R. I. 4349 SEPTEMEER 1948

UNITED STATES

DEPARTMENT OF THE INTERIOR

J. A. KRUG, SECRETARY

BUREAU OF MINES

JAMES BOYD, DIRECTOR

REPORT OF INVESTIGATIONS

.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~4 4-

DIAMOND DRILLING AT RUSH & BROWN COPPER MINE

KASAAN BAY. PRINCE OF WALES ISLAND

SOUTHEASTERN ALASKA

/~~~~~~~~~~~~~~~

my

S. P. HOLT, J. G. SHEPARD, R. L THoRic

A. W. ToLoNEN, AND E. L. PossE

i? i
R. I. 4349,

September 19048.

REPORT OF INVESTIGATIONS

UNITED STATES DhPARIMENT OF THE INTERIOR - BURFEAU OF MINES

DIAMOND ERILLING AT RUEH & BROWN COPPER MINE, KASIAN BAY,

PRINCE OF WALES ISLAND, SOUTHEASTERN 1S,

By S. P. Holt,2/ J. G. Shepardl/ R. L.,Thorne,4 -

A. W. Tolonen,4/ and E. L. Fosse2/

CONTENTS

\ ~~~Page

Introduction and summary.................. 1

Acknowedgments.. 2

Location and accessibility................ 2

Physical features and climate ............... 3

History and production . .............. .. 3

Property and ownership ,,., .... .. 3

Ore deposits ......... , , ,.,.i ..,, 4

Magnetite ore body .. . ............ 4

Shear zone ore body.,..............._ 4

Development.............5.......... 5

Investigation by the Bureau of Mines ...... 5

ILLUSTRATIONS

Following

Fig. -page

1. Index map showing location of Rush & Brown mine.......... 2

2. Kasaan Bay and vicinity... *............* .......... .. .. .. 2

3. Location map, Rush & Brown minen.............. 2

4. Plan of Rush & Brown mine.... .............. ...... . ... , , 6

5. Longitudinal section and assay map, Rush & Brown mine..... 6

INTRODUCTION AND SUMMARY

The Rush & Brown mine has been one of the most consistent small producers

of copper ore in the history of Alaskan mining. Approximately 50,000 tons of

ore have been shipped to smelters from the property. Production has been made

from two distinct and separate ore bodies of dissimilar types. The Shear Vein

The Bureau of Mines will welcome reprinting of, thid paper, provided the

following footnote acknowledgment is used; "Reprinted from Bureau of

Mines Report of Investigations )349."

2/ Mining-engineer, Juneau, Alaska.

3/ Senior mining engineer, Juneau, Alaska.

I/ Associate mining engineer, Juneau, Alaska.

5/ Assistant mining engineer, Juneau, Alaska.

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R. I. 4349

deposit has been mined to a depth of 500 feet below the surface without a

reduction in the size of the ore shoot or the grade of ore. The Magnetite

ore body has been partly mined to a depth of 200 feet below the surface.

Because of the favorable production record of the Rush & Brown mine, the

present need for copper, and the fadt"that the'owners were attempting to place

the mine in production, it was deemed advisable to investigate this property

under the Strategic Minerals Act of'1939 as a possible source of copper.

In August 1943 the Bureau drilled four diamond-drill holes, ranging from

36 feet to 155 feet in length. The purpose of the drilling was fourfold.

1. To explore the lateral extension of the Shear Vein system.

2. To explore lateral and vertical extensions of the Magnetite ore

body.

3. To explore for new ore bodies in a second shear zinc which was

indicatedby geologic structure.

4. To unwater the mine to'the 200-foot level, by means of one of

the drill holed.

Maps showing the location of the drilliholes, drill-hole logs, and sample

analyses accompany. this report..

ACDNOWLErDGMENTS

Special mention is made of the information and assistance obtained from

A. L. Howard, president of the Alaska Gold & Metals Co. Howard's report on

the Rush & Brown mine and his records of the Solar Development Co,, previous

operators of the mine, were extremely helpful to the Bureau of Mines.

LOCATION AND ACCESSIBILITY

Figure 1 is an index map of Alaska showing the position of the Rush &

Brown mine. Relationship to other mines in the district is shown on figure 2.

The Rush & Brown mine is at longitude 1320 35' W. and latitude 550 37' 30" N.,

near the head of Kasaan Bay, Prince of Wales Island, southeastern Alaska, about

45 miles from Ketchikan (fig. 3). It is about 1 mile from the tidewater of the

Salt Chuck, a lagoonlike arm of Kasaan Bay which is navigable by barges and

shallow-draft boats at high tide. A fair, nearly level trail 1 mile long

leads from the Salt Chuck to the unfinished tunnel. Ore was formerly transported 2-3/4 miles by surface railroad to a deep-water harbor, known as Rush

& Brown Harbor, at the head of Kasaan Bay. This railroad has completely doteriorated, except that about 2 miles of 16-pound rails remain.

A small mail boat calls'once each week, This boat carries mail, freight,

and passengers and is based at Ketchikan, the nearest source of supply. The

regular steamship lane of the inside passage is within 25 miles of the property.

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Fg I n m oA k o g a o R & B mine

'Figure 1. -Index map of Alaska showing location of Rush & Brown mine.
.56 I

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6 J~~~~~rnbo %5co/e in Mi//es~~~~~~~~~~~~OJr

Figue 2 - asa Ba ndvciiy
I Xf5a/ t Chuck Mine I Iush5a7 et &rion 5o/t Chuck Mill

* Abandoned narrow

gau~e~cqri/roatd Mine rXl /0 am Ad,', 5By |

efig-j aed bn4k

Figuep 3 ocation Trne.

,~~~~cl in Mile

132' At 541-

Figure 3. - Location map, Rush & Brown mine.
R. I. 4349

PHYSICAL FFATURES AND CLIMATE

The property is in a low, thickly timbered area having a dense ground

cover of underbrush. Outcrops are at an altitude of about 400 feet.

Climate in the area is similar to that of Ketchiken, Alaska, winters

being mild and summers cool, with about one hundred forty inches of precipitation a year. Considerable snow falls from November to March, and zero

temperatures are rare. Operations may be and were carried on throughout the

year without difficulty.

HISTORY AND PRODUCTION

The original location of this property was made by U. S. Rush and his

partner about 1904. The Alaska Copper Co. leased it for a short time and

shipped some ore to the company smelter at Copper Harbor on the west coast

of Prince of 'Wales Island. This lease was dropped after the smelter ceased

operations. The property was operated intermittently by Rush until 1926,

when it passed from his ownership. The original owners did all mining by

hand methods. Their operation necessitated handling the ore six times after

breaking and before handsorting. From the mine bin the ore was trammed to

lower bunkers at the head of a 2-3/4-mile trestled railroad leading to bunkers

at the Rush & Brown Harbor, near the head of Kasian Bay. The ore was then

placed aboard ocean steamships and. taken to the smelter. The owners never

could accumulate enough cash reserves to modernize equipment and methods.

The following data were assembled by A. L. Howard, president and manager

of the Alaska Gold & Metals Co. The Magnetite ore body produced approximately

35,000 tons of ore containing 3.25 percent copper, 0.06 ounce of gold, and

0.25 ounce of silver a ton. The owner's records show that there was shipped

from the Shear Vein deposit 9,700 tons of sorted ore averaging 10.5 percent

copper, 0.26 ounce of gold, and 1.60 ounce of silver a ton. The ore from

both ore bodies was hand sorted.

During 1929 the Solar Development Co. optioned the property. It pumped

out the workings and sampled the ore remaining in stope pillars and walls and

also sampled the bottom level. An adit tunnel was then started. This tunnel,

which was advanced 1.250 feet from the portal, was designed to meet the inclined shaft near the 300-foot level. The tunnel was driven to within 180

feet of its objective. The purpose of the tunnel was to provide a permanent

-haulageway for mine production, to provide permanent drainage above the

300-foot level, and to explore the territory along the projected route. A

diamond-drill hole was drilled from the tunnel, the hole bearing northwesterly

and at an angle of minus 460. This drill hole was intended to intersect the

shear zone about 300 feet east of the present workings. It was drilled 299

feet without encountering ore. The map would indicate a change in tho strike

of the shear zone, and the drill hole may have cut through the zone in a

barren area, as it terminated in intrusive rocks.

PROPERTY AND OWNERSHIP

The property consists of four claims and two mill sites, all unpatented,

the title to which is held by the Alaska Gold & Metals Co.

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R. I. 4349

ORE DEPOSITS

The ore bodies lie in contact zones between diorite intrusives and greenstones. They are of two types - a contact metamorphic deposit of magnetite

containing chalcopyrite and a vein type containing sulfide minerals in a tabular ore body within a shear zone.

Mineralization in both types consists of chalcopyrite with associated

gold and silver. Gangue is principally metamorphosed greenstone, with associated magnetite, pyrite, quartz, calcite, garnet,'and amphibole. The contact

replacement deposit contains very much more magnetite than the Shear Vein

deposit.

The contact metamorphic deposit, an irregular mass of magnetite enriched

locally with disseminated chalcopyrite and pyrite, has been named the Magnetite

ore body. This deposit is cut by numerous basic dikes and horses of country

rock. About 160 feet north of the Magnetite ore body a shear zone exists,

which contains a tabular sulfide ore shoot called the Shear Vein ore body.

Same faulting and cross fracturing occur. The faulting, however, was not

complex and was easily solved. At least one other parallel shear zone is

known to exist.

Magnetite Ore Body

The contact metamorphic Magnetite ore body, having been discovered first,

was the earliest to be put into production. A glory hole was started and

mined to a limited depth. Numerous hard dikes and horses of country rock

were encountered. Since the operators were mining by hand methods, single

Jack and hand steel being used, this feature, as well as the fact that copper

mineralization was not uniform, made profitable mining questionable. The

operators made an estimated production of 35,000 tons of ore from this deposit,

containing 3.25 percent copper, o.06 ounce of gold, and 0.25 ounce of silver

a ton.

The ore body was drained to the 200-foot level by a Bureau of Mines drill

hole and an examination made of the old workings at the 100-foot level. Ore

was found remaining in large pillars and as a shell around the perimeter of

the old glory hole.

The old workings showed that the lateral limits of the main ore body had

been reached and that only small veins extended any distance into the walls.

Bureau of Mines drilling confirmed the opinion that no ore extended to the

west on the 300-foot level.

Shear Zone Ore Body

Upon the discovery of the Shear Vein ore body, mining was centered on

this ore shoot because of its higher topper, gold, and silver content and

greater- regularity. A drift was driven from the 200-foot level to the Shear

Vein. The shoot was developed laterally and stoped through to the surface.

Some ground above the 200-foot level remains unexplored. Maps and other

2490 -4..
R. I. 4349

information would indicate that the ore'eabct was about 200 feet long, with an

average width of 4 feet, The ore on the 500-foot level does not appear to

have diminished either in grade or size from that mined in the stopes above.

DEVELOPMENT

Shortly after discovery of the Magnetite ore body, an open pit or glory

hole was started. This method of mining was followed to a limited depth.

Subsequently a 200-foot vertical shaft was sunk just outside of the ore body,

and ore from the bottom of the glory hole was mined by means of short V-cuts

and raises and hoisted through this shaft to the surface. The drifts and

raises were not timbered and are reported to be in good condition. No maps

are available of these workings, but they are'known to be rather limited. No

exploration was carried on outside the glory hole.

The Shear Vein deposit was developed by cross cutting 165 feet from near

the shaft on the 200-foot level. After encountering the ore body, drifts were

driven along the vein until the grade of ore was below the economic cut-off.

An inclined winze was sunk along the dip of the Shear'Vein to the 500-foot

level, and levels were opened at 50-foot intervals. These levels were extended

beyon4 the confines of the oreshoot. The greenstone walls stood well, and

very little timber was used beyond an occasional stull. No serious faulting

was present, and the mine made very little water. The stopes were left open

and were 4 to 12 feet wide. Blocks of ore considered low grade by the owners

remain in place. It is reported that in 1929 the open stopes could readily

be traversed.

INVESTIGATION BY THE BUREAU OF MINES

At the time of the preliminary examination, reliable records indicated'

that a considerable tonnage of ore could be obtained from the Shear Vein ore

body. Records of the Magnetite ore body were incomplete, but its past production suggested that marginal ore might be left in the old workings and also

that a small amount of exploration was justified. The old workings were filled

with water during the preliminary work.

A program of drilling was laid out by the Bureau of Mines to accomplish

the following:

(1) To explore the lateral extension of the Shear Vein system for

new ore shoots

(2) To explore for lateral and vertical extensions of the Magnetite

ore body.

(3) To explore for new ore bodies in a second shear zone which was

indicated by the geologic structure.

(4) To unwater the mine to the 2QO-foot'level by means of one of

the exploratory drill holes.

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R. I. 4349

Four drill holes, varying from approximately 36 feet to 155feet in

length, were drilled, for a total footage of 431 feet and 7 inches. No ore,

or favorable indication was encountered in any of the holes.

The locations of holes drilled. by the Bureau of Mines and the Solar

Development Co. are shown in figure 41.. A longitudinal section and assay

map of the Rush & Brown mine is shown on figure 5, and. the analyses are

given in table 1.

TABLE 1. - Assays by Solar Development Co.

\ Vein Ounces Ounces

Sample width, Cu, a ton Sample width, Cu a ton

No. feet pecnt Ag- Au No. feet percent Ag Au

1 1.06 Tr. 2r. 37 1 .64 .10 0.02

2 3 2.54 0.46 o.o6 38 3 .52 .14 .02

3 2 8.48 1.40 .32 39 3.5 .90 .31 .03

4 3 4.31 .84 .o6 40 3 1.06 Tr. .03

5 2.5 1.72 .54 .04 41 2 .38 Tr. .02

6 4 .98 .24 .02 42 2 .75 .19 .05

7 2 2.73 .. 55 .13 43 3.5 1.00 .19. .05

8- 1.5 4.80- .94 .36 44 2.5 1.90 .48 .02

9 2.5 3.90 1.02 .26 45 2 3.74 .62 .22

10 3 1.41 .44 o6 46 2 8.08 2.44 .22

11 3 1.00 .43 .05 47 3 7.02 1.24 .26

12 5 .22 Tr. Tr. 48 1.5 >,5.21 1.40 .24

13 3 6.72 1.45 .19 49 2 8.02 2.23 .17

14 2 16.24 2.80 .26 5o 5 1.74 .54 .10

15 2 5.36 .9 .27 51 7 5.12 1.28 .o8

16 :1 5.98 1.47 39 52 2 2.76 .80 .16

17 4 .72 .19 .05 53 3 1.70 .10 .03

18 4 2.00 .54 .o6 54 2 8.41 .87 .05

19 4 4.96 .87 .05 .55 3 .58 Ir. Tr.

20 4 1.86 .52 04 56 6 1.04 .10 .o4

21 5 4.92 .65 .09 57 6 3.76 .85 .09

22 2 6.78 .66 .30 58 5 3.94 1.04 .10

23, 3 .74 .20 t.02 59 1.5 10.06 1.6o .10

24 2 4.15 .76 .40 60 4 4.79 1.16 .o8

25 3 8.54 1.41 .21 61 4 2.00 .66 .o6

26 3 2.86 .53 .37 62 2 7.16 2.00 .30

27 2 7.40 1.40 .1e, 63 4 5.02 .81 .09

28 4 8.26 1.56 ,32 64 2.5 3.94 .73 .17

29 4 10.-0 1.66 .14 65 5 3.28 .74 .22

30 4 8.81 1.46 .10 66 2 .87 .12 .04

31 2 ,38 .17. .03 67 3 .14 .14 .01

32 3 .42 .14 .o4 68 1 11.72 2.o8 .02

33 3 84 .17 .05 69 3 6.88 .82 .20

34 3 1.08 .18 .02 ! .7O 2.5 3.14 .52 .20

35 3 5.98 1.25 .19 1 71 4 3.52 .43 .05

36 2 1.15 .34 .02 ¶ 72 2.5 2.20 .27 .05

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Figure 4. - Plan of Rush & Brown ine.
Aoe: Tracing ft-m moo, marked-

';qash b, Crowr, 7in*e Compojss5urvey.

.Sam/-,o/g ai1d 0ssay/n9 by 5o/rDeve/oomenf4 Co. /, /930.

5ee Assay 7-ob/e for- ossays.

_ -- GLORY HOLE (Dhd)

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FAVORABLE ZONE FOR ADDITIONAL ORE j

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T ~ O lie~~~~~~~~~~~~~lT e rJ 40 ' .BOCK'F' X f

5CALE fIN FEET (4a0)

Figure 5. - Longitudinal section and assay map, Rush & Brown mine.
- R. I. 4349

TABLE 1. - Assays by Solar Development Co. (Cont'd.)

f Vein Ounces Vein Ounces

Sample width, Cup a ton Sample width, Cup a ton

No. feet percent Ag Au No. feet percent Ag Au

-19 1.5 7y18 1-.31 0.11 105 1.5 1.32 -- 30 0.35

74 3 4.60 .70 .14 1o6 .9 13.78 1.90 .56

75 3 3.66 .77 .09 107 .36 Tr. .02

76 1.5 9430 1.79 .11 1108 3 .34 Tr., .01

77 3 2.91 .78 .o6 119o 2 .20 Tr. Tr.

78 4 1.96 .36 .o4 ilo 2.5 22.88 3.55 .09

79 2.5 4.10 ! .88 .28 ,in 2.5 1,78 .10 .04

80 3 9.36 1.19 .13 112 1 .37 .16 .02

81 6 .06 Tr. Tr. 113 5 Tr. Tr. Tr.

82 4 .18 Tr. Tr, 114 4 .48 .10 .01

83 4 .11 Tr. Tr 115 1 .36 Tr. .01

84 | 4 .12 Tr. .01 116 2 Nil. Tr. Tr.

85 4.5 2.56 i .86 .14 117 3 Tr. Tr. Tr.

86 4 5,64 .96 .24 t118 4 Nil. Tr. Tr.

87 4.5 5.50 1.14 .30 119 5 2Tr. Tr. Tr.

88 5 11.18 1.42 .16 1120 3 ,67 .lo .01

89 4 4.15 .87 .25 :121 3 .20 Tr. Tr.

90 4 14.32 2.10 .18 j122 4 g.77 .62 .14

91 4 7.42 1.32 .30 123 3 2.19 .40 .12

92 4 1.95 .30 .04 124 4 1.60 .30 .o4

93 3 .96 .28 .02 125 3.5 1.72 .10 .o4

94 2 4.6o .59 .17 t1126 0.5 7.36 1.66 .20

95 2.5 I 20.05 1.86 .12 11127 4 1 64 .40 .o8

96 3 5.58 .64 .14 Ij28 4 Nil. Tr. Tr.

97 3.5 3.58 .54 .26 I I

98 2.5 6.42 .82 .o8 i | Bureau of Mines

99 2 5.02 .50 .161

100 1.5 3.80 .86 .14 133-34 5.0 0.82 0.03

101 Fw 3.48 .29 ,17 S147 I 3.0 .07 .07

102 5 2.08 .76 .o4 s s162 2.0 3.54 .10

103 8x6 1.86 .34 .10 S246 3,5 .49 .02

104 ! 1.5 2.95 46 .o6 lS26 3.0 .18 .102

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