Colorado Gossan

The Colorado Gossan 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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Site Name

Primary: Colorado Gossan

Commodity

Primary: Gold
Secondary: Antimony
Secondary: Arsenic
Secondary: Mercury

Location

State: Alaska
District: Innoko

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

Model Name: Polymetallic replacement

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Extensive oxidation of original sulfide mineralization.

Rocks

Role: Associated
Age Type: Associated Rock
Age in Years: 71.000000+-
Age Young: Late Cretaceous

Analytical Data

Not available

Materials

Ore: Arsenopyrite
Gangue: Tourmaline

Comments

Comment (Geology): Age = the Colorado Gossan prospect is inferred to be Late Cretaceous based on 71.0 Ma age of adjacent plutonic rocks (Moll and others, 1981).

Comment (Exploration): Status = Inactive

Comment (Geology): Age = Chronological age is for adjacent plutonic rocks.

Comment (Reference): Primary Reference = Bundtzen and others, 1997

Comment (Workings): Workings / Exploration = No previous surface working were detected in 1996. Three large, continuous, chip-channel samples taken across 700 feet (213 m) of the long axis of the zone averaged 1,815 ppm arsenic, 80 ppb gold, 3,540 ppb mercury, and 154 ppm antimony (Bundtzen and others, 1997).

Comment (Deposit): Model Name = Polymetallic replacement deposit (Cox and Singer, 1986; model no. 19a)

Comment (Geology): Geologic Description = The Colorado Gossan is a rectangular shaped, 1,500 feet by 950 feet (457 m by 290 m) zone of iron rich ferricrete-tourmaline flooding in hornfels adjacent to the Cripple Creek Mountains pluton. Most of the zone is rubble crop with only a few outcrops observed. Disseminated arsenopyrite grains were seen in selected hand specimens but most samples are extensively oxidized. The gossan area is approximately 2,500 feet (762 m) away from the contact between the hornfels and plutonic phases of the Cripple Creek Mountains stock. The Colorado Gossan prospect is inferred to be Late Cretaceous based on 71.0 Ma age of adjacent plutonic rocks (Moll and others, 1981). Three large, continuous, chip-channel samples taken across 700 feet (213 m) of the long axis of the zone averaged 1,815 ppm arsenic, 80 ppb gold, 3,540 ppb mercury, and 154 ppm antimony (Bundtzen and others, 1997).

Comment (Deposit): Other Comments = Similar morphological features at Won-North prospect (MD021) and Win prospect (MD060).

Comment (Commodity): Gangue = Ferricrete

References

Reference (Deposit): Patton, W.W., Jr., Moll, E.J., Dutro, J.T., Jr., Silberman, M.L., and Chapman, R.M., 1980, Preliminary geologic map of Medfra quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-811-A, 1 sheet, scale l:250,000.

Reference (Deposit): Mertie, J.B., Jr., 1936, Mineral deposits of the Ruby-Kuskokwim region, Alaska: U.S. Geological Survey Bulletin 864-C, 115-245.

Reference (Deposit): Bundtzen, T.K., Pinney, D.S., and Laird, G.M., 1997, Preliminary geologic map and descriptive data tables from the Ophir C-1 and western Medfra C-6 quadrangles, Alaska: Alaska Division of Geological and Geophysical Surveys Public Data File Report 97-46, 10 p., 1 sheet, scale 1:63,360.

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