Tantalite on the international market generally contains a minimum of 30% Ta2O5, while lower grade material with a minimum of 20% Ta2O5 may also be of interest. The commercial payable value is based on the Ta2O5 content alone, any Nb2O5 is generally ignored.
Should material contain mainly Nb2O5 and only little Ta2O5, then it would be sold as columbite and should contain a minimum of 50% Nb2O5. The payable value is based on the Nb2O5+Ta2O5 content payable entirely as Nb2O5; the Ta2O5 content is not paid a higher rate.
Tantalum and niobium raw materials 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. Such raw materials are then also known as Naturally Occurring Radioactive Materials (NORM).
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. This is reflected in the T.I.C.’s Transport Policy. 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 alone the levels of concern are an order of magnitude higher, i.e.10 Bq/g or 0.13% ThO2 plus 0.048% U3O8.