The empirical formula calculated on the basis of nine Al atoms is Mg 18.00Al 9.00(OH) 54.00(Sr 1.79Mg 0.48Ca 0.09) 2.36 (Ca 3) 8.26(PO 4) 0.46(H 2O) 6.54(H 3O) 4.18. The idealized formula is [Mg 18Al 9(OH) 54][Sr 2(CO 3, PO 4) 9(H 2O, H 3O) 11]. The new ...