The original excavators believed that the workshop must have been an early iron smelting site, based on those iron oxides. However, instead of iron, the workers at Kvemo Bolnisi were smelting copper using iron oxide as a substance added to the furnace to increase the yield. Adding the iron oxide hematite to the furnace helped the copper metal to separate more easily from the impurities in the ore. Iron itself is one of the most abundant elements on Earth, while naturally occurring iron metal is actually very rare. Extracting iron from iron ore and working it into tools and weapons is considered one of history’s biggest technological advancements.