Ore was a form of mineral suitable for smelting or processing. It was mined by droid or organic workers from ore deposits, and processed at command centers or ore processing centers. The ore could then be processed into durasteel. Ore was found on many planets. Most ores were mined and sold on the same world because of the costs associated with lifting bulk cargoes out of a gravity well. Unless there were no feasible substitutes available in a region, useful but common ores such as copper, iron, and titanium were seldom exported from a planet and only in very rare cases out of a system. Only ores valuable enough to turn a profit after the transportation costs were taken into account for being shipped to other galactic markets.