Capranicaite, (K,square)(Ca,Na)Al(4)B(4)Si(2)O(18): a new inosilicate from Capranica, Italy, with a peculiar topology of the periodic single chain [Si(2)O(6)]

Capranicaite, ideally (K,square)(Ca,Na)Al(4)B(4)Si(2)O(18), is a new inosilicate mineral from the Vico volcanic complex collected at Capranica, Viterbo Province, Latium, Italy. It occurs in miarolitic cavities of a feldspathoid-bearing syenite ejectum and formed by late-stage metasomatic processes related to the activity of the Vico volcano.