Petrified Wood - PWAZ
Petrified Wood, Arizona (Araucarioxylon Arizonicum)
Araucarioxylon arizonicum is an extinct species of conifer and is the state fossil of Arizona. The petrified wood of this tree is frequently referred to as "Rainbow Wood" because of the large variety of colors some specimens exhibit. The red and yellow are produced by large particulate forms of iron oxide, the yellow being limonite and the red being hematite. The purple hue comes from extremely fine spherules of hematite distributed throughout the quartz matrix. In the Triassic period (ca. 250 to 200 million years ago), Arizona was a flat tropical expanse in the northwest corner of the super-continent Pangaea. There, a forest grew in which A. arizonicum towered as high as 60 meters (200 ft) and measured more than 120 centimeters (4 ft) in diameter.