If they used a combination rig they could pre collar drill with...

If they used a combination rig they could pre collar drill with the RC bit then change over at depth when hitting the mineralisation to a diamond bit.
THat way they could conceivably use a smaller/lighter rig on the salt lake as the diamond drill rods are only about 1/3 the weight of RC drill Rods.
The cores from the diamond drilling also will show not just mineral assemblage but also structure ie if disseminated or massive and orientation of veins.
I am not a geo or gynacholagist but prepared to take a look anyway.