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

Abstract

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_0.9Mg_0.2Al_6.0)[Si_6.4Al_1.6O₂₀](OH)10 · 3.3H₂O, from elements was experimentally determined by melt solution calorimetry in a high-temperature Calvet microcalorimeter: Δ_fH_el^o(298.15 К) =–15087 ± 26 kJ/mol. The standard entropy and Gibbs free energy of formation of this mineral were evaluated.