Petrified Wood (Arizona)

Mineralogy of Petrified Wood

Petrified Forest National Park, AZ, USA

Rock Type: Fossil, Mineral Preservation

Color: Varies widely depending on locality
Gravity: 2.58-2.91
Hardness: 6.5-7
Luminescence: Varies depending on locality, often Purple (long wave) / Green (short wave)
Texture: Bark/wood texture, vitreous when polished
Transparency: Opaque

Location: The largest occurrence of petrified wood is near Holbrook, Arizona in the United States. However, this area is protected as a National Park and it is illegal to mine or remove any fossils. Smaller deposits exist in several locations around the world. The most important are in Australia, Argentina, Egypt, Greece, India, Madagascar, Mongolia, Namibia, and the United States.

Rock Type: Petrified Wood is a fossil, a remnant or impression of an organism which lived in the past. Fossils come in many different forms and, depending on what is being preserved, the fossilization process can also be very different. In the case of Petrified Wood, the wood is completely replaced by minerals. In fact, the mineralization process can be so exacting that it literally replaces the wood with minerals on a cell by cell basis. As a result the detail of the original organism is preserved exactly.   

Formation: Petrified wood is the fossilized remains of ancient trees which flourished millions of years ago. Typically when a tree dies, it decomposes relatively quickly, leaving no trace behind. But occasionally, a tree may fall into a river or be swept away in a flood. When this happens there is a chance that the tree may be quickly covered with fine-grained sedimentary materials, such as clay or ash. As the wood decomposes, its outer structure is preserved and replaced by various silica minerals found in the sediment, including Jasper, Chalcedony, and less frequently, Opal. These crystals create the rainbow of colors found in petrified wood. While any tree can potentially be fossilized, most Petrified Woods are a type of conifer tree, similar to modern Pine, Fir, and Redwood trees.

Mining: Typically mined from the primary deposits which still have their original relationship with the host rock. In some locations, whole logs and even entire trees may be found.

Petrified Forest National Park, USA

Enhancements: While Petrified Wood has been artificially produced in a lab in the United States, all tumbled Petrified Wood on the market is fully natural, enhanced only by tumbling, cutting, and polishing.

Map courtesy of TravelBlog
Photos: Raw Petrified Wood, Petrified Forest National Park