| Summary: | The layered kakortokites in the southern part of the Ilímaussaq Intrusion are of great economic interest due to their high concentrations of REE, Zr, Nb and Ta. The prospective metals are largely contained in eudialyte, a complex sodium‐zirconosilicate and one of the major cumulus phases. Eudialyte‐group minerals are easily extracted from the host rock through magnetic separation, and contain 12 wt% ZrO2, 2 % TRE2O3 and 1% Nb2O5 on average. Petrographic investigations show that a large fraction of eudialyte at Ilímaussaq is replaced by complex aggregates of secondary minerals as a result of interaction with late‐stage magmatic, presumably Na‐ and F‐ rich aqueous fluids. The alteration effectively fractionates the major components into the secondary minerals, producing separate Zr‐, Nb and REE‐ phases, leading to an increased complexity of the mineralisation and potential ore recovery.
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