Unnamed (on headwater tributary to Porcupine Creek)

Occurrence in Alaska, United States with commodities Silver, Gold, Copper
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 10308252
Record type Site
Current site name Unnamed (on headwater tributary to Porcupine Creek)

Geographic coordinates

Geographic coordinates: -136.28213, 59.32974 (WGS84)
Relative position This occurrence is at an elevation of approximately 3,500 feet on the east side of an unnamed headwater tributary to Porcupine Creek near the divide to Cottonwood Creek. It is in the the SW1/4, section 23, T. 29 S., R. 54 E. of the Copper River Meridian. It is shown as location 146 by Still and others (1987) and as site R by Gilbert and Redman (1989) who informally referred to it as the 'Porcupine Roof Pendant'.

Site location context

Political divisions (FIPS codes)

Haines(Borough)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Skagway B-4(quadrangle 1:63,360 scale)

Skagway SE(quadrangle 1:100,000 scale)

Skagway C(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Chilkat-Skagway Rivers(hydrologic unit)

Northern Southeast Alaska(hydrologic accounting unit)

Southeast Alaska(hydrologic subregion)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Gold Primary
Copper Secondary

Materials information

Materials Type of material
Pyrite Ore

Alteration

  • (Local) Development of calc-silicate minerals.

Mineral occurrence model information

Model code 59
USGS model code 18b
Deposit model name Skarn Cu
Mark3 model number 8
Model code 60
USGS model code 18c
Deposit model name Skarn Zn-Pb
Mark3 model number 22

Nearby scientific data

(1) -136.28213, 59.32974

Economic information

Comments on the geologic information

  • Geologic Description = According to Still and others (1991), this occurrence is a mineralized, 400 foot by 1,000 foot, roof pendant surrounded by diorite. The pendant consists of metamorphosed slate and limestone that form bands of garnet and diopside at some locations. Samples from the pendant contained up to 0.068 ppm gold, 1.1 ppm silver, 192 ppm zinc, and 230 ppm copper (Gilbert and others, 1991), and a sample of gossan rubble with 20% pyrite collected 500 feet below the pendant contained 6.33 ppm gold, 18.2 ppm silver, and 515 ppm copper (Still and others, 1991). The metamorphosed slate and limestone are of probable Paleozoic age (MacKevett and others, 1974). The bands of garnet and diopside and the mineralization are probably due to to contact metasomatism by the surrounding Cretaceous diorite (MacKevett and others, 1974).
  • Age = Probably Cretaceous or younger based on the age of the surrounding diorite (MacKevett and others, 1974).

Economic information about the deposit and operations

Development status Occurrence

Comments on exploration

  • Status = Probably inactive

Mining district

District name Juneau (Skagway subdistrict)

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Still and others, 1991

General comments

Subject category Comment text
Deposit Model Name = Based on limited information, this is probably a skarn related occurrence (Cox and Singer, 1986; model 18b? or 18c?).

Reporter information

Type Date Name Affiliation Comment
Reporter 04-FEB-01 T.C. Crafford T. Crafford & Associates

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Authoritative Alaska resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.