Ametrine

Hardness: 7 on the Mohs scale. Color: Zones of purple (amethyst) and yellow-orange (citrine). Luster: Vitreous (glassy). Crystal Structure: Trigonal. Cleavage: None. Specific Gravity: 2.65.

Ametrine is a variety of quartz that occurs when conditions during the formation of amethyst lead to heating of some areas, causing the iron impurities responsible for the purple color to change their oxidation state, creating the yellow/orange citrine hue. This process typically happens in hydrothermal veins. The geological age can vary, but generally, quartz forms over millions of years.

Primarily used as a gemstone in jewelry, where its unique bicolor composition is highly valued. It is cut into various shapes, including faceted stones that highlight the color zones. Also sought after by mineral collectors.

Ametrine is almost exclusively found in the Anahi Mine in Bolivia, which is legendary for its deposits. According to legend, the mine was discovered by a Spanish conquistador in the 17th century who received it as a dowry when he married an Ayoreos princess named Anahi. After introducing ametrine to Europe, the mine was lost for centuries and only rediscovered in the 1960s.

In the field, ametrine is primarily identified by its distinct bicolored purple and yellow/orange zones within a single crystal. It shares characteristics with amethyst and citrine, being a variety of quartz. Look for transparent to translucent crystals with these color zones. The hardness of 7 can be tested by scratching glass. While large, gem-quality crystals are rare, smaller specimens are more common. Bolivia is the main source, but small deposits have been reported in Brazil and India. For collectors, well-defined color zoning and clarity are key.