| Fluellite | |
|---|---|
| General | |
| Category | Phosphate minerals |
| Chemical formula | 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]