Barite (Sulfate)

Hardness: 3.0 - 3.5
Specific Gravity: 4.5

Characteristics: Usually white or colorless; dense compared to most other nonmetallic minerals; vitreous luster; perfect cleavage in one direction; insoluble in water and many acids; may be fluorescent in ultraviolet light.

Found in limestones, siltstones, clays and hydrothermal deposits.

A principle use of barite is as a weighting agent in oil well drilling mud; other uses include barium compounds, in paints, in glass, in paper fillers, and in refining sugar

(Primary text: Perkins, D. 2002. Mineralogy. Prentice Hall.)