The Bronze Age (c. 3300-2500 b.c.) is the period of human culture when man began using bronze metal to make objects-principally, tools. The Neolithic Age slowly came to an end as various cultures in Eurasia that had depended on wood, stone, and bone for tools began to develop the techniques for metallurgy. Bronze proved to be an excellent material for making tools and weapons. People in the Middle East learned to produce bronze by mixing tin and copper (hence, the transition years between the Neolithic Age and the Bronze Age are sometimes referred to as the Copper Age). Bronze had considerable hardness, strength, and density, and it proved more reliable and durable than the stone, wood, and bone tools that had been in use. The Bronze Age lasted until the beginning of the Iron Age.
AnswerThe Bronze Age did not occur all at once in every place. Some cultures never had a Bronze Age at all, jumping directly from mixed copper and stone tools and ornaments (a Chalcolithic Period) to using and/or producing iron tools. Nevertheless, modern scholars tend to use the rise of bronze artifacts in the ancient Near East as the more-or-less "official" date of the Bronze Age's onset, and while the actual dates are much in dispute, it seems safe to say that the Bronze Age was in full swing in some places by 3000 BCE or so. When the Bronze Age ended is even more problematic. In many ways, it didn't end until well into modernity. Bronze armor was highly prized by Greek hoplites long after iron and carbonized iron had come onto the scene. Even once relatively high-grade steel was available, bronze was still used to make smooth-bore cannons right into the late-middle of the 19th century. Naval cannons in the Age of Sail were a mixuture of iron and bronze, but bronze was more highly prized because it was stronger in most cases and didn't rust. Since the onset of the Bronze Age is usually dated from the alloy's use in the ancient Near East, it seems appropriate to date its end from the rise of iron weapons in the same area. That would have occurred around 1200 to 1100 BCE but, once again, it didn't occur all at once, and in many cases, bronze was still a vastly superior metal to early iron weapons. Bronze is not an inherently inferior metal to iron. In fact, in many ways, it is superior. It doesn't rust and is quite strong; usually stronger, in fact, than iron before it is carbonized and quenched. Iron does have one enormous advantage: In its ore-locked state, if one can figure out how to get an oven hot enough to smelt it, it is much more plentiful than tin (the alloy that is mixed with copper to make bronze), and therefore much, much less expensive. The Iron Age was simply a time when hard and useful metals became more available to everyone because the price dropped. The first bronze artifacts were alloys of copper and arsenic. Arsenic is a naturally occurring contaminant in copper desposits and, in sufficient concentrations (10% to 15% of the copper), produces a high-quality bronze. Over time, though, a smith will suffer nerve damage from the arsenic fumes. Eventually, smiths learned to avoid that fate by mixing copper with tin to make bronze. The late Bronze Age (LBA) represents one of the three high points of civilization in the Mediterranean/Mesopotamian area (the other two are the ages of the Roman Empire and the Modern Age). During this time, trade flowed from at least as far east as Afghanistan to at least as far west as Spain -- and perhaps as far west as the British Isles. Great and small kings from Greece to Babylon corresponded with each other, exchanged gifts, entered into treaties and alliances, and regulated, taxed, and protected merchants. The LBA gave us Ramses II, the Trojan War (or at least the conflict between the Greeks and Wilusa/Ilios), and the enlightened Hittite law code.
Aluminum comes mostly from an aluminum ore called bauxite. It is mined out of the ground in large geological formations found in Ghana, Indonesia, Jamaica, Russia and Surinam, but it is also abundantly deposited in Australia and Brazil. We recover the bauxite and process it concentrate the aluminum, which is combined with oxygen and oxygen-hydrogen ions in the minerals of the ore.