Résumé
Borosilicates of rubidium and cesium with the analcime structure can be formed under mild hydrothermal conditions. The formation of a solid solution is possible for any intermediate composition between borosilicate and aluminosilicate pollucite. K-danburite is obtained in the presence of potassium. The easy formation of borosilicates in the presence of the largest alkali cations is related to the organic-templated synthesis of borosilicate zeolites and confirms the relevance of a hydrophobic effect in the insertion of born in tetrahedral lattice sites.