™fG T HT ND ] DEVELOPMENTS IN SOUTHEASTERN ALASKA. 59 
vicinity of the ore body, and a few miles distant by a wide grano- 
diorite belt, both of which have probably been controlling- factors in 
the mineral deposition. 
The mine developments include an 800-foot crosscut tunnel, the 
buildings for a 120-stamp mill, a small power plant, and a narrow-gage 
railroad 7 miles in length from the mill to the wharf. The ore is 
reported to be of very low grade, and the work which has been done 
has not demonstrated the possibility of profitable mining. 
Freshwater Bay. — The only mineral locations on Chichagof Island 
have been made on a gypsum bed outcropping about a mile from the 
shore of Iyoukeen Inlet, a harbor just north of Freshwater Bay. 
This deposit is interstratified in a limestone of Carboniferous age, the 
beds of which have been much folded and sheared. The gypsum is 
unsuitable for ornamental purposes on account of cleavage and joint- 
ing planes, but it is of an excellent quality for the manufacture of 
plaster of Paris. The stratum has been exposed by an open cut for 
50 feet along its strike and for 20 feet in width, and by a shaft for 40 
feet in depth, but its full extent has not yet been defined. About 300 
tons of the material are in sight. The favorable location of this prop- 
ert}^ and the value of calcined gypsum is sufficient to warrant further 
development. 
WRANGELL MINING DISTRICT. 
This mining district extends along the mainland from Cape Fanshaw 
to Bradtield Canal and includes Kuiu, Kupreanof, Mitkof, Zarembo, 
Etolin, and Wrangell, and several other smaller islands. Prospecting 
in this section, has been meager, and at only one locality, the Olympic 
mine, has there been extensive development and a production of gold. 
Duncan Canal. — On the west side of the small island of Woewodski, 
at the south entrance to Duncan Canal, is the property of the Olympic 
Mining Company, embracing some 60 claims. Operations have been 
confined principally to what are known as the "Hattie" Ledge at the 
lower camp and the " Helen S." at the upper or Smith's camp. The 
country rock is a greenstone which is probably extrusive and which is 
more or less schistose. The main cleavage planes strike north -south 
and dip 70° E. The mineral deposits are quartz ledges from 5 to 
15 feet in width, which apparently fill brecciated zones in the green- 
stones. They strike in a northeast-southwest direction, and are nearly 
vertical. Large masses of the greenstone are included in these ledges, 
and the stringers of quartz penetrate the country rock in all directions 
near the main ledge. Portions of the ledges consist of a network of 
quartz stringers inclosing the altered greenstone, and sulphides, carry- 
ing the gold values, are disseminated in small particles in the quartz as 
well as in the greenstone. Practically none of the ore is free milling. 
It concentrates about 18 to 1, which product is said to yield $32 in gold. 
