ERYTHRITE, the name given to (I) a mineral composed of a hydrated cobalt arsenate, and (2) in chemistry, a tetrahydric alcohol (see ERYTHRITOL). (I) The mineral has the formula Co3 and crystallizes in the monoclinic system. It sometimes occurs as radially-arranged groups of brilliant crimson blade-shaped crystals. On exposure to light the colour and lustre deteriorate. Cleavage flakes are soft (H=2), sectile and flexible ; specific gravity 2.95. The mineral is, however, more often found as an earthy encrustation with a peach-blossom colour, and in this form was early known as cobalt-bloom. It occurs as a product of alteration of smaltite and other cobaltiferous arsenides. The finest crystallized specimens are from Schneeberg in Saxony. The earthy variety has been found in Thuringia, Cornwall, Cobalt (Ont.) and some other places.