Agatized wood is a type of fossilized wood where organic material has been completely replaced by silica, specifically chalcedony, while retaining its original cellular structure. Collectors often look for high-contrast colors and intact growth rings, commonly found in areas of ancient volcanic ash fall or sedimentary riverbeds.
Is this agatized wood?
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 agatized wood with a known reference. Agatized Wood sits at Mohs 6.5-7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Agatized Wood leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Agatized Wood typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: brown, red, yellow, white, black, gray.
- 5Look at form & habitCrystal system: trigonal. Typical habit: pseudomorph.
Often confused with
Agatized Wood vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Agatized Wood and waxy on Jasper.
How to tell apart: Luster reads vitreous on Agatized Wood and waxy on Chalcedony.
How to tell apart: Luster reads vitreous on Agatized Wood and waxy on Flint Nodules.
Often found alongside agatized wood
Minerals reported to co-occur with agatized wood. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SiO₂
- Mohs hardness
- 6.5-7
- Density
- 2.58-2.65 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Pseudomorph
- Cleavage
- None
- Rarity
- Common
- Uses
- Lapidary, Collector, Decorative
- Host rock
- Sedimentary Deposits
- Typical price
- $5-50 for small slabs, $100-500+ for large polished display pieces
Where rockhounds find agatized wood
51 mapped spotsClassic worldwide localities
- Arizona, USA
- Madagascar
- Argentina
- Indonesia
- Australia
U.S. states with agatized wood
Each link opens a state-specific list of mapped rockhounding spots that produce agatized wood.
Field-hunting tip
Look in sedimentary deposits country — that is the host setting where agatized wood typically forms. If you start seeing quartz, opal, calcite in float, you are in the right ground. Field specimens usually show a pseudomorph habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Nebraska, Texas, New Mexico — start trip planning there.
Common questions
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Find agatized wood on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
