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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>Jian-Wei Li</dc:contributor>
  <dc:contributor>Robert O. Rye</dc:contributor>
  <dc:contributor>William H. Benzel</dc:contributor>
  <dc:contributor>H.A. Lowers</dc:contributor>
  <dc:contributor>Ming-Zhong He</dc:contributor>
  <dc:creator>Lei Chen</dc:creator>
  <dc:date>2013</dc:date>
  <dc:description>Supergene jarosite-group minerals are widespread in weathering profiles overlying Pb-Zn sulfide ores at Xitieshan, northern Tibetan Plateau, China. They consist predominantly of K-deficient natrojarosite, with lesser amounts of K-rich natrojarosite and plumbojarosite. Electron microprobe (EMP) analyses, scanning electron microcopy (SEM) investigation, and X-ray mapping reveal that the jarosite-group minerals are characterized by spectacular oscillatory zoning composed of alternating growth bands of K-deficient and K-bearing natrojarosite (K&lt;sub&gt;2&lt;/sub&gt;O &gt;1 wt.%). Plumbojarosite, whenever present, occurs as an overgrowth in the outermost bands, and its composition can be best represented by K&lt;sub&gt;0.29&lt;/sub&gt;Na&lt;sub&gt;0.19&lt;/sub&gt;Pb&lt;sub&gt;0.31&lt;/sub&gt;Fe&lt;sub&gt;2.66&lt;/sub&gt;Al&lt;sub&gt;0.22&lt;/sub&gt;(SO&lt;sub&gt;4&lt;/sub&gt;)&lt;sub&gt;1.65&lt;/sub&gt;(PO&lt;sub&gt;4&lt;/sub&gt;)&lt;sub&gt;0.31&lt;/sub&gt;(AsO&lt;sub&gt;4&lt;/sub&gt;)&lt;sub&gt;0.04&lt;/sub&gt;(OH)&lt;sub&gt;7.37&lt;/sub&gt;. The substitution of monovalent for divalent cations at the A site of plumbojarosite is charge balanced by the substitution of five-valent for six-valent anions in XO,&lt;sub&gt;4/sub&gt; at the X site. Thermogravimetric analysis (TGA) of representative samples reveal mass losses of 11.46 wt.% at 446.6 &amp;deg;C and 21.42 wt.% at 683.4 &amp;deg;C due to dehydroxylation and desulfidation, respectively. TGA data also indicate that the natrojarosite structure collapses at 446.6 &amp;deg;C, resulting in the formation of NaFe(SO&lt;sub&gt;4&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt; and minor hematite. The decomposition products of NaFe(SO&lt;sub&gt;4&lt;/sub&gt;)&lt;sub&lt;2&lt;/sub&gt; are hematite and Na,&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt;. Powder X-ray diffraction (XRD) analyses show that the jarosite-group minerals have mean unit-cell parameters of &lt;i&gt;a&lt;/i&gt;=7.315 &amp;auml; and &lt;i&gt;c&lt;/i&gt;=016.598 &amp;auml;. XRD and EMP data support the view that substitutions of Na for K in the A site and full Fe occupancy in the B site can considerably decrease the unit-cell parameter &lt;i&gt;c&lt;/i&gt;, but only slightly increase &lt;i&gt;a&lt;/i&gt;. The results from this study suggest that the observed oscillatory zoning of jarosite-group minerals at Xitieshan resulted mainly from substitutions of K for Na at the A site and P for S at the X site.</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1007/s00710-012-0258-y</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Springer</dc:publisher>
  <dc:title>Mineralogical, chemical, and crystallographic properties of supergene jarosite-group minerals from the Xitieshan Pb-Zn sulfide deposit, northern Tibetan Plateau, China</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>