Mineral, quartz variety
Ametrine containing amethyst and citrine, from Bolivia

Ametrine, also known as trystine or by its trade name as bolivianite, is a naturally occurring variety of quartz. It is a mixture of amethyst and citrine with zones of purple and yellow or orange. Almost all commercially available ametrine is mined in Bolivia.

The colour of the zones visible within ametrine are due to differing oxidation states of iron within the crystal. The citrine segments have oxidized iron while the amethyst segments are unoxidized. The different oxidation states occur due to there being a temperature gradient across the crystal during its formation. Artificial ametrine is created from natural citrine through beta irradiation (which creates an amethyst portion), or from an amethyst that is turned into citrine through differential heat treatment.[2]

Ametrine in the low price segment may stem from synthetic material. Green-yellow or golden-blue ametrine does not exist naturally. This gem only exists in Bolivia, it comes from the Ricón del Tigre area, from the Anahí mine.

Structure

Ametrine is composed of silicon dioxide (SiO2) and it is a tectosilicate, which means it has a silicate framework linked together through shared oxygen atoms.

History

Legend has it that ametrine was first introduced to Europe by a conquistador's gifts to the Spanish Queen in the 1600s, after he received a mine in Bolivia as a dowry when he married a princess from the native Ayoreos tribe.[3]

References

  1. ^ "Ametrine Value, Price, and Jewelry Information". International Gem Society. Retrieved 2019-09-14.
  2. ^ "What does Amethyst, Ametrine and Citrine have in common?". Gem Rock Auctions. Retrieved 2019-09-15.
  3. ^ Vasconcelos, Paolo; Wenk, Hanz-Rudolf; Rossman, George. "The Anahí Ametrine Mine, Bolivia," Gems and Gemology, Spring 1994, p. 4-23

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