English

Noun

kimberlite pipe ‎(plural kimberlite pipes)

1. (geology) A natural volcanic pipe composed of kimberlite, by which geological matter from deep within the Earth can be projected violently to the surface.
   • 2003, Bill Bryson, A Short History of Nearly Everything, BCA, p. 190:

     Because they come up from such depths – up to 200 kilometres down – kimberlite pipes bring up all kinds of things not normally found on or near the surface: a rock called peridotite, crystals of olivine and – just occasionally, in about one pipe in a hundred – diamonds.