E. V. Limanov, V. G. Butvina, O. G. Safonov, A. V. Spivak, A. V. Kuzmin, L. Ya. Aranovich
{"title":"Crystal Structure and Raman Spectroscopy of Synthetic Potassium Richterite","authors":"E. V. Limanov, V. G. Butvina, O. G. Safonov, A. V. Spivak, A. V. Kuzmin, L. Ya. Aranovich","doi":"10.1134/s1028334x24602906","DOIUrl":null,"url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The structures of two K-richterite crystals with the crystal chemical formulas (K<sub>0.44</sub>Na<sub>0.32</sub><span>\\(\\square \\)</span><sub>0.24</sub>)<sub>Σ=1</sub>(Ca<sub>1.18</sub>Na<sub>0.82</sub>)<sub>Σ=2</sub>Mg<sub>5</sub>Si<sub>8</sub>O<sub>22</sub>OH<sub>2</sub> and (K<sub>0.83</sub>Na<sub>0.02</sub><span>\\(\\square \\)</span><sub>0.15</sub>)<sub>Σ=1</sub>(Ca<sub>1.11</sub>Na<sub>0.89</sub>)<sub>Σ=2</sub>Mg<sub>5</sub>Si<sub>8</sub>O<sub>22</sub>OH<sub>2</sub> synthesized at a pressure of 3 GPa and a temperature of 1000°С in the MgSiO<sub>3</sub> + CaMgSi<sub>2</sub>O<sub>6</sub> + K<sub>2</sub>CO<sub>3</sub> + Na<sub>2</sub>CO<sub>3</sub> + CO<sub>2</sub> + H<sub>2</sub>O system were studied by single-crystal X-ray analysis and Raman spectroscopy. The monoclinic cell parameters were obtained: <i>a</i> = 10.0256(5) and 9.9748(11) Å, <i>b</i> = 17.9874(7) and 17.9879(16) Å, <i>c</i> = 5.2687(3) and 5.2746(6) Å, <i>V</i><sub>e.c.</sub> = 916.17(18) and 918.52(8) Å<sup>3</sup>, β = 104.520(12)° and 104.821(5)°, sp. gr. <i>С</i>2/<i>m</i> (12), and <i>Z</i> = 2. The sites <i>M</i>(1), <i>M</i>(2), and <i>M</i>(3) are inhabited by Mg<sup>2+</sup>, while site <i>M</i>(4) is occupied simultaneously by Ca<sup>2+</sup> and Na<sup>+</sup>. The Na<sup>+</sup> cations not included in <i>M</i>(4) are located in position <i>A</i>, which also accommodates K<sup>+</sup> cations. Raman spectroscopy made it possible to reveal vacancies in position <i>A</i> in both samples. The structure corresponds to the “ideal” structure of richterite group minerals. The unit cell volume of the measured crystals is directly proportional to the K content in position <i>A</i>. Based on the generalization of new and published data, an equation of the dependence of <i>V</i><sub>u.c.</sub> for amphiboles of the richterite Na(NaCa)Mg<sub>5</sub>Si<sub>8</sub>O<sub>22</sub>(OH)<sub>2</sub>–K-richterite K(NaCa)Mg<sub>5</sub>Si<sub>8</sub>O<sub>22</sub>(OH)<sub>2</sub> series with a low tremolite component on the K content in position <i>A</i> is proposed.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":"25 1","pages":""},"PeriodicalIF":0.7000,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Doklady Earth Sciences","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1134/s1028334x24602906","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The structures of two K-richterite crystals with the crystal chemical formulas (K0.44Na0.32\(\square \)0.24)Σ=1(Ca1.18Na0.82)Σ=2Mg5Si8O22OH2 and (K0.83Na0.02\(\square \)0.15)Σ=1(Ca1.11Na0.89)Σ=2Mg5Si8O22OH2 synthesized at a pressure of 3 GPa and a temperature of 1000°С in the MgSiO3 + CaMgSi2O6 + K2CO3 + Na2CO3 + CO2 + H2O system were studied by single-crystal X-ray analysis and Raman spectroscopy. The monoclinic cell parameters were obtained: a = 10.0256(5) and 9.9748(11) Å, b = 17.9874(7) and 17.9879(16) Å, c = 5.2687(3) and 5.2746(6) Å, Ve.c. = 916.17(18) and 918.52(8) Å3, β = 104.520(12)° and 104.821(5)°, sp. gr. С2/m (12), and Z = 2. The sites M(1), M(2), and M(3) are inhabited by Mg2+, while site M(4) is occupied simultaneously by Ca2+ and Na+. The Na+ cations not included in M(4) are located in position A, which also accommodates K+ cations. Raman spectroscopy made it possible to reveal vacancies in position A in both samples. The structure corresponds to the “ideal” structure of richterite group minerals. The unit cell volume of the measured crystals is directly proportional to the K content in position A. Based on the generalization of new and published data, an equation of the dependence of Vu.c. for amphiboles of the richterite Na(NaCa)Mg5Si8O22(OH)2–K-richterite K(NaCa)Mg5Si8O22(OH)2 series with a low tremolite component on the K content in position A is proposed.
期刊介绍：
Doklady Earth Sciences is a journal that publishes new research in Earth science of great significance. Initially the journal was a forum of the Russian Academy of Science and published only best contributions from Russia. Now the journal welcomes submissions from any country in the English or Russian language. Every manuscript must be recommended by Russian or foreign members of the Russian Academy of Sciences.
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