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The image shows the middle of a polished slice of a petrified tree from Arizona. After the enlargement of the image it is possible to see the homesteads and the remains of living things deep in the tree. They lived approximately 230 million years ago in the late Triassic

Petrified log at the Petrified Forest National Park

Polished Petrified Wood

Polished slice of petrified wood

Petrified logs

The outline of cells visible in a segment of petrified wood

Petrified wood (from the Greek root "petro" meaning "rock" or "stone", literally "wood turned into stone") is a type of fossil: it consists of fossil wood where all the organic materials have been replaced with minerals (most often a silicate, such as quartz), while retaining the original structure of the wood. The petrifaction process occurs underground, when wood becomes buried under sediment and is initially preserved due to a lack of oxygen. Mineral-rich water flowing through the sediment deposits minerals in the plant's cells and as the plant's lignin and cellulose decay away, a stone mould forms in its place.

In general, wood takes less than 100 years to petrify. The organic matter needs to become petrified before it decomposes completely.^[1] A forest where the wood has petrified becomes known as a petrified forest.

[edit] Elements

Elements such as manganese, iron and copper in the water/mud during the petrification process give petrified wood a variety of color ranges. Pure quartz crystals are colorless, but when contaminants are added to the process the crystals take on a yellow, red, or other tint.

Following is a list of contaminating elements and related color hues:

• carbon - black
• cobalt - green/blue
• chromium - green/blue
• copper - green/blue
• iron oxides - red, brown, and yellow
• manganese - pink/orange
• manganese oxides - black/yellow

Petrified wood can preserve the original structure of the wood in all its detail, down to the microscopic level. Structures such as tree rings and the various tissues are often observed features.

Petrified wood has a Mohs hardness of 7, the same as quartz.

Petrified wood is the provincial stone of Alberta and also the state gem of Washington.

[edit] Locations

• Argentina - Considered to be one of the world's best petrified reserves, the Petrified Forest National Monument in Chubut Province in the Argentine Patagonia has many trees that measure more than 3 m (10 ft) in diameter and 30 m (100 ft) long. Compared to petrified trees in the United States that measure less than 1.8 m (6 ft) in diameter, the trees of the Central Steppes of Argentina are significantly larger.
• Belgium - Geosite Goudberg near Hoegaarden.^[2]
• Brazil - In the geopark of Paleorrota, there is a vast area with petrified trees.^[3]
• Canada - In the badlands of southern Alberta; petrified wood is the provincial stone of Alberta. Axel Heiberg Island in Nunavut has among the largest petrified forests in the world
• China - in the Junggar Basin of Xinjiang, northwest China government has issued a crackdown on collecting of this material, but large slabs and even large meeting tables have been made out of this colorful replaced wood.
• Czech Republic, Nová Paka - The most famous locality on Permian-Carboniferous rocks in the Czech Republic.
• Germany - The museum of natural history in Chemnitz has a collection of petrified trees found in the town in 1737.
• Egypt petrified forest in Cairo-Suez road, declared a national protectorate by the minstery of environment, also in the area of New Cairo at the Extension of Nasr city, El Qattamiyya, near El Maadi district, Al Farafra oasis^[4], Al Fayoum depression and actually the entire western desert^[5].
• Greece - Petrified Forest of Lesvos, at the western tip of the island of Lesbos, is possibly the largest of the petrified forests, covering an area of over 150 km² and declared a National Monument in 1985. Large, upright trunks complete with root systems can be found, as well as trunks up to 22 m in length.
• Libya - Great Sand Sea - Hundreds of square miles of petrified trunks, branches and other debris mixed with Stone Age artifacts.
• Namibia - Petrified forest of Damaraland
• Ukraine - Petrified araucaria trunks near Druzhkivka.
• United States - Some of the better known petrified wood sites include:
  • Petrified Wood Park in Lemmon, South Dakota.
  • Ginkgo/Wanapum State Park in Washington State.
  • Grotto of the Redemption, a private park in Iowa.
  • Petrified Forest National Park in Arizona.
  • Petrified Forest (California) in California.
  • Mississippi Petrified Forest in Flora, Mississippi.
  • Florissant Fossil Beds National Monument near Florissant, Colorado.
• Australia - Has vast deposits of petrified and opalised wood.
• India- A geological site famous for its petrified woods Thiruvakkarai Village in Chennai, Tamil Nadu. The site is protected by the Geological Survey of India. Petrified woods covers a large area in this site.
• New Zealand - Curio Bay on the Catlins coast contains many petrified wood examples.

[edit] Artificial petrified wood

Artificial petrified wood has been produced in a Washington laboratory. In the process small cubes of pine were soaked in an acid bath for two days, then in a silica solution for another two. The product was then cooked at 1400 °C in an argon atmosphere for two hours. The result was silicon carbide ceramic which preserved the intricate cell structure of the wood. Soaking in a tungsten solution produced a tungsten carbide petrified wood.^[6][7]

[edit] See also

• Petrified palmwood
• Araucarioxylon arizonicum
• Petrified Forest of Lesbos

[edit] References

[edit] External links

Wikimedia Commons has media related to: Petrified wood

• The Petrified forest of Lesvos - Protected Natural Monument
• The Town Museum of Nová Paka
• The Mississippi Petrified Forest