Mineralogy of Niobium and Tantalum: Crystal Chemical Relationships, Paragenetic Aspects and Their Economic Implications

Abstract

A systematic review of the oxide minerals of niobium and tantalum is presented, including varietal names, crystal chemistry, structural features, relationships to other phases and paragenesis of each mineral group, series or species. A separate section deals with oxide minerals that occur exclusively as secondary, low-temperature phases of largely metasomatic origin. Oxide minerals of Sn, Ti and W that carry substantial Nb and Ta are discussed as well. A new crystal chemical classification of the oxide minerals of Nb and Ta is presented.