Barite (Sulfate)
BaSO4Hardness: 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.)