30 -
a. «

Figure 5-A. - Map of Home area showing stream location of placer and lode scheelite.
I

R. I. 4174

"The scheelite occurs for the most part along the sides

of quartz stringers and disseminated in the mica schist.

Locally the scheelite is present in the quartz. It is

reported that gold occurs in the iron-stained schist outside

of the zone of scheelite mineralization, but no gold is

reported to have been found in the scheelite-boaring rock.

Besides scheelite, however, arsenopyrite, pyrite, and galena

are found in the form of later veinlets definitely cutting

the quartz.

"It is said by the owners that the belt of scheelite

mineralization is about 50 feet wide and has so far been

traced about 500 feet in each direction from the open cut.

The trend of this zone appears to be that of the iron-stained

quartz veins and stringers---that is, about N. 45° E. The

northwest side of the lode is reported to carry more scheelite than the other side. Two shafts--one 52 feet deep, northeast of the open cut, and the other 28 feet deep, southwest

of the cut-have been driven to ascertain the value of the ore

along the lode. It is said that these shafts show a higher

content of schoelite in depth than at the surface,

Miscellaneous Localities

"Several other small tungsten lodes in Seward Peninsula

have been worked by placer-mining methods. These include

the lode on Twin Mountain Creek, the Lynx claim, on the north

side of Glacier Creek, and another small lode on the divide

between Glacier and Rock Creeks."

Lost River

The Lost River tin mine on Cassitcrite Crook, a tributary of Lost River,

in the York district, is a potential source of tin and tungsten. Wolframite,

an iron-manganese tungstatc, and cassiterite are constituents of three types

of deposits, as follows: the Cassitorite dike, 0.56 percent Sn and 0,18

percent Wo3; the granite ore zone, 1.27 percent Sn and 0.287 percent WO;

and a very large contact metamorphic zone, 0.25 percent Sn and 0.03 percent

WOA, The Bureau conducted extensive investigations at Lost River from

1942 to 1944 and reported the results of this work in R. I. 3902, "Investigation of the Lost River Tin Deposit, Seward Peninsula, Alaska."

PLACER DEPOSITS OF THE NOME AEEA

Location

The Snake and Nome Rivers in the Nome region on Seward Peninsula are

easily accessible from Nome by gravel roads or the Seward Peninsula Railway

on Nome River. Figure 5A shows the location of streams from which' scheelito-bearing gravels were mined,

1935 - 51 -
R. I. 4174

History

The presence of scheelite in many of the streams in the Nome region was

reported by MoffitL1 / in 1905 and 1906. Scheelite remained in the sluice

boxes or pans and caused trouble in cleaning the gold.

J. B. Mertie, Jr.,ll/ reported that in 1916 the Pioneer Mining Co. on

Sophia Gulch mined 4,000 to 5,000 cubic yards and produced a large part of

the scheelite mined in Alaska in 1916.

Placer-mining operations for scheelito also were pursued on Rock and

Glacier Creeks. In 1916 other gold-placer operators started saving the

scheelite recovered-from their operations.

Approximately 47 tons of tungsten concentrate, mainly scheelite but

including a little wolframite, was produced in Alaska during 1916.

Several prospectors wore searching for scheelite in 1942. In recent

years no attempt has been made to save scheelite in gold placer operations.

Physical Featuros

The portion of the Snake River visited by Hoido in the summer of 1942

lies in a flat valley about 1-1/2 milos wide, through which the river

meanders in a southerly direction. In the vicinity of Glacier Creek, drilling has shown the bedrock to be over 100 foot below the surface. Surface

elevation is approximately 100 .fot above soa level. Mining the river

gravels would require the use of dredges with exceptional digging capacity..

Tributaries on both sides of Snake River oetond easterly or westerly for a

few miles into the hills forming the drainage system.

Ore Dcposits. -

The following tributaries of Snake River have shown notable amounts of

scheolito in past gold dredging operations:

Anvil Creek, for throo-quarters of a mile near its;upper end, was

dredged to a width of about 250 feet. Appreciable amounts of scheelite

were found in this portion of the stream and were discarded. in the tails.

Depth of gravel was reported as approximately 14 foot. A stroam of water

flows all season.

10/ Moffit, F. H., Geology of the Nomo and Grand Central Quadrangles, Alaska:

U. S. Gool..Surv. Bull. 533, 1915, . 154. :

11/ Mertie, J. B., Jr., Placer Mining on Sewacd. Pe-insiula: U. S. Geoa. Sirv.

Bull. 662, 1918, p. 457.

1955 - 32 -
I

R. I, 4174

Snow Gulch was mined hydraulically for 3,000 feet. It was worked. for

a width of about 150 feet and a depth of 6 feet. Snow Gulch is dry, but

the United States Smelting, Refining & Mining Co. ditch crosses its head.

Glacier Creek was dredged for about l mile for a width of 300 feet.

Mining depth was reported to average 12 feet. Running water is available.

throughout the working season.

Rock Creek gravel is known to contain scheelite for a length of 1-1/2

miles. The gravel is 200 to 300 feet wide and about 12 feet deep. A portion

of the length has been mined hydraulically. Ruining water is available

throughout the working season.

Between Rock Creek and Balto Creek are two dry gulches - Lindblom and

Prospect Creeks - about 1/2 mile long, 25 feet wide, and 4 -to 5 feet deep.

Balto Creek gravel is 25 feet wide and 4 to 5 feet deep for half a mile.

No information was obtained on whether water flow was constant or intermittent.

Sledge Creek gravel is 50 feet wide and 5 feet deep for a length of

half a mile. Running water is available throughout the working season.

Boulder Creek gravel was mined hydraulically for four claim lengths

below the mouth of Twin Mountain Creok. At the mouth of Twin Mountain Creek,

the Boulder Creek gravel is about 100 foot wide and 10 feet deep. Three

claims downstream it is 300 foot wide and 25 feet deep. Virgin gravel

remains downstream from the hydraulicked portion, whore the gradient was too

flat for hydraulicking. Running water is available throughout the working

season.

Twin Mountain Creek is tributary to Boulder Creek. The gravel was

mined hydraulically for about three claim lengths. A portion;of Twin

Mountain Creek was worked for scheelite as well as gold. It Js uncertain

what portion of the gravel may still contain schoelite. Running water is

available throughout the working season.

Bangor Creek gravel was dredged for about 1-1/2 iiles in 1921. The

deposit was dredged for 200 foot to depths of 10 to 18 feet.. Running water

is available throughout the working season.

Butterfield Creek, at the head. of Bangor Crook, also was worked. No

other information was obtained on this creek.

Divining Creok gravel is virgin ground for three-quarters of a mile.

The width of this deposit is 125 foot and the depth ranges from 5 to 6 feet.

Schoelite content and water flow are unknown.

1935 - 33 -
R. I. .4174

The Oro

Most of the foregoing creeks have alrqady boon exploited for gold.

Insofar as is known, scheelite is the only other valuable mineral remaining

in the tails. Lindblom, Prospect, Balto, and Divining Crook gravels have

not been mined and are reported to carry small amounts of gold. During past

gold placer operations, scheelite in concentrates was generally considered

a nuisance, and few records of its value were kept.

The examining engineer was unable to obtain reliable reports on scheelito content of,the gravel. Various conversations wore hold with officials

of the United States Smelting, Rofining & Mining Co. and with individuals

who were prospecting for scheolito in 1942, as a result of which it appears

possible that the schoolite content may range from 1/2 pound to 2 pounds

per cubic yard. The lower figure is probably closer to the average. The

higher figures were reported from prospects on Prospect and Balto Creeks.

Scheelite concentrates soon by the Bureau of Mines engineer contained

10.to 20 percent impurities, chiefly garnet, magnetite, and other unidentified minerals. Some of the impurities could be removed magnetically, and

it is believed that a 6 0-percent concentrate could be shipped. Scheolite

particles in the concentrate wero slightly rounded grains ranging in size

from about 10-mesh to 1/2 inch diameter. Gravel was commonly composed of

schist and quartz. Few boulders over 2 feet in diametpr were noted.

WILLOW CREEK DISTRICT

Scheelite in amall amounts has boon found at the Independence, Gold

Cord, and Fern mines, all gold producers in the Willow Creek district, 15

miles northwest of Palmer, Alaska.

Independence Mine

In the Independenco mine, the vein is composed of quartz and a "fill"

of crushed quartz diorite. Scheelito is present in the quartz as small

grains, blobs, and stringers, but it does not occur in the quartz diorito

"fill." The mineral is found on the 1,100-, 1,200-, 1,250-, 1,300-, and

1,500-foot levels, but the distribution is spotty; most of the.quartz is

barren of scheelite.

It is found in greatest abundance in stopo 1 on the 1,200-foot level,

where the quartz is 18 inches thick and the ore is believed to average a

few percent in WO , Pockets of ore as large as 8 inches in diameter and

containing 50 percent scheelite were found in stoping.

The exposed vein on the 1,100-foot level shows scattered grains and

short stringers of schoolite between raises 2 and 3. The mine is worked

primarily for the gold, the schoclite alone being too scarce to warrant

production. The principal vein minerals are quartz, schoelite, pyrite,

galena, and soricito. The scheelito is often readily distinguished without

the use of an ultra-violet ray lamp, because its light-'to,'da.k-brown color

contrasts sharply with the milky quartz.

1935 - 34 -
R. I. 4174

Gold Cord Mine

Scattered grains of scheelite occur In a quartz vein at the Gold Cord

mine. In most places, the scheelite is present.in insignificant amounts.

The highest-grade occurrence is on the 300-foot level 70 feet from the

south face, where a 2-inch quartz stringer shows, for a length of 1 foot,

a scheelite content of several percent. The 350- aed 400-foot levels appear

to be nearly barren of scheelite.

Fern Mine

The Webfoot vein in the Porn mine shows a fairly persistent, though

sparse, distribution of tungsten throughout its exposed length on the 200-

foot level and in the stope between the 200- and 300-foot levels. At this

mine the mineral is croamy in color and occurs in the quartz as scattered

grains and stringers. ..In the first drift.south of the 200-adit portal a

stringer 8 inches long and 2 inches thick is estimated to contain 15 percent scheelite.

R YDER DISTRICT IN SOUIEASTEIR ALASKA

Location and Accessibility

The Salmon River of Hydcr district is in the West Coast Range of

Southeastern Alaska. Hyder is at the mouth of the Salmon River and at the

head of the Portland Canal, about 155 miles north of Prince Rupert, British

Columbia. Prince Rupert is the western terminus of the Grand Trunk Pacific

Railroad of the Canadian National Systdt. Hydor is 2 miles southwest of

Stewart, British Columbia, which is at the mouth of the Bear River, which

flows entirely in British Columbia. The international boundary follows

approximately the summit of the Boar River ridge, the divide between the

Bear and the Salmon Rivers. The prominent peaks exceed 5,000 feet in

altitude; the highest are Mount Dolly and Mount Wc.lker. The principal mines

of the Rydor district lie in this region.

A good highway leads from Stewart to Hyder and from Hydor up the

Salmon River for 11 miles, then along Cascade Creek to the Premier mine

in British Columbia about 15 miles from Hyder. Hyder is a town of about

100 inhabitants. It has postal and steamship service. At present there

is weekly service to Stowart by the Union Steamship Co. from Vancouver,

whore direct connections are made to Seattle. The Canadian boats make the

trip from Vancouver to Stewart in three days. A weekly mail boat operated

from Kotchikan to Hyder by the McKay Transportation Co. can carry all

ordinary freight. Ketchikan is served by the Alaska Steamship Co., Northland Transportation Co., Canadian Pacific Railroad Co., Canadian National

Steamship Co., and the Alaska Transportation Co.

Since the discontinuance of the Hyder Radio Co. in January 1945, the

only telegraphic service is through Stewart, British Columbia.

1955 - 55 -
R. I. 4174

There is only one large mine in the area, the Silbak-Premier mine at

Premier, British Columbia. This mine is connected to the Steasrt dock by

an 11-mile aerial tramray. The communities of Ryder and Steward depend

largely on the operation of the Premier mino. As a result of this operation there are stores at both Ryder and Stewa±t from which most ordinary

items can be purchased at moderate prices. There are good living conditions

in Ryder and Stewart, and during the summer months it is feasible for men

to drive back and forth to the Riverside mine; some even drive to the

Premier.

The Riverside tungsten mine is 7 miles north of Hydor on the east side

of the Salmon River highway at latitude 56° 0' N., longitude 150° 04' W., as

shown in figure 6.

The Mountain View property is at latitude 55° 59' N., longitude 150° 03'

W., in the Salmon River mining district of southeastern Alaska, about 5 miles

in a northwesterly direction from the town of Hydor." Vein outcrops and surface workings occur at an elevation of 950 feet and occupy the west flank of

a low ridge between Skookum and Fish Creeks, as shown in figure 6. The portal of the long adit is on Skookum Creek, about 550 feet north of the confluence of Skookum and Fish Creeks.

Access to the property is over a 4-foot-wide trail built and maintained

by the U. S. Forest Service. This trail is suitable for pack animals and

ample for transportation of supplies and material for exploratory work.

: Physical Features and Climate

The topography is characterized by steep mountains, narrow canyons, and

rugged peaks. The principal streams in the Hydor district are the Salmon

River, Fish Creek, Texas Creek, and the West Fork of Texas Creek. The

higher elevations are covered with valley glaciers and a large ice field.

Theprincipal glaciers in the area arc the Chickamin, Salmon, and Texas.

Vegetation is the dense growth typical of southeastern Alaska. Spruce,

and hemlock, the principal timber trees, furnish fair rood for heating

purposes, but neither yields good lumber. The best fuel comes from alder,

which grows in the valleys. Timber line is at 2,500 to 3,000 feet.

Temperature is variable in both sumeor and wint6r. The temperature is

normally moderate, though subzero weather occurs during some of the winters.

The winter of 1942-45 was one of the coldest on record. A temperature of

-20° F. was recorded in January at the Riverside mine. From April throughout

October the temperature is mild. The rainfall is least from April through

June and increases from July through October. Snow falls from Novoebor

through March and is heaviest during December and January.

The Rivsrsido mine surface plant is 300 feet above sea level.

1935 - 36 -
I

MODIFIED FROM

Figure 6. - Hyder and vicinity.
__ I

R. I. 4174.

History and Production

The first discovery of mineral in the Salmon River or Hyder district

was on the Bear River at Stewart in 1898 by early placer miners. The first

record of any mining on the Alaska side was in 1901 on the Salmon River.

Mining operations were limited until a small boom occurred in the area during

1909, but real interest in the district did not occur until the opening of

the rich gold-silver deposits at Premier, British Columbia, in 1918. Activity was then intensified in both Alaska and British Columbia, In 1923; after

a forest trail was built up the West Fork of Texas Creek, a number of claims

were staked and considerable development work was done in that area, chiefly

for lead, silver, and gold, though some molybdenum claims were staked. The

Big Missouri mine was located above the Salmon Glacier in British Columbia.

The Riverside mine and a number of other properties along the Salmon

River became active in 1924. By 1925 over 5;000 foot of development work

had been completed and a 50-ton mill, with flotation unit and tables, had

been erected at the Riverside. It is reported that during this time 218

tons of load-silver-gold concentrate was shipped. There was a small leasing

operation at the Riverside in 1928.

With the drop in the price of silver in that year, activity began to

decrease, and by 1932 the camp had almost reached its present status, a

nearly abandoned mining community. The only operations to persist have been

those of the Silbak-Premior and the Riverside, the latter operating intermittently on a small scale.

The Riverside mine was examined by Durant Hill'of San Francisco in 1940

for the J. H. Scott Co., which did some developing during the fall and

winter of 1940-41. The flow shoot was changed to adapt the mill for scheelite

recovery. During the summer of 1941. the owners reported-milling 3,400 tons

of ore, which came from the northwest drift stopo, the sublevel stopes,

intermediate level stopes, and the Nos. 1 and 2 stopcs in the upper tunnel

level. Thirty tons of scheelite concentrate containing 44 percent WO was

produced from this ore. This concentrate was shipped to tho General Electric

Co. in June 1942. The operators also recovered 49 tons of galena concentrate,

which was shipped to the Bunker Hill and Sullivan smelter at Kellogg, Idaho.

The reported content of this concentrate was 68 percent lead, 31 ounces silver,

and 1.1 ounces gold a ton. From the available data, it is estimated that the

ore mined avoraged about 1.3 percent WO, 1.0 percent lead, 0.5 ounce silver,

and 0.01 ounce gold a ton, and sand tailings carried about 0.1 percent W03.

- About 1,800 tons of slime tailings were impounded during the 1941 operation. Approximately 1,300 tons of these tailings, together with 100 tons of

mined ore, were milled during the summer of 1942. Considerable test work

was carried on to develop a suitable flow shoot in the mill; however, according to the company's reports, 36.6 tons of 10.15-percent WO3 concentrate'was

shipped in October 1942 to the General Electric Co.

During the summer of 1942, the mill operatd. intermittently and demonstrated a capacity of about 1 ton an hour.

1935 - 7 -
_I _

R. I. 4174

The Mountain View property was discovered in 1917 by John Hovland. In

March 1924, a group of Ketchikan businessmen obtained an option on the Hovland

group of five claims. On July 15 of that year, the Mountain View Gold Mining

Co. was incorporated under the laws of Alaska for the purpose of exploring

and developing the property. License fees have been maintained, and the

corporation, although almost dormant, is still intact.

From 1924 to November 1, 1928, the property underwent active development, Under the supervision of Arthur 0. Moa, general manager, a camp was

constructed, a hydraulically operated power plant and compressor were

installed, a 4,000-foot aerial tramway to the Salmon River Highway was built,

the surface was trenched and mapped, and over 4,000 feet of crosscut and

drift were driven. In addition, the original five claims plus two additional

claims were patented, and payments on the property were completed. The Gray

Copper vein, on which the Bureau of Mines later undertook exploration, was

explored by driving the adit in December 1927, but little drifting was done

on the vein at that time, as the presence of scheelite was unknown. Operations wore suspended November 1; 1928, and, aside from limited repair work,

no further development has boon carried on by the Mountain View Gold Mining

Co.

No ore has boon shipped from the property, nor has any appreciable amount

of ore been stock-piled on the dump, as most of the development work consisted of crosscuts.

RIVERSIDE MINE

Property and Ownorship

The Riverside mine is owned by Strong & Black of Seattle and is under

option to J. H. Scott Co., Merchants Exchange Building, San Francisco,

Calif. The plant and equipment are owned by the J. H. Scott Co. There are

10 patented claims in the Riverside group.

General Geology

The country rock is the Texas Crock granodiorito of the West Coast Range,

batholith.2/ .Bands of Hazelton rocks are included. The Hazolton group

comprises greenstone, tuff, volcanic breccia, graywackes, slate,.argillite,

quartzite, and occasionally some limestone. The granodiorite and the shear

zones are cut by dark malchito, lamprophyre, and monzonito dikes. The dike

rocks are post mineral in age and apparently have no bearing on deposition

of the ore. These dikes strike in a northerly direction and dip to the-wost

at about 65 degrees. The marked shearing has occurred over a length of

several thousand feet and ranges in width from 50 to 100 feet. Folding

within the zone has boon noted. Tho principal shcar-zono is known as the

Lindeborg. On the footwall side 6f the zone a gneissoid granodiorite is

first encount'ored, which passes into gneiss and schist. On the hanging-wall

side, granodiorite porphyry is generally encountered.

12/ Buddington, A. F., Geology of Bydor and Vicinity, Southeastern Alaska:

Geol. Surv. Bull. 807, 1929, p. 15.

1935 - 38 -
R. I. 4174 -

Occurrence of Deposits

Three veins are developed on the Riverside property - the Lindeborg,

Riverview, and Cross. These veins areof the $uartz fissure-vein type.

The Rivorview and Cross veins lie in the granodiorite, where the shearing

has not been extensive, though considerable movement is shown by gouge

and slickensides. The Lindeborg or main vein lies in a shear zone of

gneissoid and schistose rock.

There are two types of ore occurrence. One is the narrow pyrite schist

vein structure moro common along the hanging wall of the shear zone; the

other consists of wide, massive, white quartz containing large cream-yellow

crystals of scheelite. The quartz type is not as continuous as the pyrite

schist mineralization, as it widens or pinches in relatively short distances.

The scheelito is principally of a light brownish-yellow color-and is

rarely white. Under the ultraviolet ray lamp it fluoresces a creamy white,

only occasionally a golden yellow. Very little powollite occurs.

The Riverview vein has a general strike of N. 60° W. It is parallel

to the Lindoborg vein and lies about 500 foot east of it. The vein consists

of quartz with some galena and pyrite. The quartz is several feet wide

at the surface but ranges from 10 inches to small stringers underground for

a distance of 250 feet.

The Cross vein lying between the Riverview and Lindeborg veins strikes

north-south with a westerly dip of 30 to 50 degrees. Vein widths range

from 6 inches,to 4.5 feet both along the strike and the dip. The minerals

are quartz, galena, and pyrite, with some chalcopyrite, sphalerite, and

phrrhotito. The vein is traceable for 650 feet, and a largo part of it,

where exposed, averages 2 feet in width but pinches out as it approaches the

shear zone in which the Lindeborg vein occurs.

The Lindeborg vein-occurs more or less in the center of the shear zone,

has an average strike of N. 50° W. and an average northeasterly. diptof 65

degrees. This vein is traceable underground for 1,000 feet along the strike

and for a depth of 300 feet. On the surface, the vein can be traced over

1,500 feet, and the difference in elevation between the two extremities is

approximately 700 feet. On the surface and near the west end of the underground workings the quartz vein is.5 feet wide: however, the vein increases

in size from a few stringers in the gneissoid and schistose rock to several

feet of the mineralized material, the average width being 5 feet.

The principal minerals of the Lindeborg vein are quartz of a milky and

vitreous nature, galena and pyrite in varying amounts, with some chalcopyrite, sphalerito, barite, and scheolite. Tetrahodrite has been reported,

and in some places galena up to a foot in width has been found. The

Lindeborg is the principal scheelite-bearing vein, though there are a few

minor occurrences of scheelite in both the Riverview and Cross veins. In

a number of places schcolite veinlots are several inches thick and contain

large crystals. The schoolite-bearing stringers range in width from seams

1935 - 39 -
R. I. 4174

to as much as 10 inches. The widest occurrence of scheelite is in stope 2

on the upper level, where the quartz vein carried scheelite for a width of

6 feet. The longest ore shoot is on the upper level in.what is termed, in

this report, the East ore body. In this ore body the schoelite mineralization is 250 feet long; of this, the measured ore shoot is about 160 feet

long. This lens extends for nearly 400 foot on the dip, as indicated by

the diamond-drill holes. Smaller lenses occur in the upper tunnel level

to the east, one about 25 feet in length at stope 3, one about 20 feet in

length at crosscut 2, and one 20-foot lens at raise 1. Other scheelito occurrences in the upper tunnel are of minor importance.

The other principal occurrence of scheelite is in the West ore body in

the Mill tunnel level. This lens extends along the strike for about 90

foot and on the dip for about 100 feet. This is a narrow ore shoot, but

it has-possibilities of a downward extension that would justify further

exploration.

There are several minor occurrences of scheelite in narrow stringers in

the southeast drift.of tho.Mill tunnel level.

Scheelite occurs in the sublevel and in the. intermediate level in a

divided vein, one on the hanging wall and one on the foot-wall side of the

shear zone. Most of the ore in this area has been mined out.

Scattered scheelite occurrences were noted in the upper surface tunnels

and the open cuts along the outcrop. Mineralization has been observed over

a vertical rangeoof 700 feet and a horizontal range of 1,000 feet. With

this wide distribution, there are possibilities of developing other minablo

ore shoots.

Work Done.by the Bureau of Mineos

Exploration by the Bureau of Mines began in June 1942 and was completed

in March 1945.

Diamond drilling was the major function and the most important part of

the work. Four surface holes totaling 1,560 feet and 37 underground holes.

totaling 3,100.5 feet with an over-all total of 4,660.5 foot were completed.

Underground work by the Bureau of Mines consisted of cross-cutting and

raising. Several stations were excavated at underground diamond drill sites.

Throe full stations were cut for diamond-drill sot-ups and seven partial

cut-outs for diamond drill set-ups were made. Crosscuts 1 and 2 in the

upper tunnel level were driven 42 feet and 24.5 feet, respectively. These

crosscuts were driven ptimarily to obtain favorable sites for diamond-drill

exploration above and below the level; but, in addition, important geologi- cal information was disclosed. Raise 1 in the upper tunnel level was

advanced 15.5 feet to disclose the limited extent of ore above the level.

A total of 82 foot of underground developing was done by the Bureau of

Mines.

1935 - 40 -
7

// rL/x K. . Pi . ,n AlVr'LtU/

0/lry Ho/#

L/ndebory Levrl

Infmrmeftofe Level

Rlverv/nw VO/7

FWSfope

id

-- MA. Z X-Cuf

^No. X-Cuf

H.W5. $'pe

- No. I Raise

,

*

.^ UpAPr Levyel- -

- X- Vern ODrff

No I Raise: M48 2-O0

wdtet. 0/ZWOi

Tunn/ - . :

El. 555

03Pn Cut-c : i No`

SM"

'U of

A/a

0 /1 00 ZO

Sco/l in Fcft

:* Compi/d frwn Oeo/l;ioa/

-v"ra M op 'CompositF Leve w/op

fhe Rivers/id Mine.-yder Os/',

'sko,5ft y RG /t MByirs.

Figure Figure 7. 7. -- Plan Plan map map of of Riverside Riverside mine. mine.
r.

/'"ooW^ iL/Zk

- ,- - aO l l-Z-*

nd o r -roe -L "

/Lower r Tunnel - / A

Cuz/I/ne -' / / /' a Ouf//ne of ,Mesured Orex f / M

Ouf/ire of /nAerred Ore se A /

/ -- -Nor/we NMi./ r/f <A/orfhwesa Mi// Drif'£

Ws T ORE 80DY

Nofte Compiled from Oeolof/co/ Survey Maop

"Lon9giudi 70/ Work/qfs i/7 L/ndebort

Shear Zone, by M fByers, Ocf,1s4 Z.

All anolyses / vern ore ^ WO

P/one of Pho/ec ion N-46 '3 W

0 100 200 300

Scale in FeetFigure 8. - Vertical projection, Riverside mine.
1.

Figure 9. - Section A-A, east ore body, Riverside mine. Figure 10. - Section B-B', east ore body, Riverside mine.
700

-o-

,; ~ , -.. 2. 2ao3Y.

-3 ^-: \ *N-

^ ^^^^^^ A' ^^^

;i- 1 ^22dsPOO'7.;. ^ 600 "' "

" - , -? ' . : ." .

Aver 53- ;/.03'r. ' t .-'~ .

J Upper Leve,

'7 <- <A- 500 WaE -> -- r asT

, t,, t -. 7 L wB 3

,' ': ; L2 80'5w0 3

-I ,

Zl- - -//-/ I "? / ,

-

ZP600 7-

A

,- - - -////' , - «'ed - "

,./...., '_ / 

-" Schee : ;ie

Onelss aned/Scr-is

''^-^^

/I/FR 51E M4//INE

0 50- /0

SCchCe7 ,'Fee

Figure 12. - Section E-E, sublevel ore extension.

Legend

r3 Schee/if-e

i GOneiss ondSchisf/

' OIranodiori te . COroanodorife Porphyry

0 50 /00

Sco/e in Feet

Figure II. - Section C-C, east ore body, Riverside mine.
Na Feet

M-26 /.8

M-25 4.4

M-24 7.9

M-23 28

M-22 2.

------

%wom

245

441

0Z9

0/7

1o08

ai4

041

0.20

0a76

RIVERS5DE MINE

0 /0 20 30 40 50

Sc/I in Feet

Figure 13. - Analyses, underhand stope, Mill tunnel.

Figure 14. - Analyses, stopes I, 2, 3, and east raise.
i

-. 5. 05 0./9

M-3/ 5-3 58 2.60

03

M-36 Q3 0Q/

M-16 /9 004 M-/6 29 0.0 M-17 47 0.75

M/5 1.5 057'x

M-28 /.7 //8

M3* M2 Q02 080

Legend

\-D.0 C Ho/es --- Sample Ao. -Feef -. W0s

Channel sample averages

shown above wCork/n7s

RI VER SIDE MINE

0o 50 /00

Scale in Feet

Figure 15. - Section on plane of the vein, east ore body.
R. I. 4174

In conjunction with exploratory work, it was necessary to repair ladderways, put in stull timbers and staging for channel samples, repair pipe lines,

maintain trails, remove snow from roads and around buildings, and repair

buildings.

Sampling and Analysis

A plan of the Riverside mine is shown on figure 7, a section through

the workings on figure 8. Sections through the drill holes on the East ore

body and the sublevel ore extension are shown on figures 9, 10, 11, and 12.

Figure 15 shows analyses of samples taken in the underhand stope in the Mill

tunnel. Figure 14 shows analyses of samples in stopes 1, 2, and 5 and the

East raise. Figure 15 is a section on the plane of the vein in the East ore

body.

Fifty-three channel samples were cut at the Riverside mine. Thirtyseven core samples and 47 sludge samples were taken from the d.amond-drill

work.

Samples of diamond-drill cores were taken only where scheelite was shown

by the ultraviolet ray lamp to be present. The entire core of the intervals

sampled was analyzed. Core recovery in the scheelite-bearing zone averaged

better than 95 percent. Considering the good core recovery, sludge analyses

were discounted except in holes M-2 and M-32. In most cases sludge recovery

was low.

The true or normal thickness of the vein has been calculated for each

core sample, and the-weighted W03 content has been calculated for each hole.

West ore body. - Nine samples cut in the underhand stope in the northwest drift, Mill tunnel level, over a length of 33 feet and width of 2.4.

feet, averaged 1.21 percent WO3 . West of this underhand stope, five samples

wore cut over a length of 20 feet and an average width of 2.9 feet. The

average content of those samples was 0.18 percent W 5 .

East ore body. - In stope 1 an average of nine sample intervals showed

a zone 1.5 feet wide and containing 0.43 percent W0O. In the East raise an

average of four samples over a distance of 80 feet shows a width of 1.4 feet

containing 1.24 percent W0O. In the main drift from the East raise to stope

2 an average of three samples over 18 feet shows a width of 3.6 feet containing 0.20 percent WO. The best ore in the mine was found in stope 2,

where an average of 12 Iamplo intervals over 46 feet shows a width of 5.25

feet of ore containing 1,03 percent W07 . East of this stopo two samples

showed a 12-foot zone 0.9 foot in width containing 1.41 percent W05 . The

diamond-drill holes encountered ore in the East ore body as follows:

D. D. H. Width, foot Percent W0O

S-3 5.8 2.60

M-18 6.0 1.65

M-15 1.5 0.57

M-17 4.7 0.75

M-28 1.7 1.18

1935 , 41 -
Ri I. . 174

The tungsten content of ore in the West ore body is close to the average

of the East ore body, and"an average for measured and indicated ore'has been

taken at 1.21 percent W03*

The study of the analysis values near the limits of the indicated ore

body and in the diamond-drill holes outside of the limits of indicated ore

demonstrates that 0.5 percent W03 can be considered a fair average for

inferred ore.

The most pronounced lead-silver occurrence encountered in the diamond

drilling was in holes M-18 and S-5. These indicated the possibility of producing a substantial quantity of lead in the East ore body. The following

percentages of lead, silver, and gold were obtained from analysis of core

samples in holes M-18 and S-3.

tI Normal thickness of i Load, Ounces per ton

D. D. Hole Sample I vein interval, feet percont Silver Gold

M-18 C 14 .' 3.22 2.25 0.075

HC 15 0.8 1.22 1.20 0.050

HC 16 i 0.7 4.78 12.44 0.195

HC 17 0.8 1.77 4.27

HC 18 . 0.9 6.89 3.80

S-3 HC 33 1.9 7.00

HC 54 1.8 0.15

___ HC 55 _ 2.1 5.00o '_

Development

The Riverside mine is developed by over 6,000 feet of underground workings. The main.or Mill tunnel level is driven on the Riverviow vein at an

elevation 60 feet above the highway on a level with the top of the mill.

Below this level are two short tunnels driven on the Riverview vein and

which are now covered by the Mill-tunnel dump.

The Riverview fissure was followed for 500 feet to a point where it

intersects the Cross vein. The vein pinches at 200 foet from the mouth of

the tunnel and virtually disappears at 250 feet. No ore of economic value

was found on this vein.

The Cross vein was developed to a depth of 250 feet below the Mill

tunnel level by a winze and two levels at depths of 140 feet and 250 feet.

The drifts wore driven, according to the reports, north and south from this

winze at these levels. The first level is reported to have some 500 feet

of drifting. Stoping was carried on from these levels and from two stopes

south and two stopes north of the winze above the Mill level. There are no

authentic records of the production, but reports indicate that considerable

high-grade lcad-silver-gold ore was mined from these stopes. The present

water level in the Cross vein winze is now 75 foot below tho Mill tunnel

level.

1935 - 42 -
R. I. 4174

The Lindeborg vein has been developed by fbur tunnel levels, an intermediate level, a sublevel, numerous raises, crosscuts, and stopes. The lower'

tunnel is a150-foot drift on the vein from a large surface outcrop in the

gulch north of the bunkhouse. This tunnel is 20 feet below the elevation of.

the mill and 70 feet below the Lindeborg tunnel. Near the mouth of the

tunnel a 2-foot quartz vein.breaks up into quartz stringers and shear-zone

seams within a distance of 50 feet. No scheelito was observed.

The Lindeborg vein on the Mill tunnel level is reached by the Cross vein

drift and also by a crosscut driven 500 feet easterly from the drift on the

Riverview vein at a point 250 feet in from the mouth of the tunnel. The

shear zone has been drifted on easterly for 450 feet and west for 575 feet,

with about 120 feet of work in four crosscuts. Scattered scheolite was

observed in several places in the East drift. Mineralization was more prominent where the main crosscut cuts the shear zone. Several showings of

scheelite 'in the Northwest drift encouraged exploration with the diamond

drill, but no parallel veins wore developed. The underhand stope bf the

Northwest drift in the East ore body is the most pr6mising scheelite occurrence on this level.

From the offset crosscut at the east end of the Northwest drift an

inclined raise is driven to the intermediate level, a vertical distance of

118 feet. The sublevel is at 80 feet vertically above the Mill tunnel level

extending to the east of the raise. The Lindeborg adit tunnel is 76 feet

above the Mill tunnel level. The upper tunnel is 202 foot vertically above

the Mill level. Two fairly extensive stopes from the West drift of the Mill

tunnel level were carried up to the Lindeborg tunnel on the lead-silver-gold

ore during the early operations. These wore extended to the intermediate

level.

The sublevel shows both a footwall and hanging-wall vein from which

considerable schoolito ore was stoped to a height of 40 foot above the intermediate level in 1941. This sublevel is about 100 foot in length. The hanging wall and footwall stopes are connected above the intermediate level. A

small amount of ore was removed from the hanging wall stope in 1942.

East of the main raise from the Mill tunnel level, schoolite-bearing ore

was mined to a height of 40 feet above the intermediate level. Fifty feet

east of this stope a raise 75 feet high is in ore containing scattered occurrences of scheelite. West from the main raise on the intermediate level

towards the surface are two fair showings of scheelito. However, there is

not much unmined ore above those points. It is reported that most of the

schoolite ore from the intermediate level stope came from the old pillars

left after mining the lead-silver-gold ore in the early operations.

The Lindeborg tunnel is open for 175 foot, at which point it becomes

part of the old stope that extends from the Mill level through the Lindoborg

tunnel to the surface. This stope was on the largest shoot from which loadsilver-gold ore was removed in the early operations.

1935 - 43 -
R. I. 4174

The upper.tunnel level has been driven east on the Lindeborg vein for

1,000 feet. The quartz-bearing vein inr'thb shear zone is a few inches to 7

feet wide. Galena .and pyrite are the principal minerals. In the early operations, two stopes were worked - one, 100 feet east of the tunnel mouth, for a

distance of 120,.feet to a height of 55 feet, and another, 500 feet bast of

the tunnel mouth, -for a length of 70 feet and a height of 35 feet.

Though pyrite is seen in a number of places throughout the length of the

tunnel, there is only one important scheelite ore body on this level, namely, the East ore body in the vicinity of the East raise. The East raise is 640

feet from the mouth of the tunnel and reaches a height of 80 feet. During

1941-42 the present owners removed about 350 tons of ore from what are known

as stopes 1 and 2 on the East ore body.

On the outcrop, in line with the face of the upper tunnel and about 400

feet above the upper tunnel, the quartz vein is exposed by an open cut for

about 150 feet. :Scattered schoelite shows in this cut.

Typical Texas Creek granodiorito is encountered in the various levels.

In the main workings the altered granodiorite porphyry, gneissold granodiorite, gnelssoid schist, also aplite, malchite, lamprophyre, and monzonite

are exposed by the underground workings and diamond-drill holes.

Benoficiation by the Scott Co.

In 1943, the mill had a capacity of a ton an hour dr 25 tons a day.

After making tests with their flow sheet and the use of reagents, in

January 1943 the Scott Co. planned to use 0.15 pound of "quebracho" per ton

to depress the scheelite in the sulfide circuit and to use "elastoil" at rates

of 0.6 to 0.75 pound per ton as a collector instead of soap and oleic acid.

Elastoil is a fish-oil product sold by the Industrial Oil Products Co. of Los

Angeles. Quebracho is a tannic-acid product developed by the American

Cyanamid Co. It is an effective depressant of scheolite at low pE percentages. After the pH is raised in the scheelite circuit, the scheelite floats

readily, and quebracho then acts as a depressant for calcite and silicate

minerals.

The flow sheet shown in figure 15A was used during the latter part of

the summer of 1942.

Scheelite concentrate produced prior to 1943 was sold to the General

Electric Co. at Cleveland. The concentrate, being virtually molybdenum free,

is a good product for the manufacture of tungsten-filament lamps. The lead

concentrate was sold to the Bunkerhill & Sullivan Smelter at Kellogg, Idaho.

The cost of tungsten products at the Riverside mine during 1941 and 1942

was high, owing to the intermittent operation, experimentation, labor conditions, and numerous difficulties encountered. No accurate representative

tonnage costs are available.

1935 - 44 -
Rougher cone - scheelite

Scheelite cleaner unit - 2 Iraut type C cells - 1 - 15-h.p. motor

c Gangue dispersers - (sodium silicate, aerosol)

Scheelite concentrate I

I Tails - to 2-inch Wemco slime pump

Oliver filter - 6-foot drum 5 h.p. motor

l complete unit

Scheelite concentrate - sacked Sulfide

Figure 15-A. - Flow sheet 2, Riverside tungsten mill, July 1942.

Mine ore Slime pond tailing

t f

Grizzly 6 by 3 feet 2-inch Wemco slime pump

I { 5 h.p. mo

8-inch Trayler gyratory crusher 20- by 10-foot Dorr thickener

I 30 h.p. motor 1

1/2-inch product to 100-ton ore bin 3-inch Wemco slime pump

4- by 5-foot Ball mill

f

27-inch by 14-foot Dorr classifier

Oversize

Overflow- 6 0 mesh

16- b 10-foot Dorr thickener

3-inch Wilfley-Wemco slime pump 5 h.p. motor

Flotation circuit

25-percent density pulp

Sulfide rougher unit - 10 Kraut type C cells - 5 - 15-h.p. motors

Frother - creolic acid

Collector - zanthate Z-6

Tails Tails - scheelite and sand Concentrate - sulfdes - scheelite and sand Concentrate - sulfides

tor

i

1 Wilfley tableI Tails - to waste--

Sulfide concentrate

l-----------:-- -t

Scneellte rougher unit - d Kraut C cells - 4 - JI-n.p. motors

Frother - pine oil

Collector - oleate flakes and oleic acid

I*

Tails from cleaner--

"pH" control - soda ash-dry

1r- ~ Tails - sand - to waste - .1

I

I

I

I

P

River

pond
Figure 16. - Mountain View mine and vicinity.
Figure 17. - Workings topography and assay map of surface sampling.
1

R. I. 4174

MOUNTAIN VIEW MINE

Property and Ownership

Seven patented claims and two unpatented.claims make up the Mountain

View property. The patented claims are Fish Creek Nos. 1 to 5,,inclusive,

Silver Falls, and Silver Falls Fraction; the unpaented .claims are Fish

Creek No. 6 and Fish Creek Fraction. .

The Mountain View Gold Mining Co. has. title to the patented ground,- and,

as far as can be ascertained, its locations of the unpatented claims have not

been contested nor invalidated.' The company also held a preliminary permit :

from the Federal Power Commission covering the water-power rights of Fish

Creek. Present status of this permit is not known.

General Geology13/

Portland Canal (fig. 16), at tho head of which lies the Salmon River

mining district, cuts obliquely across the Coast Range batholith.. This batholith, trending northwest, extends 1,100 miles from southern British Columbia

into Yukon Territory and ranges from 20 to 110 miles in width. The deposit

examined lies near the northeast flank and within tho intrusive, which at this

point is about 50 miles wide. Outlying dikes, sills, and stocks genetically

related to the main batholith further increase the width affected byAintrusives to over 100 miles. (See fig, 16.)

Four main groups of rock are present in the district:. (1) the Texas

Creek granodiorite, a great central intrusive mass; (2) the Hazolton group,

of probable Jurassic age, comprised of greenstone, tuff, volcanic breccia,

graywackc, slate, argillite, quartzite, and rare :limestone; (3) the Hyder

quartz monzonite, a pinkish intrusive composing.the Hydor batholith; and (4)

the Boundary granodiorite, a pink intrusive composing the Boundary stock.

Only the Texas Creek granodiorito and the Hazelton group, the Boar River

series of which is in contact with the bathlith' on its northeast flank, are

known to carry mineral deposits of economic importance. The contact, which

has a northwest trend, is locally.irregular in..strike.

Occurrence of the Deposits . :

The deposit occurs as a steeply dipping fissure vein having a general

strike of about north 48° west and a dip of 500 northeast, as shown in

figure 17. The vein has been exposed by open cuts for a disttnce of 460 feet

along the' strike as well as by a crosscut; a drifts and a shaft. Underground

drifting, including that done by the Bureau of Mines, exposes the vein for a

distance of 315 feet. The distance .along the dip between this drift and theoutcrop is 560 feet. The exposed'part of the vein lies entirely within the

Texas Creek granodiorito.

3f/ Work cited in footnote 12.

I

1935 - 45 -
R. I. 4174

A tentative interpretation of tha geological structure of the deposit is

shown on figure 18, prepared from observations made during Bureau of Mines

exploration. It will be noted that the vein, though continuous, pinches and

swells in corresponding lengths both on the surface and underground. Pinched

lengths, in both cases, show shattering, thin traces of gouge and poor mineralization. The wider portions of the vein show slight shattering, no gouge,

and generally good minoralization. It will also be noted that the strike of

the better portions of the vein is, in every case, 5 to 15 degrees nearer

north than the pinched segments. From the above it is believed that contomporanoously with or following the establishment of the fissure, slight movement, as indicated by the arrows in figure 18, caused both the formation of

openings favorable for deposition and lengths of sheared, tight rock unfavorable for deposition. Movement having a horizontal component of 2 to 3 foot

would have been ample for the establishment of this structural control.

Four shoots of mineralization raking approximately north 60° east are

shown on figure 18. Shoot 2 has boon established from underground and surface exploration, shoot 3 is not well defined underground, shoot 4'is

exposed on the surfaco but not underground, and shoot 1 is eoposed partly

on the surface and for a few feet underground.

Character of the Ore

Segregation of galena, sphalerite and silver indicates that mineralization took place in two or more stages. Pyrrhotite and schoolito appear to

have boon deposited contemporaneously, or nearly so, followed by chalcopyrite

and pyrite and finally by sphalorito, galena, and quartz. Gold and silver

in the native form are present in small but appreciable amounts.

Vein gangue consists of barite, quartz, sericite, chlorite, and small

altered inclusions of granodiorite.

Development

Underground development is confined entirely to drifting and crosscutting, of which there is a total of over 4,200 foot, including 226 feet completed by

the Bureau of Mines. (See fig. 16.) The Gray Copper vein was encountered

1,823 feet from the portal.

At a point 1,428 feet from the portal a branch crosscut was driven by the Mountain View Gold Mining Co. in a northeasterly direction to cut at

depth other veins that apparently are not related to the Gray Copper vein.

No positive results were obtained from this work. Several veins were found,

but they were of low grade, lacked any apparent continuity, and could not

be correlated with surface showings. The Gray Copper vein was not found at

or near its projected strike in this crosscut, and it is believed that the

deposit extends only a short distance into the Bear River series, it at all.

All underground exploration by the ownors took cognizance of the possi- bility of future full-scale operations. Cross sections of the drifts and

1935 - 46 -

I
Wf

Figure 18. - Plan showing structural control of ore shoots.
O

-

NUMBER OF SAMPLE WIDT W3 OLD ILVER

CFT) PECT OZITO OZITON

/4SB 1/67 176 045 1.75 - 72. 1.08 1.22 04 3.20 - /.05 o o./8 0_,/ 3./6 - 69.5 1.25 0.22 TRAGE 0.72 - 7"'3B /1.7 c0.05 0.72 114-24-

65.4 .. 2.92 0.85 0.24 5.26 - S LL 60 0 . 7 0 0./5 .0 0.8/ - S.3 ZOO00 NIL TRA /.20 .- 547 .7 ' O.75 0.47 TRACE .66

S/LL 55.0 1.17 <005 0.2 7 J./5

SILL 50.0 0_3 0.05 0.02 / 6 -

44.875 <050,0 0.37 - 40.6 /.25 NIL 0.0/ 080 -

- 363 /. 25 ANIL TRACE 0.O0 - SILL3.0 0.00 OO SA MPLE "A KEN - 32.4 1.00 NILL 0.0/ 1.70 -

SILL .30.0 /.43 0./9 0.// 6.59 - 28,5 /.67 N/L 0.0./ /.20 - 241.6 /.67 4.// 0.27 2.39 - SILL 25.0 2.67 4.52 0.045 19./6 - 20.0 2.16 0.8 0.2 .60 - SILL 20.0 2B3 4. 17 0T21. 487

/3.5 2,16 0.77 TRAC ~3 6 - .SLL 15.0C " 0. 0.2 0.06 42,7/4 - S/LL /50A 05O 40 80 02 2.28 - /0.0 1.42 0.06 TRACE 0.40 - SILL /0.0 0.92 0. 0.05.2 2.49 - 5. 1.17 (0.05 0.03 0.77 - SILL 5 /. 00 .05 0.055 0.6 7 - 0.0 /.33 0./6 TRACE J0.36 - S/LL 3 1.00 L56 0.03 6.54 - 205 0.75 /94 0.0/5 4.09 - SILL 00 0.83 06 7 -T ACE--

2 /0 0.66 0.96 0.02 /.65 - 2/5 I0.83 /.55 0.04 ).94 -

220 1/33 227 00 4 1.57 - 2.25 "2.7/ /36 0.02 .6 - " 230 /.75 306 0.04 1.16 -

235 ' /.83 /.35 0.01 /. 0 - 240 2 5 106 0./0 229 -

245 1,25 0.31 0,7 2.8/ - 250 .O. 3 0.03 1.22 -

255 1.58 1.33 0.21 ~3.9 - 260 1-.59 3,7 0.31 2 3 -

ANALYSES OF SAMPLING - LOWER DRIFT

I--

/,

/

/-

/

1/-

¢, 5'

U34

-- I

L133

/ U32

NOTE

4/

E: VEIN MAPPED AT BREAST LEVEL

.4/

O 0 20

SCALE IN FEET

MOUNTAIN VIEW - TUNGSTEN

I

-1111

03

2

. . . -

. . - ------ -

Figure 19. - Assay map - lower drift.
/

/

/

/

i

0

ANALYSES

UPPER

OF SAMPLING -

DRIFT

WEST WALL, I FOOT

ABOVE FLOOR

WEST WALL, 2 FEET

ABOVE FLOOR

WEST WALL, 4 FEET

ABOVE FLOOR

WEST WALL,5 FEET

ABOVE FLOOR

EAST WALL. I FOOT

ABOVE FLOOR

EAST WALL. I FOOT

ABOVE FLOOR

CENTER OF CROSSCUT,

IN FLOOR

EAST WALL, FOOT

ABOVE FLOOR

EAST WALL, 2 FEET

ABOVE FLOOR

EAST WALL. 2 FEET

ABOVE FLOOR

EAST WALL,3 FEET

ABOVE FLOOR

FACE, 4 FEET ABOVE

FLOOR

LOCATION OF SAMPLE WIDTH

IN FEET

1.75

1.42

1.33

1.75

0. 75

090

/.33

1.50

1.75

1,92

442

4.00

W0 3

PERC'1

<0.05

0.67

<005

(0.05

0.15

0.22

080

TR.

(005

(aos

(0.05

o0e

GOLD

OZ/TO`

0.01

0.08

0.04

0.10

0.14

002

0.14

009

0.06

ao/

0.0/

0.04 O.-0

SILVER

OZ/TON

1.92

1.21

0.36

1.05

/.77

0.61

1.10

0.62

1.39

0.47

a25

172

NOTE: VEIN MAPPED AT BREAS1

I-, ,

20 0

SCALE IN FEET

20

4-! II I !

Figure 20. - Assay map - upper drift, Mountain View mine.
R. I. 4174

crosscuts range from 5 by 7 feet to 9,by 9 rest. Average tunnel grade is 1.9

percent. Mine track from the portal to the present face on the Gray Copper

vein is 12-pound rail.

Roofs and walls stand well throughout the mine without timbers. Water

seepage into underground workings presents no problem, as total flow from all

rock openings amounts to less than 10 gallons a minute.. A drainage ditch has

been excavated along the entire length of the tunnel.

Both the granodiorite and the vein material are moderately hard. Properly tempered drill steel generally drills 14 to 20 inches for each sharpening.

Breaking qualities of both country rock and vein material are such that holes

generally break to the bottom.

Work Done by the Bureau of Mines

An exploratory project at the Mountain View property was begun May 22

and ended October 24, 1944. In the course of this work the camp buildings

were rehabilitated; the dam, hydraulic line, and machinery were repaired; 226

feet of drifting was completed; 80 channel samples aggregating 3.9 tons were

collected; and the area was mapped in detail. Figure 17 shows the position of

the Bureau drifting with respect to the vein.outcrop.

Sampling and Analysis

Eighty channel samples 12 inches wide and 6 inches deep were cut from the'

vein. These were reduced at the project site in accordance with standard

procedure by means of a Chipmunk crusher with shims of various sizes and a

nest of screens.

A part of the analyses was made by a local assayer in Hyder and a part

by assayers in Los Angeles. Samples were tested for tungstic oxide, fold,

and silver. Lead, zinc, and copper were present in such small amounts that

they were of no economic importance.

The position, width, and grade of all surface samples are shown on figure

17. Similar information for samples from the upper drift is shown on figure

20 and for samples from the lower drift on figure 19. Shoot 2 has an average

width of 1.95 feet and contains 0.52 percent WO , 0.052 ounce gold per ton,

and 2.04 ounces silver per ton.

Beneficiation

During the exploration program at the Mountain View mine, a metallurgical

sample was taken from the lower level, which at the time-was thought to be

representative of the mineralized material. The sample was essentially quartz

with some pyrrhotite and pyrite and minor amounts of barite, scheelite,

sericite,- chalcopyrite, and chlorite. Small amounts of galena and calcite

also were present. The sample contaihed.2.64 percent tungstic oxide, 11.95

percent iron, and had 0.18 ounce of gold and 14.09 ounces of silver to the ton.

1935 - 47 -
R. I. 4174

Silver was present as native silver in wire form. A qualitative spectrographic

analysis of the free silver shows a high gold content, which indicates the

gold is alloyed with the silver. The bulk of the scheelite and sulfides was

free of gangue at minus 20-mesh, but a small amount of these minerals remained

locked to minus 65-mesh.

Detailed sampling of the deposit indicated that the metallurgical sample

was of much higher grade than the average tenor of the mineralized material.

However, it was thought that the results obtained would be indicative of the

recoveries that could be expected from the lower-grade material.

Results of tabling tests indicated that the sample was not amenable to

gravity concentration. The schoolito concentrate contained 34.53 percent

tungstic oxide, representing a recovery of 64.1 percent. Gold and silver

recoveries were 55.1 and 25.8 percent, respectively. The sulfide middlings

contained 17.9 percent of the gold and 46.3 percent of the silver and assayed

0.136 ounce gold and 26.96 ounces silvor a ton.

The flotation tests evidence further the refractory nature of the sample.

The procedures followed in the flotation tests wore basically as follows:

The sample was crushed to minus 20-mesh and wet-ground in stages to minus

6 5-mesh. A sulfide rougher concentrate was floated with Xanthate Z-6, reagent

208, and frother 52. The sulfide rougher .concentrate was not cleaned. A

schoelite rougher concentrate was then floated with oleic acid, quebracho,

and frother 52, and cleaned.

The metallurgical sample consisted of five sacks. For test purposes

various combinations of the five sacks wore made. Table 1 summarizes the

results obtained, giving concentrate grades and percentage recoveries of

metals.

The results of the tests illustrated in table 1 indicate that the sample

iB not amenable to concentration by flotation. Recovery of the scheelite

was 43.0 to 79.3 percent, whereas the scheolito concentrates contained 39.85

to 57.52 percent tungstic oxide. The test giving the highest recovery, 79.3

percent, produced the lowest-grade concentrate, 39-85 percent tungstic oxide.

In producing a concentrate containing 57.52 percent tungstic oxide, 54.9 percent of the scheelite was recovered.

APEX-EL NIDO MINE

Location

The Apex-El Nido mine is in the northwest part of Chichagof Island near

Lisianski Inlet, 115 nautical miles west of Juneau. The property is 2-1/2

miles from Pelican City, a small settlement on the opposite shore of the

inlet, as shown in figure 21. A 1-3/4-mile foot trail leads from the beach

to the mine, the lower lovel of which is at an altitude of 1,057 feet.

1935 - 48 -
i"~O

a

a

'/0oo

.o0

v

C

5,

C

&

-'

LOWER

CAMP

/

'I

4 *

,/ .

in

mO

(-4

'>

I

0 I

% -

/MILL CAMP

/ ELEV. 900'

APEX ADIT '

_ _---7M I NE CAMP

,/

EL NIDO 0*..""

ADIT *"

ELEV. 800

S

-. . .I

: L °

0 I"

s/' ·" 

'5',

I. . .. . ........ -:^.^ 0 .. ...... .

/

<

I

'00o

-'

"I -. --

U I

SCALE OF NAUTICAL MILE - SCALEE OF NAUTICAL MILE

. . .-- TRACED FROM US.G.S. CHK820

Figure 21. - Location of Apex El Nido mine.
4

R. I. 4174

Test- A Test B Test C Test D

Analy- PerntnalPercentAnal Perent Analy- Percent ;Analy- Percent

Weight, sis, of Weight, , i, Weight, of iWeight,| ss, of percent WO 3 total Product I percent W03 total 3 total 3 prcent total W0 tot ercent W03 tot

Scheeiite

concentrate.. 5.87} 39.85 7931 2.75 53.40 5 :17 57.42 4.9 2.03 5588 43

Sulfide [

concentrate.. 26.30 1.63 14.51 24.88 2.19 18.sl 23.62 1.43 -18.0 27.97 1.81 19.2 coIt~ I :1 .79[

Scheelite l. 5 1

middlings.... 5.99 1.85 3.7 10.23 5.75 20.4 4.47 7.4 17.8 5. 5.96 11.

Rougher I

tailing...... 61.841 0.12i 2.5 62.14 0.45 9.7[ 70.121 0.251 9.3 64.82 1 1.06 26.1

Composite ..... 100.0 f .951 .100. 100.0. 2.881 100.0 100.0 1.87 10.o. 100.0 2.641 100.0

TABLE 1. - Results of flotation tests, Mountain View mine, fyder. Alaska

a

1935 - 49 -
R. I. 4174

History

From 1925 to 1928, and again from 1934 to 1955, inclusive, the El Nido

mine was worked for its gold content. The presence of scheelite was known as

early as 1923, but no effort was made to separate it from the gangue as a

marketable concentrate.

Physical Features and Climate

The El Nido and Apex adits are in a rugged area with mountains heavily

wooded at the base and rising to barren peaks at 2,500 feet and higher. The

mine is situated several hundred feet above a cirque valley, where the formations outcrop prominently in an area void of vegetation. Streams feeding into

the valley furnished water for power during operating periods.

The climate is mild, with heavy snowfall in the winter. As much as 12

feet of snow has been recorded on the ground at one time, and snow is likely

to remain on the ground from early November until the latter part of April.

Description of the Deposits

Hornblende diorite is the principal country rock in the vicinity of the

Apex-El Nido mine. The Apex vein is 5 inches to more than 4 feet wide, and

in places it divides into a stockwork of branching veinlets. It strikes N.

60° E. and dips 45° NW.

Fine grains of scheelite are disseminated in the quartz at several places,

but the amount of tungsten is low at most of the occurrences. Broken material

from stopes on the vein also shows a low tungsten content.

The El Nido vein according to Buddington 4/ fills a fracture in an aplito

dike which is intrusive into the diorite country rock. The vein has a strike

of N. 60° E. to N. 85° E. and a dip of about 60° SE. The width is 5 inches to

5 feet, averaging 10 inches.

The El Nido mine is opened by a lower and an upper adit at altitudes of

1,057 and 1,242 feet, respectively. On the lower level the vein is intersected by an 800-foot crosscut from the surface,' whereas the upper level is

opened to the surface by a 220-foot crosscut. (See fig. 22.)

Soheelite in small streaks and disseminated grains is found on the

lower level between the crosscut and the raise. Scheelite is more abundant

near the raise, particularly in the floor of the drift, but it is very

sparsely distributed between the raise and a point about 6 feet from the face.

A face sample collected from a vein 7 inches wide contained 8.75 percent

tungstic oxide. A sample of the best exposure of schoelite contained 56.15

percent tungstic oxide.

i4 Buddington, A. P., Mineral Invostigations in Southeastern Alaska: U. S.

Gool. Surv. Bull. 773, 1925, p. 119.

1935 - 50 -

------- · ----- · ------- --
a

*

\1 \

\ \

\,

44

\ \

\ \

\ \

\ ^, 15"

\ 4-

\V

4'~

Cd4- N

24"

BARREN QT

4"-

. NO

r1 12- MARCH 1947

0 40 80

A- :._ 8.73 PERCENT .=

=" ."

SCALE OF FEET

Figure 22. - Map of part of El Nido mine, Chichagof Is.
I

R. I. 4174

On the upper level the scheelite content of the vein is very low between

the crosscut and the raise to the surface. The portion of the vein between

the raise and the face shows more abundant scheelite, most of which occurs

as small lenses or pockets. A streak of nearly solid schoelite 2 inches wide

and 3 feet long occurs at one place in a veinlet that diverges from the main

vein at a slight dip into the hanging wall.

BIBLIOGRAPHY

Brooks, Alfred H., et. al. Mineral Resources of Alaska, 1915. U. S. Geol.

Surv. Bull. 642, pp. 61-62.

Buddington, A. F. Geology of Hyder and Vicinity, Southeastern Alaska. U. S.

Geol. Surv. Bull 807, 1929, p. 13.

Buddington, A. F. Mineral Investigations in Southeastern Alaska. U. S.

Geol. Surv. Bull. 773, 1925, p. 119.

Joesting, Henry R., Strategic Mineral Occurrences in Interior Alaska, March

1943. Territorial Department of Mines Pamphlet No. 2, pp. 19-24.

Mertie, J. B. Jr. Mineral Resources of Alaska, 1916. U. S. Gcol. Surv.

Bull. 662, pp. 418-421.

Meotio, J. R. Jr. Lode Mining and Prospecting on Seward Peninsula. U. S.

Gool. Surv. Bull, 662, 1918, pp. 435-437.

Mortie, J. B. Jr. Placer Mining on Seward Peninsula. U. S. Geol. Surv.

Bull. 662, 1918, p. 457.

Moffit, F. H. Geology of the Nome and Grand Central Quadrangle Alaska.

U. S. Geol. Surv. Bull. 533, 1913, p. 134.

9

1935 - 51 -