Spectroscopic, Raman, EMPA, Micro-XRF and Micro-XANES Analyses of Sulphur Concentration and Oxidation State of Natural Apatite Crystals
Sulphur is the third most abundant volatile element in deep Earth systems. Analytical methods for accurately and efficiently determining the sulphur content and oxidation state in natural minerals are still lacking. Natural apatite is widely distributed in the Earth and incorporates a large amount o...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2020-11-01
|
| Series: | Crystals |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4352/10/11/1032 |
| _version_ | 1797548121326092288 |
|---|---|
| author | Bo Xu Guanyu Kou Barbara Etschmann Daiyue Liu Joël Brugger |
| author_facet | Bo Xu Guanyu Kou Barbara Etschmann Daiyue Liu Joël Brugger |
| author_sort | Bo Xu |
| collection | DOAJ |
| description | Sulphur is the third most abundant volatile element in deep Earth systems. Analytical methods for accurately and efficiently determining the sulphur content and oxidation state in natural minerals are still lacking. Natural apatite is widely distributed in the Earth and incorporates a large amount of sulphur. Therefore, apatite is an ideal mineral for performing sulphur measurements. Here, we used spectroscopic, Raman, X-ray diffraction, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), electron microprobe (EMPA) and micro-X-ray fluorescence spectrometry (micro-XRF) analysis techniques and developed a new analytical approach (i.e., micro-X-ray absorption near-edge structure (micro-XANES) analysis of the sulphur K-edge) to investigate the chemical characteristics of natural apatite. These multiple methods were developed to measure in situ sulphur concentration and S oxidation states and to assess a potential natural apatite reference material. Apatite contains chemically homogeneous sulphur, with micro-XANES located at the peak energies corresponding to S<sup>6+</sup> (sulphate; ~2482 eV), S<sup>4+</sup> (sulfite; ~2478 eV), and S<sup>2−</sup> (sulphide; ~2467, 2470 and 2474 eV). The Durango apatite contains total S presented as SO<sub>3</sub> at amount of 0.332 ± 0.012 wt.% (1σ), with a large amount of S<sup>6+</sup> and a small contribution of S<sup>4+</sup>. The Kovdor apatite contains 44–100 ppm of S and is dominated by S<sup>6+</sup>. These results indicate that the Durango apatite crystallised under relative oxidising conditions, and the Kovdor apatite has a higher oxygen fugacity than Durango. In addition, this study indicates the potential use of the natural apatite reference material with its S composition and S oxidation state. |
| first_indexed | 2024-03-10T14:55:00Z |
| format | Article |
| id | doaj.art-76cffc8dbe324aff982f445cb598ccc2 |
| institution | Directory Open Access Journal |
| issn | 2073-4352 |
| language | English |
| last_indexed | 2024-03-10T14:55:00Z |
| publishDate | 2020-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Crystals |
| spelling | doaj.art-76cffc8dbe324aff982f445cb598ccc22023-11-20T20:41:39ZengMDPI AGCrystals2073-43522020-11-011011103210.3390/cryst10111032Spectroscopic, Raman, EMPA, Micro-XRF and Micro-XANES Analyses of Sulphur Concentration and Oxidation State of Natural Apatite CrystalsBo Xu0Guanyu Kou1Barbara Etschmann2Daiyue Liu3Joël Brugger4State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, ChinaState Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, ChinaSchool of Earth, Atmosphere and the Environment, Monash University, Clayton, VIC 3800, AustraliaState Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, ChinaSchool of Earth, Atmosphere and the Environment, Monash University, Clayton, VIC 3800, AustraliaSulphur is the third most abundant volatile element in deep Earth systems. Analytical methods for accurately and efficiently determining the sulphur content and oxidation state in natural minerals are still lacking. Natural apatite is widely distributed in the Earth and incorporates a large amount of sulphur. Therefore, apatite is an ideal mineral for performing sulphur measurements. Here, we used spectroscopic, Raman, X-ray diffraction, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), electron microprobe (EMPA) and micro-X-ray fluorescence spectrometry (micro-XRF) analysis techniques and developed a new analytical approach (i.e., micro-X-ray absorption near-edge structure (micro-XANES) analysis of the sulphur K-edge) to investigate the chemical characteristics of natural apatite. These multiple methods were developed to measure in situ sulphur concentration and S oxidation states and to assess a potential natural apatite reference material. Apatite contains chemically homogeneous sulphur, with micro-XANES located at the peak energies corresponding to S<sup>6+</sup> (sulphate; ~2482 eV), S<sup>4+</sup> (sulfite; ~2478 eV), and S<sup>2−</sup> (sulphide; ~2467, 2470 and 2474 eV). The Durango apatite contains total S presented as SO<sub>3</sub> at amount of 0.332 ± 0.012 wt.% (1σ), with a large amount of S<sup>6+</sup> and a small contribution of S<sup>4+</sup>. The Kovdor apatite contains 44–100 ppm of S and is dominated by S<sup>6+</sup>. These results indicate that the Durango apatite crystallised under relative oxidising conditions, and the Kovdor apatite has a higher oxygen fugacity than Durango. In addition, this study indicates the potential use of the natural apatite reference material with its S composition and S oxidation state.https://www.mdpi.com/2073-4352/10/11/1032spectroscopyRaman and micro-XANES |
| spellingShingle | Bo Xu Guanyu Kou Barbara Etschmann Daiyue Liu Joël Brugger Spectroscopic, Raman, EMPA, Micro-XRF and Micro-XANES Analyses of Sulphur Concentration and Oxidation State of Natural Apatite Crystals Crystals spectroscopy Raman and micro-XANES |
| title | Spectroscopic, Raman, EMPA, Micro-XRF and Micro-XANES Analyses of Sulphur Concentration and Oxidation State of Natural Apatite Crystals |
| title_full | Spectroscopic, Raman, EMPA, Micro-XRF and Micro-XANES Analyses of Sulphur Concentration and Oxidation State of Natural Apatite Crystals |
| title_fullStr | Spectroscopic, Raman, EMPA, Micro-XRF and Micro-XANES Analyses of Sulphur Concentration and Oxidation State of Natural Apatite Crystals |
| title_full_unstemmed | Spectroscopic, Raman, EMPA, Micro-XRF and Micro-XANES Analyses of Sulphur Concentration and Oxidation State of Natural Apatite Crystals |
| title_short | Spectroscopic, Raman, EMPA, Micro-XRF and Micro-XANES Analyses of Sulphur Concentration and Oxidation State of Natural Apatite Crystals |
| title_sort | spectroscopic raman empa micro xrf and micro xanes analyses of sulphur concentration and oxidation state of natural apatite crystals |
| topic | spectroscopy Raman and micro-XANES |
| url | https://www.mdpi.com/2073-4352/10/11/1032 |
| work_keys_str_mv | AT boxu spectroscopicramanempamicroxrfandmicroxanesanalysesofsulphurconcentrationandoxidationstateofnaturalapatitecrystals AT guanyukou spectroscopicramanempamicroxrfandmicroxanesanalysesofsulphurconcentrationandoxidationstateofnaturalapatitecrystals AT barbaraetschmann spectroscopicramanempamicroxrfandmicroxanesanalysesofsulphurconcentrationandoxidationstateofnaturalapatitecrystals AT daiyueliu spectroscopicramanempamicroxrfandmicroxanesanalysesofsulphurconcentrationandoxidationstateofnaturalapatitecrystals AT joelbrugger spectroscopicramanempamicroxrfandmicroxanesanalysesofsulphurconcentrationandoxidationstateofnaturalapatitecrystals |