Mercury mining took place at the Roy and Barnum-McDonnell mines in Morton, WA intermittently from the period of 1924 to 1940. The peak year for these mines was 1929. The mines produced $509,717 (historic value) of mercury between 1924 and 1940. The Morton District had the most significant production of mercury in the state.
There are two historical deposits of naturally occurring mercury ore in Washington state. The largest source of mined mercury in Washington was in Morton. The second was in King County, in the Green River District near Cumberland. Both deposits contained cinnabar, mercury sulfide.
The Roy Mine (also called Morton, Gillespie, or Fisher Mine) opened in 1926 by the Morton Cinnabar Company. This mine was most active in the late twenties. However, it also produced elemental mercury from 1933 - 1938 and during World War II.
From 1916 - 1961, mercury mines in Washington produced 503 thousand pounds of mercury. Most of this was used in industry, and some was used to concentrate gold-bearing ores.