A fractite bar is a bar of refined Fractite ore. It can be created through the Smithing skill in Dungeoneering by using fractite ore on a furnace, requiring level 40 Smithing and granting 32.2 Smithing experience. The fractite ore itself can be mined from the rocks scattered throughout the dungeon, obtained as a monster drop, or bought from the Smuggler.
A fractite bar can be smithed on an anvil through the Smithing skill to create Fractite equipment, granting between 46 and 50.5 Smithing experience per bar used. A list of fractite items that can be smithed from fractite bars and the Smithing levels required can be found here. However for those training smithing, it would be better to train with kratonite ore/bars because they cost nearly half as much as fractite ore, yet give a similar amount of experience.