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Schroff-O'Neil

Past Producer in Alaska, United States with commodities Gold, Copper, Lead, Tellurium, Zinc
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Geologic information

Identification information

Deposit ID 10000945
MRDS ID A011616
Record type Site
Current site name Schroff-O'Neil
Alternate or previous names Newman and Miller, Miller-Newman
Related records 10282758

Geographic coordinates

Geographic coordinates: -149.30158, 61.81067 (WGS84)
Relative position 2,000 ft east of the end of unimproved road that parallels Craigie Creek. Marked with quarry symbol and labeled 'Schroff-O'Neil Mine' on the Anchorage D-7 1:63,360-scale topographic map. Accurate within 400 ft. Locality 15 of Cobb (1972) and locality 12 of MacKevett and Holloway (1977).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Copper Secondary
Lead Secondary
Tellurium Secondary
Zinc Secondary

Materials information

Materials Type of material
Altaite Ore
Chalcopyrite Ore
Coloradoite Ore
Galena Ore
Gold Ore
Nagyagite Ore
Pyrite Ore
Sphalerite Ore
Tetrahedrite Ore
Quartz Gangue

Alteration

  • (Local) 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).

Mineral occurrence model information

Model code 273
USGS model code 36a
Deposit model name Low-sulfide Au-quartz vein
Mark3 model number 27

Nearby scientific data

(1) -149.30158, 61.81067
ListMap

Comments on the geologic information

  • 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).
  • Age = Late Cretaceous or younger; vein cuts the Late Cretaceous Willow Creek Pluton.

Economic information

Economic information about the deposit and operations

Development status Past Producer
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Willow Creek

Comments on the workings information

  • 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).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A011616
USGS Alaska Resource Data File ARDF AN027

Bibliographic references

  • Deposit

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

  • Deposit

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

  • Deposit

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

  • 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.

  • 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.

  • 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.

  • 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.

Comments on the references

  • Primary Reference = Ray, 1954

General comments

Subject category Comment text
Deposit Model Name = Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)
Deposit Other Comments = This mine apparently was originally referred to as the Newman and Miller prospect (Brooks, 1925).

Reporter information

Type Date Name Affiliation Comment
Reporter 30-JUL-1998 D.P. Bickerstaff U.S. Geological Survey
Reporter 30-JUL-1998 S.W. Huss U.S. Geological Survey