R. I. 4419 MARCH 1949

UNITED STATES

DEPARTMENT OF THE INTERIOR

J. A. KRUG, SECRETARY

BUREAU OF MINES

JAMES BOYD, DIRECTOR

LIBRARY COPY

U. S. Bwreau Mins

Boulder City, Nevada

REPORT OF INVESTIGATIONS

INVESTIGATION OF CLAIM POINT CHROMITE DEPOSITS

KENAI PENINSULA, ALASKA

BY

R. S. SANFORD AND J. W. COLE
R. I. 4419,

March 1949. a .

REPORT OF INVESTIGATIONS

UNITED. STATES D.EPAR UMT. OF THE. INTERIOR - BUREAU OF MINES

t. INVESTIGATION OF CLAIM-POINT -COMITE -EPOSIts, ENAI PENINSULA, ALASKAY1/'

^ -* By R. S. Sanfford2/ andJ. W. bet '- r~~~~~~~~~ i

-CONTENTS . . . . . . . . . . . . .... ........................... .. i. ........-

* . ,,. . . t'a ge

Introducti on and urmmary ;;...... ..... .... . ........ 2

Ackn~owledgments ;;;. . . . ............... ,; . . . .. .. ... ' '.,; ..'. t.' . ...- 2

Location and-accessibility-. . .;............. ....... 3

Physical features;.... .... .. . ... 3

History History . ~~.;........ * .. ; ;.,;. ;.. .. ,..;,::..........,;.''''4*.C. 4

Property and ownership . . .................... .... , ., 4...... 4

Ore deposits . . ................. .............. 4

General geology. . ..........................., 4

Mine±'alogy *..... ... ............. ...... .................*. 5

Description 6f the deposits . ' .. . ..... ... 6

No. 1, or Reef mine ......... I , 6

No. 10 . ,.,' .............. '.', ' ' ,.i.' .. '... ...... 6

Nos. 7, 8a, 8b (S) and 8b (N) ....... ' . . 6

Development ............ 7

Sampling and assaying ............ .'.,.... . 7

Beneficiation of Claim Point chromite . ' ..'. . ., . . 7

Ndtur6'of ore ............................... ...7 i..., 7

'Methods of concentration .. 8

Tabling sized fractions of ore groun'd to minus 48 plis 200-meeh,

table tailings and middlings reground to minus 200-mesh before

making finished tailing ........ ...... ......... ...... 8 

Discussion.. '.,,.'. ' 4i ...... . ............. 10

Conclusions ............ ............ . . . *. . . . .10

ILLUSTRATIONS

* ''' '.Following

Fig. page

1. Index map Kenai Peninsula, Alaska . .... 2

2. Kenai Peninsula chromite areas ........... 2

*3. Geologic and topographic map ,..'. ...... .. .. ....'..... .. 4

1/ 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 4419."

2/ Senior mining engineer, Bureau of Mines, Juneau, Alaska.

3/ Associate mining engineer, Bureau of-Mines, Juneau, Alaska.

2745
R. I. 4419

ILLUSTRATIONS, (Cont'd.) ,

-~ ; #xwtFollowing

Fig.. - -> - . page

4. Plan oiieef Min'ou-ttops.i 6.

5. Assay section, Reef' mine outcrop **a>+ .-. .... 6

6. Assay plan, Deposit No. 10, Claim Point, Alaska .......... 6

6a. Assay data, Deposit No. 10 ................. 6

6b. Assay data, Deposit No. 10 ................ ............. 6

7. Section B-B, Deposit No. 10 ....... ..... 6

8. Section A-A, Deposit No. 10 ...... ................... 6

9. Sejtion C-C, Deposit No. 10 .......................... 6

10. ,ectiQ;,DD, Dposi No.10 ....... ............. ........... ..6 10. Sectio~. P, Deposit No. 10.6

11. SectiQr;E-EA Deposit No.' d .'....... .. .* .. 6

12. Assay pJ,,,,flposit.Nos.7'K8a; eid 8b . ' 6

12a. Ass~yAt ,epsitNos. 7 and.8a ..... | 6

12b. Assay, qta, Deposit Nos.i7 and'8 6 . 6

13. Section.G-G .Deposit N~o8s.,' n. 86 .................. - 6; n ,.;6 ; 

14. Section F-,F,,~ DpitN.a .* ....................... 6' >.

INT0tEiCTION'ANIDSUMMARY

Thea, a.im ip~nt chromite eposits ab'&at tidewater near the southern tip

of' the Kenai. epiprl..in south b'stei-n' Al&a3k. The, United States Geological

Survey hat a. fied party in th'e reion fro' Jaly until' September 1940 under

P. W. Guild, jsasaistan~t geologist'; iMa'p's' an'd geological data were assembled and

made availa41a .to the Bureau of Mines'.''' ,

A preli=IrAryivestigatiorn of 'thd'deposits at Claim Point by the senior'

author d.uringJuly 1941 was foQlowedd 'by 'urfdce sampling and core drilling to

determine the quantity and grade of ti ore.- The Geological Survey was represented at the project by George 0. Gates, geologist., Cores were checked and

the stri tureW d4tarevealed by drill cores were interpreted.

Thepipincipal.'phromite deposits have'ben' sampled'and delimitated by trenching and core drilling, Other t eposits'wr~ie ti-enched'and sampled but were too

small or too low-grade to warrant core drilling.

ACKNOWLEDGMENTS

metaliurgiceal data included in this report were obtained from tests at

the Salt Lake ,Cit-y_ Exxperiment S'tati'rn of the Bureau of Mines.

Acknowledgment is made to the 'Gol'ddidal Survey for the use ef geologic

maps and reports of the Claim Point,,area. Special acknowledgment is made to

P. V. Guild and George 0. Gates, of the Geological Surv ''oi"detailedstu'dy

and mapping in the area..

2745 2
5 /&ER/AX -

DOMA/N/oN

FtV1Vlks CANADA

55ER//G > AnchorageV

SEA \ ,AOR

/ 2 iD \ G( F OF ~ts

AL~EuTIA maV ~ PAil ALASKAX

Figure I. - Index map, Kenai Peninsula, Alaska.
l TV gAD<.IVAE COVE

-k,< Y. UEA T 8A Y 5940do 

L~~~~~jl

ACR xonM/rTovskE °/IE AREA

K<AYUKrTOLIC)t

C/-/ROA/17rE rcAdC 

AREA b

_ _ _ _ _ _ J5 9 0

5' 0 5 /0 15

.Sca/e of Miles

Modified from Geological Survey Bull. 742, Plate I.

Figure 2. - Kenai Peninsula chromite areas.
R. I. 4419

LOCATION AND ACCESSIBILITY

Claim Point is a small peninsula about one-fourthvsquare mile in extent

extending into the mouth of Port Chatham Bay from the north shore, Its general

location is shown on figure 1. It is separated from the mainland by Chrome Bay,

except for a grass- and tree-covered sandspit.

The nearest'supply base is Seldovia, a Small fishing-village of about 400

population, about twenty-five miles by boat north of Claim-Point on Cook Inlet.

(See fig. 2.) The entire area under discussion-is part' of the Third Judicial

Division of Alaska, with headquarters at Valdez.

Cook Inlet is served by the Alaska Steamship Co., which has maintained

once-a-month iervice to'Seldovia since.the entrance of the United States into

the War. The c mpany's basic freight.rate on machinery from Seattle to Seldovia

during the summer of 1942 was 41-1/4 cents a cubic foot; or 82-1/2. 'cents a hundred pounds, whichever was greater, plus a 25-percent emergencyisurcharge.

Rates on groceriled and :6ther' supplies varied but were generally higher than

the above figures.' Freight on bulk ore valued at $60 a short ton is $7 a short

ton plus 25 percent emergency surcharge.from Seldovia to Juneau or from Seldovia

to Seattle and $4;50. ashort ton plus 20.percent emergency surcharge from

Juneau tQ Seattle. Wharfage at Seattle is $0.07 a hundred pounds.

Minimum first-class passage by steamship from Seattle to Seldovia during

the summer of 1942;'was& lll;.:65 plus:10 percent Federal tax. The one-way trip

required about 2 weeks. Transportation may be had at slightly higher cost on

the'more frequent 'ships from. Seattleto Se-ward, Alaska, thence by train to

Anchorage, and from there to Homer, or Seld6via by plane. Passengers and air

express are carried by Pan American Airways-from Seattle to Fairbanks and by

local pldne companies from Fairbanks to other parts of 'Alaska. Plane fare is

$175.00'plus tax from Seattle to Fairbanks and $65.00 plus tax from Fairbanks

to Homer. Charter plane service is also available at Anchorage..

There is a privately owned radio station at Seldovia that furnishes commercial telegraph service through the Alaska Communication System. Small

ocean-going motorships maintaTn irregular freight service on Cook Inlet, but

most local travel-i-s by' small gasoline-powered fishing boats. Groceries and

.other eupplie3'are available at Seldovia and Homer. Standard Oil Co. maintains

a bulk oil plant'at Seldovia to serve the Cook Inlet area. Fuel and lubricating oils in reasonable quantities may be obtained at prices comparing favorably

with the United States prices., Low-grade coal may be obtained from Homer at

$10 to $12 a ton. There is a grade school and facilities for rather primitive

living across Port Chatham Bay at Portlock. There are a high school and a

modern hospital in Seldovia.

PHYSICAL FEATURES

Kenai Peninsula is typical of the Alaikan coastal'region in vegetation

and clizate-. G.Claim Point and the adjacent mainland is covered by a jungle

growth o6fvegetation, spruce-trees df -Togging size beingfa4rly abundant.

Although the nearest weather station at Homer, Alaska, records an annual rainfall of only 30 to 4.0 inches, itdXs believed that the precipitation at Claim

Point is nearly twice that amount. Seda-level temperatures range from zero to

80 degrees, rarely remaining below freezing for more than a few days at a time.

2745 -3-
R. I. 4419

However, above 600 feet freezing weather and heavy snowfall are the rule from

October to May. Tides are high on Cook Inlet, the maximum range at S6ldovia

being 28 feet, causing difficulty 'in the construction of docking facilities

that can be used at both low and high tides.

HISTCRY

The earliest reference to the Claim Point' chromite deposit is by. U S.

Grant. / A. C. Gill2/ 'examined them in 1918', and P. W. Guild6/ investigated

them from June to September 1940..

Past production has been limited to 1,000 long tons averaging 46 to 49

percent Cr203 in 1917 and 1,000 long tons averaging 40'peroent Cr2O3 in 1918.

Most of this ore came from the Reef mine. During 1918 and 1919, a stamp mill

was constructed to mill the ore from Deposit No. 10, but no ore was milled,

and operations ceased with the end of the war. The location of the principal

deposits on Claim Point is shown on figiure 3.

PROPERTY AND OWNERSHIP

The Bluff No. 1 claim, which covers Deposit No. 10, is the only patented

property at Claim Point. To the southeast of this is the Bluff No. 2 claim,

which covers deposits Nos. 7 to 8b, inclusive. The Reef mine is covered by a

Claim parallel to the strike. Most of the mining property at Claim Point is,

held by Red Mountain Chromite, Inc., 900 Public Service Building, Portland, Ore.

ORE DEPOSITS

General Geology

The ore deposits are found in an intrusion of ultramafic'rock, which

underlies all of Claim Point, Chrome Bay, and an area on the mainland extend-

^ing 800 to 1,000 feet from the shore of Chrome Bay. Except for the land area

on the mainland opposite Claim Point, the contact is covered by the sea, so

that the size and shape of the intrusion are not'known.

According to Guild|7/:'

The surrounding rocks consist of a series of graywackes,

slates, cherts, limestones, and interbedded volcanic rocks. The

ultranafic rocks are'discordant intrusives into the graywacke

4/ Grant, U. S., and Higgins, D, F., Preliminary Report on the Mineral

Resources of the Southern Part of Kenai Peninsula, Alaska: U. S.

Geol. Surv. Bull. 442, 1910, pp. 168-169.

5/ Gill, A. C., Chromite of Kenai Peninsula, Alaska: U. S. Geol. Surv.

Bull. 742, 1922.

6/ Guild, P. W., Chromite Deposits of Kenai Peninsula, Alaska: U. S. Geol.

Surv. Bull. 931-G, 1942.

7/ Op. cit., abstracted by authors.

2745 ' -4-
50001 N,,',"'__'-

o~~~~~~~~~~~~~~~~~

LECGENC

?- Cbromi f c OuLcrops

0 /000 2000

5co/e in? Fee,

Dacf'vm Appr-ox. Mecrn Sec L eve!

Figure 3. - Geologic and topographic map.
series. The predominant rock is dunite. Along the margins of

the mass the dunite has been altered to serpentine. The Kenai

Peninsula was strongly glaciated in Pleistocene and Recent time.

The ultramafic rocks are characterized chemically by their high

content of magnesium and iron, low silica and alumina, and almost

complete absence of alkalies. The dunite consists almost entirely

of olivine (Mg, Fe)2SiO4, with accessory chromite grains, averaging

about 0.5 millimeter across, which usually constitute less than one

percent of the rock. The:.chromite-bearing intrusives are tentatively

assigned a late Jurassic or Cretaceous age. No ultramafic dikes

are.known to have been intruded into the surrounding sedimentary

and metamorphic rocks.- The outstanding characteristic of the intrusive bodies is the banding. Faulting .atd-'-ointing are common.

These deposits were appartntly formed by magmatic segregation. The mineral deposits are irregularly distributed' throughout the dunite without apparent pattern, where exposed, and undoubtedly occur through the unexposed volume

of the dunite in about the same proportion. The total volume of ore is so

small,, compared to the volume ofthe dunite, that discovery of buried ore bodies by present known methods is both uncertain and expensive.

Mineralogy

According to Guild:

Chromite is a'black, opaque mineral with a submetallic lus-'

ter belonging to the spinel group.pdf'the isometric class. It is

distinguished from magnetite by its brown streak and low degree

of magnetism. Its theoretical chemical composition is FeQ.Cr203, with 32 percent FeF and 68 percent Cr203, but in fact it always.

.-contains MgO, Fe2 Q0, and A1,0 Its formula, therefore, is usually

written as (Fe,Mg)O. (Cr,Al,;e)2 03. The percentage of Cr2 03 in

the mineral may thus range.betwedn wide limits, but with few exceptions.the range in the deposits under.discussion is small, and the-E

percentage of. is near 58.

The chromium-iron.,ratio of concentrate from this ore is expected.to range

from 2.5.to 2.8 to I, The 45 percent concentrate of a' sample of ore from deposit No. 10 was found to have a chromium-iron ratio of 2.71'to 1.

The dunite is composed principally of olivine containing approximately

40 percent magnesium oxide and 6 percent iron.

Similar rock has been found to have desirable' qualities'for the manufacture of refractories,8/ and investigations are-s id to be in progress to recover magnesium metal from olivine. .

8/ U. S. Department of Commerce, Bureau of.Standards, Research Paper R. P.

645, Bureau of Standards Journal of Research vol. 12, February 1934.

2745 5
P. I. 4419

Recent analysis of one sample of chromium ore from deposit No. 10 shows

a trace of nickel. The nickel appears to occur as a'silicate in the olivine.

DESCRIPTION OF TLEPOSITS

Deposit No. 1 or Reef Mine

A deposit of bandedl chromite crops out about 400 feet south of Claim

Point on a reef connected to the mainland at low tide. The main part of the

ore body consists of two parallel lenticular bands in contact with each other

at one point. Each band is more than 100 feet long and approximately 25 feet

in maximum width. A hole drilled from the mainland to intersect the ore zone

at 180-foot depth under the widest part of the ore body proved that direct

shipping ore does not extend to that depth. The best zone intersected was 2

feet of 34.24 percent Cr20. The ore body may rake to one side or the other

of the hole. A geologic plan of the deposit'is shown on figure 4, and an

assay section through the drill hole exploring the deposit is shown on figure 5.

Deposit No. 10

On the north slope of Claim Point adjacent to Chrome Bay is the largest

known body of low-grade chromate on Kenai Peninsula. Trenching and drilling

indicate that it consists of two irregular but generally parallel lenses of

banded chromite in contact with each other at their midpoint at the outcrop

elevation, striking northeast and dipping vertically. The outcrop elevation

is approximately 140 feet. The ore body feathers out to the southwest. The

lenses apparently rake to the northeast as they do not crop out above the drill

holes on the north end. Geological data revealed by the outcrop and the drilling suggest that the body is terminated at the north end between the drill

holes and the exposed bluff. Drilling indicates that the ore body is at least

350 feet long and 80 feet in maximum width where the two lenses are in contact

at the surface. The width and grade of the ore body appear'to decrease with

depth. An assay plan of the No. 10 deposit is shown on figures 6, 6A, and 6B.

Sections through drill holes on the No. 10 deposit and analyses of samples

obtained in drilling are shown in figures 7, 8, 9, 10, and 11.

Deposits Nos. 7, 8a, 8b(p), and 8b(N)

To the northeast of deposit No. 10, at slightly higher elevation, are

four deposits of low-grade banded chromite that are thought to be faulted

segments of deposit No. 10. They strike northeast and dip steeply to the

south. Drilling indicates that these deposits do not continue far in 'depth.

Deposit No. 7 is 60 feet long and averages 13.2 feet in width; No. 8a is

70 feet long and averages 14.5 feet in width; No. 8b(N) is 110 feet long and

averages 21.5 feet in width; and No. 8b(S) is 140 feet long and averages 31.4

feet in width. The assay plan of these deposits is shown on figures 12, 12A,

and 12B. Sections through drill holes and analyses of samples obtained from

drilling are shown on figures 13 and 14.

2745 -6-
ucXropie

/e~~~~~~~58

0~~~~~ gg ./ 1 t~~~Hole N/o. /8

?/8 1. 4760 1058

/ \ \ / :< ~~~Z17 2.7 45-82 10./2

2/6 0.6 3526 /023

2/5 /5 4908 //

2/4 2.8 33.42 782

0/3 50 3845 9.73

2/2 50 4784 /006

2// I.2 3958 9.40

M 2~~~~~~~~/0 0.8

209 30 3970 9./S

?08 3 6 3858 9.1 7

207 30 3522 9P09

/O 0 /0 Z0 30 40 206 /O Z//G 7.87

\Alff cr G",/d,

Figure 4. - Plan of Reef mine outcrop.
' _

I I Na P,-on7 To ~~~~~~Let'gh 6rf 0

XI § \ \ / 4065 4087 22 3424

z 4087 4/06 /9 8.93

0 1 1 3 4422 4445 2.3 2023

\b 14 48419 4869 20 43/

5 \4869 4864 /.5 3435

6 4884 4918 34 //30

7 530 53/0 /.0 93/

1554\6' 5600 52 88

9 15600 56/.8 15 /9 55

0 50 /00

Scale in Feet

Figure 5. - Assay section, Reef mine outcrop.
No

017 fie No -zo. Noz

IZIO

OF

6 '60

'59 70

14

71

zi

zz

Ai20

50

Figure 6. Assay plan, deposit No. 10, Claim Point, Alaska.
Trench Sompe Leln7/;7C0 F Tenc Sonpie7 C- 0Fe

Nlo. No. FeeA' fCz __ No: Ao. Feet Cr2__ 03

/9 4.5 /492 6.90 269 5.0 4142 6/ 7

37 5.0 /20 268 2.2 49.4 903

38 _ 094 _U/PF 267 47 3200 750

I0-A 33 __f83 v 6/8 Z 266 2.! 2050 6./7

34 6.17 6.39 265 .42 /206 5./6

35 v 834 623 264 50 Z8.96 7.40

36 _ 0Q92 Z63 40 4546 92/

/ 3 2058 754 27 -50 /256 652

/7 _ Z096 7 7Z /0-C 26 1 /572 6.48

/6 v 21/9 73/ 25 2388 7.38

/5 2286 768 259 /.7 /460 6.70

/14 _ 2-TO 750 258 50 2063 6.85

/3 _ /6.70 7/2 257 4.0 2604 72/

/0-8 / 29.7/ 777 256 ? 2853 7 74

/1 /___ 3762 854 255 35 38 79 836

/0 34/8 789 Ba.FJ 2574 50 2673 7 43

9 28/0 782 #/A 253 /.0 0 890 563

8 .45 3/07 78/ 252 50 /636 6.68

7 s0 /624 6.92 25/ _ /205 793

6 55 Z82/ 8.46 250 27 2207 7/0

/75 50 26. 70 _249 Z9 3603 838

/74 209/ 246 _ /280 6.04

/3UPf / 73 /336 _ 247 2.5 4/196 8J95

#4 /72 _ 37Z4 . 246 /0 2/83

/7/ _ 397 53 35 /085 6.09

/70 v 4 12/ /G 52 4.0 2/96 6.68

/69 /.5 /1.62 6.38 5/ 42 /259 6.34

/68 2.0 747 5,50 50 33 /72 523

/0-J /6 7 40 927 55 50 39.62 802

/66 so0 /137/ 624 56 v 2980 7.37

_ /65 40 1/ // 57 v 36/8 757

293 /.5 2963 7. A2I 56 2786 728

292 50 -25.58 7./5 59 v 24 23 829

29/ v 29/0 756 60 /14z 5 75

8UFF Z90 _ 2874 723 6 / 5 356 530

*3 289 v 2068 652 _62 5 0 860 587

288 23.98 703 /64 -/475

287 v 2256 708 /63 - /29/

Z86 2.5 3054 782 /62 v /3.00 558

265 -40 5066 /060 AD/IT /161/ / 703-

274 1.8 261 8 EXT /60 - 2090 694

273 2 Z2370 /59 3.0 9/6

9WASWF 272 50 /8164 ' 1568 45 2402 76/

# 2 2 7/ _ /51I481 I /57 / 0 126.90

270 _ 40_8_ 829 I__ /56 50 2406 7.42

Figure 6a. - Assay data, deposit No. 10.
Trench Sample IeRnh cr2 03 Fe MO ___v Oee7' __ _ __

70 40 /236 5:65

69 1.5 /3.42 542

68 45 /538 674

67 _ 6.66 396

66 30 /268 5 49

65 40 /628 574

64 50 /3941 565

63 47 /208 6.03

/0-0 3 2 50 2558 756 /0D31 - 36.78 88/

30 v 3324 758

29 _ 2787 778

28 53 30/.4 6/C

24¢ 50 35 /8 858

54 30 /182 57/

23 50 2388 692

22 ___ 2368e 7/2

2/ _ 2/32 6.97

20 _ 858 530

73 - 2090 559

72 29.74 685

7/ S /696 574

47 v 2/34 6 74

/0-E >46 __ /436 6.1

v 45 w 224.; 6.92

44 v 9.94 6.09

43 - 2820 7/8

42 4 /e96 6.83

41/ v 2O.70 6.68

236 - 3928/265

235 _ Z722 /0/2

234 _ 2437/149

/0-F 233 ~' 2498 /1/3 232 V 2887/033

23/ ' 624 830

230 ' /988 777

-229 2.0 3796 860

/0-H 49 50 /522 626

Fiue ssy 20/7 7.00

Figure 6b. - Assay data, deposit Nio. 10.
Hole Alo__ ____No. /

2 245 30 /4/

0 50 /00 3 255 /0 7/2 546

5c/ ' e? 285 30 /4/

5 36 2 7 7 239 562

6 385 2.3 /24/

7 448 63s /45

A/o 5 ~8 5/0 6.2 1/0

omple Lei~gA ep~~~h .9 558p48 65/fh

Nomp/c Dep f/ / Cra G 03 Fe /0 608 =50S 8 76

/ /90 1/3 080 // 628 2.0 809/. __

2 290 /0 -1.0/ /2 66.84 40 /55

3 37O0 850 0.66 /3 708 40 /448

4 46 7 8 7 /. 66 /4 758 50 1/42

5 570 /03 033 /5 808 5h0 /268

6 647 77 0.77 /6 853 45 /266 577

7 740 9.3 /08 /7 904 5/ /649

8 6.50 I/O 085 /_ 8 949 45 /435

9 949 9.9 075 /9 97.8 249 /66

/o /040 9/ 078 7 36 20 /02 5/ 297

/ //1/2.0 /00 0.7 2/ /079 50 /54 785

/2 /240 20 6.34O/O 22 /67. 95 /76

/3 /250 / 0 40684 23 /250 76 /.50

/4 /358 08 124 / 85 /270 2.0 3590

/5 /474 /176 280 7725 /2.7 27 577 5

/6 /574 /00 07 26 /436 /39 / 70__

7 674 /90 068 27 /533 9 7 18

/8 /760 86 368 28 /633 /00 077

/9 /81/ 5/ 985 7 / 0729 70 8. 7 9

0 1/898 817 76/ 30 /825 /05 1.08

2/ 12004 /06. 6 3/- /898 73 086__

22 /015 /1/ /08 750 S 2020 /22 070 6.48

Figure 7. - Section B-B, deposit No. 10.
/e/ev /00

A__. N0o. 2

\ 1/ss / 2.8 07/

\> 2 14.9 6.4 /. /9

0 50 /0 3 Z9.3 _4_ /.65

i17 rcale Fee;~' .4 33.2 39 /167 573 Sca/c in Feet 5 40.0 6.8 /47

6 503 /03 095

~ /a6 __7 568 6.5 32

% 3 59.-325' 726 _

/hIen/ ep C 03 9e 9 635 42 2 _Z

2 56.0 98 /.05/ /_ 68 712 850

2 3520 s9 /.05 / 712 13 750 ___

3 450 /00 /02 /2 80.3 9./ 36/ 5/8

4 526 76 5224 13 903 /0.0 /000

5 572 .48 /142 /41 /003 /00 .000 700

6 627 53 204 /5 //00 9.7 2464

7 7/9 9.Z 1/8 /6 //5.0 50 /700

8 772 53 368 /7 /200 v ZS.35

9 874 /02 364_ /8 /Z50 _ 1_15

/0 974 /0a3 2/0 /9 /329 79 /58

1/ /084-. /5 7 /0o8 20 /43/ /1.2 /0/

/2 /ZO0 /16 /02 2/ /48.5 54 97/

/3 /300 /00 2.70 594 22 /569 8.4 6.02

/4 /41 // /1/ 092 23 /67.3 /104 1/

/5 /475 64 /73 24 / 752 79 /24 733

/6 /53:4 5 9 /930 25 /8/ 3 6.1 /123

/7 /583 49 24.68 26 /866 53 /245

/8 /642 59 /01/ 27 /974 /08 072 575

/.9 /700 58 332 Z_ 2 074 /00 00 _s _

20 /765 6.5 6.40 29 2/78 /04 0

2/ /8/2 47 690 30 28.8 //0 0.92

22 /844 3.2 455 3/ z390 /02 088

23 /930 66 /34 32 2443 53 /./0

24 203/ /0/ /./7 33 255/ /08 089

25 2/5/ /20 /56 34 2655 /0.4 / 20 795

26 223/ 80 078 ___ 35 276.0 /05 065 579

27 233.2 /0/ /.1// 36 286.4/04 .980___

Figure 8. - Section A-A, deposit No. 10.
scole in Feet

A/o. 7 /N 3 _ _ 

. O_ 5___ C/Z 03 Fe NAO _ C_ 03 |_ e

/ 2/.0 /00 2.54 / 328 /00 /3/

2 31.4 /0.4 3.0/ 2 38 2 54 850 540

3 395 8/ 283 3 437 55

4 450 6.7 /47 4 537 /00 2/6 6.52

5 46.2 1.2 964 5.48 5 623 86 167

. 6 50840.6 930 6 67.4 -5/ 945

7 623 /15 243 7 720 .46 /204

.6 72.0 97 084 8 76.8 48 /754

9 775 5:5 432 9 820 52 /800 _

/0 890 /15 /49 /0 865 45 /477 5 76

// 996 /06 465 // 9/5 50 963 _

/2 /048 52 /0 83 1/2 948 33 2452

/3 V/09 8./ 85 /3 998 50 /51/54

/4 /130 /0/ 4 7/ /4 /050 52 /160 709

/5 /280 50 /232 6.97 /5 t/164 /1-4 4 70

/6 /330 v /2/6 /6 /26 7 /03 294

/7 /380 v /362 /7 /3/8 5. / /497

/8 /430 / 903 /8 /368 50 1593

/9 /4680 2293 /9 /4/48 - 3227

20 /530 v 365 20 /46 3425

2/ /580 v 20 73 2/ /527 5.9 2075

22 /630 v 2/17 22 /577 50 /3128 2

23 /703 73 588 23 /640 63 576 54/

24 /755 52 682 24 /7/8 78 584 800

25 /05 5s0 840 6.08 25 /822 104 2929_

26 /895 90 6 39 ____26 /874 52 /58

27 /9/8 23 2844 9 90

28 /958 40 500

29 2058 /00 /85

30 2/58 /00 I/ 7

-3/ 22/0 5:2 092.

Figure 9. - Section C-C, deposit No. 10.

Figure 9. - Section C-C, deposit No. 10.
0 50 /00 5 -/1 07 Cr2 0,

MM3f X O1 f Cr-z O or 5co/e /r7 Feef lZ C

ANo. 86

NO/epfh LeC/rz 03 tce

/ 280 /27 086 A/_o. 4

2 380 /00 079 o6mp. e Deop7 h LehgtM Cr Fe

3 .477 9 7 065 ___NO. Len9 cr0- Ae

4 585 /08 080 _ / 326 /06 076

5 685 /00 085 2 45.6 /30 09/

6 785 /00 /2zo0 _ 3 58o /2.4 086

7 802 /.7 4 590. /.0 126

6 903 /0/ /00 8.12 5 615 25 979 635

9 /003 /0.0 / 8Z 6 693 78 226

/0 /106 /03 //0 7 793 /00 /30

// /206 /00 /63 8 893 /00 566

/2 /306 /00 /32 9 95.0 57 /2 74 7 75

/3 /406 /00 /50 /O /0/8 6.8 /096 650

/4 /473 67 /0/ 1I /077 5_9 1/63 6.76

/5 /553 80 /2/3 762 /2 1/28 5./ /263 649

/6 1575 2.2 628 855 /3 /178 5 0 2240 7/6

/7 /620 45 875 6.9/ /4 /228 50 2,4.48 740

/68 /644 2Z4 /868 736 /S /26.0 32 Z389 860

/9 /678 2 7 /092 839 /6 /342 82 /754

20 /730 5.2 /6.35 /022 /7 /45/ /09 8.82_

Z/ /764 34 /058 83/ /& /545 9.4 .448 __

2Z /8/4 50 /1196 729 /9 /638 89 /248 11.4/

Z3 /814 3.4 778 6.76 20 /684. 50 /753 6 98

24 1894 46 167.4 770 2/ /734 50 226/ 840

25 /944 50 /6./3 76/ 22 /784 50 2262 8.07

26 /970 2.6 2740 89e 23 /608 2.4 21/5 940

27 /994 5:0 753 24 /836 28 376 760

28 2085 9 / 065 25 /940 /04 7.43 763

29 2/35 50 /50 26 2030 g0 21/

30 2/85 50 t8/2 2 7 2080 50 /83

3/ 2280 95 1.13 28 2/80 /0O 194 .

Figure 10. - Section D-D, deposit No. 10.
Hole Ao. 7

/Ho/e /o /3 _ 0 /j E£ev /00

o!) -- I -/O 7 -

50mple~~~eo;~~1- lhr20 LLe 'l. , 2i5/ 

N/O Dewfh t'7 Crz 03 ffiC \ Oe0

No L360 C-2 03/ \Fe

2 0 747 7

3 .40.0 /0 .7.47 Oool~0,

.4 .430 25 /350 Geo/og/c Orc

5 499 6.9 406

6 574 85 /34

7. 673 99 /83

8 776 83 /36 0 50 /00

9 879 /03 529

/0 /36.0 48.! /26 Scole In Feet

I i /380 2.0 /1370

/2 /480 /0.0 2/2 /1/O /7

/3 1533 53 222 ~ oe -7lql 7

14 /168 88 / 76 = C Opf/Le7g//?Cro 3 Ce

/5 /656 38 220 / 245' /00' 070

/6 /680 24 /440 2 345 /0 087

/7 /706 26 /440 3 4,47 /02 084

/8 /806 /00 708 4 523 /00 208

19 /856 50 /6.28 6.96 5 547 24 /4/6 6.96

20 /906 50 /605 6.62 6 648f /0/ 209

2/ /954 48 /4193 6.88 7 748 /00 /.58_

22 2005 5/ /986 748 8 848 /00 /35 _

23 2049 44 787 9 950 /02 / 2/

24 2/49 /00 199 /0 /050 /00 /29

25 22/9 70 080 1 ///0 6.0 208

26 233- //4 647 /135 1/2 2.5 /086 6.65

27 2430 9 7 /530 743 /3 1/176 4.4 236 6.27

28 246f5 55 /498 /4 4 //85 0. 9 /2 s.86

29 2559 79 /890 /5 /235 50 ///3 6.50

30 2590 31/ /8/6 /6 /243 08 92/ 6./6

3/ 2640 50 2480 762 /7 /26.7 24 32.6/ 777

32 2740 /00 - 730 6.00 /8 /285 /.e /153 6.60

33 2790 50 2205 722 /9 /335 50 /9768 727

34 2893 /03 /33/ 20 /390 55 686 646

35 2993 /00 762 2/ /492 /0.2 4 43

36 3093 /00 /I90 22 /15/ 89 4204

Nto Samp/e takev 370 -390od 4o42a 5'

Figure 11. - Section E-E, deposit No. 10.
30 5661

2700,N

153 t~~050tO

_________________________ C, ______________________________~ej

Figure 12.- Assay plan, deposits Nos. 7, 8a, and 8b.
Trench Saple eLi// Cr Fe

NO. NO. .Fe

297 2.8 /742

H 298 50 2042

299 / 734_

200 30 649 5.68

. /99 50 /9/9 6.75

Uj /98 v /032

/97 s/1

/96 'v /I333

302 2.7 3005

Z 30/ 5o0 3T5041

262 v /736

228 3468 795

N 227 2685

226 24.04 7Z/

224 2320 700

MW 223 36 72 809

222 1 /6/8 649

220 228 8 732

21.9 2/192 6.8

204 5.5 84/

203 5s0 2005

K02 - 207 1 

20/ 1/97

260 1543

1 16/89 /9

Figure 12a. - Assay data, deposits Nos. 7 and 8a.
.rench SlmpL im Cr 2

0 Trer7c S ple Le/?1Fe Cr2 0 Fe

NO NOc. A__ o.Nlo. ____

/43 5 0 3436 742 /02 40 2894 785

/42 v 3083 743 /0/ 3244 8 /2

1/4/ /04 1 6.26 /50 50 /35 488

B /40 v_ z95s9 707 /49 2.5 300 589

/39 -35 /0/8 599 /48 -/742 708

/38 50 /47 /47 v /729 568

/37 4.0 899 64 4 /46 v/354 65/

/36 50 /994 697 /45 2547 662

/35 v- /-48 7/5 /44 /445 6.48

/34 v 539 7/6 F 245 1 /359

/33 v 702 709 244 v 357

/32 /488 742 243 /2.16

C /3/ /798 7 74 242 1 /902

/30 11/265 536 24/ 2036

/29 v 23.44 8/9 240 2920

/28 /.0 2878 8/7 239 v32Z8

/27 5.0 885 6.7/ 238 /228

/26 - 2992 793 237 25 780 805

/25 1/580 7// /95 22 /0o/2 634

/24 3 0 /72 /94 08 398 5:83

/23 50 484 642 225 50 2.93 569

/22 30 /256 66/ /93 v 473 565

/2/ 145 /44/ 7/0 /92 1 /040 559

0 /20 5 0 224/ 638 /9/ v /29/ 67/

1/9 25 4693 958 /90 v/458 6.0/

//8 45 3055 7/5 /89 2 4 /733 723

/7 50 3765 756 /88 40 //58

//6 :40 /897 6/2 /87 50 /294

/15 5.0 243 502 0 /86 v ///8

/14 6 0 /867 59 7 /85 1.5 //22 729

/13 50 /329 5.56 /84 2 848

/12 - /376 559 /83 5S0 /047

/1/ / v /633 6 39 /82 968

//0 35 /.36 483 /8/ v /473 606

£ /09 30 872 587 /80 2/87

/08 4.0 2.2/ /79 v 3030 737

/07 50 2430 585 / 78 3571 /028

/06 -v_ 2329 6.00 /77 _ /856

/05 1 /896 6./2 /76 /5 /322 7/4

/04 40 2028 706

/03 1 /506 6.65

Figure 12b. - Assay data, deoosits Nos. 7 and 8a.
HlecAh{v 150f

0 50 /00

Scale /on Feef

mal DepCh Lenzgh a0 3 Fe

/ ' 9' 5 in 40' 

Z /8.7 9 7 /09

3 240 5.3' 084

4 440 /00 0 74

5 536 06 /300 750

6 64.5 /02 /97

7 760 /05 /80

8 855 /05 205

9 955 /00 /64

/0 /06.0 /05 0 7/

// /160 /00 0 92

/2 /26.0 /00 078

/3 /322 0 3 /1/4 9.60

/4 /459 /04 073

/5 /558 99 099

/6 /658 /00 078

/7 /705 4 2 /037 649

/8 /7// .8 /2.8/ 6.60

/9 /8/0 5.0 1/4

20 /9/0 /00 /04

2/ 20001 9/ /27

22 2092j9 2 /22

23 /891 9 7 1/4

24 2240 5./ /32_

No .5armp/es aroken, 240-340, 440-530, 536-543,

/260-13/0, /32.2-/355, /658-166.3, /705-1723, /741-1760.

Figure 13. - Section G-G, deposits Nos. 7 and 8a.
NO 2_ 0 50 /00

omrp/e Dpf rgf ° ees ~ 0 0eprh Len9/C 1-2 0.? Fe cale If? Feet*

/ 72 72 338

2 /60 8.8 /02 A/O. 9

3 26.! /0/ /4 2 ___ 5P/e70 F

4 34 5 /-5 1132 No p' L,9/ 6 ra 03 Fe

5 360 /5 6.67 6.97 / /52 2.1 374

6 435 / 2 988 6.34 2 /7/ /.9 8.97

7 5/.1 6.9 /37 3 379 26 499

8 60 7 96 /74 4 503 /o.0 /z8

9 683 79 /.39 5 602 99 3/6

/0 7/3 30 /647 748 6 702 32. //.90

// 8.25 3.3 905 643 7 752 50 /421

12 92.7 52 454 595 8 802 50 /773

/3 /08.2 /17 084 9 81.9 /7 /727 729

/4 /182 /00 /4 7 /0 852Z 33 622

/5 /282 /0.0 059 / 9/ 02 50 6.7Z

/6 /332 50 /6.75 6.8/ /2 9525 s. 6.75

17 /362 50 8.53 6.20 /3 /05.3 /0. 372

/8 /482 /00 2.15 /4 1/55 /0 2 77

/9 /582 /// /5 /1236 3.! /949 738

20 /68Z 090 /6 /264 .48 /875 8.09

2/ /782 /08 /7 /334 5.0 489

22 /6882 096 /8 /384 5 0 3/8 _

23 /982 1.06 /9 /474 90 /88

24 /02 1/2.0 oo 0 20 /595 /2./ 1.67

2OS 2205 /00 /15 2/ /645 50 2./9

No 5amop/es taA-eI7

375-42.3 /71-353

435-442 379-403

825-875 60.z-670

Figure 14. - Section F-F, deposit No. 8b.
R. I. 4419

DEVELOPMENT

A forty-foot crosscut has been driven through -depcsit'No. 10 at a, 140-foot

elevation. During the past year a 290-foot cr'sscqt. was driven'from the'site

of the old mill to intersect depoit No. lOati&25-foot olevation.'' S.oe timber was required through a failt~edsection about'. 100 feet from the poital, but

indications are that the rocki wiil,be comperatlvely.!e.ey to mine... The faceo f

the crosscut lacked 30 feet Qf reaching the'ore boundary, as indicated by drilling when operations ceased in, July 1942.:-

SAMPLING AND ASSAYING

Six-inch by one-inch samples were cut at varying Intervals calong the outcrops depending, on the apparent Qontinuity'of the'ore body-and the excavation

work required to expose it, andthe core-drill holes were. planned to intersect

the ore bodies at 80-foot intervals along the strike and 60- to 75-foot intervals in depth. Drill cuttings were collected and assays of cuttings averaged

about 1 percent less than correoponding-^core samples, probably because of

sliming and loss of chromite in overflow. Core and cuttings samples were

split before being sent for analysis, being held at the proJectuntil theassays were received. Core. and-cutting assay s'were combined by the use:-of'the .

E. J. Longyear tables29/ to arrive at the final rade of the ore. All assaying was done at the Reno station'of the Bureau of Mines.

BENEFICIATION.QF,,CLAIM POINT CHROMITtT

Results of beneficiation tests on a sample of chromite ore from deposit

No. 10 indicate that the low-grade ore is amenable to concentration. An

abstract of the report by the Metallurgical Division follows'

*----Wtua of the re- ., d<ur. . ,lre

The ore was of medium grade, and the chromite was disseminated through'-

an olivine and serpentine gangue-. ,The- bulk of `thechromite was-freed by grinding to 48-mesh. However., mfany gangue particles still had chromite inclusions,

and the liberation and separation of this gangue raineral was. the chief problem

in treating the ore. The' particlezs occur in veinl'ts and ore dispersed through

the fracture planes. The 'chemical .analysis of thbe'qre follows : ' '

TABLE 1. - Chemical analysis of the Claim Po'.nt chromite ore

Assay, percent

Cr 2 03 j Fe j SiO2 A12 03 | MgO S CaO ITiO2 I ZrO2| P

28.2 7.7, 19.2 3.2 31.4 , No Tr. 0.05 0.40 Tr.

9/ Jackson, C. F., 6nd Knaebel, J. B., Sampling and Estimation of Ore

Deposits: Bureau of Mines Bull. 356, 1932, 155 pp.

2745
R. I. 4419

Methods of Concentration

A8 the chromite in the ore was uniformly disseminated throughout the

olivine and serpentine groundfass, tabling, magnetic separation, and flotation

appeared to be the most favorable methods of concentration. Although many separate experiments involving variations in procedures and treatment were made,

the following methods were found to be most effective and will be discussed in

detail:

1. Tabling unsized sands from ore ground to all minus 65-mesh.

'2 Tabling sized-sand fractions of ore ground to minus 48-mesh and all

plus 200-mesh table tailings and middlings reground to minus 200-mesh before

finally being discarded as a tailing.

3. Magnetic concentration of chromitefrom sized fractions of ore ground

to all minus 48-mesh,

4. Magnetic concentration of chromaite from sized fractions of ore ground

to all minus 48-mesh, followed by tabling the chromite products to reject the

gangue minerals.

5. Concentration of chromite by flotation methods.

'Detailed discussion of only the most successful of the methods of concentration are discussed in detail in the following abstract.

Tabling sized fractions of ore ground to minus 48-plus 200-mesh,

table tailings and middlings reground to minus 200-mesh

before making finished tailing.

A sample of ore.crushed to minus 10-mesh was ground to minus 48-mesh,

deslimed by decantation, and screen-sized into the following products: Minus

48 plus 65-mesh, minus 65 plus 100-mesh, minus 100 plus 150-mesh, minus 150

plus 200-mesh, and minus 200-mesh sands. These products were then tabled,

and the table rejects were ground to minus 200-mesh and retabled. The results

of this test are shown in table 2. Table 3 gives.the results obtained on a

similar test, wherein.the table middlings were combined and ground to all minus

65-mesh before retabling.

2745 .8 .
R. I. 4419

Table 2. -.Tabling sized fractions of ore, table middlings ground to minus-200-mesh

Distribution Cumulative Cumulative grade, Chromium

Weight, Assay percent Cr 2 03 recovery, -_percent to

Products percent Cr2n3 Fe SiO2 percent percent Cr 2 03 Fe SiO2 iron ratio

Table concentratea ... 43.3 52.8 12.6 3.7 81.8 - 81.8 52.8 12.6 3.7 2.9

Table midd-lings(iuLnus 200-mesh)...... 5.3 25.1 7.0 23.6 4.8 86.6 49.7 12.0 5.9 2.85

Slines............. ..... 9.8 15.6 7.5' 28.3 5.5 - 92.1 44.0 11.2 9.6 2.70

Table tailings(minus 200.mesh). .. 41.6 5.4 4.9 33.7 , 7.9 100.0 28.0 8.6 19.7 _

Heads .calculated 100.0 28.0 8.6o9.7 , 100.0 ' _ - - 2.1

Table 3. - Tabling sized fractions of ore table middlings reground to minus 65-mesh and retabled-

,,,- rDistribution Cumulative Cumu-atvegrade, Chromium

Weight, Assay, percent , Cr2°0- recovery percent * to

0 Products - pe r 0cent 30 iO2 percent Re~ CF2 percent G r2°3- i i ` ratio

Table concentrates ................ -44.1 51.20 12.3 4.9 80.4 80.4 51.2- '12.3 '49 85

Table middling(minus 200-mesh) 5.3 25.15 7.0 23.6 4.7 85.1 48.4 1L7 7L6.9 '2.83

Slime .. ....... ' 6.0 17.90 8.6 25.8 3.9 89.0 4.a 11.4 9.0 ' 2.71

Table middling -(plus 200-mesh) 5.5 14.14 6.2 31-.6 2.8 91.8 42.3 10.9 11.0 2.66

Table tailing .. 39.1 5.9 4.7 35.4 8.2 100.0 28.1 8 20.5 2.26

Total . X . ....... .-. 100.0 28.1 8.5 20.5 100.0 _ -

2745
R. I. 4419

Discussion '

As is shown in table 2- by tablingsize.d frftctio4s of the ore. plus regrinding of all plus 200-.meph table middlings 'nd-tainings to minufrd 200-mesh

and retabling before finally rejecting a -tailip'g, 81.8&percent o4' the-Cr203

was recovered as high-grade:"concenttetes assaying '52.8 percent COr20, J12.6

percent iron, and 3.7 percent siliea; As the :combined table con cenrates

assay higher than the 45 percent Cr203 spedifiled for high-grade 'chrome: ores,

the middling can be mixed witli -the concentrates and more chromium can 1e :'saved;

the combined middlings and 6oncentrates assayed 49.7 ~percent.CriO3 ''and cofntained

86.6 percent of the Cr203, in the ore. Further, by 'combining the. mid jinis and

slime with the high-grade concentrates,.92.1 percent of the chromi'te .Wes'recovered in a concentrate assyIng 44 percent Cr 0 ,9,6l.2:pefentiror, aiA 9.6

percent silica, or, as isalshown in.table 3, 9;percant 0 of -the'CrC203' wa_ recovered at a grade of 45.1 percent Cr203 , wherein a slightly srimpler. gVin ing

procedure was used; however, it was necessary tolretable the reground mi4dlings

several times to obtain results comparable to the fineri grind. '.These:results

clearly show that the ore rqsponds readily to gravity concentration i~ the

table feed is closely sizedland the middling particies regrounji. before rejecting a final tailing. .

TABLE 4. - Grade of chromite at differett recoveries

..__Cr/F6 _ ____Assa.y, per4ent

Cr cratio SiO2 p- - -

Product min. . min. max. max. max. Al2OA T±02 MgO Cap Fe irO2 ------------- -

Specifications,

high-grade chromic

ore ..... . 45.0 2.50 11. 0.20 0.50! _ . _ - -_

Concentrate plus

middling, table .

2; 86.6 percent

recovery , . 49.0 2.85 5.9 Tr. None 9.7 °r,50 18.2 t'r. 12.0 b.60

Concentrate plus i

minus 200-mesh . :

middling plus

grinding slimes, .:

table 3; 89.0 . ;, . -

percent recovery. 45.1 2.71 11.0 Tr. None '13.8 O,4646.. 4 O 1 52

Cohclusions .

1. The lot of chromi'.te ore' from the Clhim Point property on thel enai

Peninsula was found to be i4eadlily amenable to.the production of high-grade

chromite concentrates by ore-dressing i eatment,

2. The best results were 'obtaineh by tabling sized fractiOns of the ore

plus grinding and retabling middiing-_products-. In this manner 81.8 percent of

the Cr203 was recovered as product aisaying 52.8 percent Cr203; 86.6 percent

2745 -16-
R. I. 4419

was recovered as a 49.0 percent product;_and 89.0 percent was recovered as a

45.1 percent product. All these products met the chemical specifications of

the Metals Reserve Company for high-grade chrome ore, and the choice of grade

would depend on the economic conditions.

3. By tabling the entire 65-mesh ore without sizing, 744.4 percent of the

chromite was recovered as a product assaying 41.5 percent Cr203 and showed the

importance of sizing the table feed prior to tabling.

4. By magnetic separation of sized fractions of ore ground to minus 48-

mesh, 74.0 percent of the Cr203 was recovered as a product assaying 43.4 percent Cr203.

5. By a combination of magnetic separation and tabling of sized fractions

of the ore, 81.7 percent of the chromite was recovered in, a product assaying

49.6 percent Cr203.

6. Neither flotation of the chromite with fatty acid nor flotation of

the gangue with cationic reagents gave results comparable with those obtained

by gravity or magnetic concentration methods.

7. The chromium to iron ratio of the concentrates made from this ore

was very favorable, ranging from 2.7 to 2.9.

2745 -11-