Color is typically blue, but also colorless and yellowish. Luster is vitreous. Transparency crystals are transparent to translucent. Also found as small grains. Cleavage is absent.
Fracture is irregular.
Streak is white. Associated Minerals are serpentine , neptunite, natrolite and joaquinite. Notable Occurrences include only the San Benito County, California mine for good crystals, SW Texas produces tiny grains in eocene sands. Best Field Indicators are crystal habit, fluorescent, color, associations and locality.