Wavellite
Wavellite is an aluminium basic phosphate mineral with formula Al3(PO4)2(OH, F)3·5H2O. Distinct crystals are rare, and it normally occurs as translucent green radial or spherical clusters.[5]
Wavellite | |
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![]() Wavellite cluster from din Mountain Quarries, Mauldin Mt., Montgomery County, Arkansas, USA | |
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] |
Discovery and occurrence
![](../I/m/Wavellite-199443.jpg)
Wavellite was first described in 1805 for an occurrence at High Down, Filleigh, Devon, England and named by William Babington in 1805 in honor of Dr. William Wavell (1750–1829),[3] a Devon-based physician, botanist, historian, and naturalist, who brought the mineral to the attention of fellow-mineralogists.[6][3][5][7]
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.[8]
See also
- List of minerals
- Apatite, fluoro-phosphate of calcium
- Pyromorphite, chloro-phosphate of lead
- Turquoise, a hydrated phosphate of copper and aluminium
References
- Handbook of Mineralogy
- Webmineral
- Mindat
- Klein, Corneis and Cornelius S. Hurlbut, Jr., Manual of Mineralogy, Wiley, 20th ed. 1985, p. 362-3 ISBN 0-471-80580-7
- Chisholm, Hugh, ed. (1911). Encyclopædia Britannica. 28 (11th ed.). Cambridge University Press. p. 430. .
- Green, David; Cotterell, Tom; Jones, I.; Cox, D.; Cleevely, R. (2007). "Wavellite: its discovery and occurrences in the British Isles". UK Journal of Mines and Minerals. 28: 11–30.
- Curtis, Samuel and Hooker, William Jackson (1827). Memoirs of the Life and Writing of the Late Mr. William Curtis, Curtis's Botanical Magazine; or Flower Garden Displayed, v. 1 (new series), v-xxxii.
- Gemstones: Properties, identification and use by Arthur Thomas, p. 132.
External links
- "Wavellite at museum of Barnstaple and North Devon". Retrieved 9 May 2020.
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