Schroff-O'Neil

The Schroff-O'Neil 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: Schroff-O'Neil
Secondary: Newman and Miller
Secondary: Miller-Newman

Commodity

Primary: Gold
Secondary: Zinc
Secondary: Lead
Secondary: Copper
Secondary: Tellurium

Location

State: Alaska
District: Willow Creek

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

Record Type: Site
Operation Category: Past Producer
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: Wall-rock alteration within a few inches of the veins is intense, but seldom extends more than 10 to 12 inches beyond the quartz filling. Sericitization and carbonate alteration predominate, but there is some pyritization and in the outer parts of the alteration zone chloritization is present (Ray, 1954).

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Pyrite
Ore: Gold
Ore: Galena
Ore: Coloradoite
Ore: Chalcopyrite
Ore: Altaite
Ore: Tetrahedrite
Ore: Sphalerite
Ore: Nagyagite
Gangue: Quartz

Comments

Comment (Exploration): Status = Inactive

Comment (Geology): Age = Late Cretaceous or younger; vein cuts the Late Cretaceous Willow Creek Pluton.

Comment (Deposit): Other Comments = This mine apparently was originally referred to as the Newman and Miller prospect (Brooks, 1925).

Comment (Reference): Primary Reference = Ray, 1954

Comment (Workings): Workings / Exploration = Developed by 60 ft of open cuts in 1923 (Brooks, 1925). Most of the erosisional remnant was mined out by 1950 (Ray, 1954).

Comment (Deposit): Model Name = Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)

Comment (Geology): Geologic Description = Mine located on an erosional remnant of a 1 to 6 inch thick quartz vein that cuts the Willow Creek Pluton. The coarsely crystalline quartz vein carries gold; the tellurides nagyagite, altaite, and coloradoite(?); galena in large cubes; pyrite; sphalerite; chalcopyrite; and tetrahedrite. The vein strikes N 70 E and dips 21 to 34 NW. The main vein is crossed by a barren copper-stained quartz vein. Ore deposition was apparently localized at the vein intersections. Nagyagite is an important mineral in that free gold shows a preference to it, especially in the richer ore. Some nagyagite and gold deposition appear to be contemporaneous (Ray, 1954).? the Willow Creek Pluton is a zoned pluton: the outer part consists of hornblende quartz diorite and lesser hornblende tonalite; the core consists of hornblende-biotite granodiorite, and lesser hornblende-biotite quartz monzodiorite and biotite quartz monzonite. Wall-rock alteration within a few inches of the veins is intense, but seldom extends more than 10 to 12 inches beyond the quartz filling. Sericitization and carbonate alteration predominate, but there is some pyritization and in the outer parts of the alteration zone chloritization is present (Ray, 1954).

References

Reference (Deposit): Brooks, A.H., 1925, Alaska's mineral resources and production, 1923: U.S. Geological Survey Bulletin 773, p. 3-52.

Reference (Deposit): Ray, R.G., 1954, Geology and ore deposits of the Willow Creek Mining district, Alaska: U.S. Geological Survey Bulletin 1004, 86 p.

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Anchorage quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-409, 1 sheet, scale 1:250,000.

Reference (Deposit): Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials in the Anchorage quadrangle, Alaska: U.S. Geological Survey Open-File Report 79-1095, 184 p.

Reference (Deposit): MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous mineral deposits in the western part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-F, 38 p., 1 sheet, scale 1:1,000,000.

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): Chapin, Theodore, 1921, Lode developments in the Willow Creek district: U.S. Geological Survey Bulletin 714-E, p. 201-206.

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