Sveinbergeite
Sveinbergeite is an IMA-recognized mineral species in the silicate class, with the chemical formula (H₂O)₂[Ca(H₂O)](Fe²⁺₆Fe³⁺)Ti₂(Si₄O₁₂)₂O₂(OH)₄[(OH)(H₂O)].
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Astrophyllite-Devitoite structural group.
Key properties: Mohs hardness 3; specific gravity 3.152; Pale green streak; Vitreous to pearly luster; optically biaxial.
IMA symbol Sve, IMA status: approved, named in 2010.
A late forming mineral in cavities in syenite pegmatite in an alkaline plutonic complex.
It is found associated with Microcline, magnesiokatophorite, aenigmatite, aegirine, albite, calcite, fluorapatite, molybdenite, galena, a hochelagaite-like mineral.
The mineral was named to honor Svein Arne Berge (b. 1949), the Norwegian amateur mineralogist who observed and collected the first specimens.