Wavellite

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Wavellite
Wavellite-132292.jpg
Wavellite cluster from Saline County, Arkansas (size: 4.5 x 4.2 x 3.6 cm)
General
Category Phosphate minerals
Formula
(repeating unit)
Al3(PO4)2(OH,F)3·5H2O
Strunz classification 08.DC.50
Crystal symmetry Orthorhombic dipyramidal
H-M symbol: (2/m 2/m 2/m)
Space group: Pcmn
Unit cell a = 9.621 Å, b = 17.363 Å,
c = 6.994 Å; Z = 4
Identification
Color Green to yellowish-green and yellow, brown, white and colorless
Crystal habit Spherical, radial aggregates; striated prisms; crusty to stalactitic
Crystal system Orthorhombic
Cleavage [110] perfect, [101] good, [010] distinct
Fracture Uneven to subconchoidal
Mohs scale hardness 3.5 - 4
Luster Vitreous to resinous, pearly
Streak White
Diaphaneity Translucent
Specific gravity 2.36
Optical properties Biaxial (+)
Refractive index nα = 1.518 - 1.535 nβ = 1.524 - 1.543 nγ = 1.544 - 1.561
Birefringence δ = 0.026
Pleochroism Weak; X = greenish; Z = yellowish
2V angle Measured: 60° to 72°
Fusibility Infusable, swells and splits on heating
Solubility Insoluble
References [1][2][3][4]

Wavellite is a phosphate mineral with formula Al3(PO4)2(OH, F)3·5H2O. It normally occurs as translucent green radial or spherical clusters.

Discovery and occurrence[edit]

It was first described in 1805 for an occurrence within the High Down Quarry, Filleigh, Devon, England and named for William Wavell (20 Dec 1750 - 15 Jan 1829) of England who discovered the mineral.[3]

It occurs in association with crandallite and variscite in fractures in aluminous metamorphic rock, in hydrothermal regions and in phosphate rock deposits.[1] It is found in a wide variety of locations notably in the Mount Ida, Arkansas area in the Ouachita Mountains.

See also[edit]

References[edit]

  1. ^ a b Handbook of Mineralogy
  2. ^ Webmineral
  3. ^ a b Mindat
  4. ^ Klein, Corneis and Cornelius S. Hurlbut, Jr., Manual of Mineralogy, Wiley, 20th ed. 1985, p. 362-3 ISBN 0-471-80580-7
Wavellite from the Avant Mine, Garland County, Arkansas, showing spherical structure (size: 3.4 x 2.0 x 1.1 cm)