How does petrified wood form?
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Petrified wood is wood that has turned to stone. Often it
shows beautiful colors that were not present in the original
wood. How does wood turn to stone?
When wood dies it begins decaying immediately. To become
petrified it must be quickly covered by a layer of volcanic
ash, mud, or other material that excludes oxygen, thus
preventing it from decaying.
If conditions are right, the organic part of the wood
dissolves slowly, and at the same time minerals replace the
organic matter, duplicating its structure exactly. The
mineral replacement can be silica, calcite, pyrite, or
marcasite.
The colors are caused by impurities in the replacing
mineral. The most common impurity is iron, which causes
red, orange, or yellow colors. Manganese or copper can
cause blue, black, or green colors.
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