fluorite - student specimens of a mineral often associated with metallic ores - massive fluorite - Unit of 5 specimens

fluorite - calcium fluoride: CaF2 Fluorite is frequently a gangue mineral with metallic ores. “Gangue” describes uneconomic minerals that are associated with ores. Used as a flux in the manufacture of steel, fluorite derives its name from the Latin fluere, to flow, since it melts at a low temperature compared with other minerals with which it is confused.Circa 1852, Sir George Stokes, mathematics professor at the University of Cambridge, coined the term fluorescence, from the property of fluorite from some locations. Fluorite varies widely in color, most commonly Coke-bottle (remember those?) green, yellow, bluish green and purple. Its hardness is 4 on the Mohs Scale of Mineral Hardness. Good fluorite has been difficult to obtain. Either the specimens are raggedy or they are far too expensive, or both. This massive fluorite is from the Navidad mine, 35 km northwest of Rodeo, Durango, Mexico.  Navidad is a brecciated fluorite vein that has been mined intermittently for years. It is fa