This is a top quality slab of petrified Araucaria (extinct Conifer) wood from Ambilobe, Madagascar. It is 13.6x11.3" and one side has been polished to a mirror like finish showing off the amazing mineralization of this fossil. It is from the early Triassic period, approximately 220 million years old, close to the time the first dinosaurs appeared on the planet.
This specimen is made out of particular high quality petrified wood from the location which was hand selected for exceptional coloration. It was polished by one of the top petrified wood polishers around so it doesn't have any of the dull spots or scuff marks seen on lower quality material.
Petrified wood is the name given to wood that has been turned into stone (fossilized) through the process of permineralization. All of the organic matter becomes replaced by minerals, while much of the original structure such as tree rings in retained. For this to happen the wood needs to be buried in an environment both low in oxygen (preventing decomposition) and with flowing, mineral-laden water.