Freieslebenite is a rare sulfide mineral of antimony, lead and silver with formula AgPbSbS3 and molecular weight of 533.02 g/mol. It is an opaque non-fluorescent mineral which has a hydrothermal origin. It is metallic, with a specific gravity of 6.3 and a Mohs hardness of 2.5 - about that of a finger nail. It is non-magnetic and is usually gray in colour. It has indistinct cleavage, and is brittle and has a conchoidal fracture. It can have a white or gray streak. It crystallizes in the monoclinic system.
Freieslebenite is normally found in Europe, usually in Romania and Germany. It was discovered in 1845, and is named after Johann Karl Freiesleben (1774 - 1846), Mining Commissioner of Saxony, Germany.