amnhnyc: It’s time for #MineralMonday! The dazzling colors seen in gem tourmalines depend on t

amnhnyc:

It’s time for #MineralMonday! The dazzling colors seen in gem tourmalines depend on the metals present in each gemstone’s crystal structure. Pink tourmalines contain more manganese, while green crystals include iron, chromium, or vanadium. When conditions change during crystal growth, tourmalines can grow as bi-colored and multicolored crystals, such as watermelon elbaite—such as the specimen pictured!

Fun fact: Unlike most minerals, tourmaline, when heated, develops opposite charges at each end. This property of tourmaline crystals—pyroelectricity—produces a positive charge at one end and a negative charge at the other.

Photo: E. Louis/© AMNH

#NewYorkRocks #gems #minerals #crystals #watermelon #elbaite #tourmaline #geology #amnh (at American Museum of Natural History)
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