Abstract: Poorly or partly crystalline alkali metal aluminosilicate materials have stuffed silica polymorph related-structures in which the aluminium is at least predominantly tetrahedrally coordinated and cation exchange capacities at room temperature of at least 1 meq 100 g.sup.-1 in aqueous solution. The materials are produced by reacting an aluminosilicate, or a combination of aluminium oxide-containing and silicon oxide-containing compounds, with an alkali oxide-containing reagent. Preferably the reaction is a solid state reaction. Specific surfaces of the material are likely to be less than 45 m.sup.2 g.sup.-1. The preferred aluminosilicate reactants are kaolin group minerals.

Abstract: Amorphous derivatives of kaolin group minerals characterized by high specific surfaces and/or high cation exchange capacities and a .sup.27 AL MAS NMR spectrum having a dominant peak at about 55 ppm relative to Al(H.sub.2 O).sub.6.sup.3+. Such derivatives are prepared by reacting a kaolin group mineral with a reagent, such as, an alkali metal halide or an ammonium halide which converts the majority of the octahedrally coordinated aluminum in the kaolin group mineral to tetrahedrally coordinated aluminum. Such derivatives show high selectivity in its cation exchange towards the metals: Pb.sup.2+, Cu.sup.2+, Cd.sup.2+, Ni.sup.2+, CO.sup.2+, Cr.sup.3+, Sr.sup.2-, Zn.sup.2+, Nd.sup.3+ and UO.sub.2.sup.+.