Petrified wood is a fossil. First plant material is buried by sediment including volcanic ash, and protected from decay by oxygen and organisms. Once buried, ground water rich in dissolved solids flows through the sediment replacing the original plant material with silica, calcite, pyrite or another inorganic material such as opal. The result is a fossil of the original woody material that often exhibits preserved details of the bark, wood and cellular structures. Each piece is unique and cannot be replicated.
As petrified wood is a rare commodity it will become increasingly expensive and rare. The first pieces of petrified wood sold 5-7 years ago for roughly 10% of todays prices. In 10 years the product virtually all be exhumed from the ground and any remaining pieces will become very expensive. There are only a few places in the world left that allow the export or collection of petrified wood and as the availability dwindles the value and price of the product will go up significantly. Like the dinosaurs who disappeared from this era so to will the few remaining pieces of petrified wood.