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Reaction pathways towards the formation of dolomite-analogues at ambient conditions

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Pimentel, Carlos and Pina Martínez, Carlos Manuel (2016) Reaction pathways towards the formation of dolomite-analogues at ambient conditions. Geochimica et cosmochimica acta, 178 . pp. 259-267. ISSN 0016-7037

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Official URL: https://www.sciencedirect.com/science/article/pii/S0016703716300175



Abstract

In this paper we present results of a study of the crystallisation behaviour of the dolomite-analogues norsethite and PbMg (CO3)2 at room temperature and atmospheric pressure. Whereas precipitation of norsethite was previously obtained by mixing solutions (Hood et al., 1974; Pimentel and Pina, 2014a,b), we report, for the first time, the synthesis of PbMg(CO3)2 by using the same method. The formation of both phases was promoted by ageing slurries for periods of time ranging from a few days (norsethite) up to 6 months (PbMg(CO3)2). The crystallisation of both norsethite and PbMg(CO3)2 occurs by sequences of dissolution–precipitation reactions involving several amorphous and crystalline precursor phases, which were identified and characterised by X-ray diffraction and scanning electron microscopy. Depending on the initial composition and Ba:Mg and Pb:Mg ratios in the slurries, different precursors and reaction kinetics were observed. This demonstrates the existence of different reaction pathways towards the formation of the investigated dolomite-analogues. Our experimental results provide new insights into the possible mechanisms of formation of dolomite and other double carbonates in nature.


Item Type:Article
Uncontrolled Keywords:Crystallization; Dolomite
Subjects:Sciences > Geology > Crystallography
ID Code:51675
Deposited On:28 Feb 2019 07:56
Last Modified:28 Feb 2019 10:59

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