Fluellite

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Fluellite
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Fluellite from Leveäniemi Mine, Svappavaara, Kiruna district, Lappland, Sweden
General
Category Phosphate minerals
Formula
(repeating unit)
Al2(PO4)F2(OH)•7H2O
Strunz classification 08.DE.10
Identification
Color Colorless, white, pale yellow
Crystal habit Dipyramidal crystals commonly in aggregates; powdery, massive
Crystal system Orthorhombic Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: F ddd
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 [1][2][3]

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).[3]

It was first described in 1824 for an occurrence in the Stenna Gwyn Mine, St Stephen-in-Brannel, St Austell District, Cornwall, England.[3]

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.[1]

References

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