The effect of stoichiometry, Mg-Ca distribution, and Iron, Manganese, and Zinc impurities on the dolomite order degree: a theoretical study
The determination of the degree of Mg-Ca order in the dolomite structure is crucial to better understand the process or processes leading to the formation of this mineral in nature. <i>I<sub>01.5</sub></i>/<i>I<sub>11.0</sub></i> intensity ratios in th...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2021 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/245206 |
| Acceso en línea: | http://hdl.handle.net/10261/245206 |
| Access Level: | acceso abierto |
| Palabra clave: | Dolomite Carbonate minerals Cation ordering Intensity ratios Cation impurities |
| Sumario: | The determination of the degree of Mg-Ca order in the dolomite structure is crucial to better understand the process or processes leading to the formation of this mineral in nature. <i>I<sub>01.5</sub></i>/<i>I<sub>11.0</sub></i> intensity ratios in the X-ray powder diffractograms are frequently measured to quantify dolomite cation order in dolomites. However, the intensity of diffraction peaks can be affected by factors other than the Mg-Ca distribution in the dolomite structure. The most relevant among these factors are (i) deviations from the ideal dolomite stoichiometry, and (ii) the partial substitution of Mg and Ca atoms by Fe, Mn, and Zn impurities. Using the VESTA software, we have constructed crystal structures and calculated <i>I<sub>01.5</sub></i>/<i>I<sub>11.0</sub></i> ratios for dolomites with Mg:Ca ratios ranging from 0.5 to 1.5, and with Fe, Mn, and Zn contents up to 30%. Our results show that both deviations from dolomite ideal stoichiometry and the presence of impurities in its structure lead to a significant decrease in <i>I<sub>01.5</sub></i>/<i>I<sub>11.0</sub></i> intensity ratios, an effect which must be considered when cation orders of natural dolomites from different origins are compared. |
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