by David Jackson

Intro Bronze is an alloy that consists of copper and tin. Copper itself is easily malleable, so tin is slightly incorporated into the copper to make a stronger, more durable bronze. The optimized amount of copper to tin is nine to one (10% and 90% of bronze). Other elements can replace tin, such as arsenic, zinc, phosphorus, lead and aluminum, which can alter the new solid's physical property, sometimes dramatically. One such example is brass. Copper Copper is a fairly common element to procure in the world, but it needs to become an alloy to strengthen it. In its pure form, it is reddish in color, conducts electricity and heat, and turns green when exposed to the air. The three most common ores that copper is found in is Malachite (Cu2CO3(OH)2), Azurite (Cu3(CO3)2(OH)2), and Chalcopyrite (CuFeS2). These are extremely common (next to iron in worldwide production) and melt at relatively low temperatures. Copper can be found as a native metal, but usually it is found as these sulfide, carbonate and oxide ores. --Malachite----------Azurite-----------Chalopyrite------

Specifics on Copper Ores Malachite takes on a crystalline form, which is heavy, fragile, semi-opaque and tends to have green streaks. It can sometimes occurs in large masses with a core of azurite in the center, and is also found in sandstones formed by meteoric waters. Significant sources of this ore can be found in mines in the Urals (USSR) and also in Zaire, Chile, New South Wales, and Arizona. Azurite looks similar to malachite except that it has blue streaks within its elongated crystalline structure. It forms at a lower temperature than malachite, and since it is a secondary copper source, it is harder to find in mass quantities. It can be procured in France, Namibia, Greece, and Arizona. Chalcopyrite is a tetragonal crystal ore that is yellowish in color and has greenish-black streaks. This exists at a higher temperature than the two previous ores. Almost 80% of the world's copper comes from this ore, and it is bountiful in South West USA, Canada, Zaire, USSR, Spain, Norway, and Sweden. Smelting Smelting is the overall technique to derive metals from ores. When heated at high temperatures, the copper ores melt and the copper metal flows to the bottom. The excess matter (a large portion is silicon) sifts to the top. A sub-process called reduction is used to get rid of the oxide and to purify the metal: Copper oxide + Carbon Monoxide = Copper + Carbon Dioxide CuO (s) + CO (g) = Cu (s) + CO2 (g) In this case, the carbon monoxide is a reacting agent and the carbon dioxide is a byproduct. Heat is the energy source that makes the process work. An even more sophisticated way of purifying the copper is through electrolysis, where electrodes separate the impurities from the copper. Previous - Home - Next