Crystals are translucent to rarely transparent. Crystal System is trigonal. Crystal Habits include platy elongated crystals often aggregated and twinned . Also as crusts, fibrous and earthy. Cleavage is perfect.
Fracture is lamellar.
Streak is a pale yellow. Radioactive, non-fluorescent and cleavage sheets are surprisingly brittle. Associated Minerals include bismutite , torbernite , zeunerite , uraninite and other uranium minerals. Best Field Indicators are color, crystal habit, high density, non-fluorescence, radioactivity and associations.