oxides
Amethyst
SiO2
- Also known as
- chevron amethystVera Cruz amethyst
- Crystal system
- trigonal
- Hardness
- 7 on the Mohs scale
- Lustre
- vitreous
- Colour
- Pale lilac to deep purple, often zoned
- Where it forms
- Lines cavities in volcanic rock. The great Brazilian and Uruguayan geodes are gas bubbles in ancient basalt flows, slowly filled from the walls inward over millions of years.
- Chiefly from
- Rio Grande do Sul, BrazilArtigas, UruguayZambiaMaissau, Austria
Why it is that colour
Iron substituting for silicon, then hit by natural radiation in the ground. The iron alone does nothing; the colour is a defect centre created by irradiation, which is why heating destroys it and why laboratory irradiation can restore it.
Safety
No hazard from handling. Prolonged strong sunlight will fade it, which is a storage matter rather than a safety one.
Where it comes from
Mined at very large scale in southern Brazil and Uruguay, much of it by small operations working basalt flows. Zambian material from the Kariba mine is generally darker and more traceable. Extremely cheap at the low end, which tells you something about volumes.
Historical use
One of the traditional cardinal gems of Europe, ranked alongside diamond, ruby, sapphire and emerald until the Brazilian deposits were opened in the nineteenth century and the price collapsed. It remains the stone of a bishop's ring in the Catholic church.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
What is attributed to it, and since when
This is the rare case where the association is genuinely ancient and the evidence is in the word itself: Greek amethystos, "not intoxicated". Drinking vessels were cut from it and the Greeks and Romans held that it prevented drunkenness. Ovid supplies an origin myth involving Bacchus and a maiden turned to stone. What the ancient sources do not contain is the modern package of calm, intuition and spiritual protection, which arrives with the New Age literature of the 1970s and 80s.
Described, not endorsed. Dating a claim is not the same as assessing it — but an association that first appears in a book published in 1985 is not an ancient inheritance, whatever the label says. A sincere account of feeling better is compatible with the stone doing nothing — see the placebo effect.
Sold as this, but not
Worth knowing
Amethyst is the clearest example on this site of a real ancient association and a modern invented one wearing the same name. The sobriety link is two and a half thousand years old and left its fingerprint on the English language. The calm-and-intuition link is younger than colour television.
Its fall from the cardinal gems is worth knowing too. Until about 1800 amethyst was genuinely rare and genuinely precious. Then enormous deposits were found in Brazil, and a stone that had been set in crown jewels became something you buy in an airport. Nothing about the material changed. Only the supply did, which is a useful thing to remember about scarcity and worth in general.
Identity checked against IMA-CNMNC master list, June 2025.