{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2024,9,16]],"date-time":"2024-09-16T14:32:54Z","timestamp":1726497174859},"reference-count":19,"publisher":"Mineralogical Society","issue":"3","license":[{"start":{"date-parts":[[2018,7,5]],"date-time":"2018-07-05T00:00:00Z","timestamp":1530748800000},"content-version":"unspecified","delay-in-days":5878,"URL":"https:\/\/www.cambridge.org\/core\/terms"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Mineral. mag."],"published-print":{"date-parts":[[2002,6]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>Ilmenites from the least-altered rocks of the Beja-Acebuches Ophiolite Complex (SE Portugal), with low Ti values and excess Fe, despite rare optical evidence of hematite exsolution, were studied by <jats:sup>57<\/jats:sup>Fe M\u00f6ssbauer spectroscopy and X-ray diffraction. According to single-crystal XRD the sequence of alternate layers characteristic of the ideal ilmenite structure is preserved, the excess Fe being accommodated in the Ti layers. No superparamagnetic oxides were detected by <jats:sup>57<\/jats:sup>Fe M\u00f6ssbauer spectroscopy. The typical spectra of bulk \u03b1Fe<jats:sub>2<\/jats:sub>O<jats:sub>3<\/jats:sub> and of Fe<jats:sup>3+<\/jats:sup>-containing ilmenite, in the paramagnetic state above 49 K and magnetically ordered at 6 K, are observed. The average degree of oxidation of the ilmenites, estimated from the chemical analysis assuming ideally stoichiometric full cation site occupancies, is also confirmed by <jats:sup>57<\/jats:sup>Fe M\u00f6ssbauer data. Since our crystal chemistry study gave no evidence of crypto-exsolution textures within the ilmenite with the observed compositions, fast cooling from magmatic temperatures and decomposition of ilmenite in supergene conditions is suggested.<\/jats:p>","DOI":"10.1180\/0026461026630038","type":"journal-article","created":{"date-parts":[[2002,10,11]],"date-time":"2002-10-11T18:33:37Z","timestamp":1034361217000},"page":"421-430","source":"Crossref","is-referenced-by-count":4,"title":["Nature and mechanism of ilmenite alteration: a M\u00f6ssbauer and X-ray diffraction study of oxidized ilmenite from the Beja-Acebuches Ophiolite Complex (SE Portugal)"],"prefix":"10.1180","volume":"66","author":[{"given":"J. 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