Wood petrified - formation related to fossils. It is the wood of trees grown in past geological periods, impregnated with silica minerals (quartz, chalcedony or opal). The process of petrification occurs as follows: trees, being buried under dense sediments, are deprived of oxygen. In the absence of oxygen, their tissues avoid decomposition, but are impregnated with aqueous solutions rich in silica. In this case, the solution penetrates into plant cells and replaces their contents, settling inside the cells. Thanks to this, the internal structure of the tree (for example, annual rings) is preserved and is clearly visible.
You can see petrified wood for sale and buy it in the Minerals of Russia online store.