Barite

Formula: BaSO4

Colour: Colourless, white, yellow, brown, grey, blue, etc.; colourless in transmitted light (also tinted yellow, brown, green, blue, etc.)

Lustre: Vitreous, Pearly

Hardness: 3

Specific Gravity: 4.50

Crystal System: Orthorhombic

Member of: Baryte Group

Name: Named in 1800 by Dietrich Ludwig Gustav Karsten from the Greek βάρυζ, heavy, due to its unusual heaviness for a non-metallic mineral. Although frequently spelled barite in the US and some other places, the official IMA spelling is baryte.
Baryte Group. Baryte-Celestine Series.
The barium analogue of celestine and anglesite.
Typically found as thick to thin tabular crystals, usually in clusters with the crystals growing parallel to one another, or nearly so. Also as bladed, white masses.