PYROXMANGITE
Class : Silicates
Subclass : Inosilicates
Crystal system : Triclinic
Chemistry : MnSiO3
Rarity : Uncommon
Pyroxmangite belongs to the pyroxenoid family. It is an uncommon manganese silicate, close to rhodonite and which forms a series with the extremely rare pyroxferroite. It is a mineral from manganese deposits transformed by regional metamorphism, more rarely from certain manganiferous metamorphic rocks. Its name is built around the terms pyroxene and manganese, thus evoking the structure and composition of the mineral. Pyroxmangite is pink to purple-pink in color, but is covered with a surface film of red-brown to black-brown oxidation. It commonly occurs in xenomorphic masses, it also forms tabular crystals on {001} measuring up to 10 cm.
Main photo : Pyroxmangite from Taguchi mine, Shitara, Japan © Y. Okazaki
Pyroxmangite in the World
In France, pyroxmangite forms centimeter-sized pink masses in the mica-schists of Locmaria on the island of Groix (Morbihan). It is also reported in St-Jean-de-Maurienne (Savoie) and Nabias (Hautes-Pyrénées).
Twinning
Lamellar twins are known on {010} and single on {001} but less common.
Fakes and treatments
No fakes listed for this mineral species but very easy to confuse with rhodonite.
Hardness : 5.5 to 6
Density : 3.61 to 3.80
Fracture : Undetermined
Streak : White
TP : Translucent to transparent
RI : 1.728 to 1.758
Birefringence : 0.018
Optical character : Biaxial +
Pleochroism : None
Fluorescence : None
Solubility : Insoluble
Magnetism : NoneRadioactivity : None