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Brief Description: Rhodonite has the chemical formula (Μn,Fe,g,Ca)SiO3, and it belongs to the Inosilicates (Pyroxene). It usually occurs in compact masses of pink colour, which often tends to brown because of surface oxidation. Rhodonite crystals are usually rare. It has a perfect, prismatic cleavage, almost vertical. Its hardness ranges from 5.5 to 6.5 and its specific gravity is 3.4 ? 3.7. It has a vitreous lustre, which is often pearly on cleavage surfaces. The manganese is often partly replaced by iron, magnesium, calcium, and sometimes zinc. Rhodonite is a mineral liable to transformation, with the formation of manganese carbonate (rhodochrosite), hydrous silicates or oxides. The compact material, which is cut and polished for ornamental purposes and is often marked in a striking manner by veins and patches of these black transformation products. 
Bibliography: Ευρετήριο ορυκτών ΑΠΘ στην ιστοσελίδα http://www.geo.auth.gr/106/az_gr.htm Τσιραμπίδης Α. (2005). Ο ορυκτός πλούτος της Ελλάδας. Εκδόσεις Γιαχούδη Θεσσαλονίκη, σελ. 391. Berry, L.G., Mason, B. and Dietrich, R.V. (1983). Mineralogy. W. H. Freeman and Company, San Francisco, 561 pp. Σαπουντζής, Η. και Χριστοφίδης, Γ. (1985). Ορυκτοδιαγνωστική. University Studio Press, Θεσσαλονίκη, 241 σ.