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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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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.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Silver Secondary
Lead Secondary
Zinc 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

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

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

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF GU009

Bibliographic references

  • Deposit

    Richter, D.H., 1966, Geology of the Slana district on south-central Alaska: Alaska Division of Geological and Geophysical Surveys Geological Report 2l, 36b p., 3 sheets, scale 1:63,360.

  • Deposit

    Richter, D.H., and Matson, N.A., 1968, Distribution of gold and some base metals in the Slana area, eastern Alaska Range, Alaska: U.S. Geological Survey Circular 593, 20 p.

  • Deposit

    WGM Inc., 1980, 1979 Summary report of gold potential, Slana District, Ahtna project: WGM Inc., 10 p., 1:63,360-scale map. (Report held by Ahtna Mineral Co., Anchorage, Alaska).

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