A group of plutonic rocks containing alkali feldspar (usually orthoclase, microcline, or perthite), a small amount of plagioclase (less than in "monzonite"), one or more mafic minerals (esp. hornblende), and quartz, if present, only as an accessory; also, any rock in that group; the intrusive equivalent of "trachyte." With an increase in the quartz content, syenite grades into "granite." Its name is derived from Syene, Egypt. A.G. Werner in 1788 applied the name in its present meaning; the Egyptian rock is a granite containing much quartz.