This is a unique variety of Quartz from the one of the most impressive deposits in the world. Ametrine is the national gem of Bolivia, so much so that the locals refer to it as "Bolivinita". Ametrine is a naturally occurring purple and yellow bi-color variety that is formed by a unique twin law ("Brazil Law Twinning") where two separate individually colored crystals are intergrown to form an alternating "radiation" pattern of purple and yellow triangles when viewed down the c axis. The two colors are oriented based upon their position inside the crystal to create the famous bicolor gemstones. The Anahí Mine is the world’s only commercial source not only of gemmy Ametrine but also of naturally occurring (unheated) Citrine.