<?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:creator>James Bachelder Cathcart</dc:creator>
  <dc:date>1974</dc:date>
  <dc:description>&lt;p&gt;Discontinuous lenticular masses of phosphate rock are present near or at the contact between the green mudstone and the underlying red and yellow clay-stone units of the Serra da Saudade Member of the Rio Paraopeba Formation of the Bambui Group of late Precambrian to early Paleozoic age. The lenses are as much as 8 meters thick and 400 meters long. The phosphate rock is folded and faulted and is overlain by flat-lying rocks of Cretaceous age.&lt;/p&gt;&lt;p&gt;The phosphate mineral is a carbonate fluorapatite, but only a small amount of C0&lt;sub&gt;2&lt;/sub&gt; substitutes for PO&lt;sub&gt;4&lt;/sub&gt;. Crystalline apatite in veinlets is clearly younger than the groundmass apatite, and contains almost no C0&lt;sub&gt;2&lt;/sub&gt;. Surficial parts of the phosphate lenses have been altered to a rock characterized by aluminum phosphate.&lt;/p&gt;&lt;p&gt;Samples of the green mudstone contain muscovite-illite, quartz, and what is believed to be glauconite. Samples collected adjacent to the phosphate lenses also contain veinlets of apatite or wavellite.&lt;/p&gt;&lt;p&gt;Chemical analyses of the phosphate rock show that it contains from 16 to 35 percent P&lt;sub&gt;2&lt;/sub&gt;0&lt;sub&gt;5&lt;/sub&gt;, and all samples are deficient in Ca0 relative to P&lt;sub&gt;2&lt;/sub&gt;0&lt;sub&gt;5&lt;/sub&gt;, indicating that some of the phosphate in all samples is combined with alumina. The samples contain as much as 8 percent K&lt;sub&gt;2&lt;/sub&gt;0 in the minerals muscovite-illite or glauconite.&lt;/p&gt;&lt;p&gt;All the samples collected are extremely fine grained. The rocks are laminated and show the effects of slight deformation; for example, crumpled bedding, offset veinlets, and slight development of muscovite along bedding planes.&lt;/p&gt;&lt;p&gt;The phosphate probably is not economically important on the world market, but possibly could be used locally for direct application depending on agricultural lands.&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.3133/ofr74219</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>U.S. Geological Survey</dc:publisher>
  <dc:title>Geology and mineralogy of phosphate rock in the Bambui group near Cedro do Abaete and vicinity, Minas Gerais, Brazil</dc:title>
  <dc:type>reports</dc:type>
</oai_dc:dc>