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J.D. Lyons

Prospect, Inactive

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Commodities and mineralogy

Main commodities Cu
Ore minerals chalcopyrite; malachite; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale GU
Quadrangle map, 1:63,360-scale D-1
Latitude 62.781
Longitude -144.047
Nearby scientific data Find additional scientific data near this location
Location and accuracy The J.D. Lyons prospect (Cobb, 1979 [OF 79-1247,p. 18]) is at an elevation of about 4,400 feet on the ridge about 1/4 mile south of the confluence of the two headwater forks of Grubstake Creek . It is in the center of the N1/2, section 35, T. 12 N., R. 7 E., Copper River Meridian. Another geologically similar prospect is at an elevation of about 3,700 feet to the north, but south of Grubstake Creek. The location of these prospects is accurate; they are shown as locality 5 of Richter (1966, figure 5, p. 31), locality 16 of Richter and Matson (1972), and locality 15 of MacKevett and Holloway (1977).

Geologic setting

Geologic description

The Lyons prospect is in hornfelsed, chlorite-hornblende volcanic rocks in the border phase of the Pennsylvanian to Permian, Ahtell pluton (Richter, 1964 and 1966; Richter and Matson, 1968). The hornfels is cut by irregular, discontinuous quartz veins as much as 6 inches thick. The veins and host rock is weakly copper stained (malachite?), and the quartz veins contain small amounts of pyrite and chalcopyrite (Richter 1966, p. 31).
Geologic map unit (-144.049190813269, 62.7806096837275)
Mineral deposit model Polymetallic vein (Cox and Singer, 1986; model 22c)
Mineral deposit model number 22c
Age of mineralization The mineralization is probably related either to the Pennsylvanian to Permian, Ahtell intrusive or to mid-Jurassic dioritic rocks exposed east of the occurrence.
Alteration of deposit Chlorite-hornblende hornfels in altered border phases of the Pennsylvanian to Permian, Ahtell pluton.

Production and reserves

Workings or exploration The prospect on the ridge at an elevation of about 4,400 feet was developed prior to 1963 by prospect pits and by a 10-foot-long adit (Richter, 1964).
Indication of production None

References

MRDS Number A011846

References

Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Gulkana quadrangle, Alaska: U.S. Geological Survey Open-File Report 79-1247, 36 p.
MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.
Richter, D.H., 1964, Geology and mineral deposits of the Ahtell Creek area, Slana district, southcentral Alaska: Alaska Division of Mines and Minerals Geologic Report 6, 18 p., 1 sheet, scale 1:31,680.
Richter, D.H., 1966, Geology of the Slana district, southcentral Alaska: Alaska Division of Geological and Geophysical Surveys Geological Report 2l, 54 p., 3 sheets, scale 1:63,360.
Richter, D.H., and Matson, N.A., Jr., 1968, Distribution of gold and some base metals in the Slana area, eastern Alaska Range, Alaska: U.S. Geological Survey Circular 593, 20 p.
Richter, D.H., and Matson, N.A., Jr., 1972, Metallic mineral resources map of the Gulkana quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-419, 1 sheet, scale 1:250,000.
Reporters W.T. Ellis (Alaska Earth Sciences), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (U.S. Geological Survey)
Last report date 12/20/2000