Wardite is a hydrous sodium phosphate Al )4·2(H2O ). Wardite is of interest for its rare crystallography. It crystallizes in the tetragonal class and is one of only a few minerals in that class. Wardite forms vitreous green to bluish green to white to colorless crystals, masses, and fibrous encrustations. It has a Mohs hardness of 5 and a specific gravity of 2.81–2.87.