Amethyst geodes are hollow volcanic rocks lined with purple quartz crystals. They are formed within gas bubbles in basaltic lava where silica-rich fluids slowly deposit crystals over millennia.
Is this amethyst geode?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch amethyst geode with a known reference. Amethyst Geode sits at Mohs 7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Amethyst Geode leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Amethyst Geode typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: purple, violet.
- 5Look at form & habitCrystal system: trigonal. Typical habit: drusy crystals lining a cavity.
Often confused with
Amethyst Geode vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside amethyst geode
Minerals reported to co-occur with amethyst geode. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SiO₂
- Mohs hardness
- 7
- Density
- 2.65 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Drusy Crystals Lining A Cavity
- Cleavage
- None
- Rarity
- Common
- Uses
- Collector, Decorative, Lapidary
- Host rock
- Basaltic Volcanic Rock
- Typical price
- $20-200 small cabinet, $500-5000+ large cathedral
Where rockhounds find amethyst geode
2 mapped spotsClassic worldwide localities
- Artigas, Uruguay
- Rio Grande do Sul, Brazil
- Thunder Bay, Canada
- Maverick County, USA
Field-hunting tip
Look in basaltic volcanic rock country — that is the host setting where amethyst geode typically forms. If you start seeing goethite, hematite, calcite in float, you are in the right ground. Field specimens usually show a drusy crystals lining a cavity habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in California, Colorado — start trip planning there.
Common questions
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Find amethyst geode on the map
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