Unnamed (head of Hartman River)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Au; Mo; W
Other commodities Ag; Cu; Sb
Ore minerals chalcopyrite; molybdenite; pyrite
Gangue minerals calcite; limonite; quartz

Geographic location

Quadrangle map, 1:250,000-scale LH
Quadrangle map, 1:63,360-scale C-2
Latitude 61.7252
Longitude -153.6834
Nearby scientific data Find additional scientific data near this location
Location and accuracy 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.

Geologic setting

Geologic description

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 tungsten and 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).
Geologic map unit (-153.685645415583, 61.7245590791533)
Mineral deposit model Polymetallic veins (Cox and Singer, 1986, model 22c)
Mineral deposit model number 21c
Age of mineralization Late Cretaceous or Tertiary. The veins crosscut granitic rocks of the Upper Cretaceous or Tertiary part of the Alaska-Aleutian Range batholith.
Alteration of deposit Silicification and oxidation.

Production and reserves

Workings or exploration Reconnaissance surface observation and sampling has been completed at this locality (Reed and Elliott, 1970).
Indication of production None

References

MRDS Number A013060

References

Nokleberg, W.J., and (seven) others, 1994, Metallogeny and major mineral deposits of Alaska and Metallogenic map of significant metalliferous lode deposits and placer districts of Alaska, in Plafker, G. and Berg, H.C., eds., The Geology of Alaska: Geological Society of America, DNAG, The Geology of North America, Vol.. G1, p. 855-904, Plate 11, scale 1:2,500,000.
Reed, B.L., and Lanphere, M.A., 1973, Alaska-Aleutian Range batholith--Geochronology, chemistry, and relation to circum-Pacific plutonism: Geological Society of America Bulletin, v. 84, no. 8, p. 2583-2610.
Reporters Travis L. Hudson and Madelyn A. Millholland
Last report date 6/10/2001