This makes the few crystals that are seen all the more valuable. Crystals are generally found as cubes that have a pearly gray to brown color and the luster is a generally silky to resinous. Luster is resinous, silky or adamantine. Crystals are translucent to transparent. Crystal Habits include very scarce cubes, more commonly massive, stalactitic, crusty and columnar.
Cleavage is absent.
Fracture is conchoidal. Streak is white. Crystals darken upon exposure to light and plastic, ductile and sectile, meaning it can be molded, pounded into different shapes and cut into slices. Associated Minerals include barite , calcite , stephanite , acanthite , native silver and other silver ore minerals. Best Field Indicators are color, luster, lack of cleavage, density, associations, ductility and crystal habit.