Under UV light, clean sand appears purple or black. Some minerals, such as calcium carbonate in seashells, glow blue, as does a shovel handle in the picture above.

紫外线照射下，干净的沙子呈紫色或黑色。有些矿物，如海贝中的碳酸钙，会闪着蓝光，就如同上图中的铁锹的把手。

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They would leave subtle clues in the isotopic composition of the limestone by shifting the ratios of light to heavy carbon and oxygen atoms in its calcium carbonate.

因为如果是那样的话，阳光将会被转换成大量的碳、氧原子保存到石灰岩中的碳酸钙里，而事实却是，岩层的同位素组成（Isotopic composition）中没有留下任何蛛丝马迹。

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Coccolithophores are microorganisms that are covered in plate-like shells made out of calcium carbonate (chalk). The chalky shells reflect light, turning the ocean a milky turquoise color.

石灰质鞭毛虫(coccolithophores)是一类覆盖在碳酸钙(粉笔的主要成分)岩石板状外壳上的微生物。

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