Svanbergite

Svanbergite is a colorless, yellow or reddish mineral with the chemical formula SrAl3(PO4)(SO4)(OH)6. It has rhombohedral crystals.[3]

Svanbergite
Svanbergite w-pyrophyllite on andalusite Basic strontium aluminum phosphate Donally Mine near Thorne Minerals County Nevada 1879.jpg
Svanbergite with pyrophyllite and andalusite
General
CategoryPhosphate minerals
Formula
(repeating unit)		SrAl3(PO4)(SO4)(OH)6
Strunz classification8.BL.05
Crystal systemTrigonal
Crystal classHexagonal scalenohedral (3m)
H-M symbol: (3 2/m)
Space groupR3m
Unit cella = 6.970–6.992 Å
c = 16.567–16.75 Å, Z = 3
Identification
ColorColorless, cream-yellow, rose, reddish brown
Crystal habitRhombohedral crystals (to pseudocubic); granular, massive
CleavageDistinct on {0001}
Mohs scale hardness5
LusterVitreous to adamantine
DiaphaneityTranslucent
Specific gravity3.22
Optical propertiesUniaxial (+)
Refractive indexnω = 1.631–1.635 nε= 1.646–1.649
Birefringenceδ=0.0140-0.0150
References[1][2]

It was first described for an occurrence in Varmland, Sweden in 1854 and named for Swedish chemist Lars Fredrik Svanberg (1805–1878).[1][2]

It occurs in high aluminium medium-grade metamorphic rocks; in bauxite deposits and from sulfate enriched argillic alteration ( high silica and clay) associated with hydrothermal systems often replacing apatite. It occurs with pyrophyllite, kyanite, andalusite, lazulite, augelite, alunite, kaolinite and quartz.[1]

Svanbergite crystals on white dolomite from Radium Hot Springs, British Columbia, Canada (size: 3 x 2.5 x 2.1 cm)


This article uses material from the Wikipedia article
 Metasyntactic variable, which is released under the 
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Attribution-ShareAlike 3.0 Unported License.