Stibnite
Guangxi Mine
Hunan, China
This specimen measures 30cm x 7cm
Stibnite Sb2S3
Sulfide; antimony trisulfide; small amounts of iron, copper, or lead map be present
Color and Luster: Lead-gray; tarnish black, sometimes iridescent; metallic; streak dark lead-gray
Hardness: 2
Cleavage: Perfect in lengthwise direction
Fracture: Uneven, brittle, slightly sectile
Crystals: Orthorhombic; stout to slender, striated lengthwise; often bent or twisted; also bladed, in radiated groups, columnar masses, granular
Photo by Mary Sutherland
Descriptions taken from
The Audubon Society Field Guide to North American Rocks and Minerals