Ametrine
Ametrine (also known as trystine) is a variety of QUARTZ that displays both amethyst and citrine in the same mineral. Ametrine is mined mostly in Bolivia, with some being found in Brazil and India.
Although ametrine occurs in nature, some ametrine products on the market have been artifically colored by the irridiation or heating of quartz.
Chemistry: Silicon dioxide ♦ Class: Tectosilicate, variety of the quartz group ♦ Color: Two distinct colors, yellow-orange and purple ♦ Luster: Vitreous ♦ Transparency: Transparent to translucent ♦ Crystal system: Trigonal hexagonal prisms ♦ Moh's hardness: 7 ♦ Localities: Bolivia, Brazil, India