Tennantite is a copper arsenic sulfosalt mineral.
Its chemical formula is Cu12As4S13. It is found in hydrothermal veins and contact metamorphic deposits.
A closely related mineral, tetrahedrite (Cu12Sb4S13) has antimony substituting for arsenic and the two form a solid solution series.
The two have very similar properties and is often difficult to distinguish between tennantite and tetrahedrite. Iron, zinc, and silver substitute up to about 15% for the copper site.
The mineral was named after the English chemist Smithson Tennant (1761-1815).