225 million years ago
This petrified wood piece originates from the Chinle formation in Northern Arizona that was deposited in the Late Triassic. Petrified wood from this region is notable because of the many different colours that are present in these beautiful silica-rich specimens. So, what does petrified mean? It is when the original organic material is replaced by minerals to create a copy of the organism with its exact unique details but as a solid rock! This species of tree, Araucarioxylon arizonicum,is an extinct conifer that populated this formerly subtropical region. But not all trees were destined to become fossils, due to the numerous conditions that are required for the organic wood to become petrified. Some trees fell into aquatic environments, such as a lake, and were rapidly buried by layers of sediment. This rapid burial allowed the plant remains to stay protected from oxygen and insect destruction. Next, the water-saturated soil must contain dissolved inorganic mineral constituents, such as silica, that are often a result of volcanic ash from a nearby erupting volcano. If the tree had this rapid burial and there was abundant inorganic dissolved material in the water, the tree could begin to petrify. Quartz would slowly begin to form by chemically precipitating out of the water, and slowly but surely all of the organic material in the tree would be replaced. The petrification process usually preserves the exterior appearance of bark and occasionally maintains the internal cellular structures of the tree! Take a close look at our specimen, are the internal structures preserved?