Unnamed Occurrence (ARDF - TL076; near Heart Mtn), McGrath Mining District, Denali Borough, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - TL076; near Heart Mtn)	- not defined -
McGrath Mining District	Mining District
Denali Borough	Borough
Alaska	State
USA	Country

This site is within Denali National Park and Preserve.
Location: Reed and others (1978, locality 11) show this site in a drainage one and a half miles east of Heart Mtn at about 4500 feet in elevation in the southwest quarter of Section 3, T. 32 N., R. 15 W., of the Seward Meridian within Denali National Park and Preserve.
Geology: Reed and others (1978) describe float samples of serpentinite, collected about a mile and a half east of Heart Mtn, that contain veins and irregular segregations of pyrite, chalcopyrite, and pentlandite(?). They indicate the source of the float is ultramafic rock to the south of this site, mapped as MzPzu by Reed and Nelson (1980). Chrome and nickel contents of the serpentinite (specific site not given) average 2000 ppm each (Reed and Nelson, 1980). Curtin, Karlson, O'Leary, Day and McDougal (1978) show a cluster of heavy-mineral concentrate samples with high copper (more than 7,000 ppm) and lead (more than 12,500 ppm) values in T. 32 N., and T. 33 N., R. 14 W. and R. 15 W., SM, an area ranging from one half to two miles east of Heart Mtn. They suggest the source of the high copper values in heavy-mineral concentrate samples is most likely a small body of serpentinite mapped as MzPzu by Reed and Nelson (1980) in T. 32 N., R. 15 W., SM. The source of the anomalous lead is not known. Chalcopyrite, malachite, arsenopyrite, and fluorite were observed under the microscope in several of the heavy-mineral concentrate samples with high copper values (Curtin, Karlson, O'Leary, Day and McDougal, 1978).
Workings: Reconnaissance mapping, stream silt and rock sampling by the U.S. Geological Survey (Curtin, Karlson, O'Leary, Day and McDougal,1978; Reed and others,1978; Reed and Nelson, 1980) are all that have been described here. Chrome and nickel contents of the serpentinite (specific site not given) average 2000 ppm each (Reed and Nelson, 1980). Curtin, Karlson, O'Leary, Day and McDougal (1978) show a cluster of heavy-mineral concentrate samples with high copper (more than 7,000 ppm) and lead (more than 12,500 ppm) values in an area ranging from one half to two miles east of Heart Mountain.
Age: Mesozoic and (or) Paleozoic (Reed and Nelson, 1980).

Commodities (Major) - Cu, Ni
Development Status: None
Deposit Model: Possibly synorogenic-synvolcanic Ni-Cu (Cox and Singer, 1986; model 7a).

Other Databases

Link to USGS - Alaska:	TL076

Other Regions, Features and Areas containing this locality

References