Arsenopyrite

Arsenopyrite

Arsenopyrite is an iron arsenic sulphide  FeAsS.  With a content of 40 to 45% arsenic, it is the principal ore of arsenic. The specimen has inclusions of chalcopyrite on a different face to the one illustrated. The specimen is from Hingston Down Quarry in Cornwall, which is a site noted for the mineral arthurite, another arsenic mineral.