What is a lamproite in geology ?

Lamproite : definition

Streckeisen diagrams (or QAPF diagrams) - Classification of plutonic and volcanic rocks
Lamproite is an effusive and alkaline volcanic rock, very rich in potassium, of varied mineralogy which, depending on the variety, may contain sanidine, leucite, forsterite, diopside, phlogopite, etc... which has given rise to multiple local names. The glass content can reach considerable proportions.

Although sometimes still considered as tephrites or phonolites, which are then qualified as lamproitic, lamproites are mainly classified in volcanic lamprophyric rocks.