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The Learning Kingdom's Cool Fact of the Day for March 1, 1999
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How does petrified wood form?
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Petrified wood is wood that has turned to stone. Usually it is
millions of years old. 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.
One of the finest deposits of petrified wood:
http://www.shannontech.com/ParkVision/PetForest/PetWood.html
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