Foid monzosyenite is a rare variety of syenite that contains abundant feldspathoids and alkali feldspar, minor plagioclase, mafic minerals (biotite, hornblende, pyroxene, sodic pyroxene/amphibole), and various accessory minerals. Foid monzosyenites are characterized by a higher content of plagioclase with respect to foid syenites (10 to 50% plagioclase of all feldspar) and feldspathoids constitute 10 to 60% of the felsic minerals present in the rock. These rocks most commonly contain the feldspathoid nepheline and, less commonly, other feldspathoids. In general, the name of the most abundant feldspathoid present should appear in the name of the rock (e.g. nepheline monzosyenite). Miaskite (named after Miask, in the Urals of Russia) is a special name for a variety of nepheline monzosyenite containing biotite, plagioclase var oligoclase and perthitic alkali feldspar. The modal content of mafic minerals (color index) of foid monzosyenites typically ranges between 15 and 45%.