Stannoidite

Stannoidite is a rare copper iron tin sulfide mineral with the chemical formula Cu2FeSnS4. It belongs to the stannite group of minerals, which are characterized by their tetrahedrally coordinated atoms. Stannoidite crystallizes in the tetragonal crystal system, typically forming small, dark, metallic grains or masses. It is often found associated with other sulfide minerals such as chalcopyrite, cassiterite, and stannite, in hydrothermal veins and ore deposits.

The mineral was first described in 1930 from a deposit in the Bolivian Andes, hence its name, which refers to its tin content and its discovery in a location known for tin ore. It is relatively soft and has a metallic luster, often appearing brass-yellow to steel-gray in color. Stannoidite is considered a valuable indicator mineral in the exploration for tin and copper deposits. Due to its rarity, it is not a significant ore of any metal but is of scientific interest to mineralogists and geologists studying ore formation processes. Its occurrence is limited to specific geological environments where the necessary elements are present in the right proportions and under suitable conditions for its formation.