The Unnamed (near Helen Todd Lake) is a lead 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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Unnamed (near Helen Todd Lake) MRDS details
Site Name
Primary: Unnamed (near Helen Todd Lake)
Commodity
Primary: Lead
Location
State: Alaska
District: Ketchikan
Land Status
Not available
Holdings
Not available
Workings
Not available
Ownership
Not available
Production
Not available
Deposit
Record Type: Site
Operation Category: Occurrence
Operation Type: Unknown
Years of Production:
Organization:
Significant:
Physiography
Not available
Mineral Deposit Model
Not available
Orebody
Not available
Structure
Not available
Alterations
Alteration Type: L
Alteration Text: The trondhjemite hostrock is sericitized and contains disseminated sulfide minerals.
Rocks
Not available
Analytical Data
Not available
Materials
Ore: Pyrite
Ore: Magnetite
Ore: Galena
Gangue: Calcite
Comments
Comment (Geology): Geologic Description = The country rocks in the area of the site are undivided, metamorphosed Silurian and Ordovician volcanic, sedimentary, and intrusive rocks; and Silurian trondhjemite that intrudes the Silurian and Ordovician rocks (Berg, 1972; Berg and others, 1988). The rocks were regionally metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time. The occurrences are in foliated, sericitized, trondhjemite, and consist of pyrite, magnetite, and galena in sparse calcite veinlets up to 0.25 inch thick and 2-3 inches long (Berg, 1972, locs. 28, 29; Karl, 1992, loc. 15a, b) the sulfide minerals are also widely disseminated in the trondhjemite.
Comment (Deposit): Model Name = Disseminated sulfide and oxide mineralization of undetermined origin.
Comment (Geology): Age = the veins probably are Late Cretaceous or younger.
Comment (Reference): Primary Reference = Karl, 1992
References
Reference (Deposit): Berg, H.C., Elliott, R.L., and Koch, R.D., 1988, Geologic map of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Mineral Investigations Series Map MF-1807,27 p., scale 1:250,000.
Reference (Deposit): Berg, H.C., 1972, Geologic map of Annette Island, Alaska: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-684, 8 p., 1 sheet, scale 1:63,360,
Reference (Deposit): Karl, S.M., 1992, Map and table of mineral deposits on Annette Island, Alaska: U.S. Geological Survey Open-File Report 92-690, 57 p., 1 map, scale 1:63,360.
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