Li-Tosudite: X-Ray Diffraction, IR Spectroscopic, Thermal, and Thermochemical Studies

The paper reports data obtained in the course of a comprehensive physicochemical study of Li-tosudite, a mixed-layer mineral from hydrothermally altered rocks in western Chukotka, Russia, whose formula was reliably established. The enthalpy of formation of Li-tosudite from Chukotka, Ca 0.15 (Li 0.9 Mg 0.2 Al 6.0 )[Si 6.4 Al 1.6 O 20 ](OH)10 · 3.3H 2 O, from elements was experimentally determined by melt solution calorimetry in a high-temperature Calvet microcalorimeter: Δ f H el o (298.15 К) =–15087 ± 26 kJ/mol. The standard entropy and Gibbs free energy of formation of this mineral were evaluated.