Blacksand Island Beach

Mine, Inactive

Commodities and mineralogy

Main commodities Au; Ti
Other commodities Fe; Zr
Ore minerals ilmenite; magnetite; native gold; rutile; zircon
Gangue minerals garnet

Geographic location

Quadrangle map, 1:250,000-scale YA
Quadrangle map, 1:63,360-scale B-4
Latitude 59.417
Longitude -139.5
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Blacksand Island placer extends for about 3.5 miles along the southwest shore of the island immediately northeast of the mouth of the Ahrnklin River. It is back of the Blacksand (Spit) placer (YA008).The coordinate location given is the approximate midpoint of the placer. The placer continues for about an equal distance (1.75 miles) northwesterly in the Yakutat B-5 quadrangle. The deposit is given as location 8 in Cobb (1972).

Geologic setting

Geologic description

The Blacksand Island placer is in the depositional drainage area of the Ahrnklin River, hence possibly deltaic. The island could also be, in part, an older beach deposit that formed before Blacksand Spit. Irregular beach concentrates of black sand occur with interlocked magnetite-ilmenite and small amounts of gold.
Geologic map unit (-139.501691009895, 59.4167090088238)
Mineral deposit model Riverine delta and beach deposit
Age of mineralization Holocene

Production and reserves

Workings or exploration The occurrence is one of the older placer deposits reported along the coast. Minor and generally unsuccessful mining activity was reported by Blackwelder (1907, p. 86-87). Thomas and Berryhill (1962) reported that there was some private churn drilling done about 1957, but the results are unknown. Foley and others (1995) reported analytical results from one sample (no. 276). The sample contained 0.63 percent titanium in a spiral concentrate split and did not contain gold in either the head- or spiral-concentrate splits.
Indication of production Yes; small
Production notes Very minor production took place in the 1890s and early 1900s.

Additional comments

Information is lacking about the private drilling that was reported by Thomas and Berryhill in 1962. It is assumed, from the sparsity of recent work, that the grade of the deposit is low.

References