Diversity of Magadiite

Some differences in intracrystalline reactivity reveal a structural variability of natural and synthetic magadiites which is more pronounced than originally expected from very similar or identical X‐ray powder patterns. A highly reactive potassium silicate is strongly related to magadiite but is not identical with the potassium form of magadiite. The structural variability becomes evident in the MAS‐NMR spectra. The Q 4 /Q 3 ratio of the individual samples varies over a broad range. The general formula of the layered alkali silicates (M = Na, K) is M z H x–z SiO 2+x/2 · x′H 2 O or M m H n–m Si 14 O 28+n/2 · xH 2 O where x/z is obtained from the Q 4 /Q 3 ratio and z is determined by chemical analysis. Values of X = 0.27–0.30 and z = 0.15–0.20 are abundant.