Alright, so I've been doing a lot of missions lately and I wanted to be efficient with my mineral collecting while keeping each different type at about the same level with each other. I'd pick up the largest size, and if I found a more preferable mineral of equal or better size I'd take that. Size > type basically. But after a while I checked my inventory, and what was interesting was that Valestone was at 78 when all others were 40-50. Moonstone seems to be the inverse of Valestone, being the "rarest" to find a large - huge formation of it.