Luster is resinous to earthy. Crystals are opaque. Crystal System is isometric. Crystal Habits include pseudomorphs of lead antimony sulfides, but more commonly cryptocrystalline masses or crusts. Cleavage is not discernible.
Fracture is earthy.
Hardness is 4 - 4.5. Streak is pale yellow to brown. Best Field Indicators are crystal habit, color, associations and luster.