Ferri obertiite

Ferri-obertiite is a recently approved amphibole group mineral with the formula NaNa₂(Mg₃Fe³⁺Ti)(Si₈O₂₂)O₂. This highly-sodic amphibole is especially characterized in the presence of oxygen instead of hydroxyl group or fluorine at the W site, which compensates the relatively high positive charge due to dominance of ferric iron and presence of essential titanium. As in case of many other amphiboles, ferri-obertiite is monoclinic with space group C2/m. The root name honors prof. Roberta Oberti, University of Pavia, Italy.