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Horsfeld

Prospect in Alaska, United States with commodities Copper, Gold, Molybdenum, Silver
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Public Land Survey System information
  6. Commodities
  7. Materials information
  8. Alteration
  9. Mineral occurrence model information
  10. Host and associated rocks
  11. Nearby scientific data
  12. Economic information about the deposit and operations
  13. Mining district
  14. Mineral rights holdings
  15. Ownership information
  16. Reserves and resources
  17. Links to other databases
  18. Bibliographic references
  19. General comments
  20. Reporter information

Geologic information

Identification information

Deposit ID 10000779
MRDS ID A011422
Record type Site
Current site name Horsfeld
Alternate or previous names Horsfall

Geographic coordinates

Geographic coordinates: -141.21848, 62.04401 (WGS84)
Relative position This prospect is in the headwaters of a small, unnamed north tributary to Horsfeld Creek; it is about 6,000 feet southwest of elevation 7253 (Joe) and 3,300 feet south-southwest of peak 6895. The site is near the center of the north boundary of the NW1/4 of section 16, T. 3 N., R. 23 E. of the Copper river Meridian. This is locality 7 of Richter and others (1973), locality 52 of Richter and others (1975), and National Park Service locality WRST-85 (unpublished data). Cobb and Richter (1980) included this prospect under the name 'Horsfeld'. It is located to within a few hundred feet.

Site location context

Political divisions (FIPS codes)

Southeast Fairbanks(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Nabesna A-1(quadrangle 1:63,360 scale)

Nabesna SE(quadrangle 1:100,000 scale)

Nabesna(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Alaska(hydrologic region)

Federal lands

Wrangell-St. Elias National Preserve(National Preserve)

National Preserve NPS(Type of land area)

NPS(Federal land areas administered by NPS)

Geographic areas

Country State
United States Alaska

Public Land Survey System information

Meridian Township Range Section Fraction State
Copper River 3 N 23 E 16 NW1/4 Alaska

Commodities

Commodity Importance
Copper Primary
Gold Secondary
Molybdenum Secondary
Silver Secondary

Materials information

Materials Type of material
Chalcopyrite Ore
Magnetite Ore
Pyrite Ore
Actinolite Gangue
Quartz Gangue
Bornite Unknown
Molybdenite Unknown
Orthoclase Unknown

Alteration

  • (Local) Argillic, propylitic. Central altered zone 200 m by 700 m characterized by K-feldspar, actinolite and magnetite.

Mineral occurrence model information

Model code 53
USGS model code 17
Deposit model name Porphyry Cu
Mark3 model number 4
Model code 79
USGS model code 21a
Deposit model name Porphyry Cu-Mo
Mark3 model number 2

Host and associated rocks

  • Host or associated Associated
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite
    Rock unit name Klein Creek Batholith;
    Rock description Klein Creek Batholith;
  • Host or associated Host
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite
    Rock unit name Klein Creek Batholith;Klein Creek Batholith
    Rock description Klein Creek Batholith;Klein Creek Batholith

Nearby scientific data

(1) -141.21848, 62.04401
ListMap

Economic information

Comments on the geologic information

  • At the Horsfeld prospect, pyrite and chalcopyrite occur in quartz veinlets and as disseminations in monzonite and monzonite porphyry of the mid-Cretaceous, Klein Creek pluton (Richter and others, 1973; 1975). This porphyry copper and molybdenum deposit has a central 200- by 700-meter zone of potassium feldspar, actinolite, and magnetite alteration, and a 800- by 1,500-meter outer zone of unspecified hydrothermal alteration. Surface samples contain less than 0.5 percent copper, and average 0.10 percent copper and less than 0.01 percent molybdenum (Hollister and others, 1975; Richter and others, 1975). Gold and silver were detected in some surface samples (Matson and Richter, 1971 [OFR 71-202]). The deposit is estimated to contain 60 million tons with an average grade of 0.20 percent copper and very low amounts of molybdenum (Richter and others, 1975). The deposit is in the Klein Creek pluton near its contact with Jurassic or Cretaceous siliciclastic rocks; the associated hydrothermal alteration zone extends across this contact (Richter and others, 1973).

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic
Significant Yes

Mining district

District name Chisana

Mineral rights holdings

Type of mineral rights Located Claim

Ownership information

  • Type Owner
    Owner Oil Development Co. of Texas
    Home office Texas
    Year 1984

Reserves and resources

  • Type In-situ
    Estimate year 1979
    Inferred 54420000mt ore
    Total resources 54420000mt ore
    Commodity Subtype Grade units Group Importance Year
    Copper Cu 0.2 wt-pct Copper Primary 1979

Comments on the workings information

  • Surface exploration and some diamond drilling have been used to evaluated this deposit. Average grade from surface sampling: 0.10% Cu (all samples were below 0.5% Cu) and less than 0.10% Mo (Richter and others, 1975, USGS MF-655K, loc. 52). Au and Ag detected in analysis (Matson and Richter,, 1971, USGS OF 471, samples 148, 149).

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Richter, D.H., Lanphere, M.A., and Matson, N.A., Jr., 1975, Granite plutonism and metamorphism, eeastern Alaska Range, Alaska: Geological Society of American Bulletin, v. 86, p. 819-820.

General comments

Subject category Comment text
Age Mid-Cretaceous. The diorite of the Klein Creek pluton that hosts the deposits has a K/Ar date of 111 +/- 3.6 Ma (Richter, Lanphere, and Matson, 1975).
General One of 8 porphyry copper deposits which make up the known principal potential mineral resource of the Nabesna quadrangle. The prospect is in the Wrangell-St. Elias National Preserve.

Reporter information

Type Date Name Affiliation Comment
Reporter 28-JAN-97 Leonard, K.R. U.S. Geological Survey
Reporter 28-JAN-97 Elliott, R.L. U.S. Geological Survey
Reporter 28-JAN-97 Nokleberg, W.J. U.S. Geological Survey
Reporter 28-JAN-97 W.J.; Richter, D.H. U.S. Geological Survey
Reporter 19-FEB-88 Carnes, R. David U.S. Bureau of Mines
Reporter 24-NOV-02 Travis L. Hudson Applied Geology ARDF record NB099.

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Maps centered on this site

Authoritative Alaska resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.