There are 7055 tonnes annually of the mineral FeNb. The payable material is Nb2O3. 65% of the FeNb is actual Nb that can be hydrolyzed to Nb2O3 (niobium pentoxide).
7055 * .65 * 39.6 = ~$183.4MM
Production costs are the actual costs associated with mining the material and hydrolysis of FeNb to Nb2O3. These are operating expenses.