Fluorite

Formula:  CaF2

Origin of name:  From Latin for to flow

 

Crystal system:  Cubic

Crystal class:  4/m -3 2/m

Twinning:  Penetration on {111}; rarely by spinel law

Unit cell: a = 5.463 Ǻ

 

Colour:  Colourless, purple, blue, green, yellow, white, pink, red, brown

Diaphaneity:

Luster:   Vitreous

Habit:  Crystals cubes or octahedrons, rarely dodecahedrons; massive, coarse to fine granular; botryoidal, fibrous

Hardness:  4

Specific gravity:  3.18

Cleavage:  1; {111} perfect

Tenacity:  Subconchoidal to splintery; brittle

Streak:

 

Synonyms/varieties:  Antozonite (dark purple var.), blue john (massive colour-banded var.), chlorophane (thermoluminescent var.), fusspat, yttrocerite (Ce, Y-rich var.)

 

Comments:  Often fluoresces blue, yellow, white, reddish or pale violet, may thermoluminesce

 

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