the Tantalum-Niobium International Study Center (T.I.C.) : Typical market specifications : About Niobium

Columbite on the international market generally contains a minimum of 50% Nb₂O₅. The value is based on the combined Nb₂O₅+Ta₂O₅ content payable entirely as Nb₂O₅, there is no premium for the Ta₂O₅ content.

Other Requirements

The tantalum and niobium minerals often contain somewhat elevated levels of naturally occurring thorium and uranium, usually high enough for them to be classified as radioactive for handling and transport. It is incumbent on any producer or trader to also analyse for Th and U in order to demonstrate whether the material is radioactive or not. As a guide, these elements are of concern for the purpose of mining and handling at levels above 1 Bq/g, a level obtained from e.g. 0.013% ThO₂ plus 0.0048% U₃O₈, whereas for transport the levels of concern are an order of magnitude higher, i.e.10 Bq/g or 0.13% ThO₂ plus 0.048% U₃O₈.