Specimens of rhodonite that contain up to 20% calcium oxide are usually grayish brown in color and are known as “bustamite.” “Fowlerite” is the name given to specimens that contain up to 7% zinc oxide. Specimens with a brown color have usually been altered by weathering.

Rhodonite is one of two minerals with a chemical composition of manganese silicate. The other is a high-temperature, low-pressure polymorph known as “pyroxmangite.”

Tumbled rhodonite: Rhodonite is sometimes used to make tumbled stones in a rock tumbler. Many people enjoy the raspberry color of rhodonite against the black manganese oxide. Rhodonite is a good tumbling rough for experienced tumblers. The material most often offered as a tumbling rough is inexpensive and with significant amounts of black manganese oxide. It can be challenging to polish because the manganese oxide often has a hardness that is different from the rhodonite. This results in overcutting of one material and undercutting of the other.