Petrified Wood Bookends

North America, Arizona

Million of years old... | Stone | Item 2079

North America, Southwestern United States, Arizona, Late Triassic, ca. 225 million years ago. The trunk was sliced crossways and sharp 90 degree sides, then highly polished on one of the planar faces to showcase the interior rings of the tree that have fossilized (petrified) into quartz and agate – the minerals that replaced the once organic tree material. Arizonian petrified wood is one of the most colorful and desirable types, often called “rainbow wood” as exemplified here in warm hues of red and maroon, lilac, and ochre yellow.This set of bookends is made from cut petrified wood from Arizona.

While the two pieces are from the same cut, they are different from each other in a way that, to me, makes the set more interesting. The larger piece measures 8 3/4″ long, 6 1/2″ tall and 2 3/4″ at the widest. What’s unique about this section is it is left natural and uncut on the back side. The front is sheared to a glass type finish, but the back is rough like a unworked stone. The second piece to the set measures 7 5/8″ long, 6 5/8″ tall and 1 1/2″ wide throughout. The front face is polished smooth like glass and the back side is cut smooth but not as highly polished. It’s wonderful to see the difference in colors from the highly polished side to the lesser polished side to the rough cut. The rings of the tree are clearly visible here in many different colors.

Fossilized trees from this time period come from the Chinle Formation of the southwestern USA, and the beautiful colors found in this formation – exemplified by the colors of this fossilized tree – give the Painted Desert of Arizona its name. Due to plate tectonics, this area was near the equator on the supercontinent Pangaea during the Late Triassic, which gave it a humid, sub-tropical climate. It was a floodplain below mountains to its south and a sea to its west; as a result, massive trees washed down from the mountains and came to rest in sediments that preserved them and fossilized them. The petrification process involves the rapid burial of the tree or pieces under sediment which prevents the usual decay. Flooding and volcanic activity are usually responsible for creating the layers of sand, silt, and ash needed to create the right types and amount of sediment. Mineralized water can then permeate through the wood, coating cell walls and filling the intercellular cavities which then fossilizes into stone. The detailed preservation of the wood, including knots, rings, and bark, are possible because the organic wood molecules become coated and surrounded with smaller silica molecules. Nine different species of tree have been identified in the fossilized deposits in the region; this example may be Araucarioxylon arizonicum, an extinct conifer tree (and the state fossil of Arizona). Fascinatingly, the Ancestral Puebloan people who lived in the region approximately 1000 years ago used petrified wood for making tools and even building houses!