In Germany and in New Hampshire, it is found as an alteration product of primary phosphates such as triphyllite . Luster is vitreous. Transparency crystals are transparent to translucent. Crystal Habits include equant to prismatic individual crystals. Twinning is common and produces a fishtail contact twin.
Cleavage is perfect in one direction and distinct in another.
Fracture is conchoidal. Streak is white. Associated Minerals include triphyllite , cassiterite , mica and sulfide ores. Best Field Indicators are crystal habit, cleavage, locality and color.