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.
- 2Name the organismDecide what left the fossil before worrying about the rock. Organism: Trees and tree-like plants.
- 3Check the preservationPreservation: Silica fills vessels and cell walls and replaces the wood. That controls the weight, the hardness and how the piece takes a polish.
- 4Read the lusterHold the specimen under a strong light. Luster: waxy to vitreous.
- 5Match the color rangeCompare against the expected color range: brown, red, yellow, white, black, gray.
Often confused with
Silicified Wood vs. its common look-alikes, and how to tell them apart in the field.
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
- Mohs hardness
- 6.5-7
- Density
- 2.6-2.7 g/cm³
- Luster
- Waxy to vitreous
- Transparency
- Translucent
- Rarity
- Common
- Uses
- Lapidary, Collector, Decorative
- Host rock
- sedimentary deposits
- Organism
- Trees and tree-like plants
- Preservation
- Silica fills vessels and cell walls and replaces the wood
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
Where it forms: sedimentary deposits. If you start seeing quartz, chalcedony, hematite in float, you are in the right ground. 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.
