Pronunciation: FLUOR•ite (accent on capitalized syllable)
Color: highly variable from colorless to amethyst purple, yellow, green, blue
Luster: vitreous
Diaphaneity: transparent to translucent
Hardness: 4
Specific gravity: 3.18
Cleavage/fracture: 4 directions of cleavage, produces cleavage octahedra.
Other distinguishing properties: Fluorite commonly fluoresces (glows) when exposed to ultraviolet light (a black light). Fluorite grows in cubic crystals and cleaves into octahedra (8-sided fragments). Amethyst-colored fluorite may be mistaken for quartz, but quartz is much harder (7) and has no cleavage planes. Fluorite may be mistaken for calcite, but calcite effervesces in hydrochloric acid, has just 3 cleavage directions, and is softer than fluorite.
Klein, C., and Hurlbut, C.S., Jr., 1999, Manual of Mineralogy (after James D. Dana) [21st edition, revised]: New York, John Wiley & Sons, 682 p.
Los Angeles County Museum of Natural History, The Photo Atlas of Minerals: nhm.org/pam/
Return to the Minerals page.
