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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>M. Darby Dyar</dc:contributor>
  <dc:contributor>Howard M. May</dc:contributor>
  <dc:contributor>Owen P. Bricker</dc:contributor>
  <dc:contributor>James G. Acker</dc:contributor>
  <dc:creator>Joseph R. Smyth</dc:creator>
  <dc:date>1997</dc:date>
  <dc:description>&lt;p&gt;The crystal structure of a natural, ordered &lt;i&gt;IIb-4&lt;/i&gt; triclinic clinochlore has been refined in space group &lt;i&gt;C&lt;/i&gt;1&amp;macr; from 4282 unique X-ray intensity measurements of which 3833 are greater than 3 times the statistical counting error (3&amp;sigma;). Unit cell parameters are &lt;i&gt;a&lt;/i&gt; = 5.3262(6) Å; &lt;i&gt;b&lt;/i&gt; = 9.226(1) Å; &lt;i&gt;c&lt;/i&gt; = 14.334(3) Å; &amp;alpha; = 90.56(2)&amp;deg;; &amp;beta; = 97.47(2)&amp;deg;; and &amp;gamma; = 89.979(9)&amp;deg;, which represents the greatest deviation from monoclinic symmetry yet recorded for a triclinic chlorite. The final weighted &lt;i&gt;R&lt;/i&gt; is 0.059 for reflections with &lt;i&gt;I&lt;/i&gt; &amp;gt; 3&amp;sigma; and 0.064 for all reflections. The chemical formula is (Mg&lt;sub&gt;0.966&lt;/sub&gt;Fe&lt;sub&gt;0.034&lt;/sub&gt;)&lt;sup&gt;M1&lt;/sup&gt;(Mg&lt;sub&gt;0.962&lt;/sub&gt;Fe&lt;sub&gt;0.038&lt;/sub&gt;)&lt;sup&gt;M2&lt;/sup&gt;&lt;sub&gt;2&lt;/sub&gt;(Si&lt;sub&gt;2.96&lt;/sub&gt;Al&lt;sub&gt;1.04&lt;/sub&gt;)O&lt;sub&gt;10&lt;/sub&gt; (OH)&lt;sub&gt;2&lt;/sub&gt;(Mg&lt;sub&gt;0.996&lt;/sub&gt;Fe&lt;sub&gt;0.004&lt;/sub&gt;)&lt;sup&gt;M3&lt;/sup&gt;&lt;sub&gt;2&lt;/sub&gt;(Al&lt;sub&gt;0.841&lt;/sub&gt;Fe&lt;sup&gt;III&lt;/sup&gt;&lt;sub&gt;0.102&lt;/sub&gt;Cr&lt;sub&gt;0.004&lt;/sub&gt;Ti&lt;sub&gt;0.004&lt;/sub&gt;)&lt;sup&gt;M4&lt;/sup&gt;(OH)&lt;sub&gt;6&lt;/sub&gt;, which is consistent with electron microprobe (EMP), wet chemical analyses, M&amp;ouml;ssbauer spectroscopy and X-ray structure refinement. The high degree of ordering of the divalent versus trivalent octahedral cations in the interlayer is noteworthy, with Fe&lt;sup&gt;III&lt;/sup&gt; and Al in M4 and virtually no Fe in M3. In the 2:1 layer, M1 and M2 each contain similar amounts of Fe. The 2 tetrahedral sites have nearly identical mean oxygen distances and volumes, and thus show no evidence of long-range cation ordering.&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1346/CCMN.1997.0450406</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>The Clay Minerals Society</dc:publisher>
  <dc:title>Crystal structure refinement and Mössbauer spectroscopy of an ordered, triclinic clinochlore</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>