General discussion, page-10145

Depends on your view. Raising the COG of your assay allows you to report a higher grade but lowers your intervals (intersections). Lower intervals leads to lower ore tonnage estimates, and because tonnage reduces faster than grade increases, lower intervals leads to lower contained metal. Usually companies go for a low COG because usually the market values ore tonnage and contained metal the most.

Perhaps ENR think that tonnage is not the main game in the niobium market (with USGS's estimate of 2023 mine production at 83kt of niobium, and CBMM sitting on a "huge" resource and CMOC and Magris sitting on "large" resources)

and that the market will reward high grade more than high tonnage (as long as it is enough to get a 20-30yr LOM with reasonable, not too disruptive, mining rates - and they are confident of achieving that)

and hence have selected "high" COGs (especially the 2% for the "included" intervals which produce the high headline grade figures).