Amethyst

SiO₂ | Mohs 7 | Hexagonal Crystal System

Amethyst is a variety of quartz (SiO₂) that owes its purple colour to trace amounts of iron and other impurities within its crystal structure, which, when exposed to natural radiation, result in its characteristic violet hues. Amethyst is one of the most well-known and widely used gemstones, forming in geodes, druses, or cavities within volcanic rocks, and it can range in colour from pale lilac to deep purple.