Luster is vitreous to greasy and gumdrop. Crystals are transparent to translucent. Also accicular, granular, reniform and massive. A cryptocrystalline variety is called collophane and can make up a rock type called phosphorite and also can replace fossil fragments. Cleavage is indistinct in one basal direction.
Fracture is conchoidal.
Hardness is 5. Streak is white. Associated Minerals are hornblende , micas , nepheline and calcite . Best Field Indicators are crystal habit, color, hardness and look.