Unnamed Occurrence (ARDF - MF039; Johns Hopkins Inlet), Hoonah-Angoon Census Area, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - MF039; Johns Hopkins Inlet)	- not defined -
Hoonah-Angoon Census Area	Census Area
Alaska	State
USA	Country

The area has numerous iron-stained areas, contact zones, and has widespread weak geochemical anomalies in copper and molybdenum. Favorable area for contact or intrusive-related shear zone-type deposits. The area is in Glacier Bay National Park and Preserve.
Location: The occurrence is on a north-facing point into Johns Hopkins Inlet, almost due south of Orange Point; it is in section 24, T. 34 S., R. 50 E., of the Copper River Meridian. The location is accurate to within 0.25 mile. The location is approximately the same as number 65 of MacKevett and others (1971), number 15 of Cobb (1972) and number 29 of Kimball and others (1978).
Geology: Argillite, phyllite, and slate of Permian and Permian (?) age are cut by a small foliated granite pluton of Cretaceous age (Brew and others, 1978, plate IA). Kimball and others (1978, p.C149, fig. C38 ) reported volcanic rock, chert, and sulfides. MacKevett and others (1971, table 9, p. 52) reported a 100- to 200-foot wide altered zone in granitic rocks which extended several hundred feet on strike: fracture surfaces were stained with malachite, chrysocolla, and limonite. A grab sample collected by the U.S. Geological Survey contained 1500 ppm copper and 30 ppm molybdenum. Float samples collected by the U.S. Bureau of Mines (Kimball and others, 1978) contained as much as 4,600 ppm copper, 7 ppm silver, and 0.05 ppm gold. A rock sample collected by the Bureau contained more than 2000 ppm molybdenum and 610 ppm copper.
Workings: There are no mine workings. A grab sample representative of a shear zone in granitic rock contained 1500 ppm copper and 30 ppm molybdenum (MacKevett and others, 1978, sample 65, table 9). The U.S. Bureau of Mines (Kimball and others, 1978) collected float samples at about 150 feet elevation, in an area underlain by hornfels, that contained 4600 ppm copper, 300 ppm cobalt, 7 ppm silver, and 0.05 gold (p. C-172). A selected sample of a veinlet in hornfels at about 300 feet elevation contained greater then 2000 ppm molybdenum and 610 ppm copper.
Age: Cretaceous (?).

Commodities (Major) - Cu; (Minor) - Ag, Au, Co, Mo
Development Status: No
Deposit Model: Mineralized shear zone; possible volcanogenic mineralization.

Other Databases

Link to USGS - Alaska:	MF039

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References