The vases, about 10 inches high and three inches in diameter, are made of bronze, an alloy rich in copper.

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Exactly what that copper content is is debatable: various sites give brass or bronze as the alloy and with different copper contents.

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Many French horns, for example, are made of nickel silver, an alloy of copper, zinc, and nickel (it's silver in name and color only), and some are made of nickel bronze, an alloy of copper, tin, and nickel. (Brass itself is an alloy of copper and zinc.) Many brass instruments are silver-plated (sterling silver on brass), and some are gold-plated.

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Now they are pouring silicon bronze, a durable alloy heated to about 2, 000 degrees Fahrenheit, into the molds.

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An Oscar, once made with bronze, is now pewter alloy at its core.

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