Citation: Camara, F.; Oberti, R.; Della Ventura, G.; Welch, M. D.; Maresch, W. V. (2004). The crystal structure of synthetic NaNa2Mg5Si8O21(OH)3, a triclinic C-1 amphibole with a triple-cell and H excess Note: occupancies unreported, so calculated formula has an extra OH. American Mineralogist, 89, pp. 1464-1473.