Crystal Dust is a sand-like substance made from a blue/white crystal. It is most commonly produced by the Firmament's Factories of Crystal, but there are other ways of making it. Crystal Dust allows travel between places in the 10,000 Dawns easily by cutting open portals into the Bifrost Path, or more dangerously straight through the void between Dawns. Crystal Dust can be used to travel outside of the 10,000 Dawns (having been used in places such as the Totality), but it is more difficult to use outside of it's home multiverse.
Crystal Dust is one of the most valued resources unique to the 10,000 Dawns, as the ease of inter-universal travel it allows is uncommon in most realities.