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Pink Chalcedony
A pink chalcedony shows off its beauty. Chalcedonies include many types of cryptocrystalline quartz gems and feature a number of different colors. Geologists can tell a chalcedony from the arrangement and structure of its crystals.

Photograph by blickwinkel/Alamy

Minerals

See pictures of minerals (azurite, gypsum, and others) from National Geographic.

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