Gado Gado International

Petrified Wood: Formation and Characteristics

Posted in Informational by gadogadointl on July 16, 2009
Polished cross section of petrified log

Polished cross section of petrified log (16″D x 4″H)

The formation of petrified wood begins when a live tree is quickly buried in an oxygen-free environment.  This can occur when a landslide buries some trees, and in some cases when volcanic ash from a fast-moving pyroclastic flow buries a forest.  Over time, hot mineral-rich water passing through the sediment  or volcanic ash replaces the tree’s carbon with silica, often in the form of quartz.  Silicon is chemically similar enough to carbon that it will take its place in the organic compounds without altering the overall cellular structure of the wood. The result is that the wood slowly becomes a rock that looks very much like the original log, right down to the microscopic level in many cases.

Additionally, certain elements such as iron, copper, cobalt and manganese that are leached out of the surrounding soil can seep into the wood during the petrification process and add striking colors from blue-green to red-brown.

Petrified log with red-orange highlights

Petrified log with red-orange highlights (20″D x 25″H, 485lbs)

Due to volcanic activity Indonesian petrified wood is formed much more quickly than it is in other areas of the globe.  Hot springs act to dissolve silica present in volcanic ash and then “cook” the buried logs, accelerating the process many fold.

Petrified wood collection in Java, Indonesia.

Petrified wood collection in Java, Indonesia.

to be continued…

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