Rhodonite Sterling Silver Cranston PendantRose red stone with veins of black manganese running through it like old rivers. Rhodonite is a manganese inosilicate mineral with Mohs hardness 5. 56. 5. Its deep rose to red color comes from manganese, and the characteristic black veining is oxidized manganese dendritesgeology written visibly on the surface. First described from the Ural Mountains of Russia in the 1790s, rhodonite has since been found in India, Mexico, Sweden, Madagascar, Australia,