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  3. Mineral Resource Data System (MRDS)

Unnamed (north of Leduc Lake)

Occurrence in Alaska, United States with commodities Copper, Molybdenum, Silver, Lead, Zinc, Tungsten
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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. Host and associated rocks
  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 10001546
MRDS ID A012293
Record type Site
Current site name Unnamed (north of Leduc Lake)

Geographic coordinates

Geographic coordinates: -130.85066, 55.9767 (WGS84)
Relative position This occurrence is at an elevation of about 3900 feet in the saddle between hills 4430 and 4375, about 2.8 miles north of the outlet of Leduc Lake. The site is in section 15, T. 68 S., R. 94 E., of the Copper River Meridian. It corresponds to area M-1 in Berg and others (1977), and to loc. 16 in Elliott and others (1978). The location is accurate within 0.1 mile.

Site location context

Political divisions (FIPS codes)

Prince of Wales-Hyder(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Ketchikan D-3(quadrangle 1:63,360 scale)

Ketchikan NW(quadrangle 1:100,000 scale)

Ketchikan(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Southern Southeast Alaska(hydrologic accounting unit)

Southeast Alaska(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

Misty Fiords National Monument Wilderness(Wilderness)

Wilderness FS(Type of land area)

FS(Federal land areas administered by FS)

Tongass National Forest(National Forest)

National Forest FS(Type of land area)

FS(Federal land areas administered by FS)

Misty Fjords National Monument Wilderness(Wilderness)

Wilderness FS(Type of land area)

FS(Federal land areas administered by FS)

Geographic areas

Country State
United States Alaska

Commodities

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

Materials information

Materials Type of material
Chalcopyrite Ore
Molybdenite Ore
Pyrrhotite Ore
Quartz Gangue

Alteration

  • (Local) Conspicuous iron-staining.

Host and associated rocks

  • Host or associated Host
    Rock type Metamorphic Rock > Gneiss

Nearby scientific data

(1) g
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The country rocks in the area of this occurrence are pelitic paragneiss, subordinate quartzofeldspathic paragneiss, and minor amphibolite and tactite (Berg and others, 1977, p. 123-124; Berg and others, 1988). These rocks, accompanied by small intrusions of pegmatite and diorite, form a large roof pendant in Tertiary or Cretaceous foliated granodiorite and quartz diorite of the Coast Range batholith. The metamorphic rocks probably represent marine argillaceous, clastic, and minor mafic volcanic strata that underwent high-grade regional metamorphism in Cretaceous or Tertiary time. The premetamorphic age of the strata is uncertain, but they probably are mainly Paleozoic and may be as old as Precambrian (Berg and others, 1988, p. 26; Gehrels and others, 1990; Crawford and others, in press).? the occurrence is a band of iron-stained paragneiss 450-900 feet wide and about 3 miles long (Berg and others, 1977, p. 123-125). It consists of small quartz veins and stringers that both parallel and crosscut the schistosity of the enclosing metamorphic rocks, which locally are intruded by small pegmatite dikes and sills. Berg and others (1977) reported anomalous amounts of molybdenum in rock (table 3, no. 16) and stream-sediment (figs. 9, 12) geochemical samples collected in this area. Eleven follow-up chip samples collected by the U.S. Bureau of Mines contained up to 110 ppm Cu, 15 ppm Pb, 60 ppm Zn, 1.5 ppm Ag, 100 ppm Mo, and, in one sample, a trace of W (Berg and others, 1977, area M-1, p. 123-125). In addition, several concordant lenses of chocolate-brown-weathering amphibolite up to about 2 feet wide and 15 feet long contain a small amount of pyrrhotite and a trace of chalcopyrite.

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Mining district

District name Ketchikan

Comments on the workings information

  • Workings / Exploration = Eleven chip samples of quartz veins and metamorphic hostrocks contained up to 110 ppm Cu, 15 ppm Pb, 60 ppm Zn, 1.5 ppm Ag, 100 ppm Mo, and, in one sample, a trace of W (Berg and others, 1977, p. 125).

Reference information

Comments on the references

  • Primary Reference = Berg and others, 1977

General comments

Subject category Comment text
Deposit Model Name = Disseminated base-metal sulfides in metamorphic roof pendant
Deposit Other Comments = Occurrence is in Misty Fiords National Monument Wilderness.

Reporter information

Type Date Name Affiliation Comment
Reporter 29-JUN-1999 H.C. Berg U.S. Geological Survey

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.