{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,2]],"date-time":"2025-11-02T02:46:37Z","timestamp":1762051597422,"version":"build-2065373602"},"reference-count":47,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2022,5,10]],"date-time":"2022-05-10T00:00:00Z","timestamp":1652140800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Scientific Research Unit of Istanbul Kultur University-IKU BAP Project","award":["BAP2104","116Z294","121Z110","UIDB\/00313\/2020","UIDP\/00313\/2020"],"award-info":[{"award-number":["BAP2104","116Z294","121Z110","UIDB\/00313\/2020","UIDP\/00313\/2020"]}]},{"name":"Scientific and Technological Research Council of Turkey\u2013TUBITAK 1001 Project","award":["BAP2104","116Z294","121Z110","UIDB\/00313\/2020","UIDP\/00313\/2020"],"award-info":[{"award-number":["BAP2104","116Z294","121Z110","UIDB\/00313\/2020","UIDP\/00313\/2020"]}]},{"name":"Scientific and Technological Research Council of Turkey\u2013TUBITAK 1002 Project","award":["BAP2104","116Z294","121Z110","UIDB\/00313\/2020","UIDP\/00313\/2020"],"award-info":[{"award-number":["BAP2104","116Z294","121Z110","UIDB\/00313\/2020","UIDP\/00313\/2020"]}]},{"name":"Portuguese Science Foundation (\u201cFunda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia\u201d-FCT)\u2013Projects CQC-IMS","award":["BAP2104","116Z294","121Z110","UIDB\/00313\/2020","UIDP\/00313\/2020"],"award-info":[{"award-number":["BAP2104","116Z294","121Z110","UIDB\/00313\/2020","UIDP\/00313\/2020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Fulgurites are naturally occurring structures that are formed when lightning discharges reach the ground. In this investigation, the mineralogical compositions of core and shell compartments of a rare, iron-rich fulgurite from the Mongolian Gobi Desert were investigated by X-ray diffraction and micro-Raman spectroscopy. The interpretation of the Raman data was helped by chemometric analysis, using both multivariate curve resolution (MCR) and principal component analysis (PCA), which allowed for the fast identification of the minerals present in each region of the fulgurite. In the core of the fulgurite, quartz, microcline, albite, hematite, and barite were first identified based on the Raman spectroscopy and chemometrics analyses. In contrast, in the shell compartment of the fulgurite, the detected minerals were quartz, a mixture of the K-feldspars orthoclase and microcline, albite, hematite, and goethite. The Raman spectroscopy results were confirmed by X-ray diffraction analysis of powdered samples of the two fulgurite regions, and are consistent with infrared spectroscopy data, being also in agreement with the petrographic analysis of the fulgurite, including scanning electron microscopy with backscattering electrons (SEM-BSE) and scanning electron microscopy with energy dispersive X-ray (SEM-EDX) data. The observed differences in the mineralogical composition of the core and shell regions of the studied fulgurite can be explained by taking into account the effects of both the diffusion of the melted material to the periphery of the fulgurite following the lightning and the faster cooling at the external shell region, together with the differential properties of the various minerals. The heavier materials diffused slower, leading to the concentration in the core of the fulgurite of the iron and barium containing minerals, hematite, and barite. They first underwent subsequent partial transformation into goethite due to meteoric water within the shell of the fulgurite. The faster cooling of the shell region kinetically trapped orthoclase, while the slower cooling in the core area allowed for the extensive formation of microcline, a lower temperature polymorph of orthoclase, thus justifying the prevalence of microcline in the core and a mixture of the two polymorphs in the shell. The total amount of the K-feldspars decreases only slightly in the shell, while quartz and albite appeared in somewhat larger amounts in this compartment of the fulgurite. On the other hand, at the surface of the fulgurite, barite could not be stabilized due to sulfate lost (in the form of SO2 plus O2 gaseous products). The conjugation of the performed Raman spectroscopy experiments with the chemometrics analysis (PCA and, in particular, MCR analyses) was shown to allow for the fast identification of the minerals present in the two compartments (shell and core) of the sample. This way, the XRD experiments could be done while knowing in advance the minerals that were present in the samples, strongly facilitating the data analysis, which for compositionally complex samples, such as that studied in the present investigation, would have been very much challenging, if possible.<\/jats:p>","DOI":"10.3390\/molecules27103053","type":"journal-article","created":{"date-parts":[[2022,5,10]],"date-time":"2022-05-10T21:52:11Z","timestamp":1652219531000},"page":"3053","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Micro-Raman Spectroscopy and X-ray Diffraction Analyses of the Core and Shell Compartments of an Iron-Rich Fulgurite"],"prefix":"10.3390","volume":"27","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3604-2988","authenticated-orcid":false,"given":"Ahmet","family":"Karadag","sequence":"first","affiliation":[{"name":"Department of Physics, Faculty of Sciences and Letters, Istanbul Kultur University, Istanbul 34158, Turkey"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1945-2870","authenticated-orcid":false,"given":"Ersin","family":"Kaygisiz","sequence":"additional","affiliation":[{"name":"Department of Geological Engineering, Faculty of Engineering, Istanbul University-Cerrahpasa, Istanbul 34320, Turkey"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0907-5936","authenticated-orcid":false,"given":"Timur","family":"Nikitin","sequence":"additional","affiliation":[{"name":"Department of Chemistry, University of Coimbra, CQC-IMS, 3004-535 Coimbra, Portugal"}]},{"given":"Sinan","family":"Ongen","sequence":"additional","affiliation":[{"name":"Department of Geological Engineering, Faculty of Engineering, Istanbul University-Cerrahpasa, Istanbul 34320, Turkey"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7827-5050","authenticated-orcid":false,"given":"Gulce","family":"Ogruc Ildiz","sequence":"additional","affiliation":[{"name":"Department of Physics, Faculty of Sciences and Letters, Istanbul Kultur University, Istanbul 34158, Turkey"},{"name":"Department of Chemistry, University of Coimbra, CQC-IMS, 3004-535 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9669-7305","authenticated-orcid":false,"given":"Namik","family":"Aysal","sequence":"additional","affiliation":[{"name":"Department of Geological Engineering, Faculty of Engineering, Istanbul University-Cerrahpasa, Istanbul 34320, Turkey"}]},{"given":"Ayberk","family":"Yilmaz","sequence":"additional","affiliation":[{"name":"Department of Physics, Faculty of Science, Istanbul University, Istanbul 34134, Turkey"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8264-6854","authenticated-orcid":false,"given":"Rui","family":"Fausto","sequence":"additional","affiliation":[{"name":"Department of Chemistry, University of Coimbra, CQC-IMS, 3004-535 Coimbra, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2022,5,10]]},"reference":[{"key":"ref_1","first-page":"647","article-title":"A Perfect Glass","volume":"19","author":"Arago","year":"1821","journal-title":"Ann. Chim. Phys."},{"key":"ref_2","first-page":"4","article-title":"Global Frequency and Distribution of Lightning as Observed from Space by the Optical Transient Detector","volume":"108","author":"Christian","year":"2003","journal-title":"J. Geophys. Res."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"477","DOI":"10.1007\/s00410-012-0753-5","article-title":"Fulgurite Morphology: A Classification Scheme and Clues to Formation","volume":"16","author":"Pasek","year":"2012","journal-title":"Contrib. Mineral. Petrol."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Rakov, V.A., and Uman, M.A. (2003). Lightning: Physics and Effects, Cambridge University Press.","DOI":"10.1017\/CBO9781107340886"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"553","DOI":"10.1038\/ngeo580","article-title":"Lightning-induced Reduction of Phosphorus Oxidation State","volume":"2","author":"Pasek","year":"2009","journal-title":"Nat. Geosci."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"783","DOI":"10.1127\/0935-1221\/2009\/0021-1948","article-title":"The Fulgurite of Torre de Moncorvo (Portugal): Description and Analysis of the Glass","volume":"21","author":"Crespo","year":"2009","journal-title":"Eur. J. Mineral."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1343","DOI":"10.4236\/jamp.2015.310161","article-title":"Distribution of Microcrystalline Quartz in Glassy Fulgurites from Garuamukh and Kimin, India","volume":"3","author":"Saikia","year":"2015","journal-title":"J. Appl. Math. Phys."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1177\/095968369300300201","article-title":"Fulgurites in the Southern Central Sahara, Republic of Niger and their Palaeoenvironmental Significance","volume":"3","author":"Sponholz","year":"1993","journal-title":"Holocene"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1470","DOI":"10.2138\/am-2017-5971","article-title":"Mineralogical and Compositional Features of Rock Fulgurites: A Record of Lightning Effects on Granite","volume":"102","author":"Elmi","year":"2017","journal-title":"Am. Miner."},{"key":"ref_10","unstructured":"Block, K.M. (2011). Fulgurite Classification, Petrology and Implications for Planetary Processes. [Master\u2019s Thesis, University of Arizona]."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"177","DOI":"10.1016\/0021-9673(95)01206-0","article-title":"Application of Multivariate Self-modeling Curve Resolution to the Quantitation of Trace Levels of Organophosphorus Pesticides in Natural Waters from Interlaboratory Studies","volume":"730","author":"Tauler","year":"1996","journal-title":"J. Chromatogr. A"},{"key":"ref_12","unstructured":"Martens, H., and N\u00e6s, T. (1989). Multivariate Calibration, John Wiley & Sons."},{"key":"ref_13","unstructured":"Putz, H. (2016). Match! Phase Identification from Powder Diffraction, Crystal Impact. Version 2.4.7; Build 529."},{"key":"ref_14","unstructured":"De Wolff, P.M., and Visser, J.W. (1964). Absolute Intensities, Technische Physische Dienst. Rep. 641.109."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"292","DOI":"10.1107\/S1600576715022396","article-title":"COD::CIF::Parser: An Error-correcting CIF Parser for the Perl Language","volume":"49","author":"Merkys","year":"2016","journal-title":"J. Appl. Crystallogr."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1107\/S1600576714025904","article-title":"Computing Stoichiometric Molecular Composition from Crystal Structures","volume":"48","author":"Merkys","year":"2015","journal-title":"J. Appl. Crystallogr."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"D420","DOI":"10.1093\/nar\/gkr900","article-title":"Crystallography Open Database (COD): An Open-access Collection of Crystal Structures and Platform for World-wide Collaboration","volume":"40","author":"Merkys","year":"2012","journal-title":"Nucleic Acids Res."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"726","DOI":"10.1107\/S0021889809016690","article-title":"A Crystallography Open Database\u2014An Open-access Collection of Crystal Structures","volume":"42","author":"Chateigner","year":"2009","journal-title":"J. Appl. Crystallogr."},{"key":"ref_19","first-page":"247","article-title":"The American Mineralogist Crystal Structure Database","volume":"88","author":"Downs","year":"2003","journal-title":"Am. Miner."},{"key":"ref_20","unstructured":"(2018). The UnscramblerTM, CAMO A\/S. Version 10.5."},{"key":"ref_21","unstructured":"(1992). OMNIC, Thermo Fisher Scientific Inc.. Version 8.2.0.387; Copyright \u00a9 1992\u20132010."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Armbruster, T., and Danisi, R.M. (2015). The Power of Databases: The RRUFF Project. Highlights in Mineralogical Crystallography, De Gruyter.","DOI":"10.1515\/9783110417104"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1055","DOI":"10.1127\/0935-1221\/2009\/0021-1856","article-title":"Raman Spectroscopic Characterisation of Disordered Alkali Feldspars along the Join KAlSi3O8\u2013NaAlSi3O8: Application to Natural Sanidine and Anorthoclase","volume":"20","author":"Bendel","year":"2008","journal-title":"Eur. J. Miner."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1506","DOI":"10.2138\/am.2005.1726","article-title":"Raman Spectroscopy and Vibrational Analyses of Albite: From 25 \u00b0C through the Melting Temperature","volume":"90","author":"McKwown","year":"2005","journal-title":"Am. Miner."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1082","DOI":"10.1002\/jrs.2246","article-title":"Fast Detection of Sulphate Minerals (Gypsum, Anglesite, Baryte) by a Portable Raman Spectrometer","volume":"40","author":"Jehlicka","year":"2009","journal-title":"J. Raman Spectrosc."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"347","DOI":"10.1177\/0003702815620556","article-title":"In Situ Raman Spectroscopic Study of Barite as a Pressure Gauge Using a Hydrothermal Diamond Anvil Cell","volume":"70","author":"Liu","year":"2016","journal-title":"Appl. Spectrosc."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"967","DOI":"10.1093\/petrology\/egp028","article-title":"The Complex Hydrothermal History of Granitic Rocks: Multiple Feldspar Replacement Reactions under Subsolidus Conditions","volume":"50","author":"Plumper","year":"2009","journal-title":"J. Petrol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1795","DOI":"10.3749\/canmin.46.6.1477","article-title":"Characterization of Natural Feldspars by Raman Spectroscopy for Future Planetary Exploration","volume":"46","author":"Freeman","year":"2008","journal-title":"Can. Miner."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"205108","DOI":"10.1063\/5.0006352","article-title":"Raman Spectroscopy of Alpha-FeOOH (Goethite) Near Antiferromagnetic to Paramagnetic Phase Transition","volume":"127","author":"Abrashev","year":"2020","journal-title":"J. Appl. Phys."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1736","DOI":"10.1039\/b618790k","article-title":"Size-dependent Structural Transformations of Hematite Nanoparticles. 1. Phase Transition","volume":"9","author":"Chernyshova","year":"2007","journal-title":"Phys. Chem. Chem. Phys."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"239","DOI":"10.1002\/adic.200590026","article-title":"The Raman Spectrum of Hematite: Possible Indicator for a Compositional or Firing Distinction Among Terra Sigillata Wares","volume":"95","author":"Zoppi","year":"2005","journal-title":"Ann. Chim."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1522","DOI":"10.1002\/jrs.5824","article-title":"Polarized Raman Spectra of Hematite and Assignment of External Modes","volume":"51","author":"Marshall","year":"2020","journal-title":"J. Raman Spectrosc."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Shchipalkina, N.V., Pekov, I.V., Britvin, S.N., Koshlyakova, N.N., Vigasina, M.F., and Sidorov, E.G. (2019). A New Mineral Ferrisanidine, K[Fe3+Si3O8], the First Natural Feldspar with Species-Defining Iron. Minerals, 9.","DOI":"10.3390\/min9120770"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1007\/BF00198604","article-title":"A Raman Spectroscopic Study of Shocked Single Crystalline Quartz","volume":"19","author":"McMillan","year":"1992","journal-title":"Phys. Chem. Miner."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"88","DOI":"10.1016\/j.vibspec.2004.11.005","article-title":"Near-infrared Raman Spectra of Terrestrial Minerals: Relevance for the Remote Analysis of Martian Spectral Signatures","volume":"39","author":"Villar","year":"2005","journal-title":"Vibrat. Spectrosc."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"155","DOI":"10.1007\/s12034-008-0027-z","article-title":"Fourier\u2013transform Infrared Spectroscopic Characterization of Naturally Occurring Glassy Fulgurites","volume":"31","author":"Saikia","year":"2008","journal-title":"Bull. Mater. Sci."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"262","DOI":"10.1107\/S0021889877013466","article-title":"Application of the Pattern-fitting Structure-Refinement Method of X-ray Powder Diffractometer Patterns","volume":"10","author":"Young","year":"1977","journal-title":"J. Appl. Crystallogr."},{"key":"ref_38","first-page":"475","article-title":"Chemical Analysis by X-ray Diffraction","volume":"10","author":"Hanawalt","year":"1938","journal-title":"Anal. Chem."},{"key":"ref_39","unstructured":"Sanc, I. (1990). Pattern: 00-041-1478, Graphite-2H, Polytechna, Foreign Trade Corporation. ICDD Grant-in-Aid."},{"key":"ref_40","first-page":"854","article-title":"Electron Density Distribution in Hematite, \u03b1-Fe2O3, from Precision X-ray Diffraction Data","volume":"281","author":"Antipin","year":"1985","journal-title":"Dokl. Akad. Nauk. SSSR"},{"key":"ref_41","first-page":"1053","article-title":"Rigid-body Character of the SO4 Groups in Celestine, Anglesite and Barite","volume":"36","author":"Jacobsen","year":"1998","journal-title":"Can. Miner."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"481","DOI":"10.1524\/zkri.1936.93.1.481","article-title":"On the Lattice Shrinkage and Structure of Montmorillonite","volume":"93","author":"Nagelschmidt","year":"1936","journal-title":"Z. Krist.-Cryst. Mater."},{"key":"ref_43","first-page":"51","article-title":"Goethite from Hindlow, Derbyshire","volume":"52","author":"Harrison","year":"1975","journal-title":"Bull. Geol. Surv."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"624","DOI":"10.1038\/232624a0","article-title":"Transformation of Hematite to Goethite in Soils","volume":"232","author":"Schwermann","year":"1971","journal-title":"Nature"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"1451","DOI":"10.1021\/ac60294a032","article-title":"Thermal Decomposition of Barium Sulfate to Sulfur Dioxide for Mass Spectrometric Analysis","volume":"42","author":"Holt","year":"1970","journal-title":"Anal. Chem."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"3087","DOI":"10.1098\/rsta.2010.0022","article-title":"A Raman Spectroscopic Study of a Fulgurite","volume":"368","author":"Carter","year":"2010","journal-title":"Philos. Trans. R. Soc. A."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"185","DOI":"10.1007\/s00710-017-0527-x","article-title":"The Forensics of Fulgurite Formation","volume":"112","author":"Pasek","year":"2018","journal-title":"Miner. Petrol."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/27\/10\/3053\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T23:08:37Z","timestamp":1760137717000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/27\/10\/3053"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,5,10]]},"references-count":47,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2022,5]]}},"alternative-id":["molecules27103053"],"URL":"https:\/\/doi.org\/10.3390\/molecules27103053","relation":{},"ISSN":["1420-3049"],"issn-type":[{"type":"electronic","value":"1420-3049"}],"subject":[],"published":{"date-parts":[[2022,5,10]]}}}