Monzonite
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Monzonite is an igneous intrusive rock, formed by slow cooling of underground magma that has a moderate silica content and is enriched in alkali metal oxides. Monzonite is composed mostly of plagiocla
Monzonite specimen from Rock Library (NASA JPL)
Photomicrograph of thin section of monzonite (in plane polarised light)
The Notch Peak monzonite intrusion in Utah inter-fingers (partly as a dike) with highly metamorphosed Cambrian carbonate host rocks
Syenite
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Syenite is a coarse-grained intrusive igneous rock with a general composition similar to that of granite, but deficient in quartz, which, if present at all, occurs in relatively small concentrations.
Syenite from Corsica
Leucocratic variety of nepheline syenite from Sweden (särnaite)
Boulders of syenite near Concord, North Carolina, c. 1910