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Orange Hill

Prospect in Alaska, United States with commodities Copper, Molybdenum, Gold, Silver
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Geologic information

Identification information

Deposit ID 10308923
MRDS ID A011395
Record type Site
Current site name Orange Hill
Related records 10258737

Geographic coordinates

Geographic coordinates: -142.84454, 62.20549 (WGS84)
Relative position Best location: Richter, 1973, USGS I-789, loc. 2; on California Gulch. Accurate within 200 feet radius.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary
Molybdenum Primary
Gold Primary
Silver Primary

Materials information

Materials Type of material
Chalcopyrite Ore
Molybdenite Ore
Pyrite Ore
Calcite Gangue
Gypsum Gangue
Quartz Gangue

Alteration

  • Central altered zone 400 m by 2000 m contain abundant biotite, quartz veinlets, minor k-feldspar, chlorite, and sericite cut by late stage anhydrite veins. Outer altered zones contain chlorite, minor sericite and anhydrite.

Mineral occurrence model information

Model code 79
USGS model code 21a
Deposit model name Porphyry Cu-Mo
Mark3 model number 2

Nearby scientific data

(1) -142.84454, 62.20549
ListMap

Comments on the geologic information

  • Geologic Description = Pyrite, chalcopyrite, and molybdenite occur in quartz veinlets and as disseminations in large Cretaceous quartz diorite/granodiorite pluton. Pluton intrudes volcanic and sedimentary rocks of Permian and Triassic age. Associated skarn mineralization in metamorphosed limestone country rock (see Lemon deposit) contains Cu and Zn sulfide minerals. Plutonic rocks intruded by alaskite dikes which are crosscut by dikes of andesite, dacite, and basaltic porphyry. Other similar deposits (Bond Creek) in the pluton exhibit same mineralogy. Abundant biotite-quartz, quartz-sericite, and chlorite-sericite-epidote alteration. Late anhydrite veins common. Altered areas about 1,000 by 3,000 m. Associated skarns contain pyrite, chalcopyrite, bornite, and magnetite.
  • Age = Early Cretaceous

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Chisana

Comments on the reserve resource information

  • Reserves = Average grades from surface sampling: 0.25% Cu; all samples were below 0.4%; 0.01% TO 0.8% Mo; Au values from trace to 0.04 oz/ton, average Au grade estimated at 0.005 oz/ton; average Ag grade estimated at 0.01 oz/ton. Estimated 320 million tonnes of 0.35% Cu and 0.02% Mo.

Comments on the workings information

  • Workings / Exploration = Developed by open cuts, shafts and 14 adits totaling between 250 and 300 ft, of which most reportedly were caved in 1944 (USGS OFR 76). 3187 ft of drilling done in 1927 and 1928: 2021 ft in quartz diorite, 1166 ft in metamorphosed limestone.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF NB043
USGS Mineral Resources Data System MRDS A011395
USGS Mineral Resources Data System MRDS D000306

Bibliographic references

  • Deposit

    Moffit, F.H., 1943, Geology of the Nutzotin Mountains, Alaska, with a section on the igneous rocks, by R. C. Wayland, and Gold deposits near Nabesna, by R. C. Wayland, 1943: U.S. Geological Survey Bulletin 933-B, p. 103-199.

  • Deposit

    Van Alstine, R.E., and Black, R.F., 1944, Mineral deposits at Orange, Hill, Alaska: U.S. Geological Survey Open-File Report 76, 16 p., 1 sheet.

  • Deposit

    Moffit, F.H., 1954, Geology of the eastern part of the Alaska Range and adjacent area: U.S. Geological Survey Bulletin 989-D, p. 63-218.

  • Deposit

    Richter, D.H., 1973, Reconnaissance geological map of the Nabesna A-1 quadrangle, Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map 1-789, scale 1:63,360.

  • Deposit

    Richter, D.H., Singer, D.A., and Cox, D.P., 1975, Mineral resources map of the Nabesna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-655-K, scale 1:250,000.

  • Deposit

    Hollister, V.F., Anzalone, S.A., and Richter, D.H., 1975, Porphyry copper belts of southern Alaska and contiguous Yukon Territory: CIM (Canadian Mining and Metallurgical) Bulletin, v. 68, no. 756, p. 104-112.

  • Deposit

    Richter, D.H., and Matson, N.A., 1970, Geochemical data from the Nabesna A-4 quadrangle, Alaska: U.S. Geological Survey Open-File Report 70-276, 14 p., 1 sheet, scale 1:63,360.

General comments

Subject category Comment text
Deposit Model Name = Porphyry, stockwork, skarn
Deposit Other Comments = This record contains data which apply to both the porphyry Cu and the associated contact metamorphic (skarn) deposits at Orange Hill; for data specific to contact metamorphic deposits, see Lemon prospect (NB044).

Reporter information

Type Date Name Affiliation Comment
Reporter 27-JAN-1997 Leonard, K.R. (Elliott, R.L.); Nokleberg, W.J.; Richter, D.H. U.S. Geological Survey