Chemical composition of gahnite and degree of pegmatitic fractionation in the Borborema Pegmatitic Province, northeastern Brazil
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| Format: | Artículo científico |
| Langue: | en |
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Academia Brasileira de Ciências
2007
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| _version_ | 1876430007543267328 |
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| author | Hartmut Beurlen |
| author_facet | Hartmut Beurlen |
| contents | Chemical composition of gahnite and degree of pegmatitic fractionation in the Borborema Pegmatitic Province, northeastern Brazil Hartmut Beurlen Dwight Rodrigues Soares Ana C. M. Ferreira Marcelo R.R. da-Silva Multidisciplinaria (Ciencias Naturales y Exactas) rare gahnite mineral chemistry element granitic pegmatites Borborema Pegmatitic Province Gahnite electron probe microanalyses from three pegmatites (Mirador, Capoeira and Quintos) of the Borborema PegmatiticProvince in northeastern Brazil allowed to determine molar compositions ranging from 86.22 to 95.41 mol%gahnite (ZnAl2O4), 1.51 to 6.62 mol% hercynite (Fe2+Al2O4), 0.11 to 5.89 mol% spinel (MgAl2O4), 1.48 to 2.74mol% galaxite (MnAl2O4), and Zn/FeTotal atomic ratios ranging from 11.53 to 60.87. These data compared with gahnitecompositions from albite subtype pegmatites from Cap de Creus, Spain (Zn/FeTotal between 10 and 60) and fromthe source granite of the Separation Rapids pegmatite field, Ontario, Canada (Zn/FeTotal =3.5) indicate a high degreeof fractionation of the studied pegmatites. This interpretation agrees with conclusions based on compositional data oftourmaline (vacancy in X-site 0.42 to 0.49), white mica (K/Rb between 8 and 33), feldspar (K/Rb between 8 and 109),garnet (Mn/(Mn+Fe2+) between 0.93 and 0.97) and in Nb-Ta oxides (Mn/(Mn+Fe2+) >0.5) in the same pegmatites. 2007 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32779305 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.3 Vol.79 |
| format | Artículo científico |
| id | redalyc_32779305 |
| institution | Redalyc |
| language | en |
| publishDate | 2007 |
| publisher | Academia Brasileira de Ciências |
| spellingShingle | Chemical composition of gahnite and degree of pegmatitic fractionation in the Borborema Pegmatitic Province, northeastern Brazil Hartmut Beurlen Multidisciplinaria (Ciencias Naturales y Exactas) rare gahnite mineral chemistry element granitic pegmatites Borborema Pegmatitic Province Chemical composition of gahnite and degree of pegmatitic fractionation in the Borborema Pegmatitic Province, northeastern Brazil Hartmut Beurlen Dwight Rodrigues Soares Ana C. M. Ferreira Marcelo R.R. da-Silva Multidisciplinaria (Ciencias Naturales y Exactas) rare gahnite mineral chemistry element granitic pegmatites Borborema Pegmatitic Province Gahnite electron probe microanalyses from three pegmatites (Mirador, Capoeira and Quintos) of the Borborema PegmatiticProvince in northeastern Brazil allowed to determine molar compositions ranging from 86.22 to 95.41 mol%gahnite (ZnAl2O4), 1.51 to 6.62 mol% hercynite (Fe2+Al2O4), 0.11 to 5.89 mol% spinel (MgAl2O4), 1.48 to 2.74mol% galaxite (MnAl2O4), and Zn/FeTotal atomic ratios ranging from 11.53 to 60.87. These data compared with gahnitecompositions from albite subtype pegmatites from Cap de Creus, Spain (Zn/FeTotal between 10 and 60) and fromthe source granite of the Separation Rapids pegmatite field, Ontario, Canada (Zn/FeTotal =3.5) indicate a high degreeof fractionation of the studied pegmatites. This interpretation agrees with conclusions based on compositional data oftourmaline (vacancy in X-site 0.42 to 0.49), white mica (K/Rb between 8 and 33), feldspar (K/Rb between 8 and 109),garnet (Mn/(Mn+Fe2+) between 0.93 and 0.97) and in Nb-Ta oxides (Mn/(Mn+Fe2+) >0.5) in the same pegmatites. 2007 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32779305 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.3 Vol.79 |
| title | Chemical composition of gahnite and degree of pegmatitic fractionation in the Borborema Pegmatitic Province, northeastern Brazil |
| topic | Multidisciplinaria (Ciencias Naturales y Exactas) rare gahnite mineral chemistry element granitic pegmatites Borborema Pegmatitic Province |
| url | https://www.redalyc.org/articulo.oa?id=32779305 |