Petrified wood

Petrified Wood is fossilized wood with a mineral composition of jasper and chalcedony and sometimes opal. Petrification occurs after a tree dies and is quickly covered with fine grained sedimentary rock. This preserves the outer structure of the wood, over time, the decomposing organic materials are replaced with minerals and thus keeps the structure of the wood via bark, tree rings.

Sources for Petrified wood are Wyoming, Nevada, Australia, Canada, Madagascar, Greece and Namibia.