Gemstone profile and identification guide
Petrified Wood
Petrified wood is fossil wood in which original organic tissue has been replaced by silica minerals.
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Overview
Petrified wood is fossil wood in which original organic tissue has been replaced by silica minerals.
Did you know? Some specimens preserve microscopic wood anatomy useful for paleobotany.
Use this profile as a collector reference and educational guide for quick on-page comparison, then validate with the interactive identification system.
Identification
Name: Petrified Wood
Scientific classification: Fossilized Silicified Organic Material
Hardness: 6.75 Mohs
Transparency: opaque
Lustre: waxy to vitreous
Crystal system: Trigonal quartz/chalcedony aggregate context
Primary colour: Brown
Secondary colour: Red Brown
Colour family: Browns
Preserved growth rings and cellular textures in silica matrix are primary identifiers.
Verification Status
Status: verified-core-fields
Reference priority: GIA, Gem-A, Mindat, International Gem Society
Core identity, locality, and physical-property fields reviewed against standard gemological references.
Values are reported as practical gemological ranges where appropriate.
Physical Properties
Hardness category: hard
Hardness value: 6.75 Mohs
Chemical composition: Silicified wood, commonly quartz/chalcedony replacing original wood tissue
Crystal system: Trigonal quartz/chalcedony aggregate context
Common locations: United States (Arizona), Indonesia, Madagascar, Argentina, Egypt
Learn more: Gem-A gemstone education resources.
Colour Variations
Wood-grain patterns preserved in silica-replaced fossil wood, with brown, red, yellow, and black tones.
Optical effects: Wood Grain Pattern
Detailed Gemology
Mineral species: Silicified fossil wood (quartz/chalcedony dominant)
Mineral group: Fossilized silicate aggregate
Chemical formula: Silicified wood, commonly quartz/chalcedony replacing original wood tissue
Mohs hardness: 6.75
Crystal system: Trigonal quartz/chalcedony aggregate context
Lustre: waxy to vitreous
Transparency: opaque
Streak: White
Cleavage: None
Fracture: Conchoidal to uneven
Specific gravity: 2.58-2.65
Refractive index: 1.53-1.55
Optical phenomena: Wood grain patterning
Colour range: Brown, red-brown, yellow-brown, black, multitone
Common inclusions: Mineral-filled pores, iron oxide staining, silica veins
Geological environment: Sedimentary fossil beds with silica-rich groundwater systems
Principal mining regions: United States (Arizona), Indonesia, Madagascar, Argentina, Egypt
Important commercial sources: Commercial petrified wood is sourced from multiple fossil localities, with Arizona among the most recognized
Historical significance: Important paleontological and lapidary material worldwide.
Common treatments: Stabilization and polishing are common; dyeing can occur.
Synthetic or imitation forms: Dyed composites and printed imitations exist.
Common look-alikes: Jasper with wood-like patterns, dyed composites
Jewellery uses: Used in cabochons, slabs, carvings, and educational/collector specimens.
Care recommendations: Generally durable but can contain fractures; avoid strong impact and thermal shock.
Cross-check profile data with GIA Gem Encyclopedia and Mindat entry for Petrified Wood.
Formation
Forms by permineralization and replacement when buried wood is infiltrated by silica-rich groundwater over geologic time.
Origin
Commercial petrified wood is sourced from multiple fossil localities, with Arizona among the most recognized
Uses
Best for: Used in cabochons, slabs, carvings, and educational/collector specimens.
Ideal uses: Decorative slabs and cabochons that display preserved wood structure.
Care
Generally durable but can contain fractures; avoid strong impact and thermal shock.
Need another candidate? Use advanced gemstone search or return to the identification guide.
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Petrified Wood FAQ
How can I identify Petrified Wood?
Compare hardness (6.75 Mohs), crystal system (Trigonal quartz/chalcedony aggregate context), colour profile, and lustre (waxy to vitreous) with your sample. Then cross-check related gemstones listed above.
What colour range does Petrified Wood appear in?
Wood-grain patterns preserved in silica-replaced fossil wood, with brown, red, yellow, and black tones.
Where is Petrified Wood commonly used?
Decorative slabs and cabochons that display preserved wood structure.. For maintenance, follow the care guidance in this profile.
Scientific References
GIA: general gemstone identity (reviewed) - Batch 04 factual verification pass.
Gem-A: gemological terminology and testing references (reviewed) - Batch 04 factual verification pass.
Mindat: mineral species and principal localities (reviewed) - Batch 04 factual verification pass.
International Gem Society: gem trade context and treatment overview (reviewed) - Batch 04 factual verification pass.