Old Man Diorite

The Old Man Diorite is a molybdenum, silver, and 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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Site Name

Primary: Old Man Diorite

Commodity

Primary: Molybdenum
Primary: Silver
Primary: Gold
Secondary: Arsenic
Secondary: Barium-Barite

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

Not available

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Carbonate, pyrite, sericite, quartz

Rocks

Role: Host
Age Type: Host Rock
Age Young: Early Miocene
Age Old: Early Cretaceous

Analytical Data

Not available

Materials

Ore: Molybdenite
Ore: Pyrite
Ore: Arsenopyrite
Ore: Chalcopyrite
Ore: Gold
Ore: Pyrrhotite
Ore: Sphalerite
Gangue: Quartz
Gangue: Chlorite

Comments

Comment (Geology): Age = The host rock is late Cretaceous/Early Tertiarydiorite; the veins may be related to the diorite intrusion.

Comment (Exploration): Status = Inactive

Comment (Commodity): Gangue = Carbonate

Comment (Deposit): Model Name = Polymetallic veins

Comment (Geology): Geologic Description = At this locality a Late Cretaceous/Early Tertiary(?) diorite is cut by shallow (10-30 degree) veins less than 1 foot to 5 foot thick, and poorly developed stockwork veins. Mineralization consists of varying amounts of quartz, chlorite, arsenopyrite, pyrite, pyrrhotite, molybdenite, and carbonate. The best gold grades are associated with zones of sub-parallel veins. Gold ranges from ten's of ppb to 0.122 oz/ton (Cominco American Incorporated, unpublished reports, 1986-1987). The diorite is probably one of the late Cretaceous/Early Tertiary Kichatna plutons (TKk) described by Reed and Nelson (1980) in the Talkeetna quadrangle to the north. A K-Ar age of 67.4 +/-2 m.y. suggests that these plutons may be slightly older than the 65-km belt of composite plutons to the west. The veins may be related to the diorite intrusion.

Comment (Workings): Workings / Exploration = Exploration work included silt and rock chip geochemical sampling, mapping, and diamond drilling. The property is steep and technical climbers with Dihedral Exploration were employed to conduct geologic and geochemical surveys.

Comment (Reference): Primary Reference = Reed and Elliott, 1970

Comment (Geology): Age = Host rock is Paleogene - Late Cretaceous.

References

Reference (Deposit): Reed, B.L., and Elliot, R.L., 1970, Reconnaissance geologic map, analyses of bedrock and stream sediment samples, and an aeromagnetic map of parts of the southern Alaska Range: U.S. Geological Survey Open-file Report 70-271, 24 p., 4 plates, scale 1:250,000.

Reference (Deposit): Reed, B.L., and Elliott, R.L., 1970, Reconnaissance geologic map, analyses of bedrock and stream sediment samples, and an aeromagnetic map of parts of the southern Alaska Range: U.S. Geological Survey Open-file Report 70-271, 24 p., 4 sheets, scale 1:250,000.

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