tavninder:

I know that sand can be compressed into stone using positive pressures, but wouldn't it be difficult to code something which both turns into sand and back int itself under positive pressures. Thats why i sugested sand to turn back into stone using negative pressures, because it would be simple and realistic. 

 

 It is realistic that sand should turn into stone when in negative pressure? I think you have it backwards, my friend...

Stone could turn into sand at extreme negative pressures, and sand into stone at extreme positive pressures. Having it go both ways wouldnt make sense, although now that i think about it, what WOULD happen to stone at extreme high pressures in the real world? I would think it just melts.