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Rhodonite is most frequent of the manganese silicates. It is found in the manganese deposits formed by metamorphism or hydrothermalism.
It is generally massive and it is seldom well crystallized. Its beautiful color pink-orange (or even red) blackens under the action of air. A layer of manganese oxi-hydroxides (vernadite-birnessite) is formed at its surface. The crystals are tabular and lengthened, with a vitreous luster, they can rarely be of gemmeous quality.
The largest crystals found to date measured 20 cm, but the localities having provided beautiful samples are rare. Among those we can quote the Broken Hill deposits in Australia, Franklin (New Jersey, USA). More recently the mine of Chiurucu, in the district of Huanzala in Peru, updated superb crystallized samples.
In France, it was discovered in the Vosges close to Gérardmer, in Haute-Garonne close of Bagnières-in-Luchon and in the Hautes-Pyrénées near Nabias. Rhodonite is exploited as a decorative stone in Russia, and one can very easily find it as an engraved stone used in jewellery.
The type localization is unknown (type described in 1819 on a sample from the Kaiser Franz mine area, Schävenholz, Harz Mts, Saxony-Anhalt, Germany.
HISTORY : Name inspired from the Greek word "ροδον" [rhodon] meaning "pink", in reference to its colour
Species first described in 1783 by Ruprecht, but renamed in 1819 by CF Jasche
type-locality : Kaiser Franz mine, Schävenholz, Saxony, Germany
CHEMICAL FORMULA : (Mn2+,Fe2+,Mg,Ca) SiO3
CRYSTAL SYSTEM : Triclinic
COLOR : Pink, red, pale pink, violett
DIAPHANIETY : Transparent to translucent
LUSTER : Vitreous
STREAK : White
MORPHOLOGIE : Tabular and elongated crystals, aggregates
HARDNESS : 5,5-6,5
CHEMICAL CLASS: 3,726
DENSITY : VIII - Silicates
GROUP : Rhodonite
STRUNZ CLASS BEFORE 2001 : 8/F.20-10
STRUNZ CLASS AFTER 2001 : 9.DK.05
