Class : Silicates
    Subclass : Inosilicates
    Crystal system : Triclinic
    Chemistry : MnSiO₃
    Rarity : Common

Rhodonite belongs to the group of pyroxenoids, silicates whose structure is very similar to that of pyroxenes. It is both the most common of the pyroxenoids and manganese silicates. Its chemistry is quite variable : calcium, iron, magnesium and zinc can be used in its composition to give rise to varieties that are not widely used today, such as fowlerite. This mineral owes its name to its pink color (rhodon in Greek). It is found in manganese deposits formed by contact or regional metamorphism, and in hydrothermal veins. Very sensitive to surface alteration, rhodonite transforms into black oxides of manganese, giving pink masses veined with black according to fractures and cleavages, which can benefit from the status of ornamental stone. At high temperature, under the action of carbonate solutions, rhodonite turns into rhodochrosite. It is a mineral which has a vitreous luster, and a color usually pink, sometimes red-brown, red (gemmy crystals), more rarely brown. Its crystals are rare, usually stocky, sometimes tabular and elongated according to [001], with an almost square to rectangular section, generally with rounded edges and rough faces. Rhodonite is much more common in cleavable masses. Besides being used as an ornamental stone valued in jewelry and the sculpture of works of art, it is also sometimes an accessory ore of manganese.

Main photo : Rhodonite from Morro da Mina mine, Brazil © Rob Lavinsky

Rhodonite exhibits lamellar twinning with {010} as a composition plane.

No known fakes for this mineral.