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A nanoscopic approach to the kinetics of anhydrite (100) surface growth in the range of temperatures between 60 and 120 °C

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Morales Sánchez-Migallón, Juan and Astilleros García-Monge, José Manuel and Fernández-Díaz, Lourdes (2012) A nanoscopic approach to the kinetics of anhydrite (100) surface growth in the range of temperatures between 60 and 120 °C. American Mineralogist, 97 . pp. 995-998. ISSN Online : 1945-3027. Print: 0003-004X

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Official URL: http://ammin.geoscienceworld.org/content/97/5-6/995


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Abstract

In situ observations of the growth of the anhydrite (100) surface in contact with supersaturated aqueous solutions under conditions within the stability field of this mineral (60–120 °C) were conducted using a hydrothermal atomic force microscope (HAFM). Advancement rates were measured for [001] steps, the most stable ones on the anhydrite (100) surface. Isothermal data fit well to linear correlations between step advancement rate and supersaturation; the activation energy for step advancement is 73 ± 5 kJ/mol. This is not significantly higher than activation energies reported for the growth of gypsum
(60–70 kJ/mol) and does not support that slow dehydration rates of aqueous calcium is responsible for the well-known difficulty to precipitate anhydrite crystals from supersaturated aqueous solutions at temperatures well above the anhydrite-gypsum equilibrium temperature. The role of structural factors that could inhibit the growth of anhydrite is discussed.


Item Type:Article
Uncontrolled Keywords:Anhydrite, Kinetics, Activation Energy, HAFM
Subjects:Sciences > Geology > Crystallography
Sciences > Geology > Mineralogy
ID Code:43669
Deposited On:05 Jul 2017 07:45
Last Modified:11 Dec 2018 08:46

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