ANSWERS: 2
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Iron is one of the more common and cheapest metallic elements. By weight it makes up about 5% of the planet's crust where it is found as a range of slightly impure "iron ores," hematite, limonite, magnetite, etc. It was not until about 1200 BC that iron came into general use for the production of tools. This was because temperatures needed to process the ore exceeded what most ancient kilns were able to reach. Pure iron has a melting point of 1, 535 degrees centigrade. The limit of an ancient furnace was about 1,150. Later adding three to four percent carbon to the mixture could sometimes lower the melting temperature to as low as about 1,150, just at the furnace limit.
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"Ore," by its nature, is not pure stuff. Depending on the impurities, the melting point will vary. I believe the oxides are very common chemical ores of iron and there are less common ones. The chief iron ores are the oxides Hematite, Fe2O3 (1350C), and Magnetite, Fe3O4 (1420C), and its carbonate Siderite, FeCO3 (????C) also Limonite, Fe2O3 + H2O (????C) Sorry I couldn't find the melt temps for the third and fourth. Perhaps someone can fill them in for me.
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