Experiments were conducted to test the hypothesis that carbonatite-hosted Nb deposits owe their origin to the metasomatic alteration of K-feldspar-rich fenite by carbonatitic magma. This involved reacting K-feldspar with a synthetic mixture of CaCO3, MgCO3, Mg(OH)2, CaF2, and Nb2O5. At the experimental conditions, a phlogopite-rich calcite-bearing metasomatic rind containing pyrochlore formed on the K-feldspar. This supports the above hypothesis and also explains the origin of fenite-associated glimmerite, the association of glimmerite with calcite carbonatite, and the genesis of the carbonatite-hosted ores that supply the bulk of the world's niobium.

中文翻译：

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胶囊中的铌矿成因


进行实验是为了检验以下假设：碳酸岩型铌矿床的起源是碳酸岩浆对富钾长石长石长石的交代蚀变。这涉及到钾长石与 CaCO3、MgCO3、Mg(OH)2、CaF2 和 Nb2O5 的合成混合物的反应。在实验条件下，钾长石上形成了富含金云母、含有烧绿石的方解石交代皮。这支持了上述假设，并解释了与闪锌矿相关的闪闪石的起源、闪闪石与方解石碳酸岩的关联，以及供应世界大部分铌的碳酸岩矿石的成因。