Svanbergite

Svanbergite
Svanbergite with pyrophyllite and andalusite
General
CategoryPhosphate minerals
Formula
(repeating unit)
SrAl3(PO4)(SO4)(OH)6
IMA symbolSvb[1]
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[2][3]

Svanbergite is a colorless, yellow or reddish mineral with the chemical formula SrAl3(PO4)(SO4)(OH)6. It has rhombohedral crystals.[4]

It was first described for an occurrence in Varmland, Sweden in 1854 and named for Swedish chemist Lars Fredrik Svanberg (1805–1878).[2][3]

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.[2]

Svanbergite crystals on white dolomite from Radium Hot Springs, British Columbia, Canada (size: 3 × 2.5 × 2.1 cm)
  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b c Mineral Handbook
  3. ^ a b Webmineral
  4. ^ Richard V. Gaines, H. Catherine W. Skinner, Eugene E. Foord, Brian Mason, and Abraham Rosenzweig: "Dana's new mineralogy", p. 962. John Wiley & Sons, 1997