Do you have a brand-new, shiny penny ? If so, you know what the mineral called copper looks like. Pennies are made of almost pure copper - a gleaming, reddish-brown metal.
Copper was one of the first metals that people used. During the Stone Age, people had only stones and bones with which to make weapons and tools. But about ten thousand years ago, people found that they could pound and shape lumps of copper into knives, spearheads, and bracelets.
Those people of long ago found great lumps of pure copper in the earth. But people have taken copper out of the ground for thousands of years. Now there is very little pure copper left. Today, most of the copper we find is mixed with other minerals. Minerals that contain copper are called copper ores.
Copper is an important metal. Most of the wires that carry electricity into our house and factories are made o copper. This is because electricity moves better through copper than through any other common metal.
Tin is another metal that people have used for a long time. It is a bluish-white metal that is heavy and soft, like copper. It comes from a brownish, glassy, mineral called cassiterite. People of long ago often found pebbles of cassiterite in riverbeds. Today, most cassiterite has to be dug out of the earth.
About five thousand years ago, ancient people learned how to mix tin with copper. By melting tin and copper together, they could make a metal called bronze. Bronze is much stronger and tougher than either in or copper. From bronze, the ancient people made swords, helmets, armor, cups, bowls, and many other things. When people learned to make bronze, it was the end of the Stone Age and the beginning of the Bronze Age.
When we think of tin, we usually think of tin cans. But tin cans are really made of iron or steel covered with a thin coating of tin. The tin gives the cans a shiny look and keeps the iron or steel from rusting.
Copper was one of the first metals that people used. During the Stone Age, people had only stones and bones with which to make weapons and tools. But about ten thousand years ago, people found that they could pound and shape lumps of copper into knives, spearheads, and bracelets.
Those people of long ago found great lumps of pure copper in the earth. But people have taken copper out of the ground for thousands of years. Now there is very little pure copper left. Today, most of the copper we find is mixed with other minerals. Minerals that contain copper are called copper ores.
Copper is an important metal. Most of the wires that carry electricity into our house and factories are made o copper. This is because electricity moves better through copper than through any other common metal.
Tin is another metal that people have used for a long time. It is a bluish-white metal that is heavy and soft, like copper. It comes from a brownish, glassy, mineral called cassiterite. People of long ago often found pebbles of cassiterite in riverbeds. Today, most cassiterite has to be dug out of the earth.
About five thousand years ago, ancient people learned how to mix tin with copper. By melting tin and copper together, they could make a metal called bronze. Bronze is much stronger and tougher than either in or copper. From bronze, the ancient people made swords, helmets, armor, cups, bowls, and many other things. When people learned to make bronze, it was the end of the Stone Age and the beginning of the Bronze Age.
When we think of tin, we usually think of tin cans. But tin cans are really made of iron or steel covered with a thin coating of tin. The tin gives the cans a shiny look and keeps the iron or steel from rusting.
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