First terrestrial occurrence of the complex phosphate chladniite: crystal-structure refinement by synchrotron through-the-substrate microdiffraction
Chladniite, a complex phosphate species belonging to the fillowite group so far only found in meteorites, was identified in a pegmatite from Córdoba (Argentina) as inclusions in beusite. Applying synchrotron through-the-substrate microdiffraction technique (tts-μXRD) to polished thin sections prepar...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión enviada para evaluación y publicación |
| Fecha de publicación: | 2017 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/155837 |
| Acceso en línea: | http://hdl.handle.net/10261/155837 |
| Access Level: | acceso abierto |
| Palabra clave: | tts-μXRD Chladniite Complex phosphates Fillowite group Polished thin section Synchrotron radiation Meteorites Pegmatites Thin glass substrates Crystal structure refinement |
| Sumario: | Chladniite, a complex phosphate species belonging to the fillowite group so far only found in meteorites, was identified in a pegmatite from Córdoba (Argentina) as inclusions in beusite. Applying synchrotron through-the-substrate microdiffraction technique (tts-μXRD) to polished thin sections prepared on very thin glass substrates (0.1 mm), diffraction data with nearly single-crystal quality were directly measured at selected chladniite microvolumes of the section. Chladniite is trigonal (space group R-3), with a = 15.0133(3) Å, c = 42.887(2) Å, V = 8371.6(5) Å3. The subsequent crystal structure refinement confirms that the accuracy attainable by using 0.1 mm thick glass-substrates is comparable to that of routine single-crystal measurements [R1=3.34% for 1617 unique reflections]. The refined crystal structure of pegmatitic chladniite differs from meteoritic one in the cation ordering (Mg, Fe+Mn and Ca) at the various metal sites, with Mn being dominant at the M(1) position. |
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