James Marsh - MD Interviews, page-443

I might be wrong but my interpretation of what James said was that the concrete additive was still kaolin/halloysite but it was from a different area from the JORC resource from which we will produce the CRM and PRM products.

The reason for additional drilling to define a JORC resource is because its colour is less white - that is below the R75 brightness cut-off for the JORC resource - and so wasn't included in the JORC resource which is restricted to sufficiently bright / white kaolin/halloysite. It is likely to be adjoining the existing JORC resource area.

James said that colour and contaminants doesn't matter for concrete, so this is why the HRM product would come from a lower brightness (less white) area of the GW deposit that is considered "waste" when looking at the characteristics of the kaolin/halloysite required for the CRM and PRM product.