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<front>
<journal-meta>
<journal-id journal-id-type="archive">gsminmag</journal-id>
<journal-title>Mineralogical Magazine</journal-title>
<abbrev-journal-title abbrev-type="full">Mineralogical Magazine</abbrev-journal-title>
<issn pub-type="ppub">0026-461X</issn>
<publisher>
<publisher-name>Mineralogical Society</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.1180/minmag.1990.054.377.04</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Mineralogy and Petrology</subject>
</subj-group>
</article-categories>
<title-group>
<article-title>Transparent Bright Blue Cu-Bearing Tourmalines from Paraiba, Brazil</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname>Henn</surname>
<given-names>Ulrich</given-names>
</name></contrib>
<contrib contrib-type="author">
<name>
<surname>Bank</surname>
<given-names>Hermann</given-names>
</name></contrib>
<contrib contrib-type="author">
<name>
<surname>Bank</surname>
<given-names>Francisco Hermann</given-names>
</name></contrib>
<aff>German foundation for gemstone research, 6580 idar-oberstein, West Germany</aff></contrib-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname>von Platen</surname>
<given-names>Hilmar</given-names>
</name></contrib>
<contrib contrib-type="author">
<name>
<surname>Hofmeister</surname>
<given-names>Wolfgang</given-names>
</name></contrib>
<aff>Institute for Geosciences, University of Mainz, 6500 Mainz, West Germany</aff></contrib-group>
<pub-date pub-type="ppub">
<month>12</month>
<year>1990</year>
</pub-date>
<volume>54</volume>
<issue>377</issue>
<fpage>553</fpage>
<lpage>557</lpage>
<history>
<date date-type="received">
<day>4</day>
<month>1</month>
<year>1990</year>
</date>
<date date-type="rev-recd">
<day>10</day>
<month>4</month>
<year>1990</year>
</date></history>
<copyright-statement>Copyright &#x00A9; 1990, The Mineralogical Society</copyright-statement>
<copyright-year>1990</copyright-year>
<abstract>
<title>Abstract</title>
<p>Physical, crystal-chemical and absorption spectroscopical properties of blue tourmalines from a new occurrence in the State of Paraiba, Brazil, are described. Refractive indices, birefringence and specific gravity have been determined as <italic>n</italic><sub>e</sub> = 1.615&#x2013;1.620, <italic>n</italic><sub>o</sub> = 1.632&#x2013;1.640, <italic>&#x0394;n</italic>=&#x2212;0.017 to &#x2212;0.020 and 3.04&#x2013;3.07g/cm<sup>3</sup>. Microprobe analyses proved the samples to be elbaites, which are relatively Mn-rich and contain 2.1 wt. % CuO and 0.5 wt. % Bi<sub>2</sub>O<sub>3</sub>. Lattice constants are <italic>a</italic><sub>o</sub> = 15.854(4) and <italic>c</italic><sub>o</sub> = 7.102(1) &#x00C5;. The blue colour is due to pleochroic absorption bands of Cu<sup>2+</sup> and Mn<sup>3+</sup> with maxima at 700 and 520 nm respectively.</p></abstract>
<kwd-group>
<title>Keywords</title>
<kwd>copper</kwd>
<kwd>tourmaline</kwd>
<kwd>optical properties</kwd>
<kwd>chemical composition</kwd>
<kwd>crystal chemistry</kwd>
<kwd>absorption spectrum</kwd>
<kwd>Brazil</kwd>
</kwd-group>
</article-meta>
</front>
</article>
