LODE MINING IN SOUTHEASTERN ALASKA. 39 
DOUGLAS ISLAND. 
With the mention of Douglas Island attention is naturally directed toward the Treadwell 
Troup of mines. Its geologic features and manner of operation have been discussed at 
length by A. C. Spencera and by Supt. R. A. Kinzie, b to whose papers the reader is referred. 
At the Treadwell mine the main shaft has been sunk to a depth of 1,2.50 feet, from which 
point a working level is being started. An interval of 200 feet has been established between 
;his level and the one above, the 1,050-foot level, and in the future in these deep workings 
;his distance between levels is to be maintained. On the 1,0.50-foot level but little change 
vas observed on the ore body, with the exception that the slate horse prominent in the levels 
ibove has diminished to a width of 10 feet. The floor level of the open pits is now 600 feet 
)elow the surface, but owing to the weakness of the slate foot wall this method of mining can 
lot be employed much farther in depth. The cost of extraction from these open pits at pres- 
ent nearly equals that from the large underground stopes. The annual report for the year end- 
ng May 31, 1905, states that a total of 876,234 tons of ore was milled during the year, yield- 
ng $1.10 per ton in bullion and $1.18 per ton in concentrates. The total mining and devel- 
>pment expense was 96 cents per ton, the milling expense 15 cents per ton, and the cost of 
reatment of the concentrates 15 cents per ton of ore milled. The total gold production was 
52,007,843. 
At the Mexican mine developments were extended on the 990-foot and 1,000-foot levels 
Lnd the shaft extended to a depth of nearly 1,200 feet below the adit level. The annual 
eport for the year ending December 31, 1904, gives a total of 204,237 tons of ore milled, with 
in average value of $2.97 per ton. The ore yielded $1.39 per ton in free gold and $1.51 per 
on from the concentrates, making a total yield of $661,175. 
At the Ready Bullion mine the shaft has been continued to a depth of over 1,400 feet on the 
ncline and developments have progressed rapidly on the 1,025 foot and 1,200 foot levels, 
rhe yearly report of this mine to January 1, 1905, states that the ore milled amounted to 
96,265 tons, yielding $1.07 per ton in free gold and $1.81 per ton in the concentrates, mak- 
ng a total production of $355,312 for the year. 
Improvements which are of benefit to all this group of mines consist of a 4,000-foot flume 
,nd a 1,200-foot pipe line to bring the waters of Ready Bullion Creek into power-producing 
ise and the building of a large reservoir dam at the headwaters of Fish Creek, the initial 
>oint of the long ditch, thus increasing the capacity of the plant during the season of low 
yater. 
Several mining properties within the drainage area of Nevada Creek, located many years 
,go, are attracting renewed interest at the present time. The bed rock exposed up this 
reek is essentially greenstone and greenstone schist, with intercalated bands of slate at the 
ower end. Mineralization is general and extends through a belt 1 mile in width beginning 
,bout three-fourths of a mile from the mouth of the creek and extending to a point several 
iundred feet beyond the divide at the head of the creek. Within this belt, which is com- 
posed entirely of greenstone schist with occasional massive beds, narrow bands have been 
lefined parallel with the rock structure within which a concentration of metallic minerals 
las taken place. Where such mineralization occurs the greenstone schist is changed ton 
ale schist and is then readily recognized by its bleached appearance. 
A deposit of this character has been opened on the Red Diamond group of claims, situated 
,t 1,360 feet elevation just below the divide at the head of Nevada Creek. The country 
ock is a blocky greenstone schist of dark-green color, striking N. 30° E. and dipping 70° SE. 
i tunnel penetrates the hanging wall for 60 feet, and then, bending to the northwest , cuts 
liagonaily across the ore body for a distance of 50 feet and enters the foot wall for 10 feet. 
?he lode is not over 36 feet in width and is defined on both walls by a narrow gouge seam, 
^rite is disseminated uniformly throughout this altered-schist band; stringers of quartz are 
aThe Treadwell ore deposits. Bull. U. S. Geol. Survey No. 259, 1905, pp. 69-87. 
b Methods of mining and milling at Aiaska-Treadwell mines: Trans. Am Inst. Mm. Eng., vol. 34, pp. 
34-386. 
Bull. 284—06 4 
