Svanbergite

Svanbergite
Svanbergite
	Svanbergite with pyrophyllite and andalusite
General
Category	Phosphate minerals
Formula	SrAl3(PO4)(SO4)(OH)6
IMA symbol	Svb
Strunz classification	8.BL.05
Crystal system	Trigonal
Crystal class	Hexagonal scalenohedral (3m) ; H-M symbol: (3 2/m)
Space group	R3m
Unit cell	a = 6.970–6.992 Å ; c = 16.567–16.75 Å, Z = 3
Identification
Color	Colorless, cream-yellow, rose, reddish brown
Crystal habit	Rhombohedral crystals (to pseudocubic); granular, massive
Cleavage	Distinct on {0001}
Mohs scale hardness	5
Luster	Vitreous to adamantine
Diaphaneity	Translucent
Specific gravity	3.22
Optical properties	Uniaxial (+)
Refractive index	nω = 1.631–1.635 nε= 1.646–1.649
Birefringence	δ=0.0140–0.0150
References

Svanbergite is a colorless, yellow or reddish mineral with the chemical formula Sr Al₃(P O₄)(SO₄)(OH)₆. It has rhombohedral crystals.^[4]

Quick Facts General, Category ...

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]

References