"....surely that would have to come from drill core rather than...

"....surely that would have to come from drill core rather than grab it cheaply off the surface"

You have not read carefully. The material comes from a large adit (horizontal shaft) that was drilled though the resources some years ago. It is sort of a mullock heap that is shown as a scar of ore strewn down the hill in the aerial photos….. It represents a literal cross section of the resource and is probably a rather good sample source.
Having said that I remain critical of the prominence given to previous bench testing of the process, which appears to involve merely 20kgs of ore (about ONE home cement bag’s worth). Time will tell…