Yakobi Island; Miner Island Mine, Chichagof District, Skagway-Hoonah-Angoon Borough, Alaska, USA

The site is in Rossman's hypothetical gold belt (plate 16, 1959). The site is in Tongass National Forest on land of unknown mining status.
Location: The mine is accurately located (to within 0.1 mile) on the shore line of Yakobi island, northwest of Miner Island. It is on the point west of the junction of Lisianski Strait with Lisianski Inlet (west ). The site is location number 64 of Cobb (1972).
Geology: The Yakobi Island gold-quartz vein is within an intrusion of quartz diorite, of Cretaceous age, which forms a major granitic batholith on Chichagof, Baranof, and Yakobi Islands (Loney and others, 1975). A coarse-grained hornblendite occurs within a few feet of the vein deposit. The mineralized quartz vein is from 1to 3 feet wide, dips steeply, and strikes northwest. The quartz occurs along a shear zone, associated with clay gouge, in a dark colored phase of the quartz diorite. Locally, the vein contains small amounts of chalcopyrite and native gold. The vein was developed by a short adit; the quartz pinched out in the adit, but was picked up on strike on the surface above the workings, indicating that quartz masses along the shear zone are lenticular (Overbeck, 1919).
Workings: A 35-foot-long adit was driven about 1887 on the shear zone, just above tide level. Four claims were active in 1917.
Age: Cretaceous or younger.
Alteration: Clay gouge developed along shear zone.
Production: About 55 ounces of gold were produced before 1917.

Commodities (Major) - Au; (Minor) - Cu
Development Status: Yes; small
Deposit Model: Low-sulfide gold-quartz vein (Cox and Singer, 1986; model 36a).

References:
Cobb, E.H., 1972, Metallic mineral resources map of the Mount Fairweather quadrangle, AK: U.S. Geological Survey Miscellaneous Field Study Map MF-436, 1 sheet, scale 1:250,000. Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mt. Fairweather and Skagway quadrangles, Alaska: U.S. Geological Survey Open-File Report 78-316, 123 p. Loney, R.A., Brew, D.A., Muffler, L.J. B., and Pomeroy, J.S., 1975, Reconnaissance geology of Chichagof, Baranof, and Kruzof Islands, southeastern Alaska: U.S. Geological Survey Professional Paper 792, 105 p. Overbeck, R.M., 1919, Geology and mineral resources of the west coast of Chichagof Island: U.S. Geological Survey Bulletin 692-B, p. 91-136. Rossman, Darwin, 1959, Geology and ore deposits of the northwestern part of Chichagof Island, Alaska: U.S. Geological Survey Bulletin 1058-E, p. 139-216.