Syenites are divided into three main kinds, according to which dark, ferromagnesian (iron and magnesium) mineral predominates augite, hornblende or biotite mica. The Larvik area of southern Norway is famous for its beautiful rainbow-sheened red or grey augite syenite called larvikite or 'blue pearl granite', which are often used for pillars and facades. Similar rocks are found in the Sawtooth Mountains of Texas.