Unnamed Occurrence (ARDF - LH011; head of Hartman River), McGrath Mining District, Bethel Census Area, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - LH011; head of Hartman River)	- not defined -
McGrath Mining District	Mining District
Bethel Census Area	Census Area
Alaska	State
USA	Country

Location: This occurrence is on a ridge along the north side of the upper Hartman River valley. It is at an elevation of 6,000 feet, one mile north of the glacier in the northwest headwater tributary of Hartman River. The map site is in the NE1/4 section 19, T 19 N, R 24 W, of the Seward Meridian. This is locality 3 of Cobb (1972 [MF 412]; 1976 [OF 76-485]) and and Cobb and Reed (1981). The location is probably accurate to within a quarter of a mile.
Geology: Reed and Elliott (1970, p. 22) reported that a 2-inch-wide quartz vein containing less than 2 percent finely disseminated molybdenite crosscuts quartz diorite at this locality. A sample of this vein also contained 300 ppm tungstenand 3.2 ppm gold. Allen and others (1990, samples 104, 111, 112) collected several samples from the south flank of the ridge where this vein was found. These samples were of graywacke containing disseminated pyrite; limonite-stained quartz veins containing pyrite and some chalcopyrite; and quartz-calcite veins in granitic rock. These samples contained as much as 3.5 ppm gold, 200 ppm silver, 700 ppm copper, 150 ppm antimony, and greater than 10,000 ppm arsenic. The sedimentary rocks are Jurassic and Lower Cretaceous, and the Upper Cretaceous or Tertiary granitic rocks are part of the Alaska-Aleutian Range batholith (Reed and Lanphere, 1973; Nokleberg and others, 1994).
Workings: Reconnaissance surface observation and sampling has been completed at this locality (Reed and Elliott, 1970).
Age: Late Cretaceous or Tertiary. The veins crosscut granitic rocks of the Upper Cretaceous or Tertiary part of the Alaska-Aleutian Range batholith.
Alteration: Silicification and oxidation.

Commodities (Major) - Au, Mo, W; (Minor) - Ag, Cu, Sb
Development Status: None
Deposit Model: Polymetallic veins (Cox and Singer, 1986, model 22c)

Other Databases

Link to USGS - Alaska:	LH011

Other Regions, Features and Areas containing this locality

References