Feinglositc in polished section: (a) PPL light and (b) XPL light. In (a) note the inclusions of goethite (white) in the grey feinglosite (the black areas are holes). In (b) note the white to gray clusters of feinglosite. Black areas are goethite.
Lining a cavity in a sample of massive chalcocite from Tsumeb, Namibia. (MinMag, v61:405).