Rock Classification Scheme (BGS).pdf - The Water, Sanitation and ...
Rock Classification Scheme (BGS).pdf - The Water, Sanitation and ...
Rock Classification Scheme (BGS).pdf - The Water, Sanitation and ...
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QLevel 890906060alkali-feldspar-rhyoliterhyolitedaciteAlatitefoid-bearinglatitequartz-alkalifeldspar-trachytealkalifeldspar-trachytefoid-bearingalkali-feldspartrachyte6020phonolite10 35 65 901060quartzlatitequartztrachytetrachytefoid-bearingtrachytetephriticphonolite50basalt<strong>and</strong>esite609020105Pbasanite (olivine > 10%)tephrite (olivine < 10%)phonolitic-basanite(olivine > 10%)phonolitic-tephrite(olivine < 10%)phonolitic-foidite9090tephritic-foidite (olivine < 10%)basanitic-foidite (olivine > 10%)M > 90ultramafititeFfoiditeFigure 19 <strong>Classification</strong> <strong>and</strong> nomenclature of fine-grained crystalline rocksaccording to their modal mineral contents using the QAPF diagram (based onStreckeisen, 1978). Q = quartz, A = alkali feldspar, P = plagioclase, <strong>and</strong> F =feldspathoid.Colourindex35vol %40wt %basaltleucobasaltmela-<strong>and</strong>esite<strong>and</strong>esiteFigure 21 Division of rocks fromQAPF fields 9 <strong>and</strong> 10 into basalt<strong>and</strong> <strong>and</strong>esite, using colour index<strong>and</strong> SiO 2 content (afterStreckeisen, 1978).52SiO 2 wt %43
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