Berlinite

Berlinite (aluminium phosphate, chemical formula AlPO4 or Al(PO4) is a rare high-temperature hydrothermal or metasomatic phosphate mineral.[4] 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]

Berlinite
Synthetic berlinite
General
CategoryPhosphate mineral
Formula
(repeating unit)
AlPO4
Strunz classification8.AA.05
Crystal systemTrigonal
Crystal classTrapezohedral (32)
H-M symbol: (32)
Space groupP3121, P3221
Unit cella = 4.941 Å, c = 10.94 Å; Z = 3
Identification
ColorColorless, pale gray, may be pale rose
Crystal habitTypically granular to massive
TwinningSubparallel lamellae
FractureConchoidal
Mohs scale hardness6.5
LusterVitreous
DiaphaneityTransparent to translucent
Specific gravity2.64–2.66
Optical propertiesUniaxial (+)
Refractive indexnω = 1.524 nε = 1.532
Birefringenceδ = 0.008
References[1][2][3]

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]

References

  1. Handbook of Mineralogy
  2. Mindat.org
  3. Webmineral data
  4. Barthelmy, Dave. "Berlinite Mineral Data". webmineral.com. Retrieved 2018-05-18.

Further reading

  • Muraoka, Y.; Kihara, K. (1997). "The temperature dependence of the crystal structure of berlinite, a quartz-type form of AlPO4". Physics and Chemistry of Minerals. 24 (4): 243. Bibcode:1997PCM....24..243M. doi:10.1007/s002690050036.


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