Unnamed Occurrence (ARDF - MH039; west of Clearwater Creek), Valdez Creek Mining District, Matanuska-Susitna Borough, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - MH039; west of Clearwater Creek)	- not defined -
Valdez Creek Mining District	Mining District
Matanuska-Susitna Borough	Borough
Alaska	State
USA	Country

Copper values are locally very high, but the occurrences are small and there is a low potential for copper (Kurtak and others, 1992).
Location: This occurrence is at an elevation of about 4,500 feet about 1.6 miles south-southwest of the junction of Clearwater and Pass Creeks, in the NW1/4SW1/4 section 33, T. 20 S., R. 4 E., Fairbanks Meridian. The occurrence corresponds to locality A41 of Kurtak and others (1992), to locality 2 in figure 4 of Cobb (1979 [OFR 79-238]), and to locality 41 in table 2 of Nokleberg and others (1991).
Geology: Bedrock in the area consists of Nikolai Greenstone of Late Triassic age that is locally sheared and silicified and cut by quartz veinlets (Nokleberg and others, 1991; Kurtak and others, 1992, table A41). The deposits consist of copper minerals, including chalcocite, chrysocolla, native copper, azurite, and malachite, in quartz veins, in vesicles, and on joint and fracture surfaces of propylitized and locally silicified basalt (Smith and others, 1973; Kurtak and others, 1992). Copper content of three samples of basalt with visible copper minerals assayed from 2.52 to 4.9 percent copper and 1.2 to 5.2 parts per million silver; gold was not reported (Kurtak and others, 1992).
Workings: Several zones stained by copper oxides were sampled by the U.S. Bureau of Mines (Kurtak and others, 1992, table A41). Samples contained as much as 4.9 percent copper; a placer sample collected one mile south of the occurrence contained no gold.
Age: The copper deposits are probably either Cretaceous or early Tertiary in age (see see MH060 and MH100).
Alteration: Basalt is propylitized and locally silicified.

Commodities (Major) - Cu; (Minor) - Ag
Development Status: None
Deposit Model: Basaltic Cu (Cox and Singer, 1986; model 23).

Other Databases

Link to USGS - Alaska:	MH039

Other Regions, Features and Areas containing this locality

References