Amethyst is a purple variety of quartz (SiO₂), colored by trace amounts of iron and natural irradiation. It has a Mohs hardness of 7, making it durable for jewelry and decorative items. Amethyst forms in geodes, volcanic rocks, and hydrothermal veins, often displaying deep violet to light lavender hues. Major sources include Brazil, Uruguay, Zambia, and Russia. It is one of the most popular and widely available gemstones, often cut into faceted stones, cabochons, or used in its raw crystal form.