Hardness = 4;
Cleavage: octahedral; perfect in 4
Shape: octahedral, but often cleavage
masses or masses of
intergrown crystals masses
Color: violet, blue, green, yellow, brown,
bluish, black, pink, rose-red, colorless
Luster: vitreous (glassy)
Fluorite gives meaning to the admonition Never Trust Color! Its color is extremely variable, as the next few specimens show.
The most distinctive features are the octahedral cleavage, and the hardness. The octahedral cleavage is obvious in these perfect specimens. It is the less than perfect specimens, or the intergrown crystal masses that can be troublesome.
To identify find one crystal, and then carefully count the 4 cleavage directions. Also the cleavages form acute triangles, and is distinctively different from cubic cleavage in halite, or rhombohedral cleavage in calcite.