Powdermilk Prospect, Kiana Mining District, Northwest Arctic Borough, Alaska, USAi

Regional Level Types
Powdermilk Prospect	Prospect
Kiana Mining District	Mining District
Northwest Arctic Borough	Borough
Alaska	State
USA	Country

Location: The Powdermilk prospect is just southeast of the confluence of the two major headwater forks of a major, unnamed, southeast flowing tributary of the Omar River. Coordinates are for the approximate center of the occurrence. The prospect covers an area of 2 square kilometers. It is in sections 24, 25, T. 24 N., R. 10 W., of the Kateel River Meridian. Schmidt and Allegro (1988), location 157.
Geology: The Powdermilk deposit consists of disseminations and clots (under 2.5 centimeter diameter) of sphalerite, galena, and rare pyrite in Devonian light-gray dolostone (Schmidt and Allegro, 1988). The sphalerite is coarsely crystalline, locally zoned, and medium to dark brown and red. Barite forms veins in the dolostone. Soil samples from the western river bank exposure contain as much as 1600 ppm Pb, 420 ppm Zn and 7.2 ppm Ag. Rock samples from the more oxidized, eastern creek exposure contain as much as 280 ppm Pb, 230 ppm Zn and 21 ppm Ag. Rock samples contain as much as 20% sphalerite, 8% galena and 5% pyrite. The host dolostone strikes NE and dips nearly vertically at the prospect. Synformal structure is suggested. Some gray limestone occurs east of the prospect. The Powdermilk deposit is similar to southeast Missouri Pb-Zn (Cox and Singer, 1986; model 32a) in host rock and mineralization. The sulfides are epigenetic with respect to the host dolostone. Mineralization may be structurally controlled by the synform (Schmidt and Folger, 1986).
Workings: The U.S. Geological Survey did reconnaissance mapping, took 39 soil samples along a sample line, and collected additional rock and pan concentrate samples from the area (Zayatz and others, 1988).
Age: Devonian?
Alteration: Surficial weathering consists of rare iron oxide staining and local clay alteration.

Commodities (Major) - Ag, Pb, Zn; (Minor) - Ba, Cd(?)
Development Status: None
Deposit Model: Southeast Missouri Pb-Zn (Cox and Singer, 1986; model 32a).

Other Databases

Link to USGS - Alaska:	BM010

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References