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
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
- ^ a b Handbook of Mineralogy
- ^ Webmineral
- ^ a b 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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