Among the magmatic rocks, carbonatites are known to possess the highest concentration of rare earth elements (ΣREE = 72-15,515 ppm), and they have the best REE mineral resourses. Rare earth deposits in igneous rocks have been grouped into five distinct categories differing in the provenance and evolution of magma and in the rock types hosting mineralization, viz.: (i) carbonatites, (ii) peralkaline silica-undersaturated rocks, (iii) peralkaline granites and pegmatites, (iv) pegmatites associated with sub- to metaluminous granites, and (v) Fe oxide- phosphate deposits. Occurrence of REE minerals in rocks other than those mentioned above, especially mafic and ultramafic rocks is scantily documented; only recently, they were looked upon as hosts of REE-mineralization.
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