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Precious Metals Part 1

Precious Metals

Written for the KidsKnowIt Network by: Brandon Guymon

Precious metals: Gold, silver, platinum, brass, iron, and bronze; these metals are closely associated with our history. Mankind has searched for and fought over these metals since the end of the Neolithic (Stone Age). Metal has lifted mankind’s technology from simple stone tools and weapons to computers and space travel. Without our precious metals we would still be living in tribes, wandering in search for food.

Various metals

Metal tools emerge near the end of the Stone Age

The Neolithic ended when people stopped using stone tools and started to use tools made out of metal. No one really knows how or why people started to use metal tools rather than stone; the inventors of metal tools didn’t write anything down. Scientists think people started using copper and gold for ornaments and jewelry before they started using metal for tools. The reason scientists think jewelry came first is because they have found human skeletons surrounded by metal jewelry and stone tools . Archeologists found the Varna Necropolis in 1972. (Necropolis is a fancy scientist word for graveyard.) The gold and copper artifacts found in Varna Necropolis are mostly beads and other forms of jewelry. The tools found in the graves are mostly made from stone. These graves have been dated to 4700 to 4200 BCE. It didn’t take long for people to start making tools out of copper. In fact, Otzi, the Iceman, was found high in the Alps with several artifacts including a flint knife, flint-tipped arrows, and a copper-bladed ax. His body and his tools were preserved in the glacier ice that covered them. He is the oldest human mummy around. His body dates back to approximately 5300 BCE; so, about the same time as the Varna people.

A skeleton in the Varna Necropolis

So why use copper and gold? Copper and gold can be found as native metal. Native metal means you can pick up a nugget of copper or gold and pound on it with a hammer and make stuff out of it. You don’t have to heat it up or melt it out of the rock. However, if you pound on unheated native metal too much it will crack. So about all you can do with native metal is make beads or very simple tools. If you heat native copper, you can make better tools.

Otzi’s ax is the product of a different process. Most copper in the world is not the pure native copper. Most copper is found in what is called an ore. An ore is a mixture of metal, rock and other junk. At some point in time people learned (again, scientists don’t know when or how) that if you heat up crushed ore to a very high temperature the metal will melt and leave the junk you don’t want behind. This process is called smelting.

Otzi the Iceman's copper-bladed ax
© South Tyrol Museum of Archaeology

I’ve have tried doing this, it is very hard work and you don’t always succeed. The time I tried we didn’t get any metal out of the ore, just waste called slag. We didn’t do something right. Anyway, Otzi’s ax blade was made from copper smelted out of ore then hammered into shape.

Examining Otzi's mummy
© South Tyrol Museum of Archaeology, EURAC, Samadelli, Staschitz