AM_Heulandite_2 Formula: Si9 Al.302 Na.38 O24.46 H28.74 Name: Heulandite Unit cell: 17.611 17.933 7.398 90.0 116.29 90.0 , V=2094.75 Space group: C12/M1 (12)

Wust T , Stolz J , Armbruster T , American Mineralogist , 84 (1999) p.1126-1134, Partially dealuminated heulandite produced by acidic REECl3 solution: A chemical, and single-crystal X-ray study, Sample: REE100, Tetrahedral sites were refined as Si