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
Wavellite cluster from din Mountain Quarries, Mauldin Mt., Montgomery County, Arkansas, USA
General
CategoryPhosphate minerals
Formula
(repeating unit)		Al3(PO4)2(OH,F)3·5H2O
Strunz classification8.DC.50
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupPcmn
Unit cella = 9.621 Å
b = 17.363 Å,
c = 6.994 Å; Z = 4
Identification
ColorGreen to yellowish-green and yellow, brown, white and colorless
Crystal habitSpherical, radial aggregates; striated prisms; crusty to stalactitic
Cleavage[110] perfect, [101] good, [010] distinct
FractureUneven to subconchoidal
Mohs scale hardness3.5 - 4
LusterVitreous to resinous, pearly
StreakWhite
DiaphaneityTranslucent
Specific gravity2.36
Optical propertiesBiaxial (+)
Refractive indexnα = 1.518 - 1.535 nβ = 1.524 - 1.543 nγ = 1.544 - 1.561
Birefringenceδ = 0.026
PleochroismWeak; X = greenish; Z = yellowish
2V angleMeasured: 60° to 72°
FusibilityInfusable, swells and splits on heating
SolubilityInsoluble
References[1][2][3][4]

Discovery and occurrence
Wavellite from the Avant Mine, Garland County, Arkansas, showing spherical structure (size: 3.4 x 2.0 x 1.1 cm)

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

References
  1. Handbook of Mineralogy
  2. Webmineral
  3. Mindat
  4. Klein, Corneis and Cornelius S. Hurlbut, Jr., Manual of Mineralogy, Wiley, 20th ed. 1985, p. 362-3 ISBN 0-471-80580-7
  5. Chisholm, Hugh, ed. (1911). "Wavellite" . Encyclopædia Britannica. 28 (11th ed.). Cambridge University Press. p. 430.
  6. 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.
  7. 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.
  8. Gemstones: Properties, identification and use by Arthur Thomas, p. 132.


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