Karbonit

Karbonit is a term used in several languages to denote the carbonate-rich igneous rock group known in English as carbonatite. The exact usage can vary by region and language, but it generally refers to rocks that are dominated by carbonate minerals rather than silicate minerals. In many sources, karbonit or karbonatit is simply a local form of the same rock type.

Chemically, carbonatites are largely carbonate minerals such as calcite and dolomite and are typically silica-undersaturated. They may contain minor silicate minerals like nepheline or alkali feldspars, and often host accessory minerals such as magnetite, apatite, pyrochlore, zircon, and other minerals including rare-earth element minerals. The textures range from fine-grained to porphyritic, and the rocks can vary in color depending on mineralogy and alteration.

Geologic setting and formation descriptions emphasize that carbonatites are relatively rare igneous rocks that can form as intrusions or lava flows in continental rift zones and other tectonically active regions. They are thought to originate from mantle-derived alkaline magmas, or from melting of carbonate-bearing mantle or crustal material, sometimes involving extensive fractional crystallization and metasomatic alteration around the intrusion (fenitization).

Economic significance is notable because carbonatites host valuable minerals and elements. They are important sources of niobium (columbite-group minerals), phosphate minerals, and various rare-earth elements in some deposits. Carbonatite complexes are studied for their unusual petrology and ore-bearing potential, with notable occurrences in diverse parts of the world.