Rock IdentifierAmethyst
Key takeaways
- Amethyst is purple quartz colored by iron and natural irradiation.
- Strong heat turns it yellow — most commercial citrine is heated amethyst.
- Prolonged sunlight can fade its color; display it away from direct sun.
What it is
Amethyst is the purple variety of crystalline quartz, its color coming from trace iron combined with natural irradiation deep underground. Shades range from pale lilac to deep royal purple, sometimes with reddish flashes. It shares all quartz properties: hardness 7, glassy luster, conchoidal fracture, six-sided points.
How to recognize it
Look for purple, glassy crystals that scratch glass, often lining the inside of geodes as clusters of points on a grey matrix. Natural amethyst frequently shows color zoning — deeper purple near the crystal tips fading toward the base — a helpful sign of authenticity.
Treatments & fakes
Heating amethyst changes its color: gentle heat can lighten it, while stronger heat turns it golden — that's the origin of most 'citrine' and of green 'prasiolite.' Dyed glass and synthetic amethyst also exist; overly uniform color and trapped bubbles are red flags. Because natural amethyst is common and affordable, expensive fakery is uncommon, but treatment is routine.
Care & lore
Amethyst can fade with long sun exposure, so display it out of direct light. In tradition its name comes from the ancient Greek for 'not intoxicated,' and it was long associated with sobriety and calm — a cultural belief, shared here as folklore rather than fact.
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