The weight of a carat (200 milligrams), standard unit of measurement for gemstones, is based on the weight of the carob seed.
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Pumice is the only rock that floats on water.
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Diamonds can be shattered with a hammer.
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It takes a photon 170,000 years to travel from the core of the Sun to the surface, but only 8 minutes to travel the rest of the way to Earth.
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In zero gravity, a candle's flame is round and blue.
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The average home creates more pollution than does the average car.
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The gas that gives rotten eggs their distinctive foul smell may slow ageing and block damaging chemical reactions inside cells, according to scientists in China.
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