21.—Cinnabar.
Occurs in granular or earthy masses; resembles iron-rust, but is a yellowish-red; powder scarlet; easily cut with a knife; thrown on red-hot iron, evaporates, giving off odor of sulphur; rubbed on copper, “silvers” it; gravity 9, or about as heavy as Copper.
Value.—The source of mercury (containing eighty-four per cent.) and vermilion.
Localities.—Found in slate and limestone rocks. Centreville, Coulterville, New Idria and New Almaden, and Lake and San Luis Obispo Counties, California; Idaho.