Rhodonite Gemstones

Rhodonite Cabochon

Rhodonite is one of several gemstones that draw their name from the Greek word for rose ("rhodon"); the others are rhodolite garnet and rhodochrosite. Rhodonite, however, is rarely entirely red; it is usually rose pink to red with black dendritic inclusions of manganese oxide.

Rhodonite is composed of manganese iron magnesium calcium silicate and is a member of the pyroxenoid group of minerals. The manganese is often partly replaced by iron, magnesium, calcium, and sometimes zinc, occasionally in large quantities. A greyish-brown variety containing as much as 20% calcium oxide is called bustamite, while fowlerite is a zinciferous variety containing 7% zinc oxide.

Rhodonite is usually opaque and transparent varieties are very rare indeed. It has a hardness of 5.5 to 6.5 on the Mohs scale, and a density of 3.40 to 3.74. Its refractive index is 1.716 to 1.752.

Rhodonite Inlay in the Moscow Metro

Rhodonite from Franklin, New Jersey

Deposits of rhodonite have been found in Australia (New South Wales), Finland, Japan, Canada, Madagascar, Mexico, Russia, Sweden, South Africa, Tanzania and the United States (notably New Jersey and Nevada).

Rhodonite's attractive color and vitreous luster has made it popular as a decorative material. It is often used as cabochons for necklaces, and for ornamental objects. It has even been used as wall tiles in the Moscow subway. The Mayakovskaya Metro Station has more than 80 square meters of rhodonite inlay in the columns, which were installed during the second phase of construction of the metro in 1935-38.

The Russian deposits of rhodonite in Sverdlovsk are among the most famous in the world. Another well-known occurrence is in Franklin, New Jersey, which once yielded large specimens popular with mineral collectors.

Though rhodonite is found in a number of locations in the United States, it was named the state gem of Massachusetts in 1979, apparently because it is the most beautiful gem material native to the area.