Crocoite: an unusual mode of occurrence for lead in coal

What is believed to be a very unusual mode of occurrence for lead in coal h as been identified as crocoite (PbCrO4). As part of a larger study on trace elements and mineralogy in the Cretaceous Main Seam in New Zealand, crocoi te was found in raw coal samples within the lower part of the coal seam. X- ray diffraction (XRD) and bulk chemical data from a SEM equipped with an en ergy dispersive X-ray analyser (EDXA) have confirmed the identity of this m ineral. This is apparently the first time that crocoite has been reported i n coal. Crocoite usually occurs only in the oxidised zone of lead mineral d eposits. The occurrence of this mineral in the Main Seam coal implies that the deposit was exposed to an oxidising environment at some stage, most lik ely after coalification. Published by Elsevier Science B.V.