What are chromates in mineralogy ?

Chromates : definition

Chromates constitute a minor subclass of the mineralogical class of sulfates, chromates, molybdates, vanadates. Chromates are built on the basis of (CrO4) 2- groups, linked to one or more cations.

These are rare minerals. Only the crocoite, PbCrO4, is known for the beauty of its vermilion prismatic crystals. Historically, chromium has been discovered in this altered lead mineralization mineral traversing chromite rocks.