Bismuthinite is a mineral composed primarily of bismuth sulfide, with the chemical formula Bi2S3. It typically appears as metallic gray to black crystals and has a high density, making it quite heavy for its size. Bismuthinite is often found in hydrothermal veins and is associated with other minerals like galena and sphalerite. This mineral is an important source of bismuth, a metal used in various applications, including pharmaceuticals and cosmetics. Bismuthinite can be identified by its distinct cleavage and metallic luster, making it a notable specimen for mineral collectors and geologists alike.