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).[3]

Fluellite
Fluellite from Leveäniemi Mine, Svappavaara, Kiruna district, Lappland, Sweden
General
CategoryPhosphate minerals
Formula
(repeating unit)
Al2(PO4)F2(OH)•7H2O
Strunz classification8.DE.10
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupFddd
Identification
ColorColorless, white, pale yellow
Crystal habitDipyramidal crystals commonly in aggregates; powdery, massive
CleavageIndistinct on {001} and {111}
Mohs scale hardness3
LusterVitreous
DiaphaneityTransparent
Specific gravity2.18
Optical propertiesBiaxial (+)
Refractive indexnα = 1.473 - 1.490 nβ = 1.490 - 1.496 nγ = 1.506 - 1.511
Birefringenceδ = 0.033
Ultraviolet fluorescenceFluorescent, Long UV=creamy white
References[1][2][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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