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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>John F. Slack</dc:contributor>
  <dc:contributor>Martin R. Palmer</dc:contributor>
  <dc:creator>Shao-Yong Jiang</dc:creator>
  <dc:date>1997</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;Alkali-deficient tourmalines are found in albitized rocks from the hanging-wall of the Sullivan Pb-Zn-Ag deposit (British Columbia, Canada). They approximate the Mg-equivalent of foitite with an idealized formula □(Mg&lt;/span&gt;&lt;span class="sub"&gt;2&lt;/span&gt;&lt;span&gt;Al)Al&lt;/span&gt;&lt;span class="sub"&gt;6&lt;/span&gt;&lt;span&gt;Si&lt;/span&gt;&lt;span class="sub"&gt;6&lt;/span&gt;&lt;span&gt;O&lt;/span&gt;&lt;span class="sub"&gt;18&lt;/span&gt;&lt;span&gt;(BO&lt;/span&gt;&lt;span class="sub"&gt;3&lt;/span&gt;&lt;span&gt;)&lt;/span&gt;&lt;span class="sub"&gt;3&lt;/span&gt;&lt;span&gt;(OH)&lt;/span&gt;&lt;span class="sub"&gt;4&lt;/span&gt;&lt;span&gt;. Major chemical substitutions in the tourmalines are the alkali-defect type [Na*&lt;/span&gt;&lt;span class="sub"&gt;(x)&lt;/span&gt;&lt;span&gt;&amp;nbsp;+ Mg*&lt;/span&gt;&lt;span class="sub"&gt;(Y)&lt;/span&gt;&lt;span&gt;&amp;nbsp;= □&lt;/span&gt;&lt;span class="sub"&gt;(x)&lt;/span&gt;&lt;span&gt;&amp;nbsp;+ Al&lt;/span&gt;&lt;span class="sub"&gt;(Y)&lt;/span&gt;&lt;span&gt;] and the uvite type [Na*&lt;/span&gt;&lt;span class="sub"&gt;(x)&lt;/span&gt;&lt;span&gt;&amp;nbsp;+ Al&lt;/span&gt;&lt;span class="sub"&gt;(Y)&lt;/span&gt;&lt;span&gt;&amp;nbsp;= Ca&lt;/span&gt;&lt;span class="sub"&gt;(x)&lt;/span&gt;&lt;span&gt;&amp;nbsp;+ Mg*&lt;/span&gt;&lt;span class="sub"&gt;(Y)&lt;/span&gt;&lt;span&gt;], where Na* = Na + K, Mg* = Mg + Fe + Mn. The occurrence of these alkali-deficient tourmalines reflects a unique geochemical environment that is either alkali-depleted overall or one in which the alkalis preferentially partitioned into coexisting minerals (e.g. albite).&lt;/span&gt;&lt;/p&gt;&lt;p&gt;Some of the alkali-deficient tourmalines have unusually high Mn contents (up to 1.5 wt.% MnO) compared to other Sullivan tourmalines. Manganese has a strong preference for incorporation into coexisting garnet and carbonate at Sullivan, thus many tourmalines in Mn-rich rocks are poor in Mn (&amp;lt;0.2 wt.% MnO). It appears that the dominant controls over the occurrence of Mn-rich tourmalines at Sullivan are the local availability of Mn and the lack of other coexisting minerals that may preferentially incorporate Mn into their structures. &lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1180/minmag.1997.061.409.08</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Cambridge University Press</dc:publisher>
  <dc:title>Alkali-deficient tourmaline from the Sullivan Pb-Zn-Ag deposit, British Columbia</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>