Silithyst

Silithyst is "strange red crystalline dust" that appears in the Silithus desert, which both the Horde and the Alliance would like to assemble in quantities as large as possible for researching purposes. Doing just that is the objective of the world PvP event "The Silithyst Must Flow" and the world quest Silithyst (quest), available during the Call of the Scarab micro-holiday.

Collecting Silithyst will result in a debuff that slows the character's speed considerably.