Fluorite

Fluorite

COLOR

Grey. Takes a good polish.

REFLECTANCE

Extremely low. The lowest of all the minerals studied which facilitates its determination.

ANISOTROPISM

Isotropic. Internal reflections are abundantly developed and generally very light.

TEXTURE

The mineral is often euhedral, in small cubic crystals, commonly replaced by the other gangue minerals, especially by quartz.

ASSOCIATED MINERALS

Quartz, carbonates, barite, galena, sphalerite, pyrite, marcasite, bournonite, tetrahedrite-tennantite.

CRITERIA OF DETERMINATION

The extremely low reflectance and euhedral character permit fluorite to be readily identified. Compared to quartz, reflectance is definitely lower, as is hardness which may be verified with a steel needle.

Source

ATLAS OF ORE MINERALS (P. Picot and Z. Johan)