<abstract xml:lang="en" xmlns="http://www.w3.org/1999/xhtml"><p>Radioactive veins in shear zones of the El-Seboah granite in Egypt with anomalous concentrations of Nd, Ce, Zr, Y, Nb, Sm, Th and U were studied by petrographic microscopy, x-ray diffraction, <sup>57</sup>Fe Mössbauer and wet chemical methods. The veins are composed essentially of quartz, aegirine-augite and minor K-feldspar ± α-iron oxide (hematite) ± γ-iron oxide hydroxide (goethite). They likely represent late-stage felsic melt that was quenched and devitrified at high temperature to yield crystals and crystallites, and then subjected to low temperature alteration during which most of the K feldspar transformed to kaolinite and opal. Mössbauer parameters of the samples indicate that the existing Fe-bearing minerals are primary, with appreciable ordering in the Fe sites. The bulk-sample iron (ΣFe) contents are extremely high (12.3-22.4%). The extent of oxidation of the Fe has been found to be 100% by Mössbauer spectroscopy and 95.36-99.69% by a chemical method. These conditions of Fe enrichment and strong oxidation suggest that the veins are extreme differentiates of granite magmas where high states of oxygen fugacity prevailed.</p></abstract>

Radioactive veins in shear zones of the El-Seboah granite in Egypt with anomalous concentrations of Nd, Ce, Zr, Y, Nb, Sm, Th and U were studied by petrographic microscopy, x-ray diffraction, 57Fe Mössbauer and wet chemical methods. The veins are composed essentially of quartz, aegirine-augite and minor K-feldspar ± α-iron oxide (hematite) ± γ-iron oxide hydroxide (goethite). They likely represent late-stage felsic melt that was quenched and devitrified at high temperature to yield crystals and crystallites, and then subjected to low temperature alteration during which most of the K feldspar transformed to kaolinite and opal. Mössbauer parameters of the samples indicate that the existing Fe-bearing minerals are primary, with appreciable ordering in the Fe sites. The bulk-sample iron (ΣFe) contents are extremely high (12.3-22.4%). The extent of oxidation of the Fe has been found to be 100% by Mössbauer spectroscopy and 95.36-99.69% by a chemical method. These conditions of Fe enrichment and strong oxidation suggest that the veins are extreme differentiates of granite magmas where high states of oxygen fugacity prevailed.

Valences and site characteristics of iron in radioactive magmatic veins (Egypt): A Mössbauer and chemical study

Nuclear Materials Authority, P.O. Box 530, Maddi, Cairo, Egypt

Mineralogia

Radioactive veins in shear zones of the El-Seboah granite in Egypt with anomalous concentrations of Nd, Ce, Zr, Y, Nb, Sm, Th and U were studied by...

Valences and site characteristics of iron in radioactive magmatic veins (Egypt): A Mössbauer and chemical study

Publié en ligne: 23 févr. 2011

Pages: 23 - 33

DOI: https://doi.org/10.2478/v10002-010-0003-2

Mots clés
Egypt, Mössbauer, peralkaline rocks, aegirine-augite, Fe-oxide phases, radioactive/rare metals

This content is open access.

Valences and site characteristics of iron in radioactive magmatic veins (Egypt): A Mössbauer and chemical study

Publié en ligne: 23 févr. 2011

Pages: 23 - 33

DOI: https://doi.org/10.2478/v10002-010-0003-2

Mots clésEgypt, Mössbauer, peralkaline rocks, aegirine-augite, Fe-oxide phases, radioactive/rare metals

This content is open access.

Mots clés
Egypt, Mössbauer, peralkaline rocks, aegirine-augite, Fe-oxide phases, radioactive/rare metals