Prospect, Probably inactive

Alternative names

Alaska Treadwell Mining Co.

Commodities and mineralogy

Main commodities Mo
Other commodities Cu; Zn
Ore minerals chalcopyrite; molybdenite; pyrite; pyrrhotite; sphalerite
Gangue minerals albite; quartz

Geographic location

Quadrangle map, 1:250,000-scale PE
Quadrangle map, 1:63,360-scale A-5
Latitude 56.135
Longitude -133.458
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Shakan molybdenum prospect (also known as the Alaska Treadwell Mining Co), is near the east end of Shakan Strait on northern Kosciusko Island. This well known prospect is on the east side of Shakan Creek at an elevation of about 600 feet, just north of the center of section 23, T. 66 S., R. 77 E.

Geologic setting

Geologic description

The country rocks in the vicinity consist of Cretaceous biotite-quartz hornfels altered from Silurian graywacke turbidite of the Bay of Pillars Formation and a large Cretaceous diorite pluton that intrudes the bedded rocks (Brew and others, 1984).
The Shakan molybdenum deposit is at or near the contact between the pluton and the hornfels and probably is genetically related to the emplacement of this pluton. The deposit is a sulfide-bearing fault-breccia zone 1-10 feet thick associated with hornblende diorite pegmatite; the zone contains abundant pyrrhotite, molybdenite, and chalcopyrite, with minor sphalerite and pyrite, in quartz-albite gangue.
Geologic map unit (-133.459728113383, 56.1346373777132)
Mineral deposit model Molybdenite associated with pegmatite dike along fault zone.
Age of mineralization Probably Cretaceous based on age of associated pluton.

Production and reserves

Workings or exploration The Shakan molybdenum prospect was discovered in 1917 and developed by a 570 foot tunnel and 14 surface cuts during and immediately after World War I (Chapin, 1919). Little or no subsequent exploration work on it beyond cursory examinations by passing geologists, although it was examined at some length by government geologist during World War II (Twenhofel and others, 1946; Smith, 1942, Thorne, 1943).
Indication of production None
Reserve estimates Smith (1942) estimated the resources of the Shakan molybdenum prospect to be 10,000-20,000 tons of rock containing about 1.5% MoS2.
Production notes None


MRDS Number A010342; A010343


Coldwell, J.R., 1990, Northwest Canada Mining leads to road proposal: Southeast Alaska Business Journal, December 1990, p. 4.
Thorne, R.L., 1943, Shakan molybdenum deposit, Kosciusko Island, southeastern Alaska: U.S. Bureau of Mines War Mineral Report 108, 9 p.
Reporters H.C. Berg (Fullerton, California) and D.J. Grybeck (USGS)
Last report date 11/1/1998