Isaac Asimov's case for gold as humanity's first metal
Isaac Asimov reasoned that gold was probably the first metal people worked. Its chemistry means it lies around in nature as nearly pure nuggets, and it is soft and stretchy enough to shape with nothing more than a stone hammer and anvil. No furnace, no ore, no chemistry required, just patience and a rock.
Almost every other metal hides in ore, a mineral-bearing rock that must be heated or otherwise treated to release it. Among the seven metals ancient peoples knew, iron clings to its ore most stubbornly and gold least of all, which is why iron came last. The oldest known evidence of copper working is a pendant from northern Iraq dated to 8,700 BCE. Inhabitants of Mehrgarh in South Asia were working metal between 7000 and 3300 BCE, and around 6000 BCE copper smelting became common across southwestern Asia.
Copper alone was too soft to hold an edge. Adding tin produced bronze, which was stiffer and kept its sharpness, and it remained the best everyday material for tools and weapons until iron. The sequence differed by region. China and Britain moved to bronze with little time spent on copper, and Japan adopted bronze and iron almost together. In the Americas, copper was being hammered near Lake Michigan in Wisconsin some 4000 to 5000 years BCE, the workers heating it whenever it grew brittle, yet metal went mostly into jewellery and art rather than tools until European colonisation.
As societies grew, metalsmiths became important figures, and gold and silver trinkets turned into luxury goods valued beyond anything useful. Ingenious methods spread widely; granulation, fusing tiny beads of metal onto a surface, appears in many ancient cultures, apparently before any record of travellers sharing it, and jewellers still use it.
Modern shops sort the work into three families. Forming reshapes metal without removing any, by casting it molten into moulds or by pressing, bending and stamping. Cutting removes material, whether by drilling and milling, which throw off chips called swarf, by burning through with oxy-fuel torches, lasers or plasma, or by etching with chemicals. Joining fastens pieces together. Precision starts before any of that: good calipers measure to within a thousandth of an inch, and marking out transfers the engineer's plan onto the workpiece.
Source: Metalworking
