monzonite

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monzonite (syenodiorite) A coarse-grained igneous rock consisting of essential plagioclase feldspar (see ESSENTIAL MINERAL), orthoclase feldspar, pyroxene, and biotite. The plagioclase feldspar and orthoclase feldspar are in roughly equal proportions, the plagioclase forming between 40% and 60% of the total feldspar.