Stibnite

Stibnite, sometimes also called antimonite, is a sulfide mineral. It crystallizes in the orthorhombic system, has hardness 2 and a grey colour. Its chemical composition is described by the formula Sb2S3

Stibnite is the most important source for the rare metal antimony. It is soluble in hydrochloric acid, and is tarnished by potassium hydroxide solution.

Small deposits of Stibnite are common, large ones are rare. It occurs in Canada, Mexico, Peru, Japan, China, Germany, Romania, Italy, France, England, Algeria, and Kalimantan, Borneo. In the United States it is found in Arkansas, Idaho, Nevada, California, and Alaska.

Spectacular, large iridescent stibnite crystals are found in Japan.