This is a natural untreated slab of petrified wood from utah usa.
We have taken a pic of both sides of the slab and it has been taken wet.
It takes a great polish.
Petrified wood is a fossil. It 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. The result is a fossil of the original woody material that often exhibits preserved details of the bark, wood and cellular structures.