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

Svanbergite
Svanbergite with pyrophyllite and andalusite
General
Category	Phosphate minerals
Formula (repeating unit)	SrAl3(PO4)(SO4)(OH)6
IMA symbol	Svb[1]
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	[2][3]

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]