Dutrowite, Na(Fe<sup>2+</sup><sub>2.5</sub>Ti<sub>0.5</sub>)Al<sub>6</sub>(Si<sub>6</sub>O<sub>18</sub>)(BO<sub>3</sub>)<sub>3</sub>(OH)<sub>3</sub>O, a new mineral from the Apuan Alps (Tuscany, Italy): the first member of the tourmaline supergroup with Ti as a species-forming chemical constituent
European journal of mineralogy