If you are worried about the rock chips being 'selected' - as I...

If you are worried about the rock chips being 'selected' - as I have said before these areas are where the artisanal miners (meaning 'those working with traditional methods and tools') just found a surface outcrop and mined out the best grade ore. What they left had bits of the ore material sticking to the sides of their excavation.
Taking those samples is certainly not the most scientific method of determining value - but what else can they do.
Well of course they can drill spaced holes along strike and below the pegmatites, and that is next on the program.

Remember pegmatites are zoned. Both within the cross section and along strike** - and this is due to the method of formation where pegmatites are low melting point rocks squeezed out of a mother intrusion into the cooler country rock and where minerals selectively crystalise out of the magma. Hence the beautiful crystals that we see.
Now it is up to our geos to make what they can from what they see - and of course they will want to know the composition of the stuff left behind -- but it probably is only a vague indicator of what we will find in a fresh pegmatite.

The point is though that to my knowledge no where else where Nb and Ta are being explored for in pegmatites are there rocks like we see here.

The other source of Nb and Ta is in weathered carbonitite intrusions (Luni at WA1) and there are no large crystals and grade is much lower but more uniform over say 2 x 1 kilometers as at Luni.

A better analogy in Australia might be RR1's Nb pegmatites at Wabbi Wabbi.

Another take away point is that if those crystals which exist on the walls of the artisanal mines were left behind, what was taken must have been amazing - and that could make a discovery very valuable indeed.

DYOR, anything is possible.

** including Li pegs.