Calorimetric Study of Natural Anapaite
- 19 Downloads
The thermochemical study of natural hydrous calcium and iron phosphate, anapaite Ca2Fe(PO4)2 · 4H2O (Kerch iron ore deposit, Crimea, Russia), was carried out using high-temperature melt solution calorimetry with a Tian-Kalvet microcalorimeter. The enthalpy of formation of the mineral from elements was obtained to be Δ f Hel°(298.15 K) =–4812 ± 16 kJ/mol. The values of the standard entropy and the Gibbs energy of anapaite formation are S°(298.15 K) = 404.2 J/K mol and Δ f Gel°(298.15 K) =–4352 ± 16 kJ/mol, respectively.
Keywordsthermochemistry Calvet microcalorimetry enthalpy of formation anapaite
Unable to display preview. Download preview PDF.
- M. Catti, G. Ferraris, and G. Ivaldi, “Refinement of the crystal structure of anapaite, Ca2Fe(PO4)2 · 4H2O: hydrogen bonding and relationships with the bihydrated phase,” Bull. Minéral. 102, 314–318 (1979).Google Scholar
- I. A. Kiseleva, “Thermodynamic properties and pyrope stability,” Geokhimiya, No. 6, 845–854 (1976).Google Scholar
- I. A. Kiseleva, L. P. Ogorodova, N. D. Topor, and O. G. Chigareva, Thermochemical study of the CaO–MgO–SiO2O system,” Geokhimiya, No. 12, 1811–1825 (1979).Google Scholar
- G. B. Naumov, B. N. Ryzhenko, and I. L. Khodakovskii, Handbook of Thermodynamic Data (for Geologists) (Atomizdat, Moscow, 1971) [in Russian].Google Scholar
- J. O. Nriagu and C. I. Dell, “Diagenetic formation of iron phosphates in recent lake sediments,” Am. Mineral. 59, 934–946 (1974).Google Scholar
- R. A. Robie and B. S. Hemingway, “Thermodynamic properties of minerals and related substances at 298.15 K and 1 bar (105 pascals) pressure and at higher temperatures,” U.S. Geol. Surv. Bull. 2131 (1995).Google Scholar
- RRUFF Project // rruff.infoGoogle Scholar
- I. M. Rumanova and M. N. Znamenskaya, “The crystal structure of anapaite,” Soviet Physics–Crystallography, No. 5, 650–658 (1961).Google Scholar