Luster is vitreous, dull or pearly. Crystals are translucent transparent. Rarely in large individual barrel or tabular crystals with an hexagonal outline. Usually found as alteration products of iron-magnesium minerals and as inclusions in other minerals. Aggregates can be scaly, compact, platy and as crusts.
Fracture is lamellar.
Streak is pal green to gray or brown. Cleavage flakes are flexible but not elastic. Associated Minerals include garnets , biotite , quartz , magnetite , talc , serpentine , danburite , topaz and calcite , among many others. Best Field Indicators color, cleavage, associations and crystal habits.