Kimberlite, basaltic (14 cm x 6.5 cm), Kimberley, South Africa.
- Stuart Humphreys
- © Australian Museum
Kimberlite is a volcanic or subvolcanic rock composed largely of serpentinised olivine, with variable amounts of phlogopite mica, orthopyroxene, clinopyroxene, carbonate and chromite. Characteristic accessory minerals include pyrope garnet, rutile, monticellite and perovskite and, in some cases, diamonds.