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Unnamed (east side of Dundas Bay)

Occurrence in Alaska, United States with commodities Copper, Silver, Gold, Molybdenum, 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. Host and associated rocks
  10. Nearby scientific data
  11. Economic information about the deposit and operations
  12. Mining district
  13. Links to other databases
  14. Bibliographic references
  15. General comments
  16. Reporter information

Geologic information

Identification information

Deposit ID 10002285
MRDS ID A013189
Record type Site
Current site name Unnamed (east side of Dundas Bay)
Related records 10160899

Geographic coordinates

Geographic coordinates: -136.29013, 58.37472 (WGS84)
Relative position This occurrence is east of the mouth of the Dundas River and is mostly in the west half of section 26, T. 40 S., R. 55 E., of the Copper River Meridian. It ranges from 100 feet wide to more than 1000 feet wide and extends from the shoreline northerly for about one mile. The coordinates are at the approximate center of the occurrence, which is the same as number 31 of MacKevett and others (1971), number 57 of Cobb (1972), and within figure C73 of Kimball and others (1978).

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 B-1(quadrangle 1:63,360 scale)

Juneau SW(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
Silver Secondary
Gold Secondary
Molybdenum Secondary
Lead Secondary
Zinc Critical Secondary

Comments on the commodity information

  • Gangue = Muscovite (sericite)

Materials information

Materials Type of material
Chalcopyrite Ore
Galena Ore
Malachite Ore
Pyrite Ore
Sphalerite Ore
Quartz Gangue

Alteration

  • (Local) Local oxidation of copper minerals.

Mineral occurrence model information

Model code 184
USGS model code 28a
Deposit model name Massive sulfide, kuroko
Mark3 model number 93

Host and associated rocks

  • Host or associated Associated
    Rock type Metamorphic Rock > Metavolcanic Rock > Mafic Metamorphic Rock > Meta-Basalt
    Stratigraphic age (youngest) Late Silurian
    Stratigraphic age (youngest) Late Devonian
  • Host or associated Host
    Rock type Metamorphic Rock > Schist

Nearby scientific data

(1) -136.29013, 58.37472
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = Pyritic quartz-mica semischist, that possibly is a metarhyolite,and metabasalt appear to occur within a unit that elsewhere consists mainly of graywacke and argillite of Silurian and Devonian age (Brew and others, 1978). Foliated granitic rocks crop out west of the pyritic schists. The granitic rocks are inferred to be extensive, but are covered by water in Dundas Bay. ? the pyritic semischist, which is the mineralized unit, forms a steep, north trending body from 100 feet to more than 1000 feet thick. It in sharp contact with adjacent metabasalt. Pyrite is more abundant than chalcopyrite in the semischist unit, but chalcopyrite is generally present. The semischist is cut locally by veinlike zones that contain relatively abundant chalcopyrite.? the occurrence is probably syngenetic and volcanigenic. Chalcopyrite may have been remobilized into the vein-like zones during Cretaceous metamorphism.? Selected samples of the semischist unit contained as much as 1 ppm silver and 2000 ppm copper (MacKevett and others, 1971, table 9). Kimball and others (1978) reported 2 ppm silver, 320 ppm copper, and 230 ppm zinc in a 50 foot long chip sample of the semischist. Molybdenum is commonly present and assayed as much as 100 ppm in a 12 foot chip sample. Moerlein (1968) collected 35- and 20-ft. chip samples from a northwest-striking shear zone within the semischist; his samples contained, respectively, 0.51 and 0.34 percent copper.
  • Age = Devonian-Silurian with possible remobilization during the Cretaceous.

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Juneau

Comments on the workings information

  • Workings / Exploration = Claims reportedly staked for gold, lead, zinc and copper were reported in the east Dundas Bay area by Wright and Wright (1937). In the 1966 examination by the U.S. Geological Survey, only surface exposures were examined and sampled. A chip sample collected across 40-feet of semischist contained 1000 ppm copper; a malachite stained zone contained 2000 ppm copper (MacKevett and others, 1971). Moerlein (1968) found as much as 0.51 percent copper in a northwest trending shear zone within the pyritic semischist unit. Samples of semischist collected by the U.S. Bureau of Mines (Kimball and others, 1978) showed anomalous silver, molybdenum, and zinc as well as copper. Maximum reported molybdenum content was 100 ppm.

Reference information

Bibliographic references

  • Deposit

    Wright, F.E. and Wright, C.W., 1937, The Glacier Bay National Monument in southeastern Alaska, its glaciers and geology: U.S. Geological Survey manuscript report, 224 p.

  • 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

    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.

  • Deposit

    Moerlein, G.A., 1968, Geology and drilling results, Nunatak molybdenum prospect, Walper property, southeastern Alaska: Unpublished report available at U.S. Bureau of Land Management Library at Juneau, Alaska.

Comments on the references

  • Primary Reference = Kimball and others, 1978

General comments

Subject category Comment text
Deposit Model Name = Volcanogenic, cupriferous metarhyolite -- similar to kuroko massive sulfide (Cox and Singer, 1986; model 28a).
Deposit Other Comments = Although the reported grade of the deposit is subeconomic, its size and possible volcanogenic nature encourages further exploration and the mapping of the Devonian-Silurian volcanic stratigraphy. ? the site is in Glacier Bay National Park and Preserve.

Reporter information

Type Date Name Affiliation Comment
Reporter 14-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.