Ametrine crystals are made of alternating sectors of purple and yellow to orange color. Slabs cut perpendicular to the c axis of the crystal look a bit like a pinwheel. The purple sectors are situated under the positive rhombohedral faces (r), and the yellow sectors under the negative rhombohedral faces (z).
While the purple sectors are made of amethyst, the yellow or orange sectors are not made of citrine, because they are colored by inclusions of iron compounds and would more properly called ferruginous quartz. Accordingly, upon heating ametrine the purple sectors pale, while the yellow-orange sectors keep their color.
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Classification of Ametrine
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Other Names for Ametrine
References for Ametrine
Vasconcelos P, Wenk HR, Rossman GR (1994) The Anahí ametrine mine,
Bolivia. Gems and Gemology 30, 4-23.
Balitsky VS, Lu T, Rossman GR, Makhina IB, Mar'in, AA, Shigley JE, Elen S,
Dorogovin BA (1999) Russian synthetic ametrine. Gems and Gemology 35,
Balitsky, V. S.; Machina, I. B.; Mar'in, A. A.; Shigley, J. E.; Rossman, G. R.; Lu, T. (2000): Industrial growth, morphology and some properties of Bi-colored amethyst-citrine quartz (ametrine). Journal of Crystal Growth 212, 255-260.
Internet Links for Ametrine
Localities for Ametrine
||Ontario Gem Company|
||(Error for yellow iron-stained amethyst; not true ametrine.)|
||Rocks & Minerals 82:415-418|