CARBONATITE

A Carbonatite is an igneous rock that may be either intrusive or extrusive and is composed of at least 20% carbonate minerals.

Note that the metamorphic rock marble consists primarily of the carbonate mineral calcite. Carbonatites typically have a higher percentage of other minerals including silicates.

The rock known as natrocarbonatite primarily consists of two carbonate minerals, nyerereite and gregoryite.