Petrified Wood is a fossil. When all the organic materials of the original wood are replaced by minerals over time, while it retains its original structure, it becomes petrified. Wood becomes petrified when under sediment, and the flow of ogygen is blocked off. As water seeps into the sediment, it deposits minerals that gradually replace the orignal wood.
"Petro" comes from the Greek meaning rock or stone - thus, meaning "wood turned to stone." All the original features of the wood are still evident once petrified. Evidence of the tree rings, bark, and wood tissues can be seen. Sometimes the minerals that replace the wood can create beautiful colors, and sometimes small druzy cavities are present. In some areas, entire forests have been petrified, and become known as petrified forests. Petrified wood can be found in various locations throughout the world. One of the most well-known preserved petrified forests is in Arizona, USA. Argentina also has an excellent location where entire trees have been petrified.