Natural Stone Art

Trees were petrified -- became stone -- when very specific conditions occurred: 

1.  Ancient trees - generally conifers called araucaria - fell in flash floods or other events and were quickly covered with sediment or ash that prevented oxidation and decay.

 

2.  The buried wood was saturated with mineral-laden water.

 

3.  Chemical reactions took place between the minerals and the cellulose compounds in the cell walls of the wood.  Mineral crystals grew in porous cell walls and finally replaced the central cavity of the cell

Petrified conifer wood from the Chinle Formation, Colorado Plateau.  The outside of the stone is the cambia layer of the original tree and looks like bark.

Eden Valley blue wood from Wyoming contains tin which gives it the blue tint.

Petrified palm wood from near Nephi, Utah.  Dots in the stone are called "eyes" and represent the vascular system that supplied fluids to the living plant.

Crosscut  

                   Linear cut

Petrified wood can show a rainbow of colors, reflecting the minerals that made it:

Black -- carbon and manganese oxides

Green/blue -- chromium and cobalt

Reds, browns, yellows -- iron oxides

Pink, orange -- manganesum

Rough petrified palm showing the "eyes"