Petrified Wood Identification Guide
Identifying petrified wood by its preserved grain, rings, and bark turned to silica, and telling it from ordinary wood and plain jasper.
Read the full Petrified Wood encyclopedia entry →
What Petrified Wood Looks Like
Petrified wood is fossilized wood in which the original organic tissue has been replaced, cell by cell, mostly by silica (chalcedony, jasper, or opal). It preserves the look of wood — growth rings, grain, knots, branch scars, and even bark — but in stone. Colors are highly varied: browns, tans, grays, reds, yellows, blacks, and sometimes blue, green, or purple from trace iron, manganese, and other elements. It takes a glassy polish, is hard, and is surprisingly heavy compared with real wood.
Step-by-Step Field ID Checklist
- Look for wood structure. Growth rings, parallel grain, knots, and bark texture are the giveaways.
- Heft it. It is dense and heavy like rock, not light like wood.
- Check the luster. Polished or freshly broken faces are glassy and waxy, like agate.
- Test hardness. Silicified wood scratches glass and steel (Mohs ~6.5–7).
- Inspect the fracture. Conchoidal, glassy breaks confirm silica replacement.
Key Diagnostic Tests
- Hardness: ~6.5–7 for silica-replaced wood; scratches glass. (Opalized wood is slightly softer.)
- Streak: White.
- Fracture: Conchoidal, brittle, glassy.
- Density: High (~2.5–2.7) — far heavier than true wood.
- Acid: No reaction if silicified; fizzing means a carbonate (calcite) replacement instead.
- Magnetism: None, though iron staining is common.
Common Look-Alikes and How to Tell Them Apart
- Real/partly rotted wood: Light, soft, and burns or carves easily; petrified wood is heavy, hard, and scratches glass.
- Plain jasper or agate: Lacks organic structure; petrified wood shows preserved grain, rings, or cell patterns under a loupe.
- Concretions and banded chert: May mimic rings but show concentric mineral banding, not woody grain and bark.
- Coal/lignite: Black and light, leaves a streak and may show plant structure but is soft and combustible, not silica-hard.
- Modern stained wood/resin fakes: Feel lighter and warmer, lack stony heft, and may show mold seams or air bubbles.
Visible cellular wood anatomy combined with stone hardness and weight is the decisive test.
Where Petrified Wood Is Found
It forms where buried wood is bathed in silica-rich groundwater, often from volcanic ash, before it can decay. Famous localities include Petrified Forest National Park in Arizona, the Ginkgo Petrified Forest in Washington, Oregon and Nevada deposits, plus Argentina, Indonesia, Madagascar, and Egypt. Search sedimentary basins, ancient riverbeds, and ash-rich badlands.
Frequently asked questions
How can you tell if it's real petrified wood?
Real petrified wood preserves growth rings, grain, and bark texture, is heavy and stone-hard (scratches glass at ~6.5–7), and breaks with a glassy conchoidal fracture, unlike light, soft real wood.
What does petrified wood look like?
It looks like a log or wood fragment turned to colorful stone, showing rings, grain, knots, and bark in browns, reds, grays, and other hues, with a glassy polished surface.
Petrified wood vs jasper — how are they different?
Both can be silica, but petrified wood preserves organic wood structure (rings and cells), while plain jasper is a structureless cryptocrystalline quartz with no woody grain.
How does wood turn into stone?
Buried wood is infiltrated by silica-rich groundwater that precipitates in and replaces the cell structure before the wood decays, gradually converting it to chalcedony, jasper, or opal.
Why is petrified wood so colorful?
Trace elements in the mineralizing fluids tint the silica: iron yields reds, browns, and yellows; manganese gives pinks and blacks; and copper or chromium can produce greens and blues.
Petrified Wood identified by the community
Recent Petrified Wood specimens identified with Rock Identifier.
