Petrified Wood

Petrified wood is a plant fossil, not wood and not a single mineral species: it is ancient wood whose pores were filled and whose tissue was partly or wholly replaced by silica, so that it is now made mostly of quartz while keeping the shape and often the cell structure of the tree. Paleontologists describe the processes as permineralization and replacement; silicification (by silica) is the most common type in fossil wood.