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
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 occurrenceEdit

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.

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.

This article uses material from the Wikipedia article  Metasyntactic variable, which is released under the  Creative Commons Attribution-ShareAlike 3.0 Unported License.