Board Thread:FAQs/@comment-98.250.166.80-20180211044930/@comment-4010415-20180211050147

Anyone can use Dust, whether it's powder, crystal, or woven into clothing. World of Remnant: Dust stated that Dust can be activated by Aura and that people just need discipline to keep from losing control of Dust. While Dust can be mixed with Semblance, a person's Semblance is not required to be able to use Dust.

Using your example: Yes, anyone can take fire Dust and learn to conjure fireballs with it. Though, I think they need their Aura unlocked first, and they need training and practice to be able to accurately control it.