Crystal & mineral guide
Amethyst
SiO₂ (Quartz)
Purple quartz variety and February birthstone — common in geodes and crystal points.
Identify Amethyst with RockScanAbout Amethyst
Amethyst color comes from irradiation and iron impurities in quartz. Deep 'Siberian' purple with red/blue flashes is most valued in trade. Large geodes from Brazil and Uruguay dominate the specimen market. Heat treatment can turn amethyst into citrine — disclose when selling.
Amethyst belongs in a crystal identifier workflow because photo cues — color zoning, crystal habit, and surface luster — combine with measurable traits like Mohs 7 and specific gravity 2.65. Use RockScan’s camera to get a first-pass ID, then confirm with the checklist below.
Amethyst properties
| Mohs hardness | 7 |
|---|---|
| Crystal system | Trigonal |
| Luster | Vitreous |
| Color | Pale lilac to deep royal purple |
| Composition | Silicon dioxide with iron-related color centers |
| Formation | Hydrothermal veins and geodes in volcanic rock |
| Occurrence | Brazil, Uruguay, Zambia, Russia |
| Specific gravity | 2.65 |
| Cleavage | None (conchoidal fracture) |
How to identify Amethyst
- Hexagonal prismatic crystals with pyramidal terminations
- Color often zoning from tip to base
- Hardness 7 — scratches glass
Collector notes
- Name from Greek 'amethystos' — 'not intoxicated'
- Once ranked with ruby and emerald in classical gem lists
Value context: Deep, evenly saturated crystals command higher prices than pale mass material.
Amethyst FAQ
How do you identify Amethyst?
Amethyst (SiO₂ (Quartz)) is typically recognized by pale lilac to deep royal purple color, vitreous luster, Mohs hardness 7, and trigonal crystal system. RockScan can suggest Amethyst from a photo and surface these checks on the result card.
What is Amethyst made of?
Amethyst composition: Silicon dioxide with iron-related color centers. It forms via hydrothermal veins and geodes in volcanic rock and is found in Brazil, Uruguay, Zambia, Russia.
Is Amethyst valuable?
Deep, evenly saturated crystals command higher prices than pale mass material.
