Fossil Wood (Petrified Wood), from Arizona USA (REF:FWAU4)

When fossil wood is referred to as petrified wood this means that it has turned to stone via a mineralisation process called permineralisation. The organic materials making up the cell walls of the wood have been replicated and replaced by minerals. The petrifaction process occurs underground, when wood becomes buried in water-saturated sediment or volcanic ash. This protects the wood decaying from oxygen and organisms while groundwater rich in dissolved solids flows through the sediment, replacing the original plant material with silica, calcite, quartz, or another inorganic material such as opal.