File:Kimberlite (Jericho Kimberlite, Middle Jurassic, ~172 Ma; Echo Bay Mine, Contwoyto Lake, Slave Province, Nunavut, Canadian Arctic) (14843264863).jpg

Jericho Kimberlite from the Jurassic of northwestern Canada (8.4 cm across).

Kimberlites and lamproites have tremendous economic importance because they are host rocks for gem-grade and industrial-grade diamonds. Kimberlites & lamproites are unusual igneous bodies having overall pipe-shaped geometries. Their mode of formation is only moderately understood because they have not been observed forming. Kimberlites & lamproites are known from scattered localities throughout the world - only some are significantly diamondiferous. Classic localities for diamonds are India and Brazil. Africa was also discovered to have many kimberlites and is world-famous for producing large numbers of diamonds. Other notable diamondiferous kimberlite-lamproite occurrences include Russia, China, northwestern Australia, and northwestern Canada.

Kimberlites are named for the town of Kimberley, South Africa. Several kimberlite pipes occur in the Kimberley area. Kimberlites have a gently tapering-downward, pipe-shaped cross-section. Lamproites have a cross-section more closely resembling that of a martini glass.

The rock shown above is from the diamondiferous Jericho Kimberlite, a cluster of 3 pipes discovered in the mid-1990s at Echo Bay in northwestern Canada. The pipe complex intruded during the mid-Middle Jurassic, at about 172 million years. The rock has a bluish-gray color & is full of interesting fragments, including reddish garnets and nice phlogopite flakes.