Industrial mineral site no. 1656, known as "Slate quarry" is a site in Stevens County, Washington. This site has been associated with slate and other platy rocks. A notation found in DGER Bulletin 37 on page 129 says "Slate of fairly good quality, purple to silvery green in color, which can be split into thin, medium-smooth plates", and designates the value as "Intermittently quarried by David Symington, Seattle".