<?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>E.Y. Campbell</dc:contributor>
  <dc:creator>L. Paul Greenland</dc:creator>
  <dc:date>1974</dc:date>
  <dc:description>&lt;p&gt;After acid decomposition and evaporation to volatilize silica, samples containing 0.5 6 &lt;i&gt;μ&lt;/i&gt;g Nb are fused with pyrosulfate and dissolved in hydrochloric acid tartaric acid. Niobium is separated by thiocyanate extraction with amyl alcohol and back-extracting from the organic solvent with dilute hydrofluoric acid. Niobium is reacted with 4-(2-pyridylazo)-resorcinol to obtain a colored species. Analytical error, estimated from replicate analyses of eight U.S. Geological Survey standard rocks, ranges from 2.9 to 6.4 percent at the 1 27 &lt;i&gt;μ&lt;/i&gt;g/g Nb level. &lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:language>en</dc:language>
  <dc:publisher>U.S. Geological Survey</dc:publisher>
  <dc:title>Spectrophotometric determination of niobium in rocks</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>