Wavellite
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| 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 | 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 (?-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]
- ^ 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
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