Berlinite

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Berlinite
Berlinite.jpg
Synthetic berlinite
General
Category Phosphate mineral
Formula
(repeating unit)
AlPO4
Strunz classification 8.AA.05
Crystal system Trigonal
Crystal class Trapezohedral (32)
H-M symbol: (32)
Space group P3121, P3221
Unit cell a = 4.941 Å, c = 10.94 Å; Z = 3
Identification
Color Colorless, pale gray, may be pale rose
Crystal habit Typically granular to massive
Twinning Subparallel lamellae
Fracture Conchoidal
Mohs scale hardness 6.5
Luster Vitreous
Diaphaneity Transparent to translucent
Specific gravity 2.64–2.66
Optical properties Uniaxial (+)
Refractive index nω = 1.524 nε = 1.532
Birefringence δ = 0.008
References [1][2][3]

Berlinite (aluminium phosphate, chemical formula AlPO4) is a rare phosphate mineral. It has the same crystal structure as quartz with a low temperature polytype isostructural with α–quartz and a high temperature polytype isostructural with β–quartz.[2] Berlinite can vary from colorless to greyish or pale pink and has translucent crystals.[2]

It was first described in 1868 for an occurrence in the Västanå iron mine, Scania, Sweden and named for Nils Johan Berlin (1812–1891) of Lund University.[1][2]

It occurs as a rare mineral in high-temperature hydrothermal or metasomatic deposits.[1] Associated minerals include augelite, attakolite, kyanite, pyrophyllite, scorzalite, lazulite, gatumbaite, burangaite, amblygonite, phosphosiderite, purpurite, apatite, muscovite, quartz, hematite in granite pegmatites. It also occurs with alunite, aragonite, collophane, crandallite, francoanellite, gypsum, huntite, hydromagnesite, leucophosphite, nesquehonite, niter, and nitrocalcite in the Paddy’s River copper mine in the Brindabella Mountains of Australia.[1][2]

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