Comment on "The experimental determination of hydromagnesite precipitation rates at 22.5– 75°C" by Berninger, U.-N., Jordan, G., Schott, J. and Oelkers, E.H. (2nd January 2018)

• Record Type: Journal Article
• Authors: Xiong, Yongliang; Cetiner, Ziya
• Is Part Of: Mineralogical magazine. Volume 81:Number 3(2017)
• Page Start: 689
• Page End: 693
• Publication Date: 2018-01-02
• Subjects: hydromagnesite precipitation, -- Qinghai-Xizang Plateau, -- China, -- Berninger, -- Salda Lake, -- Turkey; Mineralogy -- Periodicals; Mineralogy -- Great Britain -- Periodicals; 549.05
• DOI: 10.1180/minmag.2017.081.019
• Languages: English
• ISSNs: 0026-461X

Abstract

Abstract: In this work, we tested the equilibrium constant of hydromagnesite [Mg5 (CO3 )4 (OH)2 ·4H2 O] at 22.5°C proposed by Berninger et al. (2014) against field observations. By field observations we mean that analytical resultsoriginate from samples in the natural environment. In our test, we calculated saturation states of hydromagnesite, using the equilibrium constant of hydromagnesite at 22.5°C from Berninger et al., for the carbonate lakes in Qinghai-Xizang Plateau in China and for Salda Lake in Turkey, based on the hydrochemical data from literature. The predictions based on this equilibrium constant indicate that all of these lakes are strongly under-saturated with respect to hydromagnesite. However, hydromagnesite has been shown to form in all of these lakes. Therefore, this equilibrium constant is clearly in direct contradiction with field observations, leading to the conclusion that the equilibrium constant of hydromagnesite of Berninger et al. (2014) is not suitable for geochemical modelling.