Citation: Laurora, A.; Brigatti, M. F.; Mottana, A.; Malferrari, D.; Caprilli, E. (2007). Crystal chemistry of trioctahedral micas in alkaline and subalkaline volcanic rocks: A case study from Mt. Sassetto (Tolfa district, Latium, central Italy) polytype. American Mineralogist, 92, pp. 468-480.