Petrified Gum Tree Wood Polished Stone Bookends Rock. Lovely bookends from Petrified Gum Tree Wood from Yakima, Washington. It is approximately 17.5 million years old, from the Miocene epoch. These bookends are 5 inches high, 4 inches wide at the bottom and 1.5 inches thick. They are polished on front and left natural rough around the edges. They are covered with felt in the inside and on the bottom to protect you furniture. This gemstone is the fossilized wood of trees. The petrified wood formed when a tree died and was buried by sediments. Minerals in the groundwater then permeated the wood, replacing the original organic matter and turning it to stone. The main mineral is silica, but trace elements in the silica create a variety of colors. Petrified wood is very hard and takes an excellent polish, making it a great stone for jewelry. Listing and template services provided by inkFrog. This item is in the category “Collectibles\Rocks, Fossils & Minerals\Fossils\Vegetation\Petrified Wood”. The seller is “oneofakindrocks” and is located in this country: US. This item can be shipped worldwide.