Petrified Wood
Image: Jon Sullivan (Public domain)
Mineral NamePetrified Wood
Chemical FormulaSiO2
Mohs Hardness6.5
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.65
Colorsred, orange, yellow, brown, gray, white, blue
Transparencytranslucent
Type LocalityPetrified Forest National Park, Arizona, USA
Mineral GroupSilicates
Usesjewelry, ornamental, collector
Associated Mineralsquartz, chalcedony, opal
Rarityuncommon
Description
A large section of petrified wood, exhibiting a rough, bark-like exterior and a vibrant, multi-colored interior with intricate banding and patterns, characteristic of fossilized tree rings.
Geological Context
Petrified wood forms when plant material is buried by sediment and protected from decay. Groundwater rich in dissolved silica (SiO2) then flows through the sediment, replacing the organic material cell by cell, preserving the original wood structure over millions of years.
