barjännite

Barjännite is a rare mineral discovered in 1984 in the Barjâk mine in the Khovd Province of Mongolia. It is named after the mine where it was first found. Barjännite is a copper-iron sulfide mineral with the chemical formula Cu2FeSnS4. It crystallizes in the tetragonal system and typically forms small, dark gray to black crystals or grains. The mineral is opaque with a metallic luster and has a hardness of approximately 4.5 on the Mohs scale.

Barjännite is notable for its unique composition, which includes the elements copper, iron, and tin. It is one of the few minerals that contain tin in its structure. The mineral is relatively rare and is primarily found in the Barjâk mine, where it occurs in association with other sulfide minerals such as chalcopyrite and pyrite. Due to its rarity and the specific conditions required for its formation, barjännite is of interest to mineralogists and geologists studying the geochemistry of sulfide deposits.

The discovery of barjännite has contributed to the understanding of the mineralogy and geochemistry of sulfide minerals, particularly those containing tin. Its unique composition and rarity make it a valuable specimen for collectors and a subject of study for researchers in the field of mineralogy.