Geologic description
The placer gold in Yakataga-area beaches was discovered in 1897 or 1898,and small-scale mining started in 1899 (Maddren, 1914). Rocker and sluice operations continued to WW II. Drill prospecting of raised beaches occurred after WW II (Thomas and Berryhill, 1962), as did sporadic attempts at small-scale mining. Most of the post-WW II mining was west of Cape Yakataga on this segment of the beach (Miller, 1971). The gold in the Yakataga area, naturally concentrated in heavy-mineral accumulations by storm waves, is fine and flat. The other heavy minerals include amphibole, garnet, chromite, native copper, hematite, magnetite, pyroxene, rutile, sphene, ilmenite, zircon, and probably some monazite (Maddren, 1914; Thomas and Berryhill, 1962; Foley and others, 1995).
The iron and titanium oxide contents of reconnaissance samples of beach sand from the Yakataga area were reported by Thomas and Berryhill (1962). These samples contained as much as 6.2 pounds of iron per ton but mostly less than 2 pounds of iron per ton. Their titanium oxide content was less than 2 pounds per ton in the magnetic fraction and as much as 7.3 pounds, but mostly less than 2 pounds per ton in the non-magnetic fraction. Foley and others (1995) collected 32 samples at 18 locations, including some raised beaches, along this segment of the Yakataga shoreline. Spiral concentrates from these samples contained less than 0.028 grams (16 samples) to 0.903 grams of gold per ton, 0.52 to 2.32 percent Ti, and 243 to 7683 ppm Zr. A heavy-mineral concentrate from one of these samples (4.79 weight percent of the original samples) contained 0.51 percent magnetite, 0.230 percent ilmenite, 2.519 percent garnet, 0.053 percent rutile, and 1.90 percent other minerals. Flotation concentrates from two samples contained 0.198 and 14.787 grams of gold per ton, 0.056 and less than 0.003 gram platinum per ton, and 0.037 and 0.042 gram palladium per ton. The placer gold in the Yakataga beaches may be derived from reworking of marine-glacial deposits of the Cenozoic Yakataga Formation (Reimnitz and Plafker, 1976). |
