Fossil formed by the infiltration of minerals into cavities between and within cells of natural wood, usually by silica (silicon dioxide, SiO2) or calcite (calcium carbonate, CaCO3). Often this replacement of organic tissue by mineral deposits is so precise that the internal structure as well as the external shape is faithfully represented; sometimes even the cell structure may be determined.
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National park, eastern Arizona, U.S. Established as a national monument in 1906 and as a national park in 1962, it has an area of 146 sq mi (378 sq km). It features extensive exhibits of petrified wood in several “forest” areas, fossilized leaves, plants, and broken logs, and the Painted Desert. Other features include petroglyphs and ancient Pueblo Indian ruins.
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