Pure silica in the form of microcrystalline quartz(the mineral varieties chalcedony, chert, and opal), is colorless. The colors of petrified wood come from impurities, tiny amounts of different materials dissolved along with the silica in the ground water that seeped through the wood.

(Photos by Josh Sadler)


 



This petrified pine tree from northern Arizona is one of the largest specimens ever to be cut and polished.
Petrified wood is ceated by precipitation of the mineral quartz from groundwater that flows through wood after it is buried in sediment.





Quartz replaces the wood, often preserving its cellular texture. The variety of colors of petrified wood results from impurities within the quartz crystals. This specimen is a perfect example of that.


These three slices are from oak trees that grew in the Northwest approximately 1.8 million years ago.
From left to right: Washington, Oregon, Oregon. See that the longer specimen has two hearts.

Cenozoic in age (Pliocene)


 

Cenozoic in age (Miocene)



Petrified wood from Jackpot, Nevada is famous for its interesting shapes and dark, rich colors. Very few logs were recovered from this area and so slices from them are rare. The center slice is from the largest of those trees