Unnamed Occurrence (ARDF - HE058; divide between Christy and Copeland creeks), Valdez Creek Mining District, Matanuska-Susitna Borough, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - HE058; divide between Christy and Copeland creeks)	- not defined -
Valdez Creek Mining District	Mining District
Matanuska-Susitna Borough	Borough
Alaska	State
USA	Country

Location: This occurrence is at an elevation of about 5,200 feet, about midway between the middle reaches of Christy and Copeland Creeks. the map site is about 1.3 mile north of VABM 5048 (Copeland), in the NE1/4 of sec. 1, T. 21 S., R. 12 W., of the Fairbanks Meridian. The location is accurate to within 0.5 mile. This is location 22 of Cobb (1978: OFR 78-1062), and location E-29 of Balen (1990: OFR 34-90).
Geology: The country rocks in the area of this occurrence are a tectonically mixed assembleges of Upper Devonian serpentinite, basalt, chert, and gabbro. The occurrence consists of talus blocks of serpentinite(?) containing pods of massive chromite. The blocks occur in an area underlain by serpentinite altered to quartz-carbonate rock containing disseminated pyrite and stained with garnierite. Samples comprising 95% chromite contain 39.5% Cr2O3 and a chromium/iron ratio of 3.1:1, along with traces of platinum group metals (principally rhenium) and 1,000 ppm nickel (Hawley and others, 1969). The platinum values in eight samples were at the lower limit of detection (Balen, 1990: OFR 34-90).
Workings: There has been surface sampling only. Samples comprising 95% chromite contain 39.5% Cr2O3 and a chromium/iron ratio of 3.1:1, along with traces of platinum group metals (principally rhenium) and 1,000 ppm nickel (Hawley and others, 1969). The platinum values in eight samples were at the lower limit of detection (Balen, 1990: OFR 34-90).
Age: Chromite probably was a magmatic segregation in Upper Devonian ultramafic intrusive rocks.
Alteration: Serpentinization of ultramafic intrusive rocks. The serpentinite is altered to quartz-carbonate rock containing disseminated pyrite and stained with garrnierite.

Commodities (Major) - Cr; (Minor) - Ni, Pt
Development Status: None
Deposit Model: Podiform chromite (Cox and Singer, 1986; model 8a)

Other Databases

Link to USGS - Alaska:	HE058

Other Regions, Features and Areas containing this locality

References