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Niobium and tantalum in the United States, exclusive of Alaska and Hawaii Niobium and tantalum in the United States, exclusive of Alaska and Hawaii
The accompanying map shows the location of the principal known deposits of niobium and tantalum minerals in the United States, exclusive of Alaska and Hawaii. Symbols of different shapes are used to depict deposits of different geologic types, and large symbols denote deposits with a record of production. Small symbols denote known occurrences of the minerals. Individual symbols may...