Pyrochlore crystallization in carbonatites; the role of fluorine

摘要: Carbonatite complexes are the principal source of mineable niobium, mainly as pyrochlore, yet no explanations exist for considerable variations in niobium content between various carbonatites, and little is known about solubility Nb carbonatite magmas or factors that control pyrochlore crystallization. The 2 O 5 synthetic magma (CaCO 3 -Na CO liquids) at 1 kb has now been determined effect dissolved fluorine evaluated. Solubility water-bearing calcitic liquids least wt % may be high 7.5 %, but diminishes to less than 0.75 CaCO more closely resemble natural