Ametrine is a rare variety of quartz that occurs naturally when amethyst and citrine grow together in the same crystal. The only source of natural ametrine in the world is the Anahi Mine located in the Brazilian state of Bolivia. The Anahi Mine is located near the Bolivian city of Santa Cruz de la Sierra in the province of Mato Grosso. This is currently the one and only place where naturally formed ametrine is mined.
The Anahi Mine was first discovered in the 1600s by Spanish conquistadors looking for gold in the South American interior. The conquistadors did find gold, but they also found unusual bi-colored quartz crystals that were unlike anything they had seen before. Samples of these crystals were sent back to Spain where they puzzled gem experts as to their origins and composition.
It wasn't until the 1980s that these unique bi-colored quartz crystals were officially identified as ametrine. Geological experts determined that the specific conditions present at the Anahi mine were perfect for the formation of ametrine crystals. The mine contains amethyst, citrine, and a transition zone where the two types of quartz intersect. This intersection results in the Yin and Yang style blending evident in ametrine.
The Anahi Mine is located in the prolific Brazilian quartz region known as the Bolivian Ametrine Belt. This geological zone contains abundant deposits of amethyst and citrine in close proximity to each other. The mine itself was carved into a high mountain valley with near vertical walls containing many quartz veins and outcroppings. The unique geology and elevation of the mine are critical factors allowing natural ametrine to form there.
While ametrine itself is quite rare, the Anahi Mine does produce a respectable quantity of this material. The ametrine yield from the mine was much higher decades ago, but the supply continues at a steady production rate. Rough ametrine crystals mined here range from small under a carat sizes to large 10+ carat specimens with exceptional color zoning.
Most of the world's supply of finished ametrine gems can be traced back to the original rough mined from the Anahi Mine in Bolivia. Some synthetic ametrine does exist for commercial jewelry, but it lacks the visual impact and value of the natural material. For now, all naturally formed ametrine in the global marketplace continues to come from this single source in the Bolivian Andes.
