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Unnamed (east-northeast of VABM Cobb)

Occurrence in Alaska, United States with commodities Gold, 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 10307477
Record type Site
Current site name Unnamed (east-northeast of VABM Cobb)

Geographic coordinates

Geographic coordinates: -144.15263, 62.72968 (WGS84)
Relative position The occurrence is on the north flank of a hill which is locally called Grizzly Hill, a broad ridge trending east-northeast of VABM Cobb. The site is approximately centered along the south half of the section line dividing sections 17 and 18, T. 11 N., R. 7 E., Copper River Meridian.

Site location context

Political divisions (FIPS codes)

Valdez-Cordova(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Gulkana C-1(quadrangle 1:63,360 scale)

Gulkana NE(quadrangle 1:100,000 scale)

Gulkana(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Upper Copper River(hydrologic unit)

Copper River(hydrologic accounting unit)

South Central Alaska(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

Ahtna, Incorporated(ANCSA Region)

ANCSA Region NTVPIC(Type of land area)

NTVPIC(Federal land areas administered by NTVPIC)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Silver Secondary
Lead Secondary
Zinc Critical Secondary

Comments on the commodity information

  • Gangue = Carbonate minerals

Materials information

Materials Type of material
Galena Ore
Pyrite Ore
Sphalerite Ore
Quartz Gangue
Tourmaline Gangue

Alteration

  • (Local) Silicification; formation of silica-carbonate and tourmaline-bearing rocks.

Mineral occurrence model information

Model code 85
USGS model code 22c
Deposit model name Polymetallic veins
Mark3 model number 46

Nearby scientific data

(1) -144.15263, 62.72968
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The higher part of the area consists of Border Phase rocks of the Pennsylvanian to Permian, Ahtell pluton. These rocks are apparently underlain by the Grubstake Phase of the pluton and are cut by east-northeast-trending dikes and masses of younger Jurassic diorite (Richter, 1966; Richter and Matson, 1968). The approximate center of the occurrence is on the east end of a locally sulfidized, silica-carbonate zone, included within the area 3a of WGM Inc. (1980, fig. 3) which is anomalous in gold. The area also has anomalous lead and zinc (Richter, 1966). A stream-sediment sample in the drainage on the north side of the occurrence contained 7,100 ppb gold (Richter and Matson, 1978). The occurrences may extend over the ridge to the south where Kirk Stanley reported (written communication, 2000) low-grade, gold-tourmaline mineral occurrences, also argentiferous galena-quartz veins. Stanley speculated that there was a large tourmaline breccia pipe in the area.
  • Age = Uncertain; possibly composite mineralization related to both the Pennsylvanian to Permian, Ahtell pluton and the crosscutting Jurassic diorite, but could be related to either.

Economic information about the deposit and operations

Development status Occurrence

Comments on exploration

  • Status = Inactive

Mining district

District name Chistochina

Comments on the workings information

  • Workings / Exploration = Most of the area has only been mapped in reconnaissance and sampled with stream sediments. Kirk Stanley (written communication, 2000) trenched a nearby area on the south flank of the Grizzly Hills in about 1970.

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Richter and Matson, 1968; WGM, 1980

General comments

Subject category Comment text
Deposit Model Name = Polymetallic veins, Au porphyry (?) (Cox and Singer, 1986; model 22c )
Deposit Other Comments = Additional information can be obtained from Ahtna Minerals in Anchorage, Alaska.

Reporter information

Type Date Name Affiliation Comment
Reporter 07-DEC-00 W.T. Ellis Alaska Earth Sciences
Reporter 07-DEC-00 Hawley, C.C. Hawley Resource Group
Reporter 07-DEC-00 W.J. Nokleberg 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.