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Kinetics of the alteration of K-feldspar in buffered solutions at low temperature

par Wollast, Roland
Référence Geochimica et cosmochimica acta, 31, 4, page (635-648)
Publication Publié, 1967-04

Article révisé par les pairs

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Résumé :

A study has been made of the release of Si and Al to solution from the alteration of a potassic feldspar in solutions buffered at pH values between 4 and 10. Release of both Si and Al is consistent with diffusion from an altered layer, presumably formed by rapid initial hydration and exchange of H+ for K+. In a limited volume of solution diffusion ceases when the Al concentration in the external solution reaches a fixed value at each pH; this value is reasonably consistent with the solubility of Al(OH)3. The Si concentration tends to reach a maximum at each pH. The interpretation is made that the maximum in Si concentration corresponds to a balance between Si diffusion into the solution, and Si removed from the solution by reaction with Al(OH)3 to form a hydrated silicate. The calculated equilibrium value for the reaction Al(OH)3 + SiO2aq = Al-silicate is 5 ppm SiO2. © 1967.