Wardite
Wardite from Rapid Creek - Yukon, Canada
General
CategoryPhosphate minerals
Formula
(repeating unit)
NaAl3(PO4)2(OH)4·2(H2O)
IMA symbolWd[1]
Strunz classification8.DL.10
Crystal systemTetragonal
Crystal classTrapezohedral (422)
H-M symbol: (4 2 2)
Space groupP41212
Unit cella = 7.03(1), c = 19.04(1) Å;
Z = 4
Identification
ColorWhite, colorless, pale green, blue-green, yellow-green, pale yellow, yellow pink.
Crystal habitDipyramidal pseudo-octahedral crystals, striated; radial, fibrous, encrustations
CleavagePerfect on {001}
Mohs scale hardness5
LusterVitreous
DiaphaneityTransparent to opaque
Specific gravity2.81 - 2.87
Optical propertiesUniaxial (+)
Refractive indexnω = 1.586 - 1.594 nε = 1.595 - 1.604
Birefringenceδ = 0.009
2V angle0.0
References[2][3][4]

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 phosphate 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.

See also

References

  1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. Handbook of Mineralogy
  3. Mindat.org
  4. Webmineral data
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