Cryroot

Cryroot glows all sorts of colours depending on their unique altitude and stay that colour. They are what hold the skylands together and keep the land mass afloat. If you can get to a skyland you can dig down until you hit a cryroot and mine it, once you start chipping pieces off they will start floating in what is zero gravity to them because they are at their unique altitude already.
Cryroot at ground level will naturally want to float up because of crytraction (the attraction to its altitude level). The force of crytraction is the exact opposite of gravity's force so the cryroot should be contained when away from it's altitude. If a piece of cryroot dropped it will fly up until it has reached its altitude then crytraction will pull the piece towards the closes skyland of it's kind.

A type of containment that takes advantage of crytraction would by having a bigger piece of cryroot mounted to a iron base to keep it from floating away, then place the smaller pieces near the bigger mounted piece, they will be attracted to the larger piece instead. Most jewelers and blacksmiths who use cryroot use this method of containment. You could just simply use a bag and tie it to something heavy if thats to much work for you.