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.^[6]

Wavellite
Wavellite cluster from Mauldin Mountain Quarries, Mauldin Mt., Montgomery County, Arkansas
General
Category	Phosphate minerals
Formula	Al3(PO4)2(OH,F)3·5H2O
IMA symbol	Wav[1]
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 greenish blue and blue. 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	[2][3][4][5]

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),^[4] a Devon-based physician, botanist, historian, and naturalist, who brought the mineral to the attention of fellow mineralogists.^[7][4][6][8]

It occurs in association with crandallite and variscite in fractures in aluminous metamorphic rock, in hydrothermal regions and in phosphate rock deposits.^[2] 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.^[9]

See also

• List of minerals
• Apatite, fluoro-phosphate of calcium
• Pyromorphite, chloro-phosphate of lead
• Turquoise, a hydrated phosphate of copper and aluminium