iV -7 .

R. 1. 4414 MARCH 1949

UNITED STATES

DEPARTMENT OF THE INTERIOR

J. A. KRUG, SECRETARY

BUREAU OF MINES

JAMES BOYD, DIRECTOR

REPORT OF INVESTIGATIONS

INVESTIGATIONS OF THE KOBUK RIVER ASBESTOS DEPOSITS

KOBUK DISTRICT, NORTHWESTERN ALASKA

f

BY

H. E. HEIDE, W. S. WRIGHT, AND F. A. RUTLEDGE
R. I. 4414,

March 1949.

REPCRT OF INVESTIGATIONS

."UNll= 'STATS 'T N T9 'MTEICQ - BUEAU OF MINES

InE8TTdAW M'OZ T M '-Utlt JiV AS;EEST OS 5DEOSITS, KOBUK DISTRICTj,

NCRTDWESRN ALASKA;

'By9 E.r E. leidae" W. S. Wrivgt, and F. A. Rutledgez3/

C CS1tifNT

. . * . -. .* . . > s * t . * NPage

Iit&fodicftzion ' aindi s-uxary... . O i'............... 2

Location and accessibility.,. .*,.*,... .............. 3

* < Phy~ieal' atus and ciimate;;; ;...... ;. .. 4

Hiltlt ty anid jprocuctt.on... 99.. 9**99* 9.9. ;; , 4 5

Geb~'geogy;. .............. 6 i; . Staini test~t chrystile a1~sbestos;.... ........................ 9 ;. 

!i6tipt5ih'P 6thf6a'epos1its-; .......................... 10

Shungnak River .............. . . . . ... 10

Cosmos Creek, ... ...... I........... 0. 11

Dahl Creek....... . .. .*' 11

'Other deposits ...,......... 13

' Jade Mountain ................... O, . 13

Value of prodiact . .O.9.'.9. . 9949 14 

Beneficiation by Bureau of Minesi...e 16

Composite sample A ........ ................. 16

Composite sample B.......... ........ .. 17

Remarks. .. ...... .. .. ' . * .... . 18

Johns -ManvilJle tests .......... ... O , . , 19

Summary.,..... .......... ' ' 19,

Treatment ...... .*..**.*. - ................. 20

Summary of recoveries from ore samples- 21

Details of fiber recoveries and gr ad ing 21

Sample C. 21

Sample D ......... ...... 0 ... ... 22

Sample F ....... o.. . .. . . . ... ..... ... .. 22

'Sample G. .... . ....... 9 23

General remarks.' , , ,,., 24.,.,,., .. Conclusions., ..... **'.. ... ** 99.9.9,94,4....* 25

Bibliography . ..,, , *.0 I4 . .. . ,25

1/'The Bureau of Mines will welcome'reprinting of this paper, piovided the

following m footnote bcknowledgment is used, '9eprinted from Bureau of

Mines Rept* of I'v'stigations 4414. ,

2/ Senior-mining engjnder ,Juneau, Alaska.

3/ Mining engineer, Juneai, Alaska.'

2723
ILLUSR RAT I.NNS

Following

Figure page

1. Index map, Kobuk River Asbestos, Alaska , , 1 .. A.4,0 A 2

2. Kobuk River asbestos areas......,,.. ...... 2~

3. Asbestos-bearing serpentine, Shungnak-Kogoluktuk area....;.. .6

4. Geologic sect ion.....,....*............. 6 

5. A, Nemalite from Bismark Mouhtain on'the right limit of Shungnak

River; B, Cross-fibered chrysotile from Cosmos Creek-Shungnak

River dvd...,....,...'..........J. 10 l

6. Trenches near.Shungnak River ........... 10

7. Cosmos Creek asbestos. deposit........................... 10

8. Details of dozer trenches, Cdsnics CCreek.,............. ......... 10

9. Dahl Creek asbestos . 0..........

10. Ing-Ihk mine, Asbestos Mountain, Alaska. 10

11. Plan and section, ing.-Ihk mie;10.................. 

12. A, Tremolite from Ing-.1hk mine'; B, Long-fiber chrysotile from

Asbestos Mountain......... ..... , ;. ... . ...... ... . . . . . . .. . . 10

13. Flow sheet for sample C........... ; ,.................. 20

14. Flow sheet for, sample F , 22

15. Flow sheet, for temple F .. ......................... . . ..... .. . . 22

16. Flow sheet fdr sample . . . . . . . . . . . . . . .

.ITfODUCTION AND SlJM1OY

The serious shortage of domestically produced asbestos during the war

prompted the Bureau of.-Mineq to investigate reported' asbestos deposits in

Alaska. The most promising appeared to be these in the Cosmos Hills and Jade

Hills areas along the Kobuk River in northwestern Alaska.

The deposits along the. west side of Shungnak River, a tributary of the

Kobuk River, werfe the first to be investigated by the Bureau, in the summer

of 1944. Four bulldozer-trenches were excavated, from which a 2-ton sample

was taken. This sample-was shipped to Rolla, Mo., for testing in the Bureau

of Mines laboratory. ..

In the summer of .1945 a investigation of asbestos deposits on Cosmos

Creek, also a tributary-of the Kob-idrRiver, was begun; the work was completed

during the field season-of 1946.

In this ate'a serpentine is sheared and cut by a stockwork of cross-fiber

and slip-fiber asbestos, for a strike 'length.Qf over a mile. Six bulldozer

trenches were excavated on this formation, from which two large samples of

asbestos material were takeni'. These samples were shipped to the Canadian

Johns-Mansville Co. for testing.

The Dahl Creek deposits, situated east of Cosmos Creek, were partly developed by Arctic Circle Exploration Co. That company had excavated four trenches

and driven an adit 228 feet in length. The Bureau cleaned out, deepened, and

sampled the trenches and obtained samples from the adit. In all, lO90 pounds

of sample from the Dahl Creek area was sent to the Bureau's Rolla laboratory

for testing.

2723 -2-
so v / ~7v /2 /50' 13 21C ' 4~~~~~E

N~~~~~~~~~~~P O

ASBESTOS

AREA 'id~~~~~~~~~~~~~~~~~~

, Lei#R Mck/ritIe @ C.,,u

Figure 1. - Index map, Kobuk River, Asbestos, Alaska.
Ine

-~~~~~~~~~~~~~(J

cm ~ ~ ~ ~ iue .- KbkRvr setsaes
R.I. 4414

Thi±'report' disduses the proceduires of sampling the.aeposits:ana

presents the resul-t of beneficiation tests.

ACKNOWLEDGMENT

'Special mention is made of the information and assistance given by the Canadian Johns-aIqnville Co., Ltd., Adbestos, Quebec, Canda; and more espe- cially of A. R. Fishe, vide president; George K. Foster, vice president;. Charles A. Borror, chief mining engineer;'H. S. Deeley, assistant to manager; H. Cl. Iaree,- mine superintemient; C. D. Chandler, assietant mine superintendent, H. F. Janson, mill superintendent; and, G. L. Gartshorpe,. assistant mill eMuperintend.enu of the Canadian Johns-M4anville Co. The diamond-drill prose- dures and specifications of the special equipment designed. at. their Jeffrey mine'-for use in the a'sbestos-bealing rdck'along with their methods o core. sampling and estimation of grade were appreciated. The Bureau of Mines also

is indebted to the Johns-Manville Co. for beneficiation tests of large sam- ples from the Kobuk River deposits with. determination.of fiber content, grades of fiber nroducts, and possible uses.

: Accknowleodgment is also made 'of the information procured from B. 'D. Stewart, commissioner of mines, Territorial Department of Mines, and. the cooperation in

the field by Eskil Anderson, mining engineer, Territorial Department of Mines

and Robort R. Coats of tho Federal Geological Survey.

" Heine Kenworthy'i metallurgist,6 f the Rolla Branch, 'Metallurgical Divisibn, of the Bureau f- MNines conducted the beneficiation tests"for tie ±'ecovery of asbdbetos fibers froim the samples submitted fr6m the Shungnak River area in

1944. -~ ~ ~ De ~ ~ ~~~~C by .- me S. .Rib.f ,'s

Thai cooperation and assistdnce given by James S Bobbin's, president, Arctic Circle Exploration, Inc., and. his-enployees, by Harry Brown, Kobuk' Alaska, and by Mr. and 4--s. Collin'si'f the CAA weather station at Shungnak- are'gratefully adciowledged.. -

LOCATION AND ACCESSIBILITY'

The location of the asbe'toe areas in the Cosmos Hills and the Jade Hills paralleling the Kobuk River in Northwestern Alaska is shown in .figuros .1 and 2. The deposits .re 30 to 45 miles north of the Arctic Circle and'lie within a.

zone approximately 245 miles long, extending from 1560 35' to 1580 15' weSt longitude. 'This zone of mineralization reaches from Jade Mountain in'the Jade Hislls on the west. to the first mountain east''of the Kogoluktuk River on the

east.,

The Kobuk River asbestos district is in the Kobuk-Noatak mining precinct in the Second Judicial District, and the mining records are' kept at Kotzebue.

: The Kobuk SRiver is navigable for rive-r boats and barges during the summer months to a point a short distance above Kobuk. Freight rates in 1946

were $20 a ton from Kotzobue. to Shungnak or Kobiuk; but for larger 'down-river

2723 -35
R.I. 4414

tonnages, rates as low as $4 a ton may be assumed. Kobuk is approximately

270 miles by water from KEtzebue but only 150 miles by air.

Kotzebue, on Kotzebue Sound, serves as the port of call for the Kobuk,

Noatak, and Salawik districts and is open to navigation between June and October of each year. The Alaska Steamship Co. freight rate on general cargo

from Seattle, Wash., to Kotzebue shipside during 1946 was 47-1/2 cents a cubic

foot. Additional charges - 16 percent surcharge, 2-1/2 cents a cubic foot

wharfage at Seattle, and a 21-1/2 cents a cubic foot lighterage at Kotzebue -

made a total charge of 80.1 cents a cubic foot or $32.o4 a-ton.

A small motorship, M. S. Meteor, makes biweekly trips between-St. Michael,

Alaska, and Kotzebue, stopping at Nome and other coastal towns enroute.

Freight rates from Nome to Kotzebue are $37.50 a ton shore to shore. In 1946

the Kotzebue Sound Lighterage Co. started a like service at the same rates

with the M. S. Kotzebue.

The district is accessible by plane from Nome, Fairbanks, or Kotzebue.

Existing landing fields are suitable for the light planes used for "bush"

flying. In 1946 air express rates were $0.35 a pound from Nome or Fairbanks

and $0.25 a pound from Kotzebue. Passenger fares were $75 from Fairba-nks,

Nome, or Kotzebue.

There are no roads in the district, but several "cat" trails have been

brushed-out and can be used for hauling heavy freight from the river to the

deposits. However, since the frost is out of the tundra during the summer

months, most of the freighting is done over the snow with tractors and sleds.

Kotzebue, with 362 inhabitants, is the closest town of any importance

and source of supplies with four general stores. The Alaska Native Service

(U. S. Department of the Interior, Indian Office) operates a school and

hospital in Kotzebue and a school in Shungnak. Shungnak, with a population

of 193, and Kobuk, with 31 inhabitants, are on the Kobuk River south of the

Cosmos Creek and Dahl Creek asbestos deposits, respectively. Staple groceries

can be obtained from a store in Kobuk.

PHYSICAL FEATURES AID CLJIATE

The Kobuk River, north of which the asbestos areas lie, rises in the

Schwatka Mountains of northwestern Alaska and flows westerly into Kotzebue

Sound and the Arctic Ocean.' Throughout most of its course, the Kobuk River

forms the line of separation between the rolling, hilly country of'the Koyukuk

Plateaus to the south and the rugged Brooks Range to the north; however, most

of the drainage area is in the Brooks Range.

The Brooks Range is composed of several mountain groups. One of these,

the Baird Mountains, lies north of the Kobuk River along its lower part

between the Kobuk and Noatak Rivers. Another, the Schwatka Mountains, lies

between the head of the _Kobuk River and the Alatna and upper Noatak Rivers.

The Jade Hills and Cosmos Hills, in which the. asbestos-bearing serpentine is

found, are part of the Baird and Schwatka mountain groups, respectively.

2723 -4-
The Cosmos Hills, though part of the Schwatka Mountains, are separated

from the rest of the group by a lowlAnd drained by the Ambler, Shungnak, and

Kogoluktuk Rivers. These rivers head in the Schwatak Mountains, flow southward into this lowland, and then cut through the Cosmos Hills to the Kobuk

River, The major axis of the Cosmos Hills is east-west. Beside these main

streams traversing the Cosmos Hills, several smaller streams originate within

the area. Although some flow north and others south, all eventually join the

Kobuk River. Those flowing north enter the lowland or a transverse stream

and unite with one of the main streams flowing south to the Kobuk River, while

the southward-flowing streams are direct confluents of the Kobuk.

The Kobuk River lowlands lie south of the Cosmos and Jade Hills (fig. 2).

The lowlands at Shungnak range from 12 to 14 miles in width and from 200 to

400 feet in altitude. Crests of the Cosmos Hills are 2,000 to 3,000 feet in

altitude and the southward facing slopes are steep and well-alined.

The Jade Hills lie north of the Kobuk River lowlands between the Hunt and

Redstone Rivers. Topographic relief in the Jade Hills is more pronounced than

in the Cosmos Hills, and the crests of the mountains are 2,000 to 3,550 feet

in altitude. Jade Mountain is the highest.

The Kobuk River lowlands are predominantly muskeg, and permanently frozen

ground is found throughout the lowlands and along the slopes of the mountains.

Fair stands of spruce grow along the banks of the river and its tributaries,

and a sufficient number are large enough to furnish logs and lumber for a

small mining operation. Birches grow on the low hillsides near the edge of

the lowlands, and the steep mountain slopes are frequently covered with small

spruce) willows, and alders to an elevation of about 1,500 feet.

The climate is typical of subarctic northern Alaska. Ice and frost conditions prevail from the middle of September to late June'. July and August

are normally the months of heaviest rainfall. The average precipitation for

a 5-year period at Shungnak was 21.06 inches. During 1944, 65.4 inches of

snow were recorded. More snow can be expected at the asbestos deposits which

are at higher elevations. The average mean temperature during the above 5-year

period was 21.70 F. The highest and lowest temperatures recorded were 900 F.

and -61o F., respectively.,

HISTORY AND PRODUCTION

The earliest recorded exploration of the Kobuk Biver Valley by white men

was in the early "eighties". Placer gold'was discovered in the Shungnak and

Squirrel River areas, and in 1898 there was a stampede of gold seekers to the

Kobuk. Alth6ugh deposits of both placer and lode gold, copper, and lead were

found in the region, only'a small amount of placer gold was produced, and most

of the prospectors soon. left. for the new strikes at Nome and the'Koyukuk.

The asbestos deposits were first noted during the gold rush, and although

a small quantity of placer gold has been produced annually since the original

discovery, there has been very little prospecting and general development of

2723 5 t
R.I. 4414.

the area. The first officially recorded reference- to asbestos deposits in

the region along Dah1 CrdekI-a tributary to the- Kobuk River (fig. 3), is found

in Federal Geological Survey. bulletin 48o. The reports on the early samples'

of asbestos taken by the Geological Survey were discouraging as the asbestos,

though of good color, had low tensile strength. In 1925 and 1926 one of the

traders at Kotzebue financed prospecting of the asbestos: deposits in the Jade

Hills west of the -lower Ambler River but no noteworthy discoveries were made.

Additional prospecting in the Cosmos Hills was undertaken in 1931 and

1932 by Michael Garland under the Territorial Department of Mines prospecting

program. The asbestos deposits- in the serpentine at the head of Dahl Creek

were discovered, and samples containing slip fiber 1 foot in length were subnitted to the Bureau of Mines for analysis. Several claims were staked by

Garland. Although the sample of slip fiber was identified as chrysotile

asbestos of fine grade, no development was attempted, and the claims were

allowed to lapse.

Until recently it has been the common assumption that all the asbestos in

the region was of the chrysotile variety. However, in 1943 James S. Robbins,_

president, Arctic Circle Exploration, Inc., of Candle, Alaska, submitted to

the Territorial Department of Mines at Fairbanks, Alaska, a sample that was

identified as tremolite asbestos. Arctic Circle EXploration located several

lode claims covering some of the old Garland group and started mining tremolite

asbestos from a -deposit near the summit of- Asbestos Mountain. Up to November

1945, when operations were recessed for the winter, Arctic Circle Exploration

had produced the following: 36.5 tons of tremolite asbestos, 1 ton of chrysotile slip fiber, and approximately 5 tons of jade boulders from'the streams

draining the area.

With'the aroused interest in the jade and asbestos occurring in the serpentine in the Jade and Cosmos 'Hills, a large number of additional claims were

staked covering the serpentine outcrops, and placer claims for jade were

located along the streams transacting the areas...

GENERAL GEOLOGY

The'asbestos deposits of the Cosmos Hills and Jade Hills occur within

serpentines altered from ultrabasic rocks. The ultrabasic rocks were intruded

in a series of black slates, schists, limestones, and conglomerates of Paleozoic and possibly pre-Paleozoic age that form both the Jade Hills and the

Cosmos Hills.2/ This series has never been studied in detail. The large

exposed thickness, since it outcrops on both the Noatak and Kobuk River, may

be dup to folding or faulting. This is apparently true since the 'schistose

conglomerate, though dipping to the south where it forms the front of the

Cosmos Hills and the capping over the repst of the series, was also found on the

Noatak River by the Geological Survey. 6 I Mapy folds in the series were observed

in the Schwatka Mountains along the transversing valleys of the Shungnak and

Ambler Rivers.

4/ Smith, P. S., and Eakin, H. MO, The Shungnak Region Kobuk Valley; Mineral

Resources of Alaska: Geol. Survey Bull. 480, 1911, pp. 306-319.

5/ Smith, Philip S., The Noatak-Kobuk Region, Alaska: Geol. Survey Bull. 536,

1913, plate II (160 pp.).

6/ Work cited in footnote 5, p. 58.

2723 - 6-
SERPENTINE OUTCROP. / 9 / / 9i < / -

}~~~~~~~~~~~~~~~~~~~~~~~~~Ij

LA ITDE 6' LAT TUD 67

(r9W} CtAFIELD X em~~~~~~~~~~~~~~~~~~~~~~~~~

COMPILED \ I I I 8 0 550 20 0

FROM: AAF PRELIMINARY BASE t77A ) | -F , if| * | X~~15

U S. GECL SURVEY BULL 536 z \ XJ | STATUTE IjILES~~~~~~~~~~~~~~~~~100

TP -V NSIT J t BRUNTON SURVEYS °~~~~~~~~~~~TIN _~~~~~~~~~~~~~0 UCO

Figure 3. - Asbestos-bearing serpentine, Shungnak-Kogoluktuk area.
t r

UNCONFORMITY G°OM°ERATE

id-- SERPENTINE

"-zS--. 60 FEET MICA SCHIST, GRAPHITIC

60-75 FEET GREY MAS- _ N a= <v3-~ SIVE LIMESTONE, QTZ. STNG

-me Zz~Z> 'NN~ 150 FEET QTZ. MICA SCHIST

10-20 FEET GREEN, CHLORITE, AMPHIBOLE SCHIST

±100 FEET GRAPHITIC, QUARTZ-MICA SCHIST

+200 FEET THIN-BEDDED LIMESTONE

SECTION TAKEN NEAR WESLEY - DAHL CREEK DIVIDE

LOOKING NORTHEAST

Figure 4. - Geologic section.
R.I. 4414

The schists in the area.have not been differentiated but.dissimilarities

in their composition have been observed. Mica schist predominates but carbonaceous and chloritic; schists. are also plentiful. Most of. the schist contains

abundant quartz.

Two limestones were noted,.in the series of' metamorphosed rocks within the

area. One was a grayxthin-bedded limestone and the other a gray massive lime- I stone containing numerous quartz stringers (see fig. 4).

The deposits of asbestos along the Shungnak River, Cosmos Creek, Wesley

Creek, and extending to the right limit of Dahl Creek are all within the same

interformational sheet of altered basic rock (fig. 3). This serpentine has

been formed from a basic intrusive, probably originally consisting mainly of

olivine, lying unconformably on the slates, schists, and limestones. Figure 4

is a sketch made west of the Cosmos Creek-Wesley Creek divide. Here the serpentine is lying on a massive gray limestone and is at least 300 feet higher in

the series than its position on the Shungnak River-Cosmos Creek divide where it

is lying ona thin-bedded limestone (fig. 6). Along Cosmos Creek the serpentine

is separated from the thin-bedded limestone by schist. Throughout the-entire

strike length of this outcrop, the serpentine is overlain by the conglomerate..

The conglomerate is composed of pebbles of chloritic schist, quartz, black

slate, mica schist, and limestone which clearly confirms the unconformity. The

conglomerate is sheared and schistose throughout much of its length, and the

grain size ranges down to an extremely coarse sandstone.

The dip of the formation along the front of the Cosmos Hills is 150 to 450

south, and the average strike of the serpentine is east-west. An anticlinal

fold is readily seen in the thin-bedde4 limestone under the serpentine along

the Shungnak River-Cosmos Creek divide and in the divide that it forms to the

north. This fold explains the flattening of the serpentine and its long horizontal outcrop west of the Shungnak River and the two small outcrops of.serpentine found on the divide east of the Shungnhk River and north.of the main outcrop.

The deposits near the head of Dahl Creek, while of similar occurrence, are

in an ultrabasic stock within an area of mica schists (fig. 8). Most outcrops

of asbestos are near the summit of Asbestos Mountain. The intrusive is generally

massive and, where unaltered, weathers to the brown color typical of peridotite.

The asbestos occurs where the intrusive has been altered.to serpentine. Small

grains of magnetite are disseminated throughout the intrusive, and locally small

* concentrations' of magnetite may be found.

The asbestos occurrences in the Jade Fills are very similar to those at

Asbestos Mountain, and the light-green serpentine forming Jade Mountain'and the

surrounding area has been formed from the same type of an ultrabasic stock in

schist. A petrographic examination of the partly altered intrusive shows serpentine replacing olivine and pyroxene'.

The term "asbestos" is applied to numerous minerals having fibrous structure, which, because of resistance to .heat, tensile strength,. and flexibility

of the fibers, may be used for certain industrial purposes. The minerals are

2723 -7-
n.I. 44I4

also more or less acid-resistant. In commercial use the asbestos minerals are

roughly divided into two classes - the. spinning variety, whioh must have fibers

of sufficient length, strength, and flexibility to permit spinning into yarn

for the manufacture of asbestos fabrics; and the nonspinning variety, which is

suitable for manufacturing such articles as molded brake blocks, asbestos

board, paper, shingles, and many other products. A test for differentiating

between spinning and nonspinning fibers is rubbing the fibers between the

fingers. Poor fibers will split into harsh, brittle pieces, sometimes even

breaking up into fine powder. The good fiber will stand considerable tension,

bending, and twisting and will come apart in silky threads.

Three mineral groups have the fibrous structure and properties relevant to

asbestos. These are the anthophyllite group - magnesium-iron silicates; the

amphibole or hornblende group - hydrated silicates of calcium, magnesium, and

ferrous iron with manganese, potassium, sodium, or aluminum; and the serpentine group - hydrated magnesium silicate.

The chrysotile variety-of asbestos is the principal source of spinning

fiber. Two forms occur - cross fiber and slip fiber - but the cross fiber is

preferred. Chrysotile is an alteration production of serpentine and virtually

identical in chemical composition.

The tremolite variety is usually short-fibered, brittle, and unsuitable

for spinning purposes, and a very minor amount of spinning-grade tremolite is

found. However, tremolite, a calcium-magnesium silicate, is highly -acidresistant. It is, therefore, especially suited to the manufacture of filter

pads for filtering acids and fruit juices and for other chemical uses involving

filtering and heating.

Both kinds of asbestos - chrysotile and tremolite - are erratically distributed along the length of the serpent ie outcrops as float and in the rock exposures. Distribution of the asbestos is hot uniform, and some outcrops are

barren or almost barren. A large part of the surface is covered with talus

material, and the quantity of asbestos float is as variable in these places

as the quantity of asbestos in the outcrops. Both cross- and slip-fiber asbestos are present.

In nearly all observed cases, the cross-fibered variety produces fibers

less than 3/4 inch long. Cross-fibered chrysotile with fibers up to 3 inches

in length was found only in float about 2 miles northwest of the Shungnak River.

The cross-fibered variety of chrysotile is generally of good quality. It

is easily separable into fine, silky'fibers of good tenacity and flexibility.

However, nearly all fibers that were found by the Bureau of Mines were'less

than 1/2 inch.

Over large areas, the serpentine is highly altered and schistose and contains short slip fibers of chrysotile along the foliations. Numerous veins up

to 6 inches in width containislip fibers of chrysotile 3 inches and-more-long,

and 20-inch fibers of good grade have been produced. Locally the fibers are

harsh; but in places they-are soft, flexible; and tenacious. The color of the

chrysotile ranges from pale yellow to brown.

2723 -8-
R.I. 4414

The tremolite is pale green to white and. occUrs mainly as slip fiber in

seams and small veins. Fibers 20 inches long have been separated from a vein

on the property of the Arctic Circle Exploration, Inc., on Asbestos Mountain.

STAIN TEST FCR CBRYSOTIIE ASBESTOS

Since both chrysotile and tremolite fibers are found in the area, a pre- requisite for identification and separation was a method of distinguishing

between the fibers of different composition. At the Johns-Manville laboratories, Asbestos, Quebec, a staining method using a 1-percent solution of iodine in

C. P. gylcerin was developed for the identification of chrysotileVl and is summarized as follows:

This iodine solution was found to have distinct staining prop- erties when used on the local chrysotile fibres, and to improve greatly their visibility under the microscope. It was soon revealed,

however, that this staining is apparently limited to the chrysotile variety of asbestos, as against other varieties. It can be readily

seen that, if such were the case, the staining test would become a

very useful tool in differentiating between chlrysotile fibre and

the other mineral fibres, without recourse to a lengthy chemical

analysis.** *

In all, thirty-seven different fibres from various parts of

the globe were examined. The technique is very simple, a pinch of the fibre being mixed thoroughly with a few drops of the stain

and then transferred to a microscope slide for observation. In

the case of chrysotile, the staining is instantaneous although varying in intensity for fibre from different mines or localities.

For maximum staining effect, the asbestos must be in a loosely fiberized state, which is easily accomplished by 'fluffing' between

the fingers or by light grinding in a motar where necessary.***

The property of iodine staining thus seems to be an exclusive'characteristic of the chrysotile fibres, regardless of source or mode

of origin.*xx

Since the apparently selective action of the iodine stain on

chrysotile fibres suggests that the staining is a consequence of

some definite property of the latter, the first question that

occurs is: Does iodine also react with the nonfibrous form of

the same material, i.e., massive serpentine?***

It can be seen that, of the minerals examined, only brucite

and serpentine, and to a lesser degree hydromagnesite, are stained

by the iodine solution. The negative reaction by the two firstnamed minerals after ignition apparently points to magnesium

hydrate as the active agent in this 'stain phenomenon. Of the mag- nesium silicates tested, apparently serpentine alone contains this

hydrated magnesia in a form such that it can acquire the stain.

7/ Morton, Maurice, and Baker, W. G., Stain Test for Chrysotile: Trans.

Canadian Inst, Min. and Met., vol. 44, 1941, pp. 515-523.

2723 - 9
R.I. 4414

The similarity of behaviour of serpentine and brucite is not surpr'ising, as X-ray studies show the spatial arrangement of the magnesium and hydroxyl groups in these minerals to be identical.

Hydromagnesite can also be expected to exhibit this activity, due

to the presence of the hydrated magnesia.

During investigation of the asbestos deposits on.Bismark Mountain by the

Bureau of Mines, an unusual variety of brucite was discovered. This was identified by Jewell J. Glass of the Geological SurVey as nemalite, an iron-bearing

fibrous brucite (fig. 5). Tests by the Bureau of Mines using the iodine solution resulted in a positive stain as expected from its composition.

DESCRIPTION OF THE DEPOSITS

Shungnak River'

The asbestos deposits along the west side of Shungnak River were the first

explored by the Bureau of Mines in 1944 (figs. 3 and 6). The outcrops are several hundred feet below the crest of Bismark Mountain on the east slope. Not

enough previous information was at hand to permit selection of the best locations for preliminary work, and dozer trenching was begun on a convenient outcrop. The serpentine at this point contained a light-colored, glassy, somewhat

brittle mineral in addition to the chrysotile. Four trenches were excavated.

Nearly 2 tons of samples were taken from the trenches and shipped to the Rolla

Branch, Metallurgical Division, Bureau of Mines, for testing. Results are

given under Beneficiation by Bureau of Mines.

Of the four trenches completed on Bisnark Mountain, only trench 4 exposed

chrysotile of fair quality. Trenches 1, 2, and 3 revealed a small quantity of

very short fibered chrysotile and a much larger proportion of asbestiform mineral nemalite. A network of slip-fiber veinlets 1/2 to 2 inches wide was disclosed in the sides and bottom of trench 4, and a sparse distribution of crossfiber veinlets was also found in the less-sheared serpentine formation 100

yards north.

A reconnaissance survey was completed along the rest of the outcrop to

the north. The serpentine along the right limit of Shungnak River, instead of

continuing in the same interformational sheet exposed in the rest of the area,

is discontinuous and forms two approximately parallel sills. The serpentine at

the location of the trenches is in one of these sills lying on the conglomerate.

To the north, for 1-3/4 miles, it is an interformational sheet capped by the

conglomerate. At this point the exposure of serpentine is discontinued, and

in its stead another serpentine outcrop is found 600 feet down the slope. The

lower outcrop is at least 900 feet wide and extends northward 3/4 mile. The

material is decomposed and talcy, showing a marked resemblance to the sheared

area at Cosmos Creek, except that it contains less asbestos.

Farther to the north is an interval of about 1/2 mile in which no serpentine outcrops; where next observed, the serpentine stands out boldly in an

almost vertical bluff reaching a height of about 500 feet. No asbestos was

found in this outcrop.

No serpentine was Sound in the area northwest of Bismark Mountain and west

of Woodchopper Creek.

2723 -10 -
I~~~~~~~~~~~~;I

I

B

Figure 5. - A, Nemalite from Bismark Mountain on right

limit of Shungnak River;

B, cross-fibered chrysotile from Cosmos

Creek-Shungnak River divide.
C V~~~C

TRENC CHHO2

TRECRH 2 C

TRENCHd XX<3; T

Figure 6. - Trenches near Shungnak River.
x 0 00 600 900 4 SCALESC7 EEE

JULY I1, 1 J46l

F igu re 7. - Cosmos Creek asbestos depos it.
6I,0

1000~~~~~~~~~

_ LOCATIO or SAM OD HOLPEL

RENTRECHH

LEGEND ~ ~ ~~~CLEO FE

JULY 10, 1946

Figure 8. - Details of dozer trenches, Cosmos Creek.
A ~~~~~~~~ml~~~~~~ ^; I, aim , no Ad d. Xr 1 4( " * -A*-IG-I'

.0A 4•', .4 ~ .*

i: l':'' -- -~~~~~V,

T E D OT. I./

L EGEND RCO

GSERPENTINE SURVE

a| SCHIST at ,CR,

LIMESTONE

2450 BAROMETRIC ELEVATION I

TRENCH WYE C

* CABIN 2 4 6000

STRIKE L DIP O SCHISTOSITY,E F FOLIATgION, OR BED C s

GEOLOGY BY R.R. COATS ,;Il GEOLOGICAL SURVEY /ZJ ,

380.WX

FEET

Figure 9. - Dahl Creek asbestos.
.. ~~~~~~~~~~~~~~ .. .. .. . . .ARTS<:

i t Do* _ r T . ' .

hi ~~ / x\ d .1~~~~~~~~~~~~~~30

*SR

FigureI10. - Ing-lhk mine, Asbestos Mountain, Alaska. ... - ~~~~~~~~~~~~~~~~~~~~

8 ~ ~ ~ ~ ~ ~ ~ ~ . ...... BSTCHYOTL

Figure 10. -Ing-lhk mine, Asbestos Mountain, Alaska.
DETAILS OF PIT

AUGUST 6 1044

ASEMST

OF AIIIESTOS

0 _0 30/ 0

SCALE OF FEET OF FEET

,+~~~~~~SE1*E IECIO ToWIG

Figure II. - Plan and section, lng-Ihk mine.

Fiue1.- lnadsetoIg-hMie
A

10 i~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Figure 12. - A, Tremolite from Ing-lhk mine;

B, long-fiber chrysotile from

Asbestos Mountain.
R. I. 4414

Cosmos Creek

Extensive exploration by the Bateau of Mines of the asbestos deposits in

the Cosmos Hills was scheduled for 1945. Only that section of the serpentineoutcrop west of Cosmos Creek and east of the Shungnak River divide was selected

for exploration (fig. 7). Here the serpentine is extensively sheared, and cut

by a stockwork of both cross- and slip-fiber asbestos for a strike length of

over a mile.

During the spring and summer of 1946 the trenches were continued and

extended. Two large samples were taken and shipped to the Canadian JohnsManville Co., Ltd., for testing. Sample C, consisting of 56 sacks, was taken

in trenches 1 and 3 and the northern portion of trench 2 (fig. 8) across the

lower portion of the asbestos-bearing formation. >Sample D (59 sacks) was taken

in the southern part of trench 2 from the upper part of the same formation.

The area sampled consists entirely of highly sheared serpentine and a large

proportion of the fiber occurs as slip fiber on the foliations of the serpentine.

The westerly continuation of the interformational sheet of altered basic

intrusive can easily be followed to the Shungnak River. At one place about

200 yards east of the crest of the ridge the sheet appears to have a thickness

of about 125 feet and to contain chrysotile fiber in nearly the same abundance

as in the trenched area. Nearer the crest, or about 200 feet east of the

saddle, the serpentine is harder, less sheared, and contains tough slip fiber

2 to 4 inches long as well as voinlets of cross fiber. Veins of cross fiber are

1/4 to 1-1/2 inch wide (fig. 5, B). Very little asbestos was found on the

Shungnak side of the ridge.

A reconnaissance of the continuation of the serpentine easterly from

Cosmos Creek to Dahl Creek (fig. 3) revealed no asbestos deposits of commercial value. Several small outcrops of chrysotile were found on the east and

north slopes of Mount Ineveruk between Dahl and Wesley Creek, and a few additional outcrops of chrysotile, both ctoss fiber and slip fiber, were found on

the east and north slopes of Cosmos Mountain between Wesley and Cosmos Creeks.

Dahl Creek

The asbestos deposits on Dahl Creek were first examined by H. E. Heide

during August 1943,. in company of Robert E. Coats of the Federal Geological

Survey and Eskil Anderson of the Territorial Department of Mines. Figure 9

is a sketch map prepared by Coats at that time. The best outcrops of asbestos

lie near the top of Asbestos Mountain (fig. 10) at an altitude of approximately

2,500 feet. At the time of the first examination, four shallow trenches had

been dug by Arctic Circle Exploration, Inc., across part of a 50-foot shear

zone trending N. 500 E. Tremolite asbestos of the slip-fiber variety, forming

a 6-inch vein, was present in all four trenches, and the vein dipped steeply

southeast. In the last trench to the east a 2.5-foot vein of slip-fiber tremolite was exposed later. Details of the exposures in this trench in September

1944 are shown in the insert on figure 11. These veins dip approximately 65

degrees to the southeast and strike N. 10-15° E. The fibers from this outcrop

were as much as 18 inches long and were light gray to white in color. (See fig.

12, A.) Although the fibers were of weak tenacity, impurities were virtually

2723 -11-
R.I. 4414

absent, and there appears to be constant demand for this type of asbestos.

From this lens of slip-fiber tremolitej 36.5 tons was produced and shipped for

use in filters.

Development by Arctic Circle Exploration, Inc., up to September 1945 is

shown on figure 11. The name given by the mine by the operators is Ingik mine

or, more properly, Ing-Ihk mine. The long trench shown on figure 11 follows

the 6-inch vein of slip-fiber tremolite exposed in the original four trenches.

All of the trenches contained up to a foot of mat composed of residual fibers

of tremolite asbestos. Fibers up to 20 inches are not unusual. Within the

25Q-foot strike interval covered by the trenches, there is considerable surface float of long-fibered tremolite.

A 228-foot adit was driven to tap the tremolite lens at a depth of 60

feet. Although small veins of asbestos were encountered throughout the length

of the adit, the lens being mined pinched out before the level of the tunnel

-was reached. Only narrow veins .of brittle asbestiform fiber were found in the

first 155 feet. From there to the face at 228 feet, five veins of asbestos 6

inches to 2 feet wide were encountered. The strike of these veins'were N. 300

E. to S. 700 E. All veins were dipping steeply.

About 300 yards east of the'trenches, indications of another sheared zone

of the same type were observed. Much of the ground is covered by overburden,

and very little float or other indications of asbestos bodies of any size were

observed.. Hand trenching at this location did not expose rock in place. However, only a small amount of short tremolite fibers of an inferior grade was

found as float in this trench.

Float at two other localities 2,000 and 2,600 feet, respectively, northeast of the mine indicated other possible deposits. Trenching at the second

of these, on the saddle of the long point running northeast, failed to show

any fiber in place. The other location was near the contact with the schist.

Here a mat of white tremolite fibers 8.to 10 inches thick covered the ground

over a width of 10 feet. Trenching here exposed a 6-inch vein of good tremolite

In addition to the tremolite asbestos, deposits, the top of Asbestos Mountain contains slip-fiber chrysotile. Varying amounts of fiber can be found

throughout the area east of the cabin comprising the main peak and the point

to the north. The zone having the best chrysotile mineralization is shown on

figure 9 approximately l,000'feet east of the adit. Arctic Circle Exploration

produced over one ton of chrysotile fibers from three trenches at the south

end of this area in 1945. The chrysotile fibers are brown and extremely long

and tough (fig. 12, B).

In the trenches excavated by Arctic Circle Exploration, the; long-fibered

asbestos was found lying along shears in the walls and bottoms' of the trenches.

The attitude of many of the seams was nearly horizontal, although others were

close to vertical. Two sets of vertical fractures at approximately right angle-,

were noticed in the trenches, Ione striking S. 450 E. and the other S. 450 W.

The seams of asbestos ranged from'1/4 inch to 4 inches in width.

2723 -12-
R. I. 4414

The Bureau of Mines extended and deepened the above trenches and dug the

remaining trenches shown within the mineralized area on.figure 10. No attempt

was made to follow individual seams of fiber, since they were too narrow to be

minedeseparately. Instead, the long fiber in the overburden and loose rock

excavated was hand:-sortedto afford an estimate of the quantity of this material present 'as well as a sample for spinning tests. In all, 1,090 pounds of

long fiber.chrysotile was obtained from 719 cubic yards of trenching.

The quantity of chrysotile float in this area is remarkable. In places,

a mat of fibers several inches thick has been formed, even'though the slope

of the hill is exceedingly steep.: -Ir places the fiber is found clinging to

the sides of large boulders, and in others, it ish.half-buried in the soil in

front of the boulders. The face of one boulder was covered with a 4-inch

vein-of long-slip fiber from which hanks of asbestos.-as much as 2-1/2 feet long,

could be torn. Althoughslip-fiber chrysotile in veins i/2 to 4 inches wide

comprises the bulk of the'fiber"' 'mall veins'of cross fiber-and slip fibers

along the,.foliations of the serpentine are also present.,

Two samples were taken for testing. The first, sample F, was a composite

channel sample along the bottom of all the trenches. This sample is representative of'the'asbestos-bearing serpentine in the area of best-chrysotile mineralization.- The second, sample G, was composed of the chirysotile fibers

hand-sorted during trenching.

.In addition to the alteration deposits of asbestos and serpentine in the

areas-of ultrabasic intrusives, small deposits of talc and soapstone are

present. In fact,, all oJ the tremolite deposits apparently are associated

with talc and it may be possible were formed at or near the contact of the

intrusive. with the schist. Several deposits'of soapstone are shown on figure

10.

Although magnetite was disseminated in much of the intrusive, no large

concentrations were noticed.. A short adit was driveni into the point marked

"magnetic peak", (fig. 10) because of the high local magnetic anomaly, but only

very small lenses of magnetite were found. :

-' , I.<.. , K': .0. ....... Other Deposits

The asbestos-bearing serpentine has.-been traced as far east as the outcrop mapped east. of. the Kogolaktuk River south' of California Creek (fig. 3).

A reconnaissance of this area did not reveal any noteworthy exposures of

.asbestos, al'though a very small amount of float and several 'thin veins of

asbestos were found.,

Jade Mountain

--The asbestos deposits. of Jape Mountain in the Jade Hills are approximately

25 miles northwest of the confluence' of the Shungnak and Kobuk Rivers (fig. 2).

Here the..a.sbestos-bearing ultrabasic. rocks of Jade Mountain appear to have

formed a stock in's-chist..similar to the occ'urrence atAsbestos Mountain. The

rocks in the lower' foothills'along.-Jade Creek are made up largely of olivine

2723 ' -13-
B. I. 4414

and pyroxene. Farther up the slope and along the ridge between Jade Creek and

West Fork,. serpentine predominates. Large boulders and ledges of nephrite are

found at the heads of Cabin Creek and a small gulch on the right limit of

Tunnel Creek.

A small quantity of float slip-fiber chrysotile with fibers up to 5 inches

in length was found on a high knoll near the north contact, but the asbestos

here was sparsely distributed. Cross fiber in veinlets l/ .to 1/2 inch wide

was found at the portal of a small tunnel on Tunnel Creek. Slide rock covered

the entire surface in'this'area, so that little of the significance of this

showing could be determined. Cross-fiber chrysotile was also found in some of

the more prominent serpentine outcrops on the left limit of West Fork. Crossand slip-fiber amphibole asbestos was found in a prominent outcrop of serpentine on the same side of West Fork about 300 yards downstream from the chrysotile showing. White talcy material associated with tremolite outcrops as veinlets 2 to 6 iniches wide at four different places along a slope distance of 125

feet.

Serpentine outcrops on the first ridge east of Jade Creek but no asbestos

was found.

On the northeast side of the Jade Hills, the intrusive appeared larger,

had a more massive texture, and showed less alteration.

VALUE OF PRODUCT

The main production of asbestos in the North American continent is in

Canada and the Canadian classification of May 1, 1940, of crude and mill fiber

asbestos is standard in the United States. Asbestos mine products are divided

into two classes: (1) Crude asbestos, consisting of the hand-selected crossvein material, and slip-fiber material, essentially in its native or unfiberized

form; and (2) milled asbestos, consisting of all grades produced by the mechanical treatment of asbestos-bearing material. Both crude and milled asbestos

is further divided into groups based on the Quebec standard testing machine.y/

Table 1 shows the various grades of crude and milled asbestos.

TABLE 1. - Subdivisions of asbestos

Class Standard designation of crude I Definition

Group 1 Crude No. 1 ................. Consists basically of crude asbestos

Ithree-quarters of an inch staple and

longer.

Group 2 Crude No. 2 ........... ...... Consists basically of crude asbestos

three-eighths of an inch staple up to

Ithree quarters of an inch.

Crude run-of-mine.. ... 'Consists of unsorted crudes.

Crudes, sundry ............... jConsists of crudes not otherwise

I _________________________ ' '"Ispecified. _ 

8| Mining Operations in the Province of Quebec for 1937, pp. 36-37.

2723 - 14 -
R.I. 4414

Subdivisions of groups of milled asbestos

Class Standard designation of crude i Definition

Group 3 Spinning or textile fiber.... Consists of fiber testing 1/ 0-8-6-2

'and' over.

Group 4 Shingle fiber, ....... , Consists of fiber testing below

0-8-6-2 to and including 0-1-1/2-9-1/2-

5.

Group 5 Paper fiber ................. Consists of fiber testing below

0-1-1/2-9-1/2-5 to: and including

o o-8-8.

Group 6 Waste stucco' or paster...'... Consists of fiber testing. below 0-0-8-8

and above'O-0-5-l.-'-

Group 7 Refuse and' shorts ..., .........' Consists of fiber testing 0.0-0.0-5.0-

11.0 and below.

Group Sand..... 'Consistsof such asbestos mill products

- l as sand weighing over 35 'lb. and under

175 lb. per-cu. ft ., loose measure, and

containing a preponderance of rock.

Group 9 Gravel and sand,,,',,,,,,,,,, Consists 6f such asbestos mill products

,weighing 75 lb. and overdper cu. ft.

' ______________ _ loose measure,

1/ There are more than 100 standard designations -of grade in the various 'fiber

groups, and each designation must meet its respective minimum requirement

for shipping.

Taking as an example the fiber. designated as 3D of the spinning or textilefiber group, the S-6-1-1 means thatof a 1 pound sample of fiber, the following

ounces are required to 'remain on the respective- meshes to meet the guaranteed

minimum shipping test:

Fiber 1 /2-mesh 1/4-mesh 10-mesh Undersize

3-D' -oz. 6-oz. l-oz. ' -oz -

3-Z O-oz. 8-oz. 6-oz. 2-oz.

The prices quoted in the Engineering and Mining Journal for Novetber 1947

for asbestos are as follows2/:-

- '' Asbestos, f.o.b. Canadian (Quebec) mines (U. S. funds), ton:

Crude No. 1...... . $800

Crude No. 2 ............. $302 @ $410

Spinning fibers. ..... $170-@ $230

Paper stock....... ...... $ 43 @ $ 65

Shorts............ $ 20 @ $ 38

The main production from the Dahl Creek deposit was tremolite asbestos.

The most important use of this kind of asbestos is not in the usual asbestos

- products but as filters in industrial plants. It'was reported that a premium

price of $1,000 a ton was paid for the exceptionally long fiber tremolite mined.

9/ Engineering and Mining Journal, vol. 148, No. 11, November 1947, p. 166.

2723 -15-

* C~~~~'
R.i. 4414

:BENEFICIATION BY BUREAU CF M1ES

The samples taken from the trenches on Bismark Mountain along Shungnak

River were submitted for beneficiation tests by the Metallurgical Division'of

the Bureau of Mines. The results of the experimental work by Heine Kenworthy,

metallurgist, Rolla Branch, follow:

Two composite samples, A 'and B, were prepared for test work. Composite

sample A, consisting of samples 1 to 19; inclusive, and sample 26, contained

considerable slip fiber and was inferior in grade to composite sample B, which

consisted of samples 20 through 25. The comppopite samples were representative

of material from areas approximately 1,500 feet apart. The samples consisted

of serpentine, nemalite, magnetite, 'atdmagnetite. The serpentine was composed

of chrysotile and antigor'ite

Tje treatment for processing the samples was similar to the method used

in the Canadian asbestos mills. This practice consists of hand-sorting the

coarse material, followed by harmmer-milling to fiberize the chrysotile, screening, and air separation of the fiberized serpentine from the antigorite serpentine. Milling tests on each composite sample are discussed in the following

paragraphs.

C omposite Sample A

The ore was screened on 1/2-inch, and the oversize material was examined

for long-fibered asbestos that might be recovered by hand sorting, but no longfibered material was present. The entire sample was then crushed in a hammer

mill, with the screen bars set 1/2 inch apart and operated at a speed of 3,000

r.p.m. The crushed ore was passed over a 32- by 16-inch shaking screen, with

35-mesh square openings, which had a suction head over the discharge end at a

height of 5/8 inch above the screen. The suction discharged into a cyclone

separator. The speed of the shaking screen was 350 tol400 strokes a minute and

the feed rate 1 to 2 pounds a, minute. Asbestos that was sufficiently fiberized

was removed from the screen by the suction, while the plus 35-mesh rock and

unfiberized asbestos were discharged as oversize and returned to the hammer

mill before it was again treated on the screen. This cycle was repeated until

all the material wa's reduced to minus 35-mesh. '

The cyclone asbestos product contained chrysotile fibers of-various lengths,

some adhering dust, coarse flat particles of rock, and magnetite. The screening and suction treatmernt .used 'in collecting this material was therefore repeated

on a 20-mesh screen with the suction-head set 1 inch above the screen discharge.

This treatment removed the better-quality material. The plus 20-mesh screen

discharge was crushed in a smaller hammer mill, again passed over the 20-mesh

shaking screen, and the process repeated until no plus 20-mesh material remained.

The minus 35-mesh material was then screened on a 32- by 16-inch shaking

screen, with 65-mesh openings, operated at the same speed, with a stroke of 1

inch. The feed rate was about 3/4 pound a minute, and the suction head was

adjusted to 3/4 inch above the screen discharge. The screening was not efficient, and some minus 65-mesh material was collected in the cyclone and in the

screen oversize.'

2723 -16-
R.I. 4414

The plus 65-mesh material was hammer-milled and again passed over the

65-mesh shaking screen, but the'"cyqlIo4'qepr'cduct obtained after two passes

through the hammer milland over the ,creen eighQ 35.pounds a cubic

foot so the treatment was carried,,no further. The final products from the

various treatments are shown in the.,.,..owIQ g tabl;,. -

Summary of'combined. treatment

: ..Classification or

, ; , ;, Weight ' pulp weight,

Product Pounds Percent pounds a cubic foot

Plus 20ehatso,............ .*,..,8a*1.6''0--

Minus '20-nmesh asbestos....-....... 87 17.4' 335

Plus 35-mesh asbestos pas8) s(fir4t 1.1*8.5 29.7 34.5

Plus 35-mesh asbestos (second, and third ,,- . ,,,..I 

passes)............. ........... . 42 8.4 39.5

Plus 65-mesh sand ................ . '. .a 47 9.4 *45

Minus 65-mesh sand ................ ... 129 25.8 43.5

Mechanical and' dust' loss................ 35 7.7___

Total.'.____________________________ 500 '100.0 I

l/ This material'.ias' classified by the standard method'of screening 16 ounces

of asbestos in a nest- of 1/2-inch, 4-mesh, and 10-mesly screens'for 2

minutes with B300 strokes a minute' and a travel of 1-9/16 inches. The'

screen was not level, and the above figures are subject to revision when

this deficiency is corrected. '

This sample contained very little asbestos of appreciable fiber 1ength,

and hence the quality of the asbestos recovered was poor.

Composite'Sample B

The ore, which as received was about minus 2-inch in size, was screened,

and the 3/8-inch oversize material 'was hand-sorted to remove the No. 1 and No.

2 grades of crude asbestos, then crushed to minus 318-inch in a jaw crusher

and added to the primary minus 3/8-inch ore. This material was passed through

a hammer mill and screened on a 10-mesh'shaking scrzeen, which had a suction

head attached to the discharge end to remove the fiberized'asbestos. The oversize ore was again crushed in the ha:mmer mill and rescreened; this operation

was repeated until there was no more oversize. The minus 10-mesh ore'was

treated in a similar manner on a 20-mesh screen, and the minus 20-mesh ore was

treated on a 35-mesh screen. Only a portion of the plus'35-mbsh material was

crushed through 35-mesh, as very little asbestos was obtained after the third

pass through the hammer mill. The minus 35-mesh ore was tested on a 65-mesh

screen, but the air-separated material weighed 37.5 pounds a cubic foot, so

the material was not treated further, although it still contained some asbestos

which was unfiberized by the treatment.'

The final products from the various treatments-are shown in the following

table:

2723 -17-
R.I. 4414

Final products

Weight

Product Pounds Percent Classification

Plus 3/4-inch asbestos.....,... 0.25 0.05 No. 1 crude.

Plus 3/8-inch asbestos .......... .5 .10 No. 2 crude.

Plus 10-mesh asbestos.......... 2.25 .45 0 - 2 - 12 - 2

Plus 20-mesh asbestos........... 5.25 1.06 0 - 0 - 7 - 9

Plus 35-mesh asbestos ............. 20.25 4.09 20.75 lb. a cu. ft.

Minus 35-mesh asbestos......... 22 4.44 ! 29 lb. a cu. ft.

Plus 35-mesh sand............ 48.5 9.80| 64.5 lb. a cu. ft.

Minus 35-mesh material........ 1 386.5 78.09 52.5 lb. a cu. ft.

Mechanical and dust loss...... 9.5 1.921

'' '' 'Total.,.................. , -500 100.00' ________

Remarks

The final products of the Rolla laboratory test runs on the samples from

Bismark Mountain were submitted'to commercial producers and fabricators of

asbestos products for identification and evaluation of their possible economic

uses. Samples were sent to Keasbey & Mattison Co., Ambler, Pa., and the United

States Asbestos Division of Raybestos-Manhatta.t, Inc.,' Manheim, Pa. All of the

products were rejected as unsatisTfactory by Keasbey & Mattison on the grounds

that the fibers were too brittle'efor 'their 'commercial uses.l1/ Their observations, based on the requirements' 'fTor the production of their textile products,

follbow:

Sample B was of good length but was a slip fibre having less

value than slip'fibre from'Vermont. We have previously worked

with Vermont slip fibre and, while it was a better quality than

sample B, we could find no'use for it in our present manufacturing operations. The quality of fibre in sample B was brittle

and of low strength.

The "on 35-mesh" portion of sample A would be useful as a

shingle fibre if the fibres were not so brittle. Asbestoscement products require fibres having a considerable tensile

strength.

Of the duplicate samples submitted to the United States Asbestos Division

of Raybestos-Manhattan only one of the milled produ~cts seemingly could be

utilized in the products this firm. manufactures.121./ Its conclusions follow:

The sample marked "B" 3/41" No. 1 Crude Asbestos has good

fibre length and the fibre has reasonably satisfactory tensile

strength. The fibre as you have'reported, has considerable iron

oxide staining. This stained condition might be'objectionable

in some finished products, but it would be suitable for other

products, which we make. Possibly this fibre was taken from a

point near the ground level, and it might be free from the iron

oxide staining at lower levels.

10/ Written communication.

1T/ Written communication.

2723 -18-
*i. 4414

The fibre represented by Sample B 3/8" No. 2 Crude Asbestos

is mostly slip fibre and very brittleA This material is-not suit-'

able for any textile process.

The material represented by the remaining samples is of no:,

value in the textile field, and as a matter of fact, I do not know

of any process of product such as asbestos paper, building materials, and molded materials, in which this material could.,be used.

-JOHNS-MANVILIE TESTS

*The samples taken during the summer of 1946 were submitted to the Fibre

Development Department, Canadian Johns-Manville Co. Ltd., Asbestos,'Quebec,

for testing. Samples C and D were representative of the material sampled on

the right limit of Cosmos Creek. Sample F was taken from the slip-fiber zone

on Asbestos Mountain and sample G was long-fiber chrysotile asbestos handsorted from the same deposit.

e Thesfollowing is taken from the Johns-Manville report on the pilot-mill

tests 12/

Summary

Approximately 10 tons of ore and fibre, reported as being from the Dahl

Creek Asbestos Project 2308, were-received from the U. S. Bureau of Mines,

Alaska.

As had'been previously arranged, the various lots were processed in the

PilQt Plant at Asbestos, Quebec, for the recovery and grading of the different

groups of inherent and free fibres.

Briefly the treatment of the ore consisted of crushing through a cone

crusher to approximately 2" size, followed by further crushing in impact mills

for-the purpose of releasing the fibre from the rock.

'The above treatment was then followed by several successive screenings to

remove the granular fines or undersizes and.to permit the free fibres to be

floated and picked up.or separated on the gangue rock by aspirating hoods over

the ends of the screens.'

'The aspirated fibres were recovered in conical collectors.and subjected to

further screenings and grader treatment and classified according to the Quebec

Standard Fibre Groups.,

Pertinent results of these tests are as follows:

The recoveries of fibre (as percent of the ore sample) for lots C, D and

F ranged from 5.38 - 11.33% for fibre groups 3 - 7 and from 13.56 - 16.55%

when including the 8S or fibrous sand group.

12/ Canadian Johns-Manville Co. Ltd., Pilot Mill Tests on Alaskan Asbestos

Ore: Rept. O-P-26-28-482, May 5, 1947.

2723 - 19 -
R.T. 4414

By fibre groups, the recoveries ranged' from 0.11 - 0.50% for group 3,

0.6 - 1.37% for group 4, 1.74 - 4.28% for group 6, 3.28 - 6.89% for group 7

and 5.06 - 8.18% for group 8.

Of the three lots of ore, Lot F had the highest recovery of the long and

medium length fibres, i.e., groups 3 and 4.

The recovered fibres are of the chrysotile variety and are considerably

darker in colour than the Canadian asbestos which could be due to mining at or

near the surface of the deposit.

In comparison with Canadian fibres, the Alaskan fibres have an unusually

high dust or fines content, a higher loose density and a somewhat shorter staple

length, the latter determined by wet screening method.

The long fibre is quite strong, is closely matted, difficult to separate

and unsuitable to normal opening processes. It lacks the silkiness of Canadian

fibre.

Much of the fibre is in the form of long ropes which are not easily separated, consequently portions of same are found after processing, in the group

3 fibre.

Despite the high dust content, the groups 4 - 6 fibres show an unusual

fast rate of filterability.

Treatment

The various lots were pan dried over a coal fired furnace and bagged and

tagged for processing separately. The total dried weight was 10.09 tons.

The ore as received varied in size up to 13 inches. It was reduced to

approximately 2 inches and smaller by crushing through a cone crusher.

Further treatment consisted in crushing in impact mills for further reduction in ore size and for the purpose of releasing the fibre from the rock (the

rock breaks along the line of weakness, which is for the most part the fibre

vein).

The above treatment was followed by screening, the purpose of same, in

addition to removing the valueless undersizes or fines, being to float the free

fibres liberated in previous treatment, to the top of the screen load so that

they could be readily picked up or separated from the gangue rock by aspirating

hoods located over the ends of the screens. The aspirated fibres having been

recovered in conical collectors were subjected to further screening and grader

treatment and classified according to lengths, all in accordance with the

Quebec Standard classification for groups 3, 4, 5, 6, 7, and 8.

2723 -20-
SAMPLE C - 56 BAGS

WHITE GREY CONE

* ~TALCY ORE DRYER

MOSTLY FINES CRUSHER

ASP'D FIRE

/ 2 M SCREEN IMPACT

20 x 20 M. MILL

O/F 20M. TAILS U/S 20M. TAILS

SCREEN O/S 6 M. GR. 3 FIBRE

6 x 6 M.

10 X 10 M. o M/S -6 +10 M. GR. 6 FIBRE

U/S 10 M.

O/S 36 M.

SCREEN

36 x 36 M. ASP'D S RRE

GR. 7. O/S 36 M. SCREEN

36 x 36 M.

O/F 36M. TAILS

U/S 36 M. GR. 8 SAND

Figure 13.
a
Sumnary of Recoveries !rrom'Ore Samples

RpecoveredIfibrets' pe of'the ore sample

Fibre Group Lot C Lot D Lot F

3' ~ 0.1<0.50

4 - .o6 1.37

6 1 74 4.27 4.28

7 3.53 6.89 3.28

(Groups 3 - 7) 5.38 11.33 9.43

8 8.18 5.22 5.o6

Total Fibre Rec'y

(Groups 3 - 8) . 13.56 16.55 14.49

''' 'eDetails of-Fibre Recoveries and Grading

Designation - Sample C - 56 bags (see fig; 13)

Location - Taken on Cosmos Creek from the lower portion of the asbestos

:formation. Weight of dried material, 6552 lb.

Description - This lot consisted of mostly light-coloured talcy, finely broken

ore.

Processing-- The ore was dried, crushed, and further treated in impact maills

. 'for the reduction of ore size and release of fibre, followed by

screening and aspiration to collect and grade the various fibres.

Recoveries

% of % of

Fibre classification Weight (lb.) ore fibre recovered

Group 3 0.11 2.05 81

Group 6 114 1.74 32.34 12.83

Group 7 231 3.53 65.61 26.03

Total, groups 3 - 7 353 5.38 100.00

Group 8 536 8.18 60.33

Total, groups 3 - 8 9 1356 0.00o

Grading

Group Que. Std. Tests- Classification Remarks

Mesh 1/2 4 10 Pan

.3. -. . : .. .l.~8. 7;0 517 1.5 3T (Low box 2

'(igh box 3

6 .0 Tr. 7.5 8.5 6D

7 .0 .0 1.0 15.0 7R

All fibres are grey-white in colour and have a high percentage of dusty

fines, resulting in their loose density or weight per cu. ft. being much higher

than usual.

2723 -21-
R.i. 4414

Designation - Sample D - 59 bags (fig.14).

Location - Taken from the upper portion of the same formation on Cosmos

Creek. Weight of dried material, 6,203 lb.

Description - This lot consisted of mostly coarse, dark-brown ore, containing

a few fibre veins

Processing - Similar to that in lot C.

Recoveries

% of % of

Fibre classification Weight (lb.) ..ore fibre recovered

Group 3 7 0.11 0.97 0,67

Group 4 4 .06 .53 .36

Group 6 264 4.27 37.69 25.80

Group 7 428 6.89 60.81 41.63

Total groups 3 - 7 703 11.33 100.00

Group 8 324 5.22 31.54

Total groups 3 - 8 1027 16.55 100.00

Grading

Group Que. Std. Tests Classification Remarks

Mesh 1/2 4 10 Pan

3 1.2 7.8 5.3 1.7 3T (Low box 2

(High box 3

4 .0 2.6 9.8. 3.6 4T6 .0 Tr. 7.6 8.4 6D

7 .0 .0 .9 15.1 7R

All fibres are light-brown in colour and have a high percentage of dusty

fines, resulting in their loose density or weight per cu. ft. being much higher

than usual.

Designation - Sample F - 93 bags (fig. 15).

Location - Taken from the slip fibre zone on Asbestos Mountain at the head

of Dahl Creek, about 9 miles (air line) east of Cosmos Creek.

Weight of material 6,819 lb,

Description - This lot consisted of mostly coarse, brown ore, and containing

some veins and loose slip fibre.

Processing - Similar to that of lot C. -

2723 -22-
SAMPLE D - 59 BAGS

COARSE DARK

BROWN ORE CORNE FEW LARGE DRYER ----------- VEINS

ASP'D FIBRE

0/s 20 M. SCREEN IMPACT

20 x 20 M. MILL

0/F 20M. TAILS 2OM. TAILS

SCREEN --- O/S 4 M. GR. 3 FIBRE

4 X 4 M.

6 X 6 M. ! M/S -4 + 6 M. GR. 4 FIBRE

,U/S 6 M.

SCREEN - O/S 10 M. GR. 6 FIBRE

10 x 10 M.

36 x 36 M. M/S -10 +36 M. GR. 7 FIBRE

kFU/S 36 M. GR. 8 SAND

Figure 14.
SAMPLE F - 93 BAGS

COARSE BR)WN

ORE V DRYER CONE

SOME: & VEINS ~~CRUSHER

FREE FIBRE

ASP'D FIBRE

0/S 20 M. SCREEN IMPACT

f X 20 20 M. - MILL

1 0, O/F 20M. TAILS U/S 20 M. TAILS

SCREEN O/S 3 M. GR. 3 FIBRE

3 x 3 M. C LONG STRINGS)

6 x 6 M. M/S -3 + 6 M. GR. 4 FIBRE

U/s 6 M.

SCREEN =/ S 10M. GR. 6 FIBRE

10 X 10 M.

36 X M. - - M/S -10 +36 M. GR. 7 FIBRE

U/S 36 M. GR. 8 SAND

Fi gure 15.
SAMPLE G - 12 BAGS

VERY LONG I /S 3 MESHi

CHRYSOTILE DRYER FIBRE

SLIP FIBRE SAMPLE F:

IMPACT IMPACT iO/F 20 MESH

MILL MILL ~~~~TAILS MILL MILL SAMPLE F:

1 ______________ I

O/S 20M. ASP'D FIBRE

SCREEN

20 X 20 M. O/F 20M. TAILS

O/s I M. F I BRE SCREEN

U/S 20M. TAILS C LONG STRINGS) I X I M.

3 x 3 M.

M/S -I+3M. GR. 3 FIBRE U/S 3 M.

O/S 5M. GR. 3 FIBRE SCREEN

5 5 M.

M/S -5+36M. GR. 5 FIBRE 36 X 36 M.

u/s 36M. REJECT SAND 4 _

Figure 16.
R.I. 4414

Recoveries

% Of % of

Fibre clif bn22Weistiffi (; _ old '0 tibr'erecovered

Ropy f -.Ibri-e 35'" 0.50

Group 4`i 94.' 1.37 14.53' 9.45

Group 6 - 292X ' 4.28 45.39 29.54

Group 7fQ 223 3.28 34.78 22.64

Total groups 3- 9-43 100.00

Group 8 '- 344 5. 06 314.92

Total groups 3 - 8 M 79 100.00

Grading

Group ' Que. Std. Tests 'Glassification Remarks

Mesh 1/2 4 10 Pan

3 N6:'test - Long strings

4 0.0 3.9 8.5 3.6 4M Low box 2

6 .0 .0 8.6 7.4 6D High box 3

7' .0 6. 0.5 15.5 7R' -

All fibres are dark grey in colour and have a high percentage of dusty

fines, resulting in their loose density or weight per cu. ft. being much higher

than usual.

Designation - Saimpl G -'12 bags (fig. 16).

Location - Taken from the surface of Asbestos Mountain.. Weight of materials

606 lb.

Description - This lot consisted of hand-sorted; longchrbysotile slip fibre.

Processing - Due to the dried'fibre being very long, tough and stringy, normal

mill processing could not be used. In an effort to treat the

'fibre to open' same and reduce its length,- a laboratory high-speed

opener was used., but the mniaterial Jammed in the -unit.

A quantity of reject rock (minus 20-mesh) from run F was therefore mixed

with the fibre and:treiated in""An-impact intll; By making 2 passes in this unit,

the fibre was opened 'up somewhat, but some still remained iT t'he. form 'of long

ropes. -

The op~en'ed and'shQrter ?'ibre was aspiratedfrom rthe' a screen and graded

by 'subsequent screening.' ,' '

Due to the d-Ifffcult'ie's' e&icbrunte'ed xii the' fib'e sticking in the machines.,

as well as the necessity of introducing the granular material as an abrasion

agent, "the recoveries fro6't'his6'o't s'hotld only be'dcons idored as'approximate.

25. lb. of long group 3 fibre from lot F was mixed with this for processing,

as it was a rboximA'ely the'astim t'ype- 6of materl.

The fibre losses were added to the:-actial recovbries:, being weighted

accordingly,

2723 A 23
R.i. 4414

Recoveries

~~~~ originale mate±'ia' Fibre classification Weigh Iii ) riia mtera 1 '

Long ropy-fibre 14 24,09

Group 3 94 15.51

Groupi .142' 23.43

Group 5 178 29.38

Reject sand 46 7-59

Total fibre & sand. 0 10.0.00

Group Que. Std. Tests Classification Remarks

Mesh 1/2 4 10 Pan

? . - Long ropy fibre

3 4.8 8.9 1.5 0.8 (High box 2

(Low box 3

3 .5 8.6 5.0 1.9 3Z Low box 3

5 .0 .4 10.6 .5.0 5R

All fibres are dark brown and have a somewhat high percentage of dusty

fines, resulting in their loose density or weight per cu, ft.-.being higher than

usual.

General Remarks

The recovered fibres were of the chrysotile variety and were-oondiderabl:y

darker in colour'than the Canadian asbestos which partly, could be due to-mining of the ore at or near the surface.

All fibres show an unusually high-dust or fines content and a. loose adensity, or weight per cux4 ft., considerably greater than Canadian fibre. This,

high fines cobtent is reflected in the somewhat shorter staple length of the

various fibres determined by wet screening method.

The long fibre is quite strong, but is closeLy matted, difficult to separate and unsuitable to normal opening processes, lacking the usual silkiness

'of Canadian fibres.

Local Textile personnel feel that the long, ropy fibres would be unsuitable

for textile use, whereas, the group 3 fibres could be processed in the carding

machines, although a high loss in drops etc. is anticipated.

The filterability of the medium or group 4 fibres shows an unusual fast

rate, considering the high dust content, and from this standpoint, they would

be of interest where good filtering .charaQteristics are required, such as in

the manufacture of shingles and other asbestos-cement products.

The use of the group 6, 5 and 4 fibres in paper products would undoubtedly

show a high loss, due to the washing out of the dusty-fines.

The dust content of the group 7 fibres is somewhat lower in proportion to

the other grades and fot this reasons they would be suitable for most of the

products where asbestos shorts are used,

2723 -24-
R. I. 4414

CONCLUSIONS

Tests on the asbestos materials from these deposits, performed at the

Bureau of Mines laboratory, Rolla, Mo., and by industrial concerns, lead to

the following conclusions:

(1) Recovery of the higher grades of asbestos is so low that these

deposits cannot be considered as a source of spinnable asbestod.

(2) There is a possibility that the material could be utilized in the

manufacture of asbestos shingles and asbestos board, although the

asbestos is more brittle than the Canadian product.

(3) There is also a possibility that this asbestos could be used as a

filter medium because of the rapidity with which water passes through the finer sizes.

BIBLIOGRAPHY

1. SMITH, PHILIP S., The Noatak-Kobuk Region, Alaska. Geol. Survey Bull.

536, 1913, 160 pp.

2. STEWART, B. D. Mining Investigations and Mine Inspection in Alaska.

Territorial Department of Mines Report for Biennium Ended March 31, 1933

and 1934.

3. MORTON, MAURICE AND BAKER, W. G. Identification Stain for Chrysotile

Asbestos. Trans. Canadian Inst. Min. and Met., vol. 44, 1941, pp.

515-523.

4. CANADIAN JOmS-MAwVILuE CO. LTD. Pilot-Mill Tests on Alaskan Asbestos Ore.

Rept. O-P-26-28-482, May 5, 1947.

2723 -25-