Nim Prospect, Valdez Creek Mining District, Matanuska-Susitna Borough, Alaska, USAi

Regional Level Types
Nim Prospect	Prospect
Valdez Creek Mining District	Mining District
Matanuska-Susitna Borough	Borough
Alaska	State
USA	Country

Location: The Nim claim block at its acme, comprised 168 claims. The block was approximately rectangular, with the long axis oriented NE - SW. The center of the prospect area is at the intersection of secs. 10, 11, 14, and 15, T. 19 S., R. 10 W., of the Fairbanks Meridian. The location is accurate to within 0.5 mile.
Geology: The country rocks in the area of the Him prospect include Upper Triassic to Upper Jurassic crystal tuff, argillite, chert, graywacke, and limestone, which are intruded successively by hypabyssal garnetiferous diorite porphyry, and by monzonite porphyry and quartz porphyry. The intrusive rocks are correlated with similar Upper Cretaceous plutons at the Golden Zone mine (HE043) (Swainbank and others, 1977). The deposits consists chiefly of pluton-hosted, porphyry-type disseminations of arsenopyrite, bornite, chalcocite, chalcopyrite, and molybdenite in a 4,000- by 4,000-foot area. Selected bedrock samples assay as high as 5% copper, 360 ppm molybdenite, 2 ppm gold and 9 ounces of silver per ton. In addition to the porphyry-type deposit. mapping and geophysical methods indicate 5 breccia-pipe anomalies similar to those at the Golden Zone mine (Bundtzen and others, 1984). The Nim deposit has a slightly different geochemical signature from the Golden Zone mine (Nim is higher in molybdenum-copper, lower in gold), but its hybrid breccia-porphyry mineralization, small alteration haloes, and complex mineralogy are essentially the same as at the Golden Zone mine.
Workings: Exploration in the late 1970's consisted of at least 18 shallow RC drill holes into the Snoopy and Nim areas. IP and magnetic surveys have also been conducted on the property (Bundtzen, 1983). Selected bedrock samples assay as high as 5% copper, 360 ppm molybdenite, 2 ppm gold and 9 ounces of silver per ton.
Age: The similarity of the Nim deposit to the Upper Cretaceous (70-65 Ma) Golden Zone mine (HE043) suggests that they are probably the same age.
Alteration: Alteration consists of widespread propylitic alteration and silicification. Local zones of potassic alteration marked by secondary biotite reported.

Commodities (Major) - Ag, Au, Cu, Mo; (Minor) - Pb, Zn
Development Status: None
Deposit Model: Polymetallic vein, Au-Ag breccia pipe, or Cu-Au porphyry (Cox and Singer, 1986;

Other Databases

Link to USGS - Alaska:	HE074

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References