Semseyite is another rare sulfosalt, a segment of sulfides where the antimony acts more like a metal than a non-metal and occupies a position where it is bonded to sulfurs. Semseyite is also one of several lead antimony sulfides , an informal group of similar minerals. Some of these minerals belong to the formal group of minerals known as the Fuloppite Group . These minerals are rather similar in characteristics and are difficult to distinguish from one another. Other members of the Fuloppite Group include fuloppite , plagionite , heteromorphite and rayite .
Color is gray to black.
Luster is metallic. Crystals are opaque. Crystal Habits include radial to spherical aggregates of tabular nearly parallel crystals. Cleavage is perfect in several oblique directions. Streak is black.