Luster is vitreous. Crystals are transparent to translucent. Crystal Habits include small prismatic to tabular, often complex, crystals and spherical aggregates and massive crusts. Twinning is the norm and just adds to the complexity of the crystals. Cleavage is perfect in one direction.
Fracture is uneven.
Streak is light red. Associated Minerals are erythrite , beta-roselite and limonite . Notable Occurrences include Rappold Mine, Schneeberg, Saxony and Shapbach, Germany and Bou Azzer, Morocco. Best Field Indicators are color, crystal habit, streak, cleavage, density and associations with cobalt ores.