From my observations it is clear that pyrite (iron) is attracted to fluorapatite. I’ll leave it to a geo-chemist to reveal which ions form the attraction. This is the only piece I have with the pyrites having an epitaxial attraction, where the micro-pyrites are denser than on the faces. Where the pyrite coating is dense enough it blocks the LW reaction. Sawn at the back. Locality: Foote Lithium Company Mine, Kings Mountain, Cleveland County, North Carolina Composition: calcium fluorophosphate and iron sulfide
