Chromium Pyroarsenate, Cr₄(As₂O₇)₃

Chromium Pyroarsenate, Cr₄(As₂O₇)₃, is produced when a small quantity of chromium sesquioxide is fused at a low temperature with sodium or potassium meta-arsenate. It yields green transparent prisms, sometimes elongated, sometimes flattened, with oblique extinctions; insoluble in dilute acids.