Foid-bearing Syenite Hand Sample
Foid-bearing Syenite Thin Section

Foid-Bearing Syenite

IUGS Definition ( QAPF Chart )

Foid-Bearing Syenite: “A collective term for syenites containing small amounts of feldspathoids (less than 10% of the felsic minerals).”
Photos
Typical Minerals
  • alkali feldspar: perthitic orthoclase and microcline
  • plagioclase feldspar
  • feldspathoids
  • pyroxene: augite, aegerine, hypersthene
  • biotite
  • accessory minerals: zircon, apatite, sphene, magnetite, and ilmenite