User blog comment:Demetri Anacona/Dust: How it can be used as well as the different kinds/@comment-24087318-20140112183516

Dust comes in a few different colors you missed. And Light Blue/Cyan are the same color, so they're posted twice.

In addition, White colored Dust appears to come from Grey colored crystals, as we see no White crystals, or Grey powdered dust.

You also missed Yellow, and a more vibrant shade of Orange.

If you look in Episode 1 and 8, you see the variety of Dust crystals, as well as various other color-labeled bags that likely contain Dust or Dust related things, given the nature of the shop as a Dust specialty store.

The colors of Crystals are Red, Dull Orange, Vibrant Orange, Yellow, Green, Blue, Light Blue, and Grey.

The colored bags reflect this, however, they are only seven shown, with only one Orange bag instead of two.

In Weiss' rapier, we've seen that the dust chambers in the revolver drum come in colors we havn't seen, like Purple. Likely hinting to that there are possibly other crystal colors out there, or that mixing various colors of powdered Dust can create specialized or combination effects. Which of these it is is yet to be seen.

In addition, there's a very good likelyhood that Grey/White dust is used in lieu of Gunpowder in the RWBY world. Given it's application as Impact, it likely posesses a concussive or kinetic force when ignited, which is the exact force involved in how bullets work. A firing mechanism strikes the bullet which ignites the gunpowder inside, causing a large expansion of gas and kinetic energy, propelling the bullet forward and out of the gun.