There is intensified interest in the petrogenesis of carbonatites and related rocks, owing to their potential to contain economic deposits of critical raw materials, such as the rare-earth elements, but also because of their importance in the cycling of deep carbon. Current nomenclature and classification schemes for carbonatites are inadequate in the light of new petrogenetic models, which recognize important roles for magmatic carbonates and CO 2 -rich fluids in the formation of most rock types comprising alkaline igneous complexes. In this contribution, we briefly review existing terminology and offer a revised classification of carbonatites and related carbothermalites. The most significant modification to the existing IUGS classification scheme is that carbonatites are now defined as igneous rocks containing ≥ 25 vol% primary magmatic carbonate minerals. Implementation of the new threshold greatly reduces the need for the term ‘silicocarbonatite’, reinforcing the argument that the diverse origin of silica in both high- and low-temperature carbonatite magmatic systems is inappropriate for a defining role in carbonatite and carbothermalite terminology. A further refinement is the integration of ‘carbothermalites’ into the IUGS system of igneous rocks, emphasising the importance of CO 2 –H 2 O-dominated fluids and brines during emplacement of carbonatite-forming magmas in the Earth's crust. We highlight that carbonatite and carbothermalite rock terminology must be based primarily on observable modal mineralogy and other descriptive attributes, where the use of geochemical information should be limited and only applied under special circumstances. It is recommended to discontinue from IUGS carbonatite terminology the uninformative type locality names sövite, alvikite and beforsite, in a continued effort to simplify the classification of igneous rocks.
Tappe et al. (Fri,) studied this question.