1. Mineral Resources
  2. Online Spatial Data
  3. Mineral Resource Data System (MRDS)

Breccia (south of Snowcap Mountain)

Occurrence in Alaska, United States with commodities Silver, Gold, Copper, Bismuth
Map
XML
JSON
KML
C
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. Nearby scientific data
  9. Economic information about the deposit and operations
  10. Mining district
  11. Links to other databases
  12. Bibliographic references
  13. General comments
  14. Reporter information

Geologic information

Identification information

Deposit ID 10307760
Record type Site
Current site name Breccia (south of Snowcap Mountain)

Geographic coordinates

Geographic coordinates: -153.58195, 61.41976 (WGS84)
Relative position This occurrence is at an elevation of about 4,500 feet on the east side of a small glacier, 2.9 miles southeast of Snowcap Mountain. It is in the SE1/4 section 4, T 15 N, R 24 W, of the Seward Meridian. The location is accurate to within 0.2 mile.

Site location context

Political divisions (FIPS codes)

Bethel(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Lime Hills B-2(quadrangle 1:63,360 scale)

Lime Hills SE(quadrangle 1:100,000 scale)

Lime Hills(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Stony River(hydrologic unit)

Upper Kuskokwim River(hydrologic accounting unit)

Southwest(hydrologic subregion)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Gold Primary
Copper Primary
Bismuth Critical Secondary

Materials information

Materials Type of material
Arsenopyrite Ore
Chalcopyrite Ore
Galena Ore
Pyrite Ore
Pyrrhotite Ore
Sphalerite Ore
Calcite Gangue
Chlorite Gangue
Epidote Gangue
Quartz Gangue
Sericite Gangue
Tourmaline Gangue

Alteration

  • (Local) Tourmaline replacement and veining.

Nearby scientific data

(1) -153.58195, 61.41976
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = A tourmaline-cemented breccia as much as 80 feet across is present in monzogranite at this locality (Gamble and others, 1989). The breccia, includes vein quartz, light-colored angular rock fragments, and monzogranite clasts to about 3 feet across suspended in a black tourmaline matrix that also contains lesser amounts of sericite, quartz, calcite, and chlorite. Discontinuous quartz-tourmaline-sulfide veins to a foot wide cut the breccia along vertical, north-south-trending fractures. Sulfides in the veins include arsenopyrite, chalcopyrite, pyrrhotite, pyrite, and lesser amounts of galena and sphalerite; gangue minerals include quartz, tourmaline, chlorite, and epidote. A composite grab sample of 5 veins in the breccia contains as much as 4.1 ppm gold, 7 ppm silver,and greater than 2,000 ppm arsenic. Selected sulfide-rich samples contain as much as 21 ppm gold, 150 ppm silver, 10,000 ppm copper, and greater than 2,000 ppm arsenic and 1,000 ppm bismuth (Gamble and others, 1989).
  • Age = Cretaceous or Tertiary the breccia and veins crosscut granitic rocks that may be Late Cretaceous or Tertiary parts of the Alaska-Aleutian Range batholith.

Economic information about the deposit and operations

Development status Occurrence

Comments on exploration

  • Status = Inactive

Mining district

District name McGrath

Comments on the workings information

  • Workings / Exploration = Reconnaissance sampling has been done in this area (Gamble and others, 1989).

Reference information

Comments on the references

  • Primary Reference = Gamble and others, 1989

General comments

Subject category Comment text
Deposit Model Name = Tourmaline-cemented breccia in granitic rocks

Reporter information

Type Date Name Affiliation Comment
Reporter 10-JUN-01 Travis L. Hudson Applied Geology
Reporter 10-JUN-01 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.