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Unnamed (Bruce Hills)

Prospect in Alaska, United States with commodities Copper, Molybdenum, Silver, Lead, Zinc
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Commodities
  6. Materials information
  7. Alteration
  8. Mineral occurrence model information
  9. Nearby scientific data
  10. Economic information about the deposit and operations
  11. Mining district
  12. Links to other databases
  13. Bibliographic references
  14. General comments
  15. Reporter information

Geologic information

Identification information

Deposit ID 10308917
MRDS ID A013172
Record type Site
Current site name Unnamed (Bruce Hills)
Related records 10002269

Geographic coordinates

Geographic coordinates: -136.34311, 58.98273 (WGS84)
Relative position The deposit is in the Bruce Hills between Wachusett Inlet and Burroughs Glacier. It occupies parts of sections 23, 24, 25, and 26, T. 33 S., R. 54 E., of the Copper River Meridian. The location given is the approximate midpoint of the outcrop of the deposit on the ridge between the inlet and glacier, at an elevation of about 2300 feet. The deposit is mainly in the Mt. Fairweather D-2 quadrangle but it extends easterly into the D-1 quadranagle. The deposit includes two occurrences investigated in detail by the U.S. Bureau of Mines (Kimball and others, 1978, figs. C62 & 63).

Site location context

Political divisions (FIPS codes)

Hoonah-Angoon(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Mount Fairweather D-2(quadrangle 1:63,360 scale)

Juneau NW(quadrangle 1:100,000 scale)

Mount Fairweather(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Glacier Bay(hydrologic unit)

Northern Southeast Alaska(hydrologic accounting unit)

Southeast Alaska(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

Glacier Bay National Park(National Park)

National Park NPS(Type of land area)

NPS(Federal land areas administered by NPS)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary
Molybdenum Primary
Silver Secondary
Lead Secondary
Zinc Critical Secondary

Comments on the commodity information

  • Gangue = K-feldspar

Materials information

Materials Type of material
Chalcopyrite Ore
Galena Ore
Hematite Ore
Malachite Ore
Molybdenite Ore
Molybdite Ore
Pyrrhotite Ore
Sphalerite Ore
Chlorite Gangue
Limonite Gangue
Montmorillonite Gangue
Quartz Gangue

Alteration

  • K-feldspar occurs as a secondary mineral in and near quartz veins, and the host granodiorite is anomalously rich in K-feldspar, particularly south and east of the deposit (Kimball and others, 1978, p. C306). Feldspathization was noted elsewhere in the area. Montmorillonite is developed locally. The deposit itself is propylitically altered, with chlorite replacing primary mafic minerals.

Mineral occurrence model information

Model code 53
USGS model code 17
Deposit model name Porphyry Cu
Mark3 model number 4
Model code 54
USGS model code 17
Deposit model name Porphyry Cu (North America)
Mark3 model number 81

Nearby scientific data

(1) -136.34311, 58.98273
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The deposit is in foliated granodiorite that is part of a batholithic mass that underlies much of the northeast part of the National Park. The intrusion, of Cretaceous age, has invaded a shale-carbonate sequence of Paleozoic age now mainly converted to marble and schist (Brew and others, 1978).The deposit is about two miles west of the main batholithic contact. Occasional masses of hornfels (roof pendants?) included in the granitic rock suggest that the deposit could lie fairly close to the roof of the intrusion. A strong fault which strikes about N. 30-40 E. seems to form the southeast limit of the deposit. (MacKevett and others, 1971, fig. 10). Andesite dikes that strike east-northeast cut through the deposit. The main ore minerals, chalcopyrite and molybdenite, occur in quartz and quartz-feldspar veinlets, as disseminations and as fracture coatings. Galena, pyrrhotite, and sphalerite occur locally. Locally the sulfide minerals have been oxidized to secondary malachite, molybdite, and limonite. The deposit is in heavily iron-stained granodiorite. The deposit appears to be low grade, on an average, but has the potential for the occurrence of substantial local zones of higher grade. The average grade is about 0.05 percent copper and less than 100 ppm molybdenum. Parts of the deposit, however, contain about 2000 ppm copper and 200 ppm molybdenum, and selected veins contain as much as 3400 ppm copper and 1000 ppm molybdenum. The area is partly soil covered.
  • Age = Tertiary.

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Juneau

Comments on the reserve resource information

  • Reserves = A resource exists in the mid 0.0X percent range for copper and low 0.0X range for molybdenum; local zones are of higher grade.

Comments on the workings information

  • Workings / Exploration = The occurrence of copper and molybdenum in the Bruce Hills was first reported by Rossman (1963, B 1121-K). Seven claims were staked in 1967 and the deposit was blanketed by 55 claims located in 1969. At the time of the U.S. Bureau of Mines investigation in 1977 (Kimball and others, 1978, p. C297) all claims were inactive. Mineralization is exposed on the surface and possibly in shallow hand-dug trenches. The average grade of the deposit is about 0.05 percent copper and 75 ppm molybdenum. An exposure at about 1750 to 1950 on the northeast side of the deposit, possibly the one originally noted by Moerlein (1971), appears to be somewhat richer. Samples collected along a northeast line about 330 feet long averaged 0.17 percent copper and 0.026 percent molybdenum (Kimball and others, 1978, p. C300-305). The values are close to Moerlein's estimate of 0.2 percent copper and 0.017 percent molybdenum. The U.S. Geological Survey sampled the southwest part of the deposit because, at the time of their investigation, the ridge and north areas were snow covered; maximum values reported were 3000 ppm copper and 1000 ppm molybdenum (MacKevett and others, 1971, p. 48-50). The USGS also conducted a soil survey. Both USGS and USBM investigators report higher-grade type samples with values to 4000 ppm Cu and 2000 ppm molybdenum.

Reference information

Bibliographic references

  • Deposit

    Rossman, Darwin, 1963, Geology of the eastern part of the Mount Fairweather quadrangle, Glacier Bay, Alaska: U.S. Geological Survey Bulletin 1121-K, p. K1-K57.

  • Deposit

    MacKevett, E.M., Jr., Brew, D.A., Hawley, C.C., Huff, L.C., and Smith, J.G., 1971, Mineral resources of Glacier Bay National Monument, Alaska: U.S. Geological Survey Professional Paper 632, 90 p., 12 plates, scale 1:250,000.

  • Deposit

    Moerlein, G.A., 1971, Report of examination of Bruce Hills copper-molybdenum deposit, Mt. Fairweather D-2 quadrangle: (Unpublished report available at U.S. Bureau of Land Management Library at Juneau, Alaska).

  • Deposit

    Brew, D.A., Johnson, B.R., Grybeck, D., Griscom, A., Barnes, D.F., Kimball, A.L., Still, J.C., and Rataj, J.L., 1978, Mineral resources of the Glacier Bay National Monument Wilderness Study Area, Alaska: U.S. Geological Survey Open-File Report 78-494, 670 p.

  • Deposit

    Kimball, A.L., Still, J.C., and Rataj, J.L., 1978, Mineral resources, in Brew, D. A., and others, Mineral resources of the Glacier Bay National Monument wilderness study area, Alaska: U.S. Geological Survey Open-File Report 78-494, p. C1-C375.

  • Deposit

    Cobb, E.H., 1972, Metallic mineral resources map of the Mount Fairweather quadrangle, AK: U.S. Geological Survey Miscellaneous Field Study Map MF-436, 1 sheet, scale 1:250,000.

Comments on the references

  • Primary Reference = Kimball and others, 1978

General comments

Subject category Comment text
Deposit Model Name = Porphyry copper-molybdenum similar to porphyry copper (Cox and Singer, 1986; model 17).
Deposit Other Comments = The Bruce Hills prospect is about 8.5 miles west of the Nunatak molybdenum deposit (MF036) and only about 2 miles north of the Wachusetts copper-molybdenum vein (MF060). The site is in Glacier Bay National Park and Preserve.

Reporter information

Type Date Name Affiliation Comment
Reporter 08-APR-99 Hawley, C.C. Hawley Resource Group

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.