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

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

Stibnite was used as mascara by Queen Jezebel of the Old Testament. Stibnite is used as an ingredient of safety matches.

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. Large iridescent stibnite crystals are found in Japan.