What is foidolite in geology ?

Foidolite : definition

A foidolite is an undersaturated, magmatic, plutonic or volcanic rock (also called foidite or feldspathoidite) in which feldspathoids make up more than 60% of white minerals. Leucitites, nephelinites, ijolites and missourites are examples of foidolites.
Streckeisen diagrams (or QAPF diagrams) - Classification of plutonic and volcanic rocks