Silicified wood is a type of fossil where organic plant material has been completely replaced by microcrystalline silica, typically chalcedony, while retaining its original cellular structure. Collectors often look for high-contrast colors caused by mineral inclusions like iron or manganese and well-preserved growth rings. It is frequently found in sedimentary beds where trees were once buried in volcanic ash or mineral-rich groundwater.
Is this silicified 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 silicified wood with a known reference. Silicified 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. Silicified Wood leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Silicified Wood typically shows a waxy to vitreous luster.
- 4Match the color rangeCompare against the expected color range: brown, red, yellow, white, black, gray.
- 5Look at form & habitTypical habit: massive.
Often confused with
Silicified Wood vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads waxy to vitreous on Silicified Wood and waxy on Agate.
How to tell apart: Luster reads waxy to vitreous on Silicified Wood and waxy on Jasper.
How to tell apart: Luster reads waxy to vitreous on Silicified Wood and waxy on Flint Nodules.
Often found alongside silicified wood
Minerals reported to co-occur with silicified 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
- 2.6-2.7 g/cm³
- Streak
- White
- Luster
- Waxy to Vitreous
- Transparency
- Translucent
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Common
- Uses
- Lapidary, Collector, Decorative
- Host rock
- Sedimentary Deposits
- Typical price
- $5-50 for small polished pieces, $100+ for large polished display specimens
Where rockhounds find silicified wood
42 mapped spotsClassic worldwide localities
- Arizona, USA
- Madagascar
- Indonesia
- Argentina
- Egypt
U.S. states with silicified wood
Each link opens a state-specific list of mapped rockhounding spots that produce silicified wood.
Field-hunting tip
Look in sedimentary deposits country, the host setting where silicified wood typically forms. If you start seeing quartz, chalcedony, hematite in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Wyoming, North Dakota, Montana. Start trip planning there.
More silicified wood photos
Common questions
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Find silicified wood on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
