Fishhook

The Fishhook is a gold and silver 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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Site Name

Primary: Fishhook

Commodity

Primary: Gold
Primary: Silver
Secondary: Molybdenum
Secondary: Copper
Secondary: Barium-Barite
Secondary: Lead
Secondary: Antimony

Location

State: Alaska
District: Fortymile

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

Not available

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Intense hydrothermal alteration and silicification is found in many of the NE-trending fault zones and in portions of intrusive units at the prospect (Curt Freeman, unpublished data, 1998).

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Chalcopyrite
Ore: Galena
Ore: Gold
Ore: Molybdenite
Ore: Pyrite
Ore: Silver
Ore: Stibnite
Gangue: Hematite
Gangue: Quartz

Comments

Comment (Exploration): Status = Active

Comment (Deposit): Model Name = Plutonic-related (?) ore deposit along NE-trending faults

Comment (Geology): Geologic Description = The country rock within the Fishhook prospect area is augen gneiss having a possible igneous protolith (Mertie, 1931; Foster, 1970). This protolith has a possible emplacement age (inferred from dating other exposures in the region) of Devonian to Mississippian (360 Ma), with resets in the Late Jurassic (190 Ma) and Early to mid-Cretaceous (135-107 Ma) time (Dusel-Bacon and Aleinikoff, 1985). Cretaceous-Tertiary, fine-grained biotite granite, granodiorite, monzodiorite, and a coarse-grained alkali granite intrude the augen gneiss and are exposed in small outcrops at the prospect. Tertiary (?) volcanics are also present (Gill, 1977). ? Local structures are dominated by numerous, high-angle, NE-trending fault zones. Many subordinate fault zones in the area parallel the NE strike and possibly reflect underlying igneous activity (Curt Freeman, unpublished data, 1998). The mineralization at the Fishhook prospect appears to be structurally controlled by the NE-trending faults. Minerals include chalcopyrite, galena, gold, molybdenite, pyrite, silver, sulfosalts, and stibnite. The more highly mineralized areas occur as breccias along the NE faults. The plutonic rocks also contain elevated values of lead, silver, barium, antimony, and gold. Anomalous bismuth along some of the faults suggests a plutonic-source fluid. Extensive hydrothermal alteration and silicification is present in many of the fault zones (Curt Freeman, unpublished data, 1998).? This property was examined in the 1970's as a porphyry-copper deposit, but no significant grades of copper were found. Soil sampling, rock-chip sampling, and stream-sediment sampling were done on the property in the 1970's. In 1978, a shallow drill hole was put in, but no significant mineralization was found. In recent years, soil and rock chip sampling, geologic mapping, and a ground-based magnetometer survey have been conducted (Curt Freeman, unpublished data, 1998).

Comment (Commodity): Ore Material = sulfosalts

Comment (Geology): Age = Late Cretaceous-early Tertiary.

Comment (Workings): Workings / Exploration = Soil sampling, rock chip sampling, and stream sediment sampling were carried out in the 1970's. In 1978, one shallow drill hole was put in, but did not encounter significant mineralization. In recent years, soil and rock-chip sampling, geologic mapping, and a ground-based magnetometer survey have been conducted (Curt Freeman, unpublished data, 1998). This prospect was examined in the 1970's as a porphyry-Cu deposit, but no significant grades of copper were found (J.M. Messing, oral communication, 1998).

Comment (Reference): Primary Reference = This description

Comment (Commodity): Ore Material = sulfosalts

References

Reference (Deposit): Foster, H.L., 1970, Reconnaissance geologic map of the Tanacross quadrangle, Alaska: U.S. Geological Survey Miscellaneous Geological Investigations Map I-593, 1 sheet, scale 1:250,000.

Reference (Deposit): Eberlein, G.D., Chapman, R.M., Foster, H.L., and Gassaway, J.S., 1977, Map and table describing known metalliferous and selected nonmetalliferous mineral deposits in central Alaska: U.S. Geological Survey Open-File Report 77-168-D, 132 p., 1 map, scale 1:1,000,000.

Reference (Deposit): Gill, R., 1977, Geology and mineral deposits of the southwest quarter of the Tanacross D-1 quadrangle, Alaska: Golden, Colorado School of Mines, M.Sc. thesis, 129 p.

Reference (Deposit): Cobb, E.H., and Eberlein, G.D., 1980, Summaries of data on and lists of references to metallic and selected nonmetallic mineral deposits in the Big Delta and Tanacross quadrangles, Alaska: U.S. Geological Survey Open-File Report 80-1086, 77 p.

Reference (Deposit): Dusel-Bacon, C., and Aleinikoff, J.N., 1985, Petrology and tectonic significance of augen gneiss from a belt of Mississippian granitoids in the Yukon-Tanana terrane, east-central Alaska: Geological Society of America Bulletin, v. 96, p. 411-425.

Reference (Deposit): Mertie, J.B., Jr., 1931, A geologic reconnaissance of the Dennison Fork District, Alaska: U.S. Geological Survey Bulletin 827, 44 p.

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