I think it would be cool if Moonstone and Valestone had a use besides surveys; since the use was removed a couple years ago.
Valestone can increase health depending on size (Small = 1 peg, Med = 2 pegs, Large = 4 pegs, Shiny = 6 pegs)
Moonstone can increase your shield size, again depending on size (Small = 10%, Med = 20%, Large = 40%, Shiny = 60%)
I suggest these uses so players can make a decision on what crystal they actually choose. I have the Drakon sprite and I've found that if a level doesn't have Crimsonite, I just leave without taking anything as Dark Matter and Luminite are useless to me. So if a level doesn't have the crystal that you want, you can at least take a Valestone or Moonstone deposit to help you throughout the level.
Will the Minerals increase Shield/HP when picked up? How long does the Minerals take effect, because you need to remember a good lot of Minerals are available AFTER an entire floor.