<?xml version='1.0' encoding='utf-8'?>
<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>C. W. Chesterman</dc:contributor>
  <dc:contributor>B.W. Troxel</dc:contributor>
  <dc:creator>D. F. Hewett</dc:creator>
  <dc:date>1961</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;Recent studies of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;manganese&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;deposits&lt;/span&gt;&lt;span&gt;&amp;nbsp;and mineral specimens&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;the Sierran belt of sedimentary rocks as well as&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;the Klamath Mountains to the north and&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;the Rand Mountains to the south, have shown the presence of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;tephroite&lt;/span&gt;&lt;span&gt;, the orthosilicate of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;manganese&lt;/span&gt;&lt;span&gt;&amp;nbsp;(Mn2Si04), at numerous localities. Earlier studies of these&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;deposits&lt;/span&gt;&lt;span&gt;&amp;nbsp;have shown that the original layered&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;deposits&lt;/span&gt;&lt;span&gt;&amp;nbsp;of carbonate and hydrous silicates of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;manganese&lt;/span&gt;&lt;span&gt;&amp;nbsp;have been widely altered by metamorphism to spessartite (Mn3Al2-(SiO.),), rhodonite (MnSi03), and piedmontite (Ca2(Al,Mn"',Fe"')3-Si3Oi2(OH)). Recent work shows that layered&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;manganese&lt;/span&gt;&lt;span&gt;&amp;nbsp;oxides also were present&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;the original sedimentary rocks. It shows also, that&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;tephroite&lt;/span&gt;&lt;span&gt;&amp;nbsp;has formed widely&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;the original assemblage of carbonate, silicate, and oxide of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;manganese&lt;/span&gt;&lt;span&gt;;&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;several localities, a little alleghanyite (2Mn2-S1O4 - Mn(OH,F)2) has been formed. Rhodonite, spessartite, and piedmontite uniformly follow the&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;tephroite&lt;/span&gt;&lt;span&gt;;&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;places, bementite and neotocite are present.&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;In&lt;/span&gt;&lt;span&gt;&amp;nbsp;one&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;deposit&lt;/span&gt;&lt;span&gt;&amp;nbsp;a little pyroxmangite ( (Mn,Fe,Ca)Si03) has been noted and&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;another, some crystals that are probably pyrophanite (MnTi03), not yet recorded&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;the United States. By contrast, the restudy of large collections of material from&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;deposits&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;sedimentary rocks of the Franciscan formation&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;the Coast Ranges indicates the&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;tephroite&lt;/span&gt;&lt;span&gt;&amp;nbsp;is very uncommon; it has been recognized with assurance at only one locality-Alum Rock Park, Santa Clara County.&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;In&lt;/span&gt;&lt;span&gt;&amp;nbsp;the Coast Ranges, rhodonite and spessartite, the high&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;manganese&lt;/span&gt;&lt;span&gt;&amp;nbsp;garnet, are very uncommon. The assemblages of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;manganese&lt;/span&gt;&lt;span&gt;&amp;nbsp;silicates indicate that the layered&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;deposits&lt;/span&gt;&lt;span&gt;&amp;nbsp;of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;manganese&lt;/span&gt;&lt;span&gt;&amp;nbsp;minerals&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;the Sierra belt have been metamorphosed to a higher degree than those of the Coast Ranges. This review also shows the presence of axinite, the boro-silicate of aluminum, calcium, and&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;manganese&lt;/span&gt;&lt;span&gt;,&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;three&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;deposits&lt;/span&gt;&lt;span&gt;.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.2113/GSECONGEO.56.1.39</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Society of Economic Geologists</dc:publisher>
  <dc:title>Tephroite in California manganese deposits</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>