In reply to silo:
The sandstone specification was a bit confusing, I know quartzite is geologically related but it is pretty different to any normal sandstone out there. Definitely worth checking out compared to the Tafraoute granite which although is near limitless and highly aesthetic, is also a recipe for scrittle and skin loss.
Obviously there's a lot of rock in the area including boulders beneath the cliffs, but don't expect to find any Caley / Porth Ysgo / Torridon -style mega boulderfields, and I have no idea what is documented. Instead if you hunt around the base of the large blocks / clusters, you could find a lot of good stuff - and it would be well worth developing. The main road through past Ksar etc has enough to try initially. There's a good cluster around the hairpin gully bend before Ksar itself, a promising block at the far end before it heads down past Dwawj, and some stuff as it rises up at the East end near the Deep Wells crag: