How is petrified wood formed?


Quick Answer

Petrified wood forms much in the same way animal fossils form; decaying plant matter is replaced by mineral deposits. First, mineral-rich water leaves deposits in the pores of the wood, creating a rocky surface layer over the plant fiber. Then, the original wood decays, with more inorganic material filling in as it disappears. Eventually, the wood is completely replaced by stone, creating a petrified fossil.

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How is petrified wood formed?
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Full Answer

Like animal fossils, petrified wood requires certain environmental conditions to form. The wood must be covered over by sediment fairly quickly to prevent it from simply rotting away, and it needs to be exposed to water with a very high mineral content to trigger the mineralization process. Finally, the oxygen content of the sediment must be low enough to preserve the wood as long as possible, creating the mould for the minerals to take over.

The appearance of petrified wood varies depending on which minerals were present during the petrifaction process. Quartz is a common material found in petrified wood, while the presence of iron oxide can give it a reddish hue and copper can turn it a vivid green. A single specimen of petrified wood may contain many different minerals, creating a rainbow effect over its surface.

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