Roman Culture/metallurgy

The ancient Romans began using metals in about 2000 B.C.E., when copper tools and ornaments begin to appear; this is much later than its origin, in the Middle East and Turkey in about 3800 B.C.E. Then, between 1800 and 1300 B.C.E., the Romans were in the Bronze Age. Most importantly, the first Iron Age settlement was in 753 B.C.E.—Rome. With this came Rome’s eventual conquest over Europe and the Mediterranean.

Mining
John F. Healy, an archaeologist, explains, “Many of the sites exploited by the Romans had already been worked for a considerable time by the Phoenicians and by the Greeks” (Healy 47), posing a difficulty for the Romans to produce more precious metals. Their largest producer of gold, silver, copper, tin, lead, iron and mercury was in Iberia (Spain), but “large-scale exploitation… is unlikely to have happened before the first century” (Healy 48). Iron was a crucial metal to the Romans, and was found in Spain, as well as Gaul (around Lugdunum), Italy, Elba, Sardinia, Sicily, Noricum, Illyria, Macedonia, Asia Minor, Near East, Africa, and Britain (Healy 63). He also mentions “The most important phase of the Roman [iron] mining industry… fell between AD 250 and AD 360” (Healy 65).

Ore Refining
The Romans obtained metals just as we do today: by mining ore and somehow extracting metal from it. Healy also explains, “An ore is basically a rock containing mineral, or occurring with it as inclusions” (Healy 35). The Romans mined for 10 different types of metals, each having multiple occurrences of compounds and crystal structures. These 10 metals are: gold, silver, copper, tin, lead, iron, zinc, mercury, arsenic and antimony. They began with the ore and prepared it for smelting by crushing the rocks. This separated ore-bearing rocks from waste rocks. This was usually done by either giant mortars or slave-powered mills (Healy 142). Sieving was also used for gold processing. The Romans used the old methods of furnace smelting, where metal is extracted from the ore by literally melting it out at high temperatures (Healy 152). They also employed methods of amalgamation, where post-ground metal-bearing ores are placed on an inclined board and rubbed while water flows over it. Romans developed advanced methods of separating gold and silver, usually by cupellation, where a gold-silver alloy is crushed into a fine powder, then heated just enough to melt the silver and leave a gold powder (Healy 156).

Metal Treatments
Roman metal treatments, known as hot and cold treatments, are still taught and used today. Hot treatments include annealing, which is where one heats a metal under the melting point and slowly cooled to recover ductility and remove dislocations from the metal from cold-working; quenching, which is the “rapid cooling of highly heated steel (Healy 233)” using a liquid to raise the yield stress (sometimes they even used blood or urine!); casting, which is where molten metal is poured into a cast; alloying, which is where two metals are melted, mixed and cooled together; and, most popular with the Romans, tempering, which is where one quenches steel at a specific temperature, “…controlled by watching the surface colour of the steel during reheating…” (Healy 234). Cold-working methods was mainly hammering, or hammering a metal while it is hot. This made a metal harder and more brittle.