Petrified Wood (Ulmus species)
Image: <a href="//commons.wikimedia.org/wiki/User:Kevmin" title="User:Kevmin">Kevmin</a> (CC BY-SA 3.0)
Mineral NamePetrified Wood (Ulmus species)
Chemical FormulaSiO2
Mohs Hardness7
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.65
Colorswhite, cream, brown, dark brown, black
Transparencytranslucent
Type LocalityYakima Ridge, Yakima County, Washington, USA
Mineral GroupSilicates
Usesjewelry, lapidary art, collector specimens
Associated Mineralsagate, jasper, opal
Rarityuncommon
Description
A sliced and polished cross-section of petrified wood, displaying distinct concentric growth rings in shades of creamy white and brown, with a prominent dark brown to black inclusion on one side.
Geological Context
Petrified wood forms when plant material is rapidly buried and protected from decay, then replaced by mineral-rich groundwater, typically silica, preserving the original cellular structure. This specimen is Miocene in age, indicating its formation during that geological epoch.
