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Formula: Al(PO4)
Anhydrous normal phosphate
Crystal System: Trigonal
Specific gravity: 2.64 to 2.66 measured, 2.618 calculated
Hardness: 6½
Streak: White
Colour: Colourless, greyish or pale pink; colourless in transmitted light.
Solubility: Readily soluble in alkalies; virtually insoluble in cold acids.
Common impurities: Fe,Si
Environments
Pegmatites
Metamorphic environments
Hydrothermal environments
Berlinite is a rare high-temperature hydrothermal or metasomatic mineral. Often found in caves after
guano fires (Webmin, HOM).
It is isostructural with quartz, which is a tectosilicate (framework silicate). Berlinite
inverts at 583° to a paramorph isotypic
with β-SiO2 (Mindat)
In granite pegmatites associated minerals include
augelite, attakolite,
kyanite, pyrophyllite,
scorzalite, lazulite,
gatumbaite, burangaite,
amblygonite, phosphosiderite,
purpurite, apatite,
muscovite, quartz and
hematite
(HOM).
At Paddy's River mine, Australia, berlinite is associated with alunite,
aragonite, apatite variety collophane,
crandallite, francoanellite,
gypsum, huntite,
hydromagnesite, leucophosphite,
nesquehonite, niter
and nitrocalcite (HOM).
At the type locality, the Västanå Iron Mine, Näsum, Bromölla, Skåne County, Sweden, berlinite is associated with
augelite and attakolite (Mindat).
augelite to berlinite,
corundum and H2O
2Al2(PO4)(OH)3 to 2Al(PO4) + Al2O3 + 3H2O
(AM 64.1175-1183)
berlinite and H2O to trolleite and phosphoric acid
4Al(PO4) + 3H2O to Al4(PO4)3(OH)3 + H3PO4
(AM 64.1175-1183)
trolleite to augelite and berlinite
Al4(PO4)3(OH)3 to Al2(PO4)(OH)3 + 2Al(PO4)
(AM 64.1175-1183)
trolleite to berlinite, corundum and
H2O
2Al4(PO4)3(OH)3 to 6Al(PO4) + Al2O3 + 3H2O
(AM 64.1175-1183)
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