Fluellite
(repeating unit)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]
H-M symbol: (2/m 2/m 2/m)
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]
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]
References
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ a b http://rruff.geo.arizona.edu/doclib/hom/fluellite.pdf Handbook of Mineralogy
- ^ http://webmineral.com/data/Fluellite.shtml Webmineral data
- ^ a b c http://www.mindat.org/min-1565.html Mindat.org
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