Petrified Wood
What is Petrified Wood?
Petrified wood is a fossil formed when the organic remains of trees are replaced by minerals, primarily silica (quartz), while retaining the original structure of the wood. The petrification process occurs underground when wood is buried in sediment and protected from decay by an anaerobic environment. Mineral-rich water seeps through the sediment, depositing minerals in the wood's cells. Over time, the organic material decays, and the minerals crystallize, creating a stone replica of the original wood. The resulting petrified wood exhibits the detailed structure of the original wood, including growth rings, knots, and even the cellular structure, often with vibrant colors due to the presence of various minerals.
Optical Properties
- Refractive Index
- 1.544 - 1.553
- Birefringence
- Typically low, but can vary depending on the mineral composition.
- Pleochroism
- Weak to absent
- Optical Character
- Uniaxial or biaxial, depending on mineral composition
- Dispersion
- Low
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Petrified Wood before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Where to Find Petrified Wood
RockHoundR, the free-to-download rockhounding map from the Ruby Glint team, shows where collectors find petrified wood in the US, with land-access notes for BLM land and national forests. Collecting is banned in national parks.
See where to find petrified woodAlways check the local rules and get the landowner's permission before you collect.
More Images
Quick Facts
Physical Properties
- Color
- Variable, including brown, red, yellow, black, and white, depending on the mineral content.
- Hardness (Mohs)
- 7
- Rock tumbling
- Tumbles well
- Density
- 2.6 - 2.7 g/cm³
- Streak
- White
Chemical Properties
- Chemical Formula
- SiO2 (with impurities)
- Elements
- Silicon, oxygen, and trace elements
Also Known As
Identify Petrified Wood Instantly
- Snap a photo, get instant results
- 6,700+ rocks, minerals & crystals
- Discover collecting spots near you
Petrified Wood FAQs
How do I identify Petrified Wood?
Petrified Wood can be identified by its hardness of 7 on the Mohs scale, Variable color. Look for these key characteristics when examining specimens.
What color is Petrified Wood?
Petrified Wood typically appears in Variable, including brown, red, yellow, black, and white, depending on the mineral content.. Color can vary depending on impurities and formation conditions.
How hard is Petrified Wood?
Petrified Wood has a hardness of 7 on the Mohs scale. This makes it a relatively hard mineral suitable for jewelry.