Thermodynamic properties of chlorite and berthierine derived from calorimetric measurements

• Published in: Physics and chemistry of minerals Vol. 41; no. 8; pp. 603 - 615
• Main Authors: Blanc, Philippe, Gailhanou, Hélène, Rogez, Jacques, Mikaelian, Georges, Kawaji, Hitoshi, Warmont, Fabienne, Gaboreau, Stéphane, Grangeon, Sylvain, Grenèche, Jean-Marc, Vieillard, Philippe, Fialips, Claire I., Giffaut, Eric, Gaucher, Eric C., Claret, F.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.09.2014; Springer Nature B.V; Springer Verlag
• Subjects: Calorimetry; Catalysis; Chemical Sciences; Clay minerals; Crystallography and Scattering Methods; Datasets; Earth and Environmental Science; Earth Sciences; Enthalpy; Geochemistry; Heat; Heat measurement; Low temperature; Mathematical analysis; Mineral Resources; Mineralogy; Minerals; Original Paper; Thermodynamic properties; Waste disposal; United States > US; Gibbs free energy; Chlorite CCa-2; Enthalpy; Heat capacity; Calorimetry; Entropy; Berthierine ISGS
• ISSN: 0342-1791; 1432-2021
• DOI: 10.1007/s00269-014-0683-z

In the context of the deep waste disposal, we have investigated the respective stabilities of two iron-bearing clay minerals: berthierine ISGS from Illinois [USA; (Al 0.975 FeIII 0.182 FeII 1.422 Mg 0.157 Li 0.035 Mn 0.002 )(Si 1.332 Al 0.668 )O 5 (OH) 4 ] and chlorite CCa-2 from Flagstaff Hill, California [USA; (Si 2.633 Al 1.367 )(Al 1.116 FeIII 0.215 Mg 2.952 FeII 1.712 Mn 0.012 Ca 0.011 )O 10 (OH) 8 ]. For berthierine, the complete thermodynamic dataset was determined at 1 bar and from 2 to 310 K, using calorimetric methods. The standard enthalpies of formation were obtained by solution-reaction calorimetry at 298.15 K, and the heat capacities were measured by heat-pulse calorimetry. For chlorite, the standard enthalpy of formation is measured by solution-reaction calorimetry at 298.15 K. This is completing the entropy and heat capacity obtained previously by Gailhanou et al. (Geochim Cosmochim Acta 73:4738–4749, 2009 ) between 2 and 520 K, by using low-temperature adiabatic calorimetry and differential scanning calorimetry. For both minerals, the standard entropies and the Gibbs free energies of formation at 298.15 K were then calculated. An assessment of the measured properties could be carried out with respect to literature data. Eventually, the thermodynamic dataset allowed realizing theoretical calculations concerning the berthierine to chlorite transition. The latter showed that, from a thermodynamic viewpoint, the main factor controlling this transition is probably the composition of the berthierine and chlorite minerals and the nature of the secondary minerals rather than temperature.