Minerals and Metals in Ancient India v2.c47.63

v2.c47.63

*Fluorite* : Fluorspar. CaF₂ Hardness 4. Octahedral or dodecahedral crystals. Luster vitreous. Colour usually white but varies over a wide range — violet, blue, yellow, red — even in different portions of the same specimen. Modified by heat, pressure, radiation etc. which also cause phosphorescence. High birefringence. Used as flux, in metallurgy, in making opalescent glass, as ornament gems.