Petrified wood is formed when all the organic material of a tree is replaced by minerals such as quartz in a way that keeps the same structure of the original wood. Whereas most fossils are formed from impressions, petrified wood is a three-dimensional representation of the original wood. It can even preserve the structure all the way down to the cellular level.
The colors of petrified wood come from carbon (black), chromium (bluish green), cobalt (bluish green), copper (bluish green), iron oxides (brown, red, & yellow), manganese (pinkish orange), and manganese oxides (blackish yellow). The primary mineral comprising petrified wood is usually quartz chalcedony.
Possible correspondences: age, ancient forests, history, prehistory, preservation, recording history, time, trees.