Judging quality
Even, slightly muted leaf green. Vivid emerald 'green amethyst' is usually green-coated or irradiated quartz rather than prasiolite.
Quartz
Prasiolite
Green quartz. Almost all of it is amethyst that has been heated to about 500°C — a stable, permanent transformation, but a treatment, and any honest seller says so. Genuinely natural prasiolite is rare and paler.
Care
Color is stable in light. Ordinary cleaning.
History & lore
The Montezuma mine in Minas Gerais produced the amethyst that first heat-treated reliably to green in the 1950s.
Cultural history, recorded as tradition rather than as medical or scientific claim.
Common questions about Prasiolite
- What is Prasiolite?
- Green quartz. Almost all of it is amethyst that has been heated to about 500°C — a stable, permanent transformation, but a treatment, and any honest seller says so. Genuinely natural prasiolite is rare and paler.
- How hard is Prasiolite and what is it made of?
- Prasiolite is a Quartz-family mineral with the composition SiO2. It crystallizes in the trigonal system and rates 7 on the Mohs hardness scale. It occurs in apple green, pistachio green, pale yellow.
- Where does Prasiolite come from?
- Notable localities for Prasiolite include Brazil (Montezuma), Poland, Arizona, USA.
- How do you tell good Prasiolite from filler?
- Even, slightly muted leaf green. Vivid emerald 'green amethyst' is usually green-coated or irradiated quartz rather than prasiolite.
- How do you care for Prasiolite?
- Color is stable in light. Ordinary cleaning.
See it in person
Photographs only go so far
Both rooms are open six days a week, and there is always someone happy to pull pieces out of the case so you can compare them under the light.