Syenite

Syenite, a rock composed essentially of orthoclase and hornblende. It is granitoid and wholly crystalline—i.e. it contains no non-differentiated mineral matter. Quartz is sometimes sparingly present, and other accessory minerals may occur, such as oligoclase, sphene, zircon, apatite, ilmenite, &c. Elœolite-syenite is characterised by the presence of elœolite—an altered variety of nepheline. Syenite is an igneous rock of deep-seated origin, occurring in the form of bosses and veins. It is not known in the British Islands, but is met with in various countries in Europe and in America.