Bismarck Creek

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Sn
Other commodities As; Cd; Cu; F; In; Pb; Zn
Ore minerals cassiterite; iron oxide
Gangue minerals anatase; axinite; quartz; tourmaline

Geographic location

Quadrangle map, 1:250,000-scale ID
Quadrangle map, 1:63,360-scale B-3
Latitude 62.42328
Longitude -157.02462
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is on an east-west trending ridge on the divide between the Bismarck and Eldorado Creek, both tributaries of the George River. The prospect is at an elevation of about 2,200 feet about 0.2 mile southwest of hill 2475 near the southwest corner of section 14, T. 27 N., R. 42 W., of the Seward Meridian. The location is accurate.

Geologic setting

Geologic description

This prospect is an east to northeast-trending stockworks of oxidized quartz veins and veinlets that contains cassiterite, axinite, and tourmaline in hornfels derived from the Upper Cretaceous, Kuskokwim Group (Miller and Bundtzen, 1994; Bundtzen and Miller, 1997). The deposit is within a 1.7 by 2 mile aureole of hornfels. The area is cut by north-northeast striking faults, one of which apparently controls the course of Bismarck Creek.
The mineralized zone can be traced in rubble for more than 1,000 feet and varies from 6 to 100 feet wide. The sulfides have been completely oxidized leaving behind a heavy residue of reddish to orange gossan. Black cassiterite has been confirmed in polished sections from the zone. The deposit is associated with brecciated blocks of altered sandstone and siltstone floating in a matrix of quartz and gossan (Bundtzen and Miller, 1997). No intrusive rocks have been identified at the site; however, a large area centered on VABM 2424 is underlain by biotite-pyroxene hornfels that suggests a buried pluton here (Miller and Bundtzen, 1994).
Chip-channel samples contain up to 2.80 percent tin, 63 parts per million (ppm) silver, 590 ppm copper, 4,600 ppm lead, more than 1.00 percent zinc, 1,100 ppm arsenic, and 310 ppm antimony (Bundtzen and Miller, 1997; McGimsey and others, 1988). Selected samples also contained up to 118 ppm indium (Miller, Bundtzen, and Gray, 2005). Based on extensive surface sampling, Bundtzen and Miller (1997) estimated that this prospect near Bismarck Creek contains an inferred resource of about 550,000 tons of material that contain 0.14 percent tin, 50.0 ppm silver, and about 0.75 percent combined base metals.
Geologic map unit (-157.027009311496, 62.422596119088)
Mineral deposit model Sn-polymetallic vein or polymetallic vein (Cox and Singer, 1986; models 20b and 22c).
Mineral deposit model number 20b or 22c
Alteration of deposit Axinite-tourmaline-quartz 'greisen'.

Production and reserves

Workings or exploration Samples were collected by the U.S. Geological Survey and Alaska Division of Geological and Geophysical Surveys in the 1980s. Bundtzen and Miller (1997) provide a geologic sketch and analyses from the prospect.
Indication of production None
Reserve estimates Based on extensive surface sampling, Bundtzen and Miller (1997) estimated that this prospect near Bismarck Creek contains an inferred resource of about 550,000 tons of material that contain 0.14 percent tin, 50.0 ppm silver, and about 0.75 percent combined base metals.

References