Granite
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Granite is a coarse-grained intrusive igneous rock composed mostly of quartz, alkali feldspar, mica and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slow
Granite containing plagioclase feldspar, potassium feldspar, quartz, biotite, and/or amphibole
Granite with a moderate amount of plagioclase, alkali feldspar, and quartz
Granite with a composition of alkali feldspar and quartz
Granite in thin section, under cross-polarized light
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