Halibut Bay 41 Occurrence, Kodiak Mining District, Kodiak Island Borough, Alaska, USAi

Regional Level Types
Halibut Bay 41 Occurrence	Occurrence
Kodiak Mining District	Mining District
Kodiak Island Borough	Borough
Alaska	State
USA	Country

Site is located in Kodiak National Wildlife Refuge.
Location: This site is located 3 miles northwest of Anvil Mountain in sec. 12, T. 33 S., R. 34 W., of the Seward Meridian (Foley and Barker, 1985, figure 25, locality 41; Foley and others, 1989, locality 32). Site location is accurate to within a few hundred feet.
Geology: This chromite occurrence, one of several known within the Halibut Bay ultramafic complex, consists of a 50-foot wide zone of elongated lenses of disseminated to massive chromite in serpentinized dunite. The zone strikes N. 10 E. and dips steeply to the west. It is exposed for 250 feet along strike and has an estimated dip length of 62 feet. Foley and Barker (1985, table 13) estimate that the deposit contains 80,000 tons of rock grading 5 percent chromite. A bulk sample had a head grade of 22.4 percent chromite and a gravity concentrate grade of 50.6 percent. The concentrate had a chrome:iron ratio of 2.1 and contained traces of gold, silver, palladium, and platinum (Dahlin and others, 1985, table A-25). The dunite is a part of the Halibut Bay ultramafic complex, which also includes gabbro, pyroxenite, and peridotite. The complex occurs within sedimentary units of the Uyak formation of Cretaceous age. A floatation sample of peridotite from an unknown localilty within the complex contained 11.8 percent copper, 1.55 percent nickel, 0.083 percent cobalt, 0.159 ounce per ton platinum, 0.336 ounce per ton palladium, 0.133 ounce per ton gold, and 20 ounces per ton silver (Foley and others 1989). Minerals identified in the concentrate include chalcopyrite, cobaltian pentlandite, pyrrhotite, stannopalladinite, uvarovite, and villamanite. Grab samples from this locality contain up to 7,700 ppm chrome, 3,626 ppm copper, 839 ppm nickel, 420 ppb platinum, and 480 ppb palladium.
Workings: Foley and Barker (1985, table 13) estimate 80,000 tons of rock grading 5 percent chromite at this occurrence. A high grade bulk sample had a head grade of 22.4 percent chromite and a gravity concentrate grade of 50.6 percent. The concentrate contained traces of gold, palladium, and platinum and had a chrome:iron ratio of 2.1.
Alteration: The ultramafic country rock is serpentinized.
Reserves: The deposit is estimated to contain 80,000 tons of rock grading 5 percent chromite.

Commodities (Major) - Cr
Development Status: None
Deposit Model: Podiform chromite (Cox and Singer, 1986; model 8b).

Other Databases

Link to USGS - Alaska:	KR016

Other Regions, Features and Areas containing this locality

References