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Unnamed (near Heart Mtn)

Occurrence, Undetermined

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Commodities and mineralogy

Main commodities Cu; Ni
Ore minerals chalcopyrite; pentlandite; pyrite

Geographic location

Quadrangle map, 1:250,000-scale TL
Quadrangle map, 1:63,360-scale D-5
Latitude 62.889
Longitude -152.078
Nearby scientific data Find additional scientific data near this location
Location and accuracy 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.

Geologic setting

Geologic description

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).
Geologic map unit (-152.080233987277, 62.8884484157996)
Mineral deposit model Possibly synorogenic-synvolcanic Ni-Cu (Cox and Singer, 1986; model 7a).
Mineral deposit model number 7a
Age of mineralization Mesozoic and (or) Paleozoic (Reed and Nelson, 1980).

Production and reserves

Workings or exploration 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.
Indication of production None

Additional comments

This site is within Denali National Park and Preserve.

References

MRDS Number 10308452

References

Curtin, G.C., Karlson, R.C., O'Leary, R.M., Day, G.W., and McDanal, S.K., 1978, Geochemical and generalized geologic maps showing the distribution and abundance of gold and silver in the Talkeetna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-870-E, 2 sheets, scale 1:250,000.
Reed, B.L., and Nelson, S.W., 1980, Geologic map of the Talkeetna quadrangle: U.S. Geological Survey Miscellaneous Investigations Map I-1174, 1 sheet, scale 1:250,000.
Reed, B.L., Nelson, S.W., Curtin, G.C., and Singer, D.A., 1978, Mineral resources map of the Talkeetna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-870-D, 1 sheet, scale 1:250,000.
Reporters Madelyn A. Millholland (Millholland & Associates)
Last report date 8/10/1998