Source Legacy of Fire Player's Guide

Aura faint evocation (fire); CL 3rd
Slot none; Price 10 gp; Weight 1/2 lb.

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.

Craft Wondrous Item, continual flame; Cost 5 gp