This sample of cassiterite exhibits a blocky, angular structure with a metallic to adamantine shine that catches the light across its dark gray surface. Despite its modest size, the specimen feels notably heavy—reflecting cassiterite’s high specific gravity.. Composed of tin dioxide (SnO₂), cassiterite is the primary ore of tin and is prized for its density and durability. The mineral’s hardness and subconchoidal fracture give it a rugged texture, while its luster and compact form make it a striking example of this economically vital oxide mineral.