Category Phosphate minerals Crystal system Tetragonal | Strunz classification 8.DL.10 Space group P41212 | |
 | ||
Formula
(repeating unit) NaAl3(PO4)2(OH)4·2(H2O) Crystal class Trapezohedral (422)
H-M symbol: (4 2 2) | ||
Wardite is a hydrous sodium aluminium phosphate hydroxide mineral with formula: NaAl3(PO4)2(OH)4·2(H2O). Wardite is of interest for its rare crystallography. It crystallizes in the tetragonal trapezohedral 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.
Occurrence
It occurs with variscite in phospatic nodules and occurs uncommonly in pegmatites and phosphate deposits through alteration of amblygonite.
Wardite was named for Henry Augustus Ward (1834–1906) of the University of Rochester in New York. It first described in 1896 for an occurrence in Clay Canyon, Fairfield, Utah County, Utah, US. Though rare it has been reported from many locations worldwide.