Calorimetric determination of the enthalpy of formation of partheite, a calcium zeolite

A thermochemical study of partheite of composition (Ca1.96Mg0.04Na0.01K0.01) center dot [(Al4.04Fe0.013+)Si3.95O14.97(OH)(2.03)] center dot 4.2H(2)O, a natural calcium zeolite extracted from gabbro pegmatites of the Denezhkin Kamen' deposit (North Ural, Russia), was performed. The enthalpies of formation of partheite from the constituent oxides, (Delta H-f(ox)degrees(298.15 K) = -359 +/- 21), and elements, (Delta H-f(el)degrees(298.15 K) = -10108 +/- 21), were determined by means of high-temperature in-melt-dissolution calorimetry. On the basis of the experimental data obtained, the enthalpy of formation of partheite of theoretical composition Ca-2[Al4Si4O15(OH)(2)] center dot 4H(2)O from the elements was evaluated, -10052 +/- 21 kJ/mol.