Crystals are transparent to translucent. Crystal Habits include the typical cube and octahedron, as well as a combination of these two and other rarer isometric habits. Fluorite usually has equant crystals, but less common habits include crusts and botryoidal forms. Twinning also produces penetration twins that look like two cubes grown together. Cleavage is perfect in 4 directions forming octahedrons.
Fracture is irregular.
Hardness is 4. Streak is white. Tenacity is brittle. Group falls under the Halides. Often fluorescent blue or more rarely green, white, red or violet and may be thermoluminescent, phosphorescent and triboluminescent.