Fluellite

Fluellite is a mineral with the chemical formula Al₂(PO₄)F₂(OH)•7H₂O. The name is from its chemical composition, being a fluate of alumine (French).^[4]

Fluellite
Fluellite from Leveäniemi Mine, Svappavaara, Kiruna district, Lappland, Sweden
General
Category	Phosphate minerals
Formula	Al2(PO4)F2(OH)•7H2O
IMA symbol	Fll[1]
Strunz classification	8.DE.10
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m)
Space group	Fddd
Identification
Color	Colorless, white, pale yellow
Crystal habit	Dipyramidal crystals commonly in aggregates; powdery, massive
Cleavage	Indistinct on {001} and {111}
Mohs scale hardness	3
Luster	Vitreous
Diaphaneity	Transparent
Specific gravity	2.18
Optical properties	Biaxial (+)
Refractive index	nα = 1.473 - 1.490 nβ = 1.490 - 1.496 nγ = 1.506 - 1.511
Birefringence	δ = 0.033
Ultraviolet fluorescence	Fluorescent, Long UV=creamy white
References	[2][3][4]

It was first described in 1824 for an occurrence in the Stenna Gwyn Mine, St Stephen-in-Brannel, St Austell District, Cornwall, England.^[4]

It is a rare secondary mineral found in complex granite pegmatites where it forms by weathering of earlier phosphate minerals. It is found in association with fluorapatite, wavellite, phosphosiderite, strengite, aldermanite, cacoxenite, variscite, turquoise, fluorite and quartz.^[2]