Mineral Sands
All I know about Mineral Sands is that my former company, BHP, had a bit of a disaster with a mining operation in them - nothing messy or environmental, just expensive.
It seems that when they built the biggest sandmine in the world, the digger buckets wore out real fast due to the hard and abrasive minerals in the sand. They spent a lot of time repairing buckets and machinery that wore out.
There were a few other problems, too, but nothing relevant.
Can't say that wishstone looks ANYTHING like a sand deposit. If it's sedimentary at all, then it's a conglomerate.