carbonatica

Carbonatica is a term used in several languages for a class of carbonate-rich igneous rocks, commonly known in English as carbonatites. These rocks are distinctive for their predominance of carbonate minerals, especially calcite and dolomite, and for their unusually low silica content. They may contain small amounts of silicate minerals such as feldspars and ferromagnesian minerals, but the carbonate phase dominates the texture and overall composition.

Formation and setting: carbonatites crystallize from mantle-derived, silica-undersaturated alkaline magmas. They typically form at shallow crustal levels and are frequently emplaced as intrusive bodies, pipes, or ring complexes within continental settings. Their genesis is linked to mantle metasomatism and extensional tectonics, and they are often associated with other alkaline rock types such as nephelinite and phoscorite–carbonatite complexes.

Mineralogy and textures: the defining feature is a carbonate-dominated mineralogy, with calcite or dolomite forming the bulk of the rock. Accessory minerals may include magnetite, apatite, pyrochlore, fluorite, alkali feldspars, and rare earth element-bearing minerals. Textures range from massive to fine-grained, with possible cumulate or vein-filling features in larger complexes. Carbonatites may host pockets of silica-rich phases at the margins or within associated intrusive units.

Economic significance: carbonatites are notable for concentrating economically important elements, particularly rare earth elements (REEs), niobium, tantalum, fluorite, and phosphate minerals. Some deposits are major sources of REEs and Nb–Ta and have been the focus of mining and exploration.

Distinctions: carbonatics should not be confused with sedimentary carbonate rocks like limestone and dolostone, or with metamorphic carbonate rocks such as marble.