What Is Amethyst? The Chemistry Behind Its Purple

Amethyst is the purple variety of quartz, colored by trace iron impurities that have been altered by natural background irradiation over geological time — a similar mechanism to how smoky quartz gets its color, but producing a different result because of how the iron is positioned in the crystal structure.

Heat changes amethyst's color permanently: enough heat shifts it toward yellow-orange, which is exactly how most commercial citrine is produced. Overheat it further and the color can disappear into clear quartz entirely. Major sources include Brazil and Uruguay, where amethyst forms in large geode cavities, and Zambia, known for darker, more saturated material.