Dust

Dust is a source of energy in the world of RWBY. The physical properties of Dust make it incredibly useful for a variety of proposes, particularly in the weapons of many characters in the series.

The name "Dust" is implied to be in reference to the primordial state from which mankind was born. As a natural resource, it is sometimes poetically referred to as "Nature's Wrath" or more prosaically as an energy propellant.

History
According to ancient legends related during the opening narration of the first episode, mankind was fighting a losing struggle with creatures of darkness known as the Grimm. However, through their resourcefulness and ingenuity, humanity managed to discover and harness a source of power they named "Dust" in order to battle the Grimm.

The advent of Dust became the turning point in the war. It would appear that after mankind drove back the Grimm and built civilizations, Dust became integrated into everyday life within Remnant.

Uses
Dust is known as an energy propellant, and acts a power source for weapons and machinery, however, Dust can still be used without the aid of weapons or machines. Technology powered by Dust is also known to glow.

Dust can be found in two discrete states, crystalline and powdered. Both crystalline and powdered Dust are known to have highly explosive properties, for example, during the Dust store robbery, Roman threw a crystal at Ruby's feet and fired at it, causing a sizeable explosion. The powdered form appears to be even more volatile, since something as innocuous as a sneeze is enough to detonate a cloud of Dust.

Different colors of Dust appear to correspond to different natures or effects. In Episode 2, Weiss identifies three types of Dust: Fire, Water, and Lightning. In the same episode, Ruby sneezes on a mixture of red, blue, and yellow powdered Dust, resulting in a large fiery explosion with ice and lightning in it.

Combat
The discovery of Dust was instrumental to humanity's initial defeat of the Grimm, and Dust continues to be used extensively in combat.

One prominent example of a Dust-powered weapon is Weiss' Multi-Action Dust Rapier, Myrtenaster, which utilises numerous forms of Dust to achieve a variety of different effects, such as enhanced speed or the generation of fire and ice.

Dust can also be used as a propellant for more conventional ammunition. Ruby's weapon, Crescent Rose, has also been mentioned to use rounds containing different kinds of Dust.

Production and Distribution
The Schnee Dust Company is one of the largest producers of Dust in the world. Dust is mined from the Schnee Quarry, purified, and transported by railway lines or by sea to distributors. Dust is then sold to the public by Dust shops such as From Dust Till Dawn.

Crystalline Dust is apparently safe enough to leave out on display like common jewelry, whereas powdered Dust is dispensed from tubes on the wall and stored in portable cylindrical canisters. Other bags seen on the shelves have the same bright hues as the tubes and their Dust, but whether they contain Dust themselves is unknown.

Trivia

 * Since most other elements and characters in RWBY have literary or historical backgrounds, the name "Dust" might be influenced by the strange and mysterious substance also called Dust found in Philip Pullman's His Dark Materials novels.