Keywords

An ultramafic igneous rock containing at least 35% olivine, with one or more of the following in the groundmass; monticellite, phlogopite, carbonate, serpentine, diopside.  No leucite is allowed in the definition of kimberlite (Woolley et al., 1966).  The name, proposed by Lewis in 1888, is for the Kimberley district, South Africa, where kimberlite is a host for diamonds.  Two types of kimberlite have long been distinguished.   Basaltic kimberlite or Type 1 kimberlite is much the more widespread, and constitutes the classic diatreme-filling diamond-bearing rocks of South Africa.   Micaceous kimberlite, also called lamprophyric kimberlite or Type 2 kimberlite, is apparently restricted to southern Africa, and differs so strongly from Type 1 that some authorities do not consider it a variety of kimberlite (Mitchell, 1986).

Mitchell, R.H. (1986): Kimberlites: Mineralogy, Geochemistry, and Petrology.  Plenum Press, New York, 441 p.

Geological keywords, such as “granite”, “lake”.  The definitions are generally taken from the AGI Glossary of Geology.  Keywords with a geographic context (e.g. Cape Smith Fold Belt, Selwyn Basin, Grenville Province) are assigned to a separate category.