The Colby is a gold mine located in Alaska.
About the MRDS Data:
All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.
Mine Info
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Colby MRDS details
Site Name
Primary: Colby
Commodity
Primary: Gold
Secondary: Arsenic
Location
State: Alaska
District: Yentna
Land Status
Not available
Holdings
Not available
Workings
Not available
Ownership
Not available
Production
Not available
Deposit
Record Type: Site
Operation Category: Prospect
Operation Type: Unknown
Years of Production:
Organization:
Significant:
Physiography
Not available
Mineral Deposit Model
Model Name: Low-sulfide Au-quartz vein
Orebody
Not available
Structure
Not available
Alterations
Alteration Type: L
Alteration Text: A thin section of quartz vein shows muscovite, pitticite, zircon and sericite alteration adjacent to and within the dike (Clark and Hawley, 1968).
Rocks
Name: Mafic Intrusive Rock
Role: Associated
Age Type: Associated Rock
Age Young: Pliocene
Analytical Data
Not available
Materials
Ore: Arsenopyrite
Gangue: Pitticite
Gangue: Muscovite
Gangue: Sericite
Gangue: Zircon
Comments
Comment (Geology): Age = Tertiary; mineralization is interpreted to be related to the felsite dikes that are described as Tertiary in age by Clark and Hawley (1968).
Comment (Workings): Workings / Exploration = Four or five shallow prospect pits were dug on the property by independant prospectors. In addition reconnaissance mapping, stream silt and rock sampling have been done by the U.S. Geological Survey (Clark and Hawley, 1968; Reed and Nelson, 1980).
Comment (Reference): Primary Reference = Clark and Hawley, 1968
Comment (Deposit): Model Name = Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a).
Comment (Deposit): Other Comments = the highest grade lode deposits in Yentna district are Colby, Bird (TL040), and Nugget Creek (TL035) prospects (Hawley and Clark, 1973, p. A6).
Comment (Geology): Geologic Description = At this locality disseminated arsenopyrite occurs in a 4-foot-wide felsite porphyry dike and also in a thin quartz vein, with euhedral quartz and arsenopyrite crystals, that borders the dike (Clark and Hawley, 1968). Alteration adjacent to and within the dike is comprised of muscovite, pitticite, zircon and sericite (Clark and Hawley, 1968). A sample of the felsite porphyry contains 0.80 ppm Au, 5000 ppm As, 1500 ppm Ba, 150 ppm Zr, 50 ppm W (Clark and Hawley, 1968). Regionally Mesozoic marine sedimentary rocks (KJs) are cut by Tertiary (?) felsite dikes (Clark and Hawley, 1968; Reed and Nelson, 1980). Dikes in this prospect area trend N35 to N50E. ? the highest grade lode deposits in Yentna district are in the Colby, Bird (TL040) , and Nugget Creek (TL035) prospects (Hawley and Clark, 1973, p. A6).
References
Reference (Deposit): Clark, A.L., and Cobb, E.H., 1972, Metallic mineral resources map of the Talkeetna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-369, 1 sheet, scale 1:250,000.
Reference (Deposit): Hawley, C.C., and Clark, A.L., 1973, Geology and mineral deposits of the upper Chulitna district, Alaska: U.S. Geological Survey Professional Paper 758-A, p. 1-10, 2 sheets, scale 1:250,000 and 1:500,000.
Reference (Deposit): Clark, A.L., and Hawley, C.C., 1968, Reconnaissance geology, mineral occurrences, and geochemical anomalies of the Yentna district, Alaska: U.S. Geological Survey Open-File Report 68-35, 64 p.
Reference (Deposit): 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.
Reference (Deposit): Reed, B.L., and Nelson, S.W., 1980, Geologic map of the Talkeetna quadrangle: U.S. Geological Survey Miscellaneous Investigations Map I-1174, scale 1:250,000.
Reference (Deposit): Cobb, E.H., and Reed, B.L., 1980, Summaries of data and lists of reference to metallic and selected nonmetallic mineral deposits in the Talkeetna quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-884, 106 p.
Reference (Deposit): C.C. Hawley and Associates, Inc., 1978, Mineral appraisal of lands adjacent to Mt. McKinley National Park, Alaska: U.S. Bureau of Mines Open-File Report 24-78, 275 p., 7 plates.
Reference (Deposit): 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.
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