This is an indication of a change in their respective crystal structures. The two are best distinguished by their crystal habits in which pirssonite has a distinctive tabular diamond-shaped crystal form. Pirssonite can lose its water molecules and specimens should be stored in a sealed container. Color is colorless, white or yellowish. Luster is vitreous.
Crystals are transparent to translucent.
Crystal System is orthorhombic. Fracture is conchoidal. Streak is white. Associated Minerals include gaylussite , northupite , trona , analcime and halite .