Fluellite Locality: Leveäniemi Mine, Svappavaara , Kiruna district, Lappland , Sweden ( Locality at mindat.org ) Colourless crystals of Fluellite. Field of view 6 mm. Specimen and photo Leon Hupperichs. — Photo: Leon Hupperichs · CC BY-SA 3.0
Fluellite
A hydrated aluminium phosphate-fluoride described in 1824 from Cornwall's Stenna Gwyn mine — its name simply means an aluminium fluoride.
Intro adapted from Wikipedia (CC BY-SA).
Fluellite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Al₂(PO₄)F₂(OH)·7H₂O.
It crystallizes in the orthorhombic crystal system (space group Fddd).
Key properties: Mohs hardness 3; specific gravity 2.14–2.18; Vitreous luster; refractive index 1.494; optically biaxial.
IMA symbol Fll, grandfathered status — known before the IMA’s founding, named in 1824.
A rare secondary mineral, formed by weathering of earlier phosphates in some complex granite pegmatites.
It is found associated with Fluorapatite, wavellite, phosphosiderite, strengite, aldermanite, cacoxenite, variscite, turquoise, fluorite, quartz.
The name comes from the Latin fluate alumine, for its fluorine and aluminum content, phosphorus having been overlooked in early analyses.