62 ALASKAN MINERAL RESOURCES IN 1904. [bull. 259. 
dated with greenstones. As the result of general metamorphism the 
limestones have been changed to marble, the greenstones to schists, 
and the argillites to crystalline schists and graphitic shales. Intrud- 
ing these older strata are masses of quartz-diorite occurring as stocks \ 
miles in width, together with dikes and small areas composed of a I 
more basic rock. On the east side of the island from Cholmondeley 
Sound northward, including Kasaan Peninsula and the west side of 1 
Cleveland Peninsula, the Kasaan greenstone forms the country rock, i 
This, as described by Mr. Brooks, a is believed to be largely effusive ] 
and later than the bed-rock series. It is of economic interest because i 
of its association with the copper ores on Kasaan Peninsula and in the j 
Skowl Arm region. 
Niblack Anchorage. — Niblack Harbor forms an indentation in the I 
southeast shore of Prince of Wales Island, and is 36 miles by water j 
from Ketchikan. The mountains rise with steep ascent from the ] 
water's edge to peaks 2,000 to 3,000 feet in elevation. Greenstone is I 
the countiy rock in the vicinity of the mines, but this, in places, has 
been altered to sericite, chlorite, and amphibole-schists. These original j 
greenstones are intrusive into the older sedimentary rocks, which occur I 
farther north and south but do not outcrop in this harbor. At a dis- I 
tance of 2 miles on the slopes to the north of Niblack Anchorage is an I 
intrusive dioritic stock, a mile or more in width, and of later date than j 
the greenstone. A similar intrusive mass occurs to the south along | 
the north shore of Moria Sound. The relation of the copper deposits j 
to these distant dioritic stocks was not determined, though it is possible j 
that they owe their genesis to the after action of the dioritic invasion. j 
The ore bodies occur both as small and irregular veins and as min- I 
eralized zones. Though the veins are rich in values, they will never I 
be of as great importance as the extensive mineralized zones. Chal- 1 
copyrite, with pyrite and pyrrhotite, carrying gold values, are the I 
principal ores. 
Developments during the past two years have been confined to i 
ore bodies exposed on the Judge claim, which lies close to tidewater I 
at the head of Niblack Anchorage. On the original locations of the I 
Lookout Group, situated at an elevation of 1,500 feet, on the south j 
slope of Niblack Anchorage, only the annual assessment work is being I 
clone. The deposits at the Judge claim are large lenticular masses I 
from 10 to 100 feet in width and 100 to several hundred feet in length i 
and depth. These are separated by unmineralized belts of greenstone- 1 
schist. The ore — essentially a massive sulphide of p3'rite and chalco- I 
pyrite — occurs in a matrix of altered greenstone, and appears to fill J 
sheared zones, as both masses and fragments of the greenstone occur, I 
completely surrounded by the mineral. Small veinlets of sulphide, 
"Op. cit., p. 97. 
