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). It was first described in 1824 for an occurrence in the Stenna Gwyn Mine,

St Stephen-in-Brannel St Stephen-in-Brannel (known locally as ''St Stephen's'' or ''St Stephen'') () is a civil parish and village in mid Cornwall, England. The village is four miles (6.5 km) west of St Austell on the southern edge of Cornwall's china clay dis ...

St Austell Saint Austell (, ; ) is a town in Cornwall, England, United Kingdom, south of Bodmin and west of the border with Devon. At the 2021 Census in the United Kingdom, census it had a population of 20,900. History St Austell was a village centred ...

District,

Cornwall Cornwall (; or ) is a Ceremonial counties of England, ceremonial county in South West England. It is also one of the Celtic nations and the homeland of the Cornish people. The county is bordered by the Atlantic Ocean to the north and west, ...

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

. It is a rare secondary mineral found in complex

granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...

pegmatite A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic c ...

s where it forms by

weathering Weathering is the deterioration of rocks, soils and minerals (as well as wood and artificial materials) through contact with water, atmospheric gases, sunlight, and biological organisms. It occurs '' in situ'' (on-site, with little or no move ...

of earlier phosphate minerals. It is found in association with

fluorapatite Fluorapatite, often with the alternate spelling of fluoroapatite, is a phosphate mineral with the formula Ca5(PO4)3F (calcium fluorophosphate). Fluorapatite is a hard crystalline solid. Although samples can have various color (green, brown, blu ...

wavellite Wavellite is an aluminium basic phosphate mineral with formula aluminium, Al3(phosphorus, Poxygen, O4)2(Ohydrogen, H, fluorine, F)3·5water, H2O. Distinct crystals are rare, and it normally occurs as translucent green radial or spherical clusters ...

phosphosiderite Phosphosiderite is a rare mineral named for its main components, phosphate and iron. The siderite at the end of phosphosiderite comes from the word "sideros", the Greek word for iron. It was published in 1890, and has been a valid species since p ...

strengite Strengite is a relatively rare iron phosphate mineral with the formula: FePO4·2H2O. The mineral is named after the German mineralogist (1830–1897). Lavender, pink or purple in hue, it is similar to variscite and is partially soluble, part ...

, aldermanite, cacoxenite,

variscite Variscite is a hydrated aluminium phosphate mineral (). It is a relatively rare phosphate mineral. It is sometimes confused with turquoise; however, variscite is usually greener in color. The green color results from the presence of small amounts ...

turquoise Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula . It is rare and valuable in finer grades and has been prized as a gemstone for millennia due to its hue. The robi ...

fluorite Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs scal ...

and

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

References

Phosphate minerals Orthorhombic minerals Heptahydrate minerals Minerals in space group 70 {{Phosphate-mineral-stub