Crystal fragments of perraultite mixed with an unknown white mineral. From: Dmitrievskii Quarry, Azov Sea Region, Donetsk Oblast', Ukraine. — Photo: David Hospital · CC BY-SA 4.0
Perraultite
Perraultite is an IMA-recognized mineral species in the silicate class, with the chemical formula BaNaMn₄Ti₂(Si₂O₇)₂O₂(OH)₂F.
It crystallizes in the triclinic crystal system (space group C2). It is a member of the Seidozerite-Bafertisite structural group.
Key properties: Mohs hardness 4; specific gravity 3.71; Pale brown streak; Vitreous on fresh surfaces to slightly waxy on exposed faces luster; optically biaxial.
IMA symbol Prt, IMA status: approved, named in 1984.
Found in pegmatite dikes in nepheline syenite in an intrusive alkalic gabbro-syenite complex.
It is found associated with Kupletskite, catapleiite, microcline, albite, aegirine, rhodochrosite, natrolite, tetranatrolite, lorenzenite, polylithionite, ancylite, fluorite, calcite.
The mineral was named to honor Professor Guy Perrault, Ecole Polytechnique, Montreal, Canada, for his work on the mineralogy of Mont Saint-Hilaire.