Barite

Hardness: 3-3.5 on Mohs scale. Color: can be colorless, white, light shades of blue, yellow, or grey; the specimen shown has reddish-brown inclusions likely due to iron oxide. Luster: vitreous to pearly. Crystal structure: Orthorhombic. Cleavage: Perfect. Specific Gravity: 4.5 (notably heavy for a non-metallic mineral).

Formed through hydrothermal processes in vein deposits, as well as in sedimentary environments such as marine deposits or as a replacement in limestone and dolostone. Common in lead-zinc ore vein systems.

Primarily used as a weighting agent in drilling mud for oil and gas wells. Also used in the manufacturing of paints, rubber, and as a contrast agent for medical X-rays ('Barium swallow'). High-quality cabinet specimens are sought after by collectors.

Barite's name is derived from the Greek word 'barys', meaning 'heavy', referencing its high specific gravity. It is chemically inert and non-toxic, despite containing the heavy metal barium.

Identify in the field by its unusual weight (density) compared to its size and its relatively low hardness. Collectors look for well-defined 'bladed' crystal habits. Common locations include Morocco (where reddish bladed varieties like the one pictured are frequently mined), China, USA (Oklahoma/Nevada), and England.