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Unnamed

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Cu
Ore minerals azurite; bornite; chalcocite; malachite
Gangue minerals epidote; iron carbonate; quartz

Geographic location

Quadrangle map, 1:250,000-scale HE
Quadrangle map, 1:63,360-scale A-1
Latitude 63.0893
Longitude -147.4403
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at an elevation of about 3,800 feet, one mile due east of the center of the airstrip at Susitna Lodge. The map site is in the SW1/4 of sec. 18, T. 21 S., R. 2 E., of the Fairbanks Meridian. The location is accurate to about 250 feet.

Geologic setting

Geologic description

The area of this occurrence is underlain by the Middle or Upper Triassic Nikolai Greenstone, a thick sequence of subaerial and submarine basalt flows and minor interbedded volcaniclastic sedimentary rocks, aquagene and epiclastic tuff, breccia, argillite, and radiolarian chert (Nokleberg and others, 1992).
The deposit is in a hydrothermally altered shear zone in greenstone and consists quartz, epidote, bornite, chalcocite, and an iron carbonate mineral. Weathering produces malachite- and azurite-coated float and encrustations.
Glavinovich (1967) described the occurrence as follows: 'Bornite, minor chalcocite and malachite occur as small discontinuous stringers in a narrow fracture zone. The fracture zone trends northeast, is about two inches wide and three feet in length. At both ends the zone narrows to a single fracture that continues along strike but is unmineralized. Gangue minerals include quartz and epidote. The paragenesis as determined in hand specimen is epidote, quartz, sulfides. The country rock is moderately altered andesite and is well jointed. Malachite coatings on joint faces are common.'
Geologic map unit (-147.442554626431, 63.0888500671821)
Mineral deposit model Hydrothermally altered shear zone
Age of mineralization Triassic or younger.
Alteration of deposit Propylitic alteration of greenstone.

Production and reserves

Indication of production None

References

References

Glavinovich, P.S., 1967, Trace element copper distribution and areal geology in a portion of the Clearwater Mountains, Alaska: University of Alaska, Minerals Industry Research Laboratory, Report No. 10, 55 p.
Kaufman, M.A., 1964, Geology and mineral deposits of the Denali-Maclaren River area, Alaska: Alaska Division of Mines and Minerals Geologic Report 4, 15 p., 1 sheet, scale 1:125,000.
Reporters D.L. Stevens (Stevens Exploration Management Corporation)
Last report date 4/7/2000