Gismondine [12251-23-9] samples from 17 localities were analyzed by electron microprobe and thermogravimetric anal. and their unit-cell dimensions have been detd. The chem. compn. varies with narrow limits from the stoichiometric formula Ca4Al8Si8O32.18H2O. The Si/(Al + Si) ratio varies from 0.514 to 0.543; Ba, Fe, and Mg are always absent and K, Na, and Sr are low or absent. The chem. and x-ray data demonstrate the non-existence of K-rich gismondines. The K-rich anal. from the literature are explained by the frequent phillipsite-gismondine intergrowths. Unit-cell dimensions were const., and no correlation with chem. compn. has been found. The largest correlation is between 2 chem. parameters: Si/(Al + Si) and (Na + K)/(Na + K + Ca). The narrow field of chem. variability of this zeolite is attributed to the (Si,Al) ordered distribution.
The crystal chemistry of gismondines: the non-existence of potassium-rich gismondines / Vezzalini, Maria Giovanna; R., Oberti. - In: BULLETIN DE MINERALOGIE. - ISSN 0180-9210. - STAMPA. - 107:(1984), pp. 805-812.
The crystal chemistry of gismondines: the non-existence of potassium-rich gismondines
VEZZALINI, Maria Giovanna;
1984
Abstract
Gismondine [12251-23-9] samples from 17 localities were analyzed by electron microprobe and thermogravimetric anal. and their unit-cell dimensions have been detd. The chem. compn. varies with narrow limits from the stoichiometric formula Ca4Al8Si8O32.18H2O. The Si/(Al + Si) ratio varies from 0.514 to 0.543; Ba, Fe, and Mg are always absent and K, Na, and Sr are low or absent. The chem. and x-ray data demonstrate the non-existence of K-rich gismondines. The K-rich anal. from the literature are explained by the frequent phillipsite-gismondine intergrowths. Unit-cell dimensions were const., and no correlation with chem. compn. has been found. The largest correlation is between 2 chem. parameters: Si/(Al + Si) and (Na + K)/(Na + K + Ca). The narrow field of chem. variability of this zeolite is attributed to the (Si,Al) ordered distribution.
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