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Inmachuk River

Producer in Alaska, United States with commodities Gold, Mercury
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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. Mineral occurrence model information
  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 10308790
MRDS ID A012714
Record type Site
Current site name Inmachuk River
Related records 10001888, 10233333

Geographic coordinates

Geographic coordinates: -163.00341, 65.90137 (WGS84)
Relative position Inmachuk River is a major drainage on northeast Seward Peninsula that flows northward to Deering on Kotzebue Sound. Its floodplain has been extensively placer mined for gold over about 8.5 miles of length starting at an elevation of about 100 feet and continuing upstream to an elevation of about 250 feet. This is locality 71 of Cobb (1972; MF 417; 1975; OFR 75-429).

Site location context

Political divisions (FIPS codes)

Northwest Arctic(Borough)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Bendeleben D-3(quadrangle 1:63,360 scale)

Bendeleben NE(quadrangle 1:100,000 scale)

Bendeleben C(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Goodhope-Spafarief Bay(hydrologic unit)

Northern Seward Peninsula(hydrologic accounting unit)

Northwest(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

NANA Regional Corporation, 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
Mercury Secondary

Materials information

Materials Type of material
Cinnabar Ore
Gold Ore
Hematite Gangue
Pyrite Gangue

Mineral occurrence model information

Model code 119
USGS model code 39a
Deposit model name Placer Au-PGE
Mark3 model number 54

Nearby scientific data

(1) -163.00341, 65.90137
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Economic information

Comments on the geologic information

  • Geologic Description = A significant part of the 578,000 ounces of gold and 32,000 ounces of silver recorded as produced from the Fairhaven district came from Inmachuk River (Hudson and DeYoung, 1978) . Its floodplain has been extensively placer mined, mostly by dredging (Cobb, 1975), over about 8.5 miles of length starting at an elevation of about 100 feet and continuing upstream to an elevation of about 250 feet. These elevations suggest that nearshore processes that accompanied Quaternary sea level fluctuations could have influenced the character of these deposits. The sides of Inmachuk River valley contain terrace gravels capped by basalt flows. Some of these gravels are gold-bearing (Moffit, 1927), and some Inmachuk River gold could have been reworked from them. However, early mining reported that the gold was little worn, some with quartz, and some in hematite pebbles (Moffit, 1905). Cinnabar pebbles up to 1/2 inch across were reported to be present in dredge concentrate by Anderson (1947). Most of the bedrock in the area is a metasedimentary schist and marble sequence of Lower Paleozoic age (Till and others, 1986).
  • Age = Quaternary; two or more cycles of erosion and placer development occurred in the area.

Economic information about the deposit and operations

Development status Producer
Commodity type Metallic

Comments on exploration

  • Status = Active?

Mining district

District name Fairhaven

Comments on the production information

  • Production Notes = A significant part of the 578,000 ounces of gold and 32,000 ounces of silver recorded as produced from the Fairhaven district came from Inmachuk River (Hudson and De Young, 1978). The majority came from the Candle Creek area (BN074).

Comments on the workings information

  • Workings / Exploration = The floodplain of Inmachuk River has been extensively placer mined, mostly by dredging (Cobb, 1975), over about 8.5 miles of length starting at an elevation of about 100 feet and continuing upstream to an elevation of about 250 feet.

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Cobb, 1975 (OFR 75-429)

General comments

Subject category Comment text
Deposit Model Name = Placer Au-PGE (Cox and Singer, 1986; model 39a)

Reporter information

Type Date Name Affiliation Comment
Reporter 15-MAR-1999 Travis L. Hudson Applied Geology

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.