Ultrastructure of a Columbite-Tantalite Mineral from the Zhaojinggou Ta-Nb Deposit in the North China Craton: Direct Evidence of the Formation Mechanism of the Columbite-Group Minerals

Figure 1

(a) Simplified geological map of the Zhaojinggou Nb-Ta deposit at the northern margin of the North China Craton (modified from Zhu true [27]). (b) Cross section of the Zhaojinggou Ta-Nb deposit (modified from Chai and Wu [31]).