Crystal & mineral guide
Petrified Wood
Fossil wood (SiO₂ replacement)
Silicified fossil wood preserving growth rings and grain.
Identify Petrified Wood with RockScanAbout Petrified Wood
Petrified wood forms when silica replaces organic wood, preserving cellular detail. Arizona's Petrified Forest is iconic; Madagascan and Indonesian material supplies cabochons. Hard as quartz — excellent for polishing. Growth rings and bark texture confirm authenticity vs jasper slabs.
Petrified Wood belongs in a crystal identifier workflow because photo cues — color zoning, crystal habit, and surface luster — combine with measurable traits like Mohs 6.5–7 and specific gravity 2.6–2.7. Use RockScan’s camera to get a first-pass ID, then confirm with the checklist below.
Petrified Wood properties
| Mohs hardness | 6.5–7 |
|---|---|
| Crystal system | Microcrystalline quartz replacement |
| Luster | Vitreous to waxy |
| Color | Earth tones, red, yellow, rainbow |
| Composition | Silica (chalcedony/quartz) replacing wood tissue |
| Formation | Silica-rich groundwater permineralization of buried wood |
| Occurrence | USA (Arizona), Indonesia, Madagascar, Egypt |
| Specific gravity | 2.6–2.7 |
| Cleavage | None |
How to identify Petrified Wood
- Wood grain and growth rings in hard silica
- Hardness 7
- SG near quartz
Collector notes
- Some specimens retain microscopic cell structure
- Arizona petrified wood is protected in national parks
Value context: Colorful complete rounds and fine polish grades price highest.
Petrified Wood FAQ
How do you identify Petrified Wood?
Petrified Wood (Fossil wood (SiO₂ replacement)) is typically recognized by earth tones, red, yellow, rainbow color, vitreous to waxy luster, Mohs hardness 6.5–7, and microcrystalline quartz replacement crystal system. RockScan can suggest Petrified Wood from a photo and surface these checks on the result card.
What is Petrified Wood made of?
Petrified Wood composition: Silica (chalcedony/quartz) replacing wood tissue. It forms via silica-rich groundwater permineralization of buried wood and is found in USA (Arizona), Indonesia, Madagascar, Egypt.
Is Petrified Wood valuable?
Colorful complete rounds and fine polish grades price highest.
