A quartz geode is a hollow, spherical or subspherical rock formation containing an internal cavity lined with crystals. These are commonly found in sedimentary limestone or within vesicles of volcanic rocks, often requiring the breaking open of dull-looking nodules to reveal the sparkling interior.
Is this quartz 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 quartz geode with a known reference. Quartz 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. Quartz Geode leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Quartz Geode typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, purple, gray.
- 5Look at form & habitCrystal system: trigonal. Typical habit: druzy crystals.
Often confused with
Quartz Geode vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Quartz Geode is noticeably harder (Mohs 7 vs. 3).
How to tell apart: Quartz Geode is noticeably harder (Mohs 7 vs. 3-3.5).
How to tell apart: Quartz Geode is noticeably harder (Mohs 7 vs. 3.5-4).
Often found alongside quartz geode
Minerals reported to co-occur with quartz 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
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Druzy Crystals
- Cleavage
- None
- Rarity
- Common
- Uses
- Collector, Decorative, Lapidary
- Host rock
- Sedimentary Limestone or Volcanic Basalt
- Typical price
- $10-200 depending on size and crystal quality
Where rockhounds find quartz geode
1 mapped spotsClassic worldwide localities
- Keokuk, Iowa
- Mexico
- Brazil
- Morocco
- Uruguay
Field-hunting tip
Look in sedimentary limestone or volcanic basalt country — that is the host setting where quartz geode typically forms. If you start seeing calcite, chalcedony, goethite in float, you are in the right ground. Field specimens usually show a druzy crystals habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Indiana — start trip planning there.
Common questions
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Find quartz geode on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
