George R. Rossman
of Geological and Planetary Sciences, California Institute of
Most tourmalines we encounter are colored by iron, titanium and manganese. Both iron and manganese are present in the 2+ and 3+ oxidation states. But rubellite color is dominated by manganese in the 3+ oxidation state. Tourmaline is a subtle mixture of colors caused by individual ions and by colors caused by interactions between ions, in particular, between Fe2+ and Ti4+. Rubellite is both a product of chemistry, namely manganese, and natural irradiation which oxidizes the manganese from the weakly colored 2+ oxidation state to the deep red 3+ state.