Quartz monzonite or
adamellite is an
intrusive,
felsic,
igneous rock that has an approximately equal proportion of
orthoclase and
plagioclase feldspars. It is typically a light colored
phaneritic (coarse-grained) to
porphyritic granitic rock. The plagioclase is typically intermediate to sodic in composition, andesine to oligoclase.
Quartz is present in significant amounts.
Biotite and/or
hornblende constitute the dark minerals. Because of its coloring, it is often confused with
granite, but whereas granite contains more than 20% quartz, quartz monzonite is only 5–20% quartz. Rock with less than five percent quartz is classified as
monzonite. A rock with more alkali feldspar is a
syenite whereas one with more plagioclase is a
quartz diorite. The fine grained
volcanic rock equivalent of quartz monzonite is
quartz latite.