Source Legacy of Fire Player's Guide
Aura faint evocation (fire); CL 3rd
This chalky yellow powder is usually kept in a finely woven canvas pouch. When you mix firepowder with fine sand, the resultant mixture quickly heats up until it combusts, creating a slow-burning flame that requires no additional fuel. Half a pound of firepowder takes 1 minute to mix, and the fire produced burns for 8 hours, equivalent to a standard campfire.