A zinc phosphate analogue of analcime: kehoeite

Abstract

Kehoeite, a hydrated zinc aluminate-phosphate, produces an X-ray powder diffraction pattern with interplanar spacings similar to those of analcime, viséite, and pollucite. The diffraction maxima appear to be compatible with a cubic (or pseudocubic) lattice witha13·7 Å. It is concluded that kehoeite is essentially isostructural with analcime and that its framework is composed of linked tetrahedra: (AlO₂)⁻, (H₃O₂)⁻, and (PO₂)⁺, as was found to be the case for viséite, which contains (SiO₂) in addition. Calculations of the density, the number of oxygens in the unit cell, and the chemical composition are consistent with the structural formula Zn_5·5Ca_2·5(H₂O)₃₂[(Al₁₆P₁₆(H₃)₁₆)O₉₆].