Wavellite
Wavellite | |
---|---|
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 | 8.DC.50 |
Crystal system | Orthorhombic |
Crystal class |
Dipyramidal (mmm) 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 |
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
![](../I/m/Wavellite-199443.jpg)
Wavellite from the Avant Mine, Garland County, Arkansas, showing spherical structure (size: 3.4 x 2.0 x 1.1 cm)
It was first described in 1805 for an occurrence within the High Down Quarry, Filleigh, Devon, England and named for William Wavell (20 December 1750 - 15 January 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.
It is sometimes used as a gemstone.[5]
See also
References
- 1 2 Handbook of Mineralogy
- ↑ Webmineral
- 1 2 Mindat
- ↑ Klein, Corneis and Cornelius S. Hurlbut, Jr., Manual of Mineralogy, Wiley, 20th ed. 1985, p. 362-3 ISBN 0-471-80580-7
- ↑ Gemstones: Properties, Identification and Use By Arthur Thomas, p.132
External links
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