Industrial mineral site no. 1529, known as "Olympic Foundry" is a site in King County, Washington. This site has been associated with sandstone. A notation found in DGER Bulletin 37 on page 122 says "A 12-ft. bank of light Oligocene sandstone, containing 61.3 percent silica and 4.7 percent ferric oxide, gave a speckled light-gray fusion below cone 10", and designates the value as "Uncertain".