Tennantite

This sample of tennantite-tetrahedrite is displayed in the Smithsonian Museum of Natural History. Tennantite is a sulfide mineral of copper, iron, arsenic and antimony with the composition (Cu,Fe)₁₂(As,Sb)₄S₁₃ . This sample is about 20x18 cm and is from El Cobre, Chihuahua, Mexico . This sample is formed with quartz and tetrahedrite.