Crystallized Air

Source
Dropped by various air, storm, and lightning themed creatures, such as:
 * Steam Rager and Enraged Tempest in Borean Tundra
 * Stormrider and Scion of Storm in The Storm Peaks
 * Ionar and Stormfury Revenant in Halls of Lightning
 * Tempest Revenant in Wintergrasp

Found while mining Titanium Veins.

Harvested by Engineers using the Zapthrottle Mote Extractor on Arctic Clouds in various zones.

Crystallized Air as an ingredient

 * (1 Eternal Air = 10 Crystallized Air and vice versa)