<?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.G. Engel</dc:contributor>
  <dc:creator>A.E.J. Engel</dc:creator>
  <dc:date>1962</dc:date>
  <dc:description>&lt;p&gt;&lt;span class="ScopusTermHighlight"&gt;Hornblendes&lt;/span&gt;&lt;span&gt;&amp;nbsp;in&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;amphibolite&lt;/span&gt;&lt;span&gt;&amp;nbsp;interlayers in the paragneiss of the&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;northwest&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;Adirondack&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;Mountains&lt;/span&gt;&lt;span&gt;&amp;nbsp;undergo systematic changes in color, composition, and density during&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;progressive&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;metamorphism&lt;/span&gt;&lt;span&gt;&amp;nbsp;from almandine-&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;amphibolite&lt;/span&gt;&lt;span&gt;&amp;nbsp;to&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;hornblende&lt;/span&gt;&lt;span&gt;-granulite facies. In contrast, indices of refraction of the&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;hornblendes&lt;/span&gt;&lt;span&gt;&amp;nbsp;remain about constant. In the almandine-&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;amphibolite&lt;/span&gt;&lt;span&gt;&amp;nbsp;facies the&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;amphibolite&lt;/span&gt;&lt;span&gt;&amp;nbsp;layers have the bulk composition of a saturated basalt and consist of bluish-green&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;hornblende&lt;/span&gt;&lt;span&gt;, andesine, and quartz. As these layers are traced into the&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;hornblende&lt;/span&gt;&lt;span&gt;-granulite facies, their composition undergoes a&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;progressive&lt;/span&gt;&lt;span&gt;&amp;nbsp;change to that of an olivine basalt with brownish-green&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;hornblende&lt;/span&gt;&lt;span&gt;, clinopyroxene and orthopyroxene, and calcic andesine as major constituents. Compositional changes in the&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;hornblendes&lt;/span&gt;&lt;span&gt;&amp;nbsp;with increasing grade of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;metamorphism&lt;/span&gt;&lt;span&gt;&amp;nbsp;include increases in Ti, Na, K, Cr, V, and Sc. Decreases occur in the amounts of Mn, Zn, OH + F + Cl, and in the ratios Fe&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;O&lt;/span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;span&gt;/FeO and Fe/Mg. Density of the&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;hornblendes&lt;/span&gt;&lt;span&gt;&amp;nbsp;increases from 3.260 to 3.278 with the increasing grade of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;metamorphism&lt;/span&gt;&lt;span&gt;. These changes in the&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;hornblendes&lt;/span&gt;&lt;span&gt;&amp;nbsp;with increasing T and P, although well denned, are less pronounced than those measured in biotites and garnets of the enclosing paragneiss. Large variations in the physical and chemical properties of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;hornblendes&lt;/span&gt;&lt;span&gt;&amp;nbsp;in metamafic rocks reconstituted above the epidote-&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;amphibolite&lt;/span&gt;&lt;span&gt;&amp;nbsp;facies appear to be induced principally by critical changes in the bulk composition of the total rock, and not by the regional gradients in T, P, or by changes in kind, or composition, of the coexisting minerals.&amp;nbsp;&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1130/0016-7606(1962)73[1499:HFDPMO]2.0.CO;2</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Geological Society of America</dc:publisher>
  <dc:title>Hornblendes formed during progressive metamorphism of amphibolites, northwest Adirondack Mountains, New York</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>