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1:30

Prospect in Alaska, United States with commodities Silver, Gold, Copper, Molybdenum, Zinc, Arsenic, Antimony
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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 10003500
MRDS ID A106258
Record type Site
Current site name 1:30

Geographic coordinates

Geographic coordinates: -152.76278, 61.95949 (WGS84)
Relative position Alaska Department of Natural Resources claim records show this prospect area two miles up a southern tributary to Portage Creek in the southeast quarter of Section 28, T. 22 N., R. 19 W. Exposed on mountain slopes on the northwest side of the creek. Approximately 7 miles west-southwest of the confluence of Portage Creek and the Skwentna River.

Site location context

Political divisions (FIPS codes)

Matanuska-Susitna(Borough)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Tyonek D-8(quadrangle 1:63,360 scale)

Tyonek NW(quadrangle 1:100,000 scale)

Tyonek(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Yentna River(hydrologic unit)

Susitna River(hydrologic accounting unit)

South Central Alaska(hydrologic subregion)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Gold Primary
Copper Primary
Molybdenum Primary
Zinc Critical Primary
Arsenic Critical Secondary
Antimony Critical Secondary

Materials information

Materials Type of material
Arsenopyrite Ore
Chalcopyrite Ore
Molybdenite Ore
Pyrite Ore
Quartz Gangue

Alteration

  • (Local) Limonite, quartz

Host and associated rocks

  • Host or associated Host
    Rock type
    Stratigraphic age (youngest) Early Oligocene
    Stratigraphic age (oldest) Early Cretaceous

Nearby scientific data

(1) -152.76278, 61.95949
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = Fine- to medium-grained, equigranular biotite-hornblende diorite intrudes and hornfels Mesozoic marine sedimentary rocks (KJs) of the Kahlitna terrane (Reed and Elliott, 1970). The hornfels is pyritic and locally sheared. Float from inaccessible portions of the diorite have thin (less than 1 inch) veins of quartz-arsenopyrite-pyrite and quartz-molybdenite-sphalerite. Samples of vein material from the diorite contained up to 4400 ppb gold and 1380 ppm silver. A 15 foot chip samples across pyritic, sheared hornfels ran 3800 ppb gold. (Cominco American Incorporated, unpublished reports, 1987-1988). The diorite is probably part of the Late Cretaceous/Early Tertiary Mount Estelle plutonic suite (Tme) (Reed and Elliott, 1970; Reed and Nelson, 1980); veins may be genetically related to the host rocks.
  • Age = Host rocks are late Cretaceous or Early Tertiary (by Reed and Elliott, 1970 and Reed and Nelson, 1980); the veins may be genetically related to the host rocks.
  • Age = Host rocks are Eocene - Late Cretaceous.

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Yentna

Comments on the workings information

  • Workings / Exploration = Exploration work included silt and rock chip geochemical sampling and mapping. (Cominco American Incorporated, unpublished report, 1987).

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Reed and Elliott, 1970

General comments

Subject category Comment text
Deposit Model Name = Polymetallic vein(s); copper-moly porphyry?

Reporter information

Type Date Name Affiliation Comment
Reporter 01-JUN-1998 Madelyn A. Millholland Millholland & Associates

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.