|syenite (sī'ə-nīt') Pronunciation Key
A light-colored, coarse-grained igneous rock consisting primarily of alkali feldspar together with some mafic minerals, especially hornblende. Unlike most igneous rocks, syenite has little or no quartz. It is believed to form from the cooling of magma that forms at very high temperatures and at great depths. It is the coarse-grained equivalent of trachyte.