Utilizing alteration (fenite) surrounding carbonatite intrusions as a REE and Nb exploration indicator

Carbonatites are the world's primary source of rare earth elements (REE) and niobium (Nb). China currently monopolizes the market, producing >95% of the world's supply. In order to meet UK government greenhouse gas emission targets, a reliable and sustainable supply of REE and Nb must be established in order to produce green technologies such as electric cars and wind turbines. The location of many carbonatite complexes are currently known, however the economic potential of few have been explored. Detailed petrological and geochemical analysis of fenite (metasomatic alteration surrounding carbonatite systems) has provided criteria to determine whether the source intrusion is enriched in these critical metals. Fenite micro-mineral assemblages enriched in REE and Nb indicate that the source of the fenitizing fluids is similarly enriched in these metals. Fenite apatite morphology and luminescence can also be used to indicate REE-enrichment in the source intrusion, showing systematic increases in Na, Sr and total REE (TREE) concentration from core to rim or homogenous late-stage crystals. These fenite alteration patterns are vertically and horizontally extensive, and can therefore be seen at a variety of erosion levels, providing a means of determining the economic potential of a system before undertaking expensive drilling campaigns.