Petrifaction
In
Processes
Permineralization
One of the processes involved in petrifaction is permineralization. The
Silicification
Silicification is the process in which organic matter becomes saturated with
Pyritization
Pyritization is a process similar to silicification, but instead involves the deposition of iron and sulfur in the pores and cavities of an organism. Pyritization can result in both solid fossils as well as preserved soft tissues. In marine environments, pyritization occurs when organisms are buried in sediments containing a high concentration of iron sulfides. Organisms release sulfide, which reacts with dissolved iron in the surrounding water, when they decay. This reaction between iron and sulfides forms pyrite (FeS2). Carbonate shell material of the organism is then replaced with pyrite due to a higher concentration of pyrite and a lower concentration of carbonate in the surrounding water. Pyritization occurs to a lesser extent in plants in clay environments.[3]
Replacement
Replacement, the second process involved in petrifaction, occurs when water containing dissolved minerals dissolves the original solid material of an organism, which is then replaced by minerals. This can take place extremely slowly, replicating the microscopic structure of the organism. The slower the rate of the process, the better defined the microscopic structure will be. The minerals commonly involved in replacement are
Uses
Not only are the fossils produced through the process of petrifaction used for paleontological study, but they have also been used as both decorative and informative pieces. Petrified wood is used in several ways. Slabs of petrified wood can be crafted into tabletops, or the slabs themselves are sometimes displayed in a decorative fashion. Also, larger pieces of the wood have been carved into sinks and basins. Other large pieces can also be crafted into chairs and stools. Petrified wood and other petrified organisms have also been used in jewelry, sculpture, clock-making, ashtrays and fruit bowls, and landscape and garden decorations.
Architecture
Petrified wood has also been used in construction. The Petrified Wood Gas Station,[9] located on Main St Lamar, Colorado, was built in 1932 and consists of walls and floors constructed from pieces of petrified wood. The structure, built by W.G. Brown, has since been converted to office space and a used car dealership.[10] Glen Rose, Texas provides even more examples of the use of fossilized wood in architecture. Beginning in the 1920s, the farmers of Somervell County, Texas began uncovering petrified trees. Local craftsmen and masons then built over 65 structures from this petrified wood, 45 of which were still standing as of June 2009. These structures include gas stations, flowerbeds, cottages, restaurants, fountains and gateposts.[11] Glen Rose, Texas is also noted for Dinosaur Valley State Park and the Glen Rose Formation, where fossilized dinosaur footprints from the Cretaceous period can be viewed.[12] Another example of the use of petrified wood in construction is the Agate House Pueblo in the Petrified Forest National Park in Arizona. Built by ancestral Pueblo people about 990 years ago, this eight-room building was constructed almost entirely out of petrified wood and is believed to have served as either a family home or ceremonial center.[13]
Artificial petrifaction
Scientists attempted to artificially petrify organisms as early as the 18th century, when Girolamo Segato claimed to have supposedly "petrified" human remains. His methods were lost, but the bulk of his "pieces" are on display at the Museum of the Department of Anatomy in Florence, Italy.[14]
More recent attempts have been both successful and documented, but should be considered as semi-petrifaction or incomplete petrifaction or at least as producing some novel type of wood composite, as the wood material remains to a certain degree; the constituents of wood (cellulose, lignins, lignans, oleoresins, etc.) have not been replaced by silicate, but have been infiltrated by specially formulated acidic solutions of aluminosilicate salts that gel in contact with wood matter and form a matrix of silicates within the wood after being left to react slowly for a given period of time in the solution or heat-cured for faster results. Hamilton Hicks of Greenwich, Connecticut, received a patent for his "recipe" for rapid artificial petrifaction of wood under US patent 4,612,050 in 1986.[15] Hicks' recipe consists of highly mineralized water and a sodium silicate solution combined with a dilute acid with a pH of 4.0-5.5. Samples of wood are penetrated with this mineral solution through repeated submersion and applications of the solution. Wood treated in this fashion is - according to the claims in the patent - incapable of being burned and acquires the features of petrified wood. Some uses of this product as suggested by Hicks include use by horse breeders who desire fireproof stables constructed of nontoxic material that would also be resistant to chewing of the wood by horses.[16]
In 2005 scientists at the Pacific Northwest National Laboratory (PNNL) reported that they had successfully petrified wood samples artificially. Unlike natural petrification, though, they infiltrated samples in acidic solutions, diffused them internally with titanium and carbon and fired them in a high-temperature oven (circa 1400 °C) in an inert atmosphere to yield a man-made ceramic matrix composite of titanium carbide and silicon carbide still showing the initial structure of wood. Future uses would see these artificially petrified wood-ceramic materials eventually replace metal-based superalloys (which are coated with ultrahard ceramics) in the tool industry. Other vegetal matter could be treated in a similar process and yield abrasive powders.[17]
See also
- Concretion – Compact mass formed by precipitation of mineral cement between particles
- Lithification – Geologic process
- Petrifaction in mythology and fiction
- Petrifying well
- Rhynie chert – Early Devonian sedimentary deposit exhibiting extraordinary fossil detail or completeness
- Substitution pseudomorph – mineral or mineral compound that appears in an atypical form
- Taphonomy – Study of decomposition and fossilization of organisms
References
- ISBN 978-1-4668-8385-7.
- ^ Babcock, Loren. "Permineralization". Access Science Encyclopedia. McGraw-Hill. Retrieved 29 March 2012.
- ^ a b c Perkins, Rogers. "Fossilization: How Do Fossils Form". Fossil Museum. Retrieved Feb 15, 2012.
- .
- ^ Mustoe, G (2008). Mineralogy and geochemistry of late Eocene silicified wood from Florissant Fossil Beds National Monument, Colorado. Geological Society of America. pp. 127–140.
- ^ Leo, R.F.; Barghoorn, E.S. (1976). Silicification of Wood. Harvard University. p. 27.
- ^ Viney, Mike. "Permineralization". The Petrified Wood Museum.
- ^ "How Does Wood Petrify?". National Computational Science in Education. Archived from the original on 17 April 2012. Retrieved 4 April 2012.
- ^ "Petrified Wood Gas Station". Google Maps. August 13, 2018.
- ^ Kirby, Doug; Ken Smith; Mike Wilkins. "Petrified Wood Gas Station". Roadside America. Retrieved 3 April 2012.
- ^ Saltarelli, Mary G. (June 2009). "Irreplaceable Works of Art". Texas Co-op Power Magazine (June 2009). Retrieved 3 April 2012.
- ^ Kuban, Glen J. "Dinosaur Valley State Park". Retrieved 3 April 2012.
- ^ "Agate House". U.S. Department of the Interior. National Park Service. Retrieved 4 April 2012.
- PMID 17580656.
- ^ "Sodium silicate composition" (PDF). Freepatentsonline.com. Retrieved 2016-09-10.
- ^ Mike Viney. "Petrified Wood : The Silicification of Wood by Permineralization" (PDF). Petrifiedwoodmuseum.org. Retrieved 2016-09-10.
- ^ "Process Engineering | Petrified wood yields super ceramics". Chemical Processing. 2005-07-25. Retrieved 2016-09-10.