One of the world’s most interesting gem materials is ametrine. It is a variety of bicolor quartz in which citrine and amethyst occur in contact with one another in a single crystal. The word AMEthyst and ciTRINE were combined to yield the name “ametrine.” This gem material is rarely found in nature, and the only commercial production is from the Anahi Mine in eastern Bolivia. There the bicolor quartz crystals have formed within the fractures and vugs of a dolomitic limestone of the Murcielago Group.