Color is pale to dark blue. Luster is vitreous. Specimens are translucent to transparent. Crystal System is triclinic. Crystal Habits include tabular crystals and radiating fibrous clusters.
Cleavage is absent.
Fracture is conchoidal. Streak is white. Associated Minerals include cassiterite , metavauxite , paravauxite , wavellite , quartz and limonite . Notable Occurrences are limited to the famous tin deposits at Llallagua, Potosi, Bolivia and a few minor localities around the world. Best Field Indicators are color, locality, crystal habit, associations and lack of cleavage.