Blacksand Beach

Occurrence in Alaska, United States with commodities Gold, Iron, Titanium, PGE, Zirconium

Geologic information

Identification information

Deposit ID 10002471
MRDS ID A013402
Record type Site
Current site name Blacksand Beach

Geographic coordinates

Geographic coordinates: -139.43223, 59.37969 (WGS84)
Relative position The Blacksand beach placer is about 10 miles long extending northwesterly between the Ahrnklin and Dangerous Rivers. The coordinate location is the approximate mid-point of the beach, which extends northwesterly into the Yakutat B-5 quadrangle. The deposit coincides with a named geographic feature (Blacksand Spit); it is location 7 of Cobb (1972). It is southeast of the Situk beach placer (YA007).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Iron Primary
Titanium Primary
PGE Secondary
Zirconium Secondary

Comments on the commodity information

  • Ore Material = Gold (native)
  • Ore Material = PGE

Materials information

Materials Type of material
Gold Ore
Ilmenite Ore
Magnetite Ore
Rutile Ore
Zircon Ore
Garnet Gangue

Host and associated rocks

  • Host or associated Host
    Rock type Unconsolidated Deposit > Sand and Gravel
    Stratigraphic age (youngest) Holocene

Nearby scientific data

(1) -139.43223, 59.37969

Comments on the geologic information

  • Geologic Description = The Blacksand deposit is on a modern spit that extends along the coast line for about 10 miles. It was derived by high-energy reworking of underlying unconsolidated sediments of Holocene age (Foley and others, 1995; Reimnitz and Plafker, 1976) and from the density stratification of the alluvium constantly brought down by the Ahrnklin and Dangerous Rivers, which head in the Fairweather Range. ? Black and garnet sand lenses 0.1 to 0.2 feet thick contain interlocked magnetite-ilmenite or garnet and, more rarely, gold. Cobb (1979, p. 19) cites a reliable report of a PGE (platinum) from the mouth of the Situk River.
  • Age = Holocene

Economic information

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Mining district

District name Yakutat

Comments on the workings information

  • Workings / Exploration = The beach has been mined on a small scale for many years. It was sampled by Thomas and Berryhill (1962), MacKevett and Plafker (1970; sample no. 67Apr76C), Reimnitz and Plafker (1976, samples 39, 40, and 41), and by Foley and others (1995, samples 276, 277 and 278). Thirteen beach locations were sampled by Thomas and Berryhill; their sample number 26 (table 12) contained 0.00012 ounce/cubic yard gold, 11.7 pounds/ cubic yard titania, and 25.8 pounds/cubic yard iron. Six of the thirteen samples contained 10 pounds or more of titania/cubic yard. The maximum amount of titania reported by Thomas and Berryhill was 47.4 pounds/cubic yard; maximum iron was about 150 pounds/cubic yard. Reimnitz and Plafker (1976) reported from 0.010 to 0.050 ppm gold in their samples. Gold was determined by atomic absorption, hence it may not correlate with the amount that could be recovered by placer mining and processing. Gold was not found by Foley and others (1995) in their head splits, but was reported in two of three spiral concentrates of the samples. Spiral concentrates also contained as much as 3.1 percent titanium and 1665 ppm zirconium.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A013402
USGS Alaska Resource Data File ARDF YA008

Bibliographic references

  • Deposit

    Thomas, B.I., and Berryhill, R. V., 1962, Reconnaissance studies of Alaskan beach sands, eastern Gulf of Alaska: U.S. Bureau of Mines Report of Investigations 5986, 40 p.

  • Deposit

    MacKevett, E.M., Jr., and Plafker, G., 1970, Geochemical and geophysical reconnaissance of parts of the Yakutat and Mount St. Elias quadrangles, Alaska: U.S. Geological Survey Bulletin 1312-L, 12 p.

  • Deposit

    Reimnitz, Erk, and Plafker, George, 1976, Marine gold placers along the Gulf of Alaska margin: U.S. Geological Survey Bulletin 1415, 16 p.

  • Deposit

    Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Bering Glacier, Icy Bay, Middleton Island, and Yakutat quadrangles, Alaska: U.S. Geological Survey Open-File Report 79-1246, 41 p.

  • Deposit

    Foley, J.Y., La Berge, R.D., Grosz, A.E., Oliver, F.S., and Hirt, W.C., 1995, Onshore titanium and related heavy mineral investigations in the eastern Gulf of Alaska region, southern Alaska: U.S. Bureau of Mines Open-File Report 10-95, 125 p.

  • Deposit

    Cobb, E.H., 1972, Metallic mineral resources map of the Yakutat quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-408, 1 sheet, scale 1:250,000.

Comments on the references

  • Primary Reference = Thomas and Berryhill, 1962; Foley and others, 1995.

General comments

Subject category Comment text
Deposit Model Name = Beach placer: single-cycle deposits of high-energy systems.
Deposit Other Comments = the beach is in the Tongass National Forest.

Reporter information

Type Date Name Affiliation Comment
Reporter 15-APR-99 Hawley, C.C. Hawley Resource Group