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

Reef

Past Producer in Alaska, United States with commodity Chromium
Map
XML
JSON
KML
B
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. Host and associated rocks
  10. Nearby scientific data
  11. Economic information about the deposit and operations
  12. Mining district
  13. Links to other databases
  14. Bibliographic references
  15. General comments
  16. Reporter information

Geologic information

Identification information

Deposit ID 10000468
MRDS ID A010646
Record type Site
Current site name Reef
Alternate or previous names Anderson, Bluff, Claim Point

Geographic coordinates

Geographic coordinates: -151.82253, 59.20946 (WGS84)
Relative position These chromite deposits occur on a small peninsula on the northern shore of Port Chatham in the SW1/4 of section 21, T. 11 S., R. 15 W., of the Seward Meridian. Most of the chromite lens and layers are found on the northeast side of the peninsula near the old mill and wharf. This is location 1 of Cobb (1972, MF-397) and is accurate to within half a mile.

Site location context

Political divisions (FIPS codes)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Seldovia A-5 NW(quadrangle 1:24,000 scale)

Seldovia SW(quadrangle 1:100,000 scale)

Seldovia C(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Lower Kenai Peninsula(hydrologic unit)

Kenai Peninsula(hydrologic accounting unit)

South Central Alaska(hydrologic subregion)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Chromium Critical Primary

Materials information

Materials Type of material
Chromite Ore

Alteration

  • (Local) Serpentization.

Mineral occurrence model information

Model code 15
USGS model code 8a
Deposit model name Podiform chromite (minor)
Mark3 model number none

Host and associated rocks

  • Host or associated Associated
    Rock type Plutonic Rock > Ultramafic Intrusive Rock > Peridotite > Dunite
    Stratigraphic age (youngest) Late Cretaceous
    Stratigraphic age (youngest) Pliocene
  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Siltstone

Nearby scientific data

(1) -151.82253, 59.20946
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The chromite at Claim Point is hosted in dunite that is part of the informally named Border Ranges ultramafic and mafic complex of Burns (1985). The Border Ranges complex is Mesozoic in age. The complex is faulted at the base and there are many small northeast-trending, high-angle faults which offset the chromite layers. In general, the chromite layers strike northeast and dip nearly vertical. ? Most of the production in the area has occurred from the Reef mine where the ore body strikes S76W with a nearly vertical dip, although some of the chrome layers show much local variation in dip and strike. The chromite layer is about 135 feet long and the width ranges from three to 35 feet. The chromic oxide content of the ore as shipped, ranged from 42 to 49 percent. ? Foley and Barker (1985) estimates there is 82,000 metric tons of ore with grades ranging from 5 to 30% chromic oxide.
  • Age = Mesozoic; based on the age of the ultramafic body that hosts the deposit.

Economic information about the deposit and operations

Development status Past Producer
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Homer

Comments on the production information

  • Production Notes = There is a little information regarding the mining of this deposit.

Comments on the reserve resource information

  • Reserves = There are conflicting estimates of the remaining reserves for this property. Foley (1992, p. 38) estimates a total resource of 82,000 metric tons of ore with 17.8% chromic oxide, while MacKevett and others (1978, p. 17) estimate a resource of 260,000 tons with17.8% chromic oxide.

Comments on the workings information

  • Workings / Exploration = Production totaled 2,000 metric tons from the Reef and Bluff mines from 1916 to 1918; development included a wharf and camp (Gill, 1922). Some drilling occured during WW II by the U.S. Bureau of Mines. Anaconda Minerals flew regional airborne geophysics over the area in the early 1980's which showed a major magnetic high underlying the outer part of Port Chatham (William Ellis, 1999 personal communcation).

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Gill, 1922

General comments

Subject category Comment text
Deposit Model Name = Podiform chromite (Cox and Singer, 1986; model 8a)
Deposit Other Comments = the airborne geophysics suggests the dunite may extend under all of the Claim Point peninsula and under Port Chatham.

Reporter information

Type Date Name Affiliation Comment
Reporter 07-MAR-99 Jeff A. Huber 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.