Whetstone Socket from Iran, Luristan, Iron Age I-II, about 1350-800 BC. Bronze, cast. Sharpening stones, water stones or whetstones are used to grind and hone the edges of steel tools and implements. The socket held the whetstone in place. The Bronze Age is a period characterized by the use of copper and its alloy bronze as the chief hard materials in the manufacture of some implements and weapons. Humans learned how to smelt, melt, cast, rivet, and to forge copper and bronze. The Iron Age is the period in cultural development succeeding the Bronze Age in Asia, Europe, and Africa, characterized by the introduction of iron metallurgy. The term "Iron Age" has low chronological value, because it didn't begin simultaneously across the entire world. Bronze preceded iron as a widely worked metal due to the fact that the metals which make bronze are easily recovered from their ores, and the resulting alloy is soft enough to be easily worked with the raw materials which were then available.