Carbonatite-associated deposits include a variety of mineral deposits that occur both within and in close spatial association with carbonatites and related alkalic silicate rocks. Carbonatite-associated deposits are mined for rare- earth elements (REEs), niobium, iron, copper, apatite, Vermiculite, and fluorite. Byproducts include barite, zircon or baddeleyite, tantalum, uranium, and in the unique Palabora carbonatite of South Africa, platinum group elements, silver, and gold. In some complexes, calcite-rich carbonatite is mined as a source of lime to produce Portland cement, and in Europe, carbonatites have provided lime and iron for hundreds of years (Dawson, 1974; Deans, 1978; Bowden, 1985).

Carbonatites are igneous rocks which contain at least 50% modal carbonate minerals, mainly calcite, dolomite, ankerite, or sodium- and potassium-bearing carbonates (nyerereite and gregoryite). Other minerals commonly present include diopside (in early carbonatites – e.g., Bond zone, Oka, Quebec), sodic pyroxenes or amphiboles, phlo- gopite, apatite, and olivine. A large number of rare or exotic minerals also occur in carbonatites. Definitions of rock names used in describing carbonatite-associated deposits are provided in Table 24-1 and chemical formulae of some less common minerals are given in Table 24-2.

Carbonatites occur mainly as intrusive bodies of generally modest dimensions (as much as a few tens of square kilometres), and to a lesser extent as volcanic rocks (flows and derived deposits), which are associated with a wide range of alkali silicate rocks (syenites, nepheline syenites, nephelinites, ijolites, urtites, pyroxenites, etc.) (Bowden, 1985; Barker, 1989). Although carbonatites are invariably associated with alkalic rocks, the inverse relationship does not necessarily hold (Möller, 1989b). Carbonatites are generally surrounded by an aureole of metasomatically altered rocks called fenites produced by reaction of country rock with peralkaline fluids released from the carbonatite complex (Morogan, 1994).