Petrified Wood - It's thousands of years old, yet suddenly back on everyone's Most Coveted list. Why? May 03 2017
A.K.A. fossilised wood or agatised wood, petrified wood is a fossil which forms when plant material is buried by sediment and protected from decay by oxygen and organisms. Then, groundwater rich in dissolved solids flows through the sediment replacing the original plant material with silica, calcite, pyrite or another inorganic material such as opal.
Essentially the organic remains are replaced by minerals in a process which can take thousands of years, and in this process, preserving the growth rings and even the bark for a stunning result.
As a member of the quartz family. It is said to offer strength and support to one's physical body and thus helps with spine and skeletal issues and general stability and healing. Pretty cool stuff for a slab of old wood.