Wiktionary
n. (context geology English) Any of several volcanic rocks having a high potassium content
Wikipedia
Lamproites are ultrapotassic mantle-derived volcanic and subvolcanic rocks. They have low CaO, AlO, NaO, high KO/AlO, a relatively high MgO content and extreme enrichment in incompatible elements.
Lamproites are geographically widespread yet are volumetrically insignificant. Unlike kimberlites which are found exclusively in Archaean cratons, lamproites are found in terrains of varying age, ranging from Archaean in Western Australia, to Palaeozoic and Mesozoic in southern Spain. They also vary widely in age, from Proterozoic to Pleistocene, the youngest known example being 56,000 ± 5,000 years old.
Lamproite volcanology is varied, with both diatreme styles and cinder cone or cone edifices known.