Before the discovery of metal, man lived in a time period that is the "Stone Age" about 6,000 BC. It is called such because man made majority of his tools and weapons out of stone. In this period he had not yet discovered or learns to use metals.
The first discovery of metal probably happens during the period of 4000 BC. And the first metal that was used by man was copper and gold. This is because, these metals occur in nature in a free state to which they are not mixed with other impurities. Man probably found nuggets of copperor gold in his surroundings wherein he was able to hammer them into various shapes and forms even without heating or melting them.
There is no reliable scientific evidence for us to know the exact date when man first discovered how to use these metals. But we do know that copper had been used for as long as 5,000 B.C. And gold was first used during the 4,000 B.C.
In about 3,000 B.C., man had discovered some of the most important usage of metals. During this time, other types of metals (like silver and lead) was also been discovered. But copper is that one widely used because it is the strongest and the most plentiful of these metals.
By now, man had learned to melt and beatmetals to form into useful shapes like utensils, or tools or weapons. Furthermore, development of some basic processes of metal fabrication was also discovered. This process includes annealing, melting, casting and smelting. By now, man can also extract copper for ores, which is much plenty in nature compared to nuggets.
In later periods, man discovered tin and learned to mix it with copper to form a bronze alloy. Between 3,500 B.C. and 1,200 B.C., bronze was the most important material for making tools and weapons of man. We now called this period as the “Bronze Age”.
Before man discovered iron from nature, he first discovered it from the meteorites he found. And by 1,200 B.C. he begins to use, developed and work with iron. This knowledge slowly spread all over the world and the use of bronze was slowly replaced by iron. This period is now what we call the “Iron Age”. During this period, there are now seven metals known to man; gold, copper, silver, lead, tin, iron, and mercury. This is the age were the Romans become known and become one of the most powerful civilization of this period.