Industrial mineral site no. 1816, known as "Isar Mountain Deposit" is a site in Whatcom County, Washington. This site has been associated with limestone and marble. A notation found in DGER Bulletin 52 on page 248 says "The apparently interbedded is black, finely crystalline and massive. It is possible that this limestone indicates an infold of older or younger material", and designates the value as "Unknown".