What is an ijolite in geology ?

Ijolite : definition

Ijolite is an exceptional, grainy, light-colored, hyper-alkaline magmatic rock formed mainly of nepheline (50 to 70%) and clinopyroxene (30 to 40% of aegyrinic augite or aegyrine); with additional quantities of apatite, calcite, titanite and garnet (melanite), which are found in alkaline complexes with carbonatites. Its name comes from Ijola, a town in Finland. It belongs to the group of foidolites.
Streckeisen diagrams (or QAPF diagrams) - Classification of plutonic and volcanic rocks