AURIFEROUS QUARTZ VEINS ON UNALASKA ISLAND. 
By Arthur J. Collier. 
INTRODUCTION. 
Unalaska Island, of the Aleutian chain, lies west of and near one of 
the most frequented routes from the Pacific Ocean to Bering Sea and isj 
important chiefly for its splendid natural harbor, on which are located 
the two coaling and trading stations, Dutch Harbor and Unalaskaj 
Several years ago an unsuccessful attempt was made to develop and 
mine some gold-bearing quartz veins near the village of Unalaska. A 
three-stamp mill and a cable tramway to connect the mill with the mine 
were erected, but these are now in a state of ruin. This locality is so| 
accessible and so conveniently situated with regard to the harbor that 
a very low-grade ore could have been handled at a profit. Although 
this deposit is not thought to be of economic value, the following descrip- 
tion of the old workings, which is based on a hasty examination made 
by the writer last summer, is given, in order that this mine may he 
compared with the gold mines of Unga Island, described by Martin, 
and also to indicate the possibilit}^ that valuable gold-bearing deposits 
may occur in the Aleutian Islands. Quartz veins of economic value 
are reported by prospectors on several of the islands farther west. 
TOPOGRAPHY. 
The topography of Unalaska Island is rough and irregular. Mount 
Makushin, its highest mountain, is over 6,000 feet high. Except for 
a few small gravel plains which fringe some of the bays the hills and 
mountains rise directly from the water and there is practically no level 
ground. 
GEOLOGY. 
The hard rocks of the islands are volcanic and consist of interbedded 
tuffs and flows that are cut by numerous dikes. The most common 
rocks are dark-gray andesites. a That some of these rocks were 
erupted in the Tertiary period is proved by fossil plant remains con- 
tained in the tuffs/' Volcanic activity has persisted to the preserB 
time in Mount Makushin, which still has occasional eruptions. 
"Emerson, B. K., Harriman Alaska Expedition, vol., 6, Geology, 1904, p. 29. 
bDall and Harris. Correlation Papers— Neocene: Bull. U. S. Geol. Survey No. 84, 1892, pp. 242-2« 
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