Coastal Oregon beach placers

Region West, Northwest
Mineral systems
Deposit types
Critical minerals
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Chromite-bearing black sands in present beaches and adjacent braided beaches stretch over 200 km along the coast of northwestern California and southwestern Oregon.
Identified resources Historical production of chromium (chromite), gold, and PGE.
Production Gold and minor Pt production circa 1850-1930s. Exploration began during WWII, and by 1955 52,000 tons of chrome-bearing concentrate had been shipped.
Status Past mining; no current mining or exploration.
Estimated resources The known reserves of Measurable and Indicated ore, minus what was mined in 1943, are 1,913,000 long tons sand in deposits averaging more than 5% Cr2O3, and 1,212,000 long tons sand in deposits averaging between 3 and 5% Cr2O3 (Griggs, 1945).
Geologic maps McClaughry and others (2013), scale 1:24,000; Dott (1971), scale 1:250,000.
Geophysical data Inadequate aeromagnetic and aeroradiometric coverage.
Favorable rocks and structures Black beach sands in modern and older raised beaches.
Deposits Southwest Oregon beach sands (MRDS dep_id: 10127508).
Evidence from mineral occurrences MRDS; Griggs (1945).
Geochemical evidence No data.
Geophysical evidence Unknown.
Evidence from other sources None.
Comments Foreshore coastal beach areas are transitory, which complicated estimates of historical resources. Beach-face retreat in the winter of 1982-83 exposed underlying placers containing the economic minerals garnet, zircon, ilmenite, and chromite (Peterson and others, 1986).
Cover thickness and description Exposed.
Authors Jane M. Hammarstrom, Laurel G. Woodruff.
New data needs None requested at this time.
Geologic mapping and modeling needs Recent mapping at 1:24,000.
Geophysical survey and modeling needs None requested at this time.
Digital elevation data needs Lidar in progress over southern portion of the focus area; incomplete in northern half.