Lake Murray Meteorite

Lake Murray Meteorite
Type	Iron
Class	Magmatic
Group	IIAB
Country	US
Region	Oklahoma
Fall date	90 to 110 million years ago
Found date	1933
TKW	600 pounds (270 kg)

Last updated April 16, 2019

The Lake Murray Meteorite, the largest of its kind ever found in Oklahoma and now ranked as the fifth largest in the world, was discovered on a farm in Carter County, Oklahoma in 1933. At that time it was considered the largest known specimen in the world. The farm was sold to the state of Oklahoma about the same time for the creation of Lake Murray State Park, for which the specimen was named. The largest piece is on display at the park.

Carter County is a county located in the U.S. state of Oklahoma. As of the 2010 census, the population was 47,557. Its county seat is Ardmore. The county was named for Captain Ben W. Carter, a Cherokee who lived among the Chickasaw.

Lake Murray is a 5,700-acre (23 km²) lake in south central Oklahoma, near Ardmore named for Oklahoma Governor William H. Murray. It was created by damming Anadarche and Fourche Maline Creeks. The lake is wholly within Lake Murray State Park, Oklahoma's largest state park, containing over 12,500 acres (51 km²) of relative wilderness. A state-operated lodge and resort is located on the west shore that serves many visitors to the lake, and serves as a base for numerous cabin and campground facilities near the lake.

The meteorite was found on the site of Lake Murray State Park in 1933 by J. C. Dodson, Sr. The core was covered by a sheathing of iron oxide and shale that was about 4 inches (10 cm) thick on the exposed part and up to 6 inches (15 cm) thick on the buried part.^[1] When the specimen was removed from the ground and the sheathing removed, the core measured 30 inches (0.76 m) long, 9 inches (23 cm) thick and tapered in width from 24 inches (61 cm) at one end to 9 inches (23 cm) at the other. It weighed 600 pounds (270 kg).^[2]

A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or moon. When the object enters the atmosphere, various factors such as friction, pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate that energy. It then becomes a meteor and forms a fireball, also known as a shooting star or falling star; astronomers call the brightest examples "bolides". Meteorites vary greatly in size. For geologists, a bolide is a meteorite large enough to create an impact crater.

Iron oxides are chemical compounds composed of iron and oxygen. All together, there are sixteen known iron oxides and oxyhydroxides.

Shale A fine-grained, clastic sedimentary rock

Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. Shale is characterized by breaks along thin laminae or parallel layering or bedding less than one centimeter in thickness, called fissility. It is the most common sedimentary rock.

Allen Graffham, a geologist and curator of the park's Tucker Tower museum, was interested in a more scientific study of the object. He contacted Dr. Lincoln LaPaz of the University of New Mexico about the specimen. LaPaz confirmed that it was a meteorite. He assessed that it was composed primarily of nickel and iron, and estimated that it may have weighed 2,000 pounds (910 kg) when it struck, about 90 to 110 million years ago, but that oxidation had since worn away 5 to 6 inches (13 to 15 cm) of the surface.^[2]

Lincoln LaPaz was an American astronomer from the University of New Mexico and a pioneer in the study of meteors.

The University of New Mexico is a public research university in Albuquerque, New Mexico. Founded in 1889, UNM offers bachelor's, master's, doctoral, and professional degree programs in multiple fields. Its Albuquerque campus encompasses over 600 acres (2.4 km²), and there are branch campuses in Gallup, Los Alamos, Rio Rancho, Taos, and Los Lunas. UNM is categorized as an R1 doctoral university in the Carnegie Classification of Institutions of Higher Education.

LaPaz, then the director of the Institute of Meteoritics at the University, carefully cut the specimen into two pieces. He performed additional tests and classed the specimen as octahedrite. He wrote that it could also be an example of a hexaoctahedrite (a transition between hexahedrite and octahedrite).^[1] A more recent reference states that the meteorite is an iron meteorite belonging to Group IIAB, which can be classified as either a hexahedrite or a coarsest octahedrite.^[3] Chemical analysis showed that the material contained 6.3% nickel (Ni), 0.5% Phosphorus (P), 53.9 parts per million (ppm) Gallium (Ga), 141 ppm Germanium (Ge), and 0.02 ppm Iridium (Ir).^[4]

Octahedrite Structural class of iron meteorites

Octahedrites are the most common structural class of iron meteorites. The structures occur because the meteoric iron has a certain nickel concentration that leads to the exsolution of kamacite out of taenite while cooling.

One half of the specimen was retained at Lake Murray, where it has been displayed at the Tucker Tower museum since the early 1950s.^[4]

The New England Meteoritical Service has posted several photos taken during analysis of the specimen.^[5]

Related Research Articles

Kamacite is an alloy of iron and nickel, which is found on Earth only in meteorites. The proportion iron:nickel is between 90:10 and 95:5; small quantities of other elements, such as cobalt or carbon may also be present. The mineral has a metallic luster, is gray and has no clear cleavage although its crystal structure is isometric-hexoctahedral. Its density is about 8 g/cm³ and its hardness is 4 on the Mohs scale. It is also sometimes called balkeneisen.

The ultimate goal of meteorite classification is to group all meteorite specimens that share a common origin on a single, identifiable parent body. This could be a planet, asteroid, Moon, or other current Solar System object, or one that existed some time in the past. However, with a few exceptions, this goal is beyond the reach of current science, mostly because there is inadequate information about the nature of most Solar System bodies to achieve such a classification. Instead, modern meteorite classification relies on placing specimens into "groups" in which all members share certain key physical, chemical, isotopic, and mineralogical properties consistent with a common origin on a single parent body, even if that body is unidentified. Several meteorite groups classified this way may come from a single, heterogeneous parent body or a single group may contain members that came from a variety of very similar but distinct parent bodies. As such information comes to light, the classification system will most likely evolve.

Desert rose is the colloquial name given to rose-like formations of crystal clusters of gypsum or baryte which include abundant sand grains. The 'petals' are crystals flattened on the c crystallographic axis, fanning open in radiating flattened crystal clusters.

The Campo del Cielo refers to a group of iron meteorites or to the area where they were found. This area is situated on the border between the provinces of Chaco and Santiago del Estero, 1,000 kilometers (620 mi) northwest of Buenos Aires, Argentina. The crater field covers an area of 3 by 18.5 kilometres and contains at least 26 craters, the largest being 115 by 91 metres.

Sikhote-Alin meteorite iron meteorite that fell in 1947 on the Sikhote-Alin Mountains in eastern Siberia

An iron meteorite fell on the Sikhote-Alin Mountains, in southeastern Russia, in 1947. Though large iron meteorite falls had been witnessed previously and fragments recovered, never before in recorded history had a fall of this magnitude been observed. An estimated 23 tonnes of fragments survived the fiery passage through the atmosphere and reached the Earth, but still less than the largest meteorite find, the Hoba meteorite of 60 tonnes.

The Willamette Meteorite, officially named Willamette, is an iron-nickel meteorite found in the U.S. state of Oregon. It is the largest meteorite found in North America and the sixth largest in the world. There was no impact crater at the discovery site; researchers believe the meteorite landed in what is now Canada or Montana, and was transported as a glacial erratic to the Willamette Valley during the Missoula Floods at the end of the last Ice Age. It has long been held sacred by indigenous peoples of the Willamette Valley, including the federally recognized Confederated Tribes of the Grand Ronde Community of Oregon (CTGRC). The indigenous peoples refer to this stone with the name Tomanowos.

Canyon Diablo (meteorite) iron meteorite

The Canyon Diablo meteorites include the many fragments of the asteroid that created Barringer Crater, Arizona, United States. Meteorites have been found around the crater rim, and are named for nearby Canyon Diablo, which lies about three to four miles west of the crater.

The pallasites are a class of stony–iron meteorite.

Iron meteorite meteorite composed of iron-nickel alloy called meteoric iron

Iron meteorites are meteorites that consist overwhelmingly of an iron–nickel alloy known as meteoric iron that usually consists of two mineral phases: kamacite and taenite. Iron meteorites originate from cores of planetesimals.

The Old Woman Meteorite is the largest meteorite found in California and the second largest in the United States. It was discovered in the Old Woman Mountains in southern California in late 1975. It is 38 inches (970 mm) long, 34 inches (860 mm) high, and 30 inches (760 mm) wide. The meteorite is mostly composed of iron, but also contains nickel, as well as small amounts of chromium, cobalt, phosphorus, and sulfur.

The Fukang meteorite is a meteorite that was found in the mountains near Fukang, China in 2000. It is a pallasite—a type of stony–iron meteorite with olivine crystals. It is estimated to be 4.5 billion years old.

The Peekskill meteorite is among the most historic meteorite events on record. Sixteen separate video recordings document the meteorite burning through the Earth's atmosphere, whereupon it struck a parked car in Peekskill, New York. Peekskill is an H6 monomict breccia; its filigreed texture is the result of the shocking and heating following the impact of two asteroids in outer space. The meteorite is of the stony variety and approximately 20% of its mass is tiny flakes of nickel-iron. When it struck Earth, the meteorite weighed 26 pounds (12 kg) and measured one foot in diameter. The Peekskill meteorite is estimated to be 4.4 billion years old.

Gibeon is a meteorite that fell in prehistoric times in Namibia. It was named after the nearest town: Gibeon.

Elbogen, also the Loket Iron, is an iron meteorite that fell in the village of Loket, Karlovy Vary Region, Kingdom of Bohemia, about the year 1400. Also known during the Middle Ages as the "bewitched burgrave" of Elbogen, due to a cursed Count at the Elbogen castle, it is the oldest of 15 recorded falls in the Czech Republic. It has not survived to our time in its original size, having been cut for scientific purposes and its pieces sent to museums all around the world.

The Muonionalusta is a meteorite classified as fine octahedrite, type IVA (Of) which impacted in northern Scandinavia, west of the border between Sweden and Finland, about one million years BCE.

The Grant Meteorite is a meteorite that was discovered in the Zuni Mountains, about 45 miles (72 km) south of Grants, New Mexico. It was unearthed in 1929 although the date of its original groundfall is unknown.

IIG meteorites are a group of iron meteorites. The group currently has six members. They are hexahedrites with large amounts of schreibersite. The meteoric iron is composed of kamacite.

This is a glossary of terms used in meteoritics, the science of meteorites.

IIAB meteorites are a group of iron meteorites. Their structural classification ranges from hexahedrites to octahedrites. IIABs have the lowest concentration of nickel of all iron meteorite groups. All iron meteorites are derived from the metallic planetary cores of their respective parent bodies, but in the case of the IIABs the metallic magma separated to form not only this meteorite group but also the IIG group.

References

1 2 "Preliminary Note on the Lake Murray, Carter County, Oklahoma, Siderite (CN = + 0970,341)." La Paz, L. Meteoritics and Planetary Science, Vol. 1, pp. 109–113 (1953).
1 2 "Rare Meteorite Found, Exhibited In State Park." Resourceful Oklahoma. Volume 3, Number 10, October,1952. Retrieved July 25, 2014.
↑ Meteorite.fr – All about Meteorites. December 9, 2012. Retrieved July 28, 2014.
1 2 "Lake Murray, Oklahoma, U.S.A." Handbook of Iron Meteorites. Volume 2. Buchwald V. F. 1975. pp. 752–754. Retrieved July 26, 2014.
↑ "Lake Murray Restoration and Preservation Images." November 2000. Retrieved July 26, 2014.

External links

A map that is claimed to show the location where the Lake Murray meteorite was discovered.

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[LaPaz-1] 1 2 "Preliminary Note on the Lake Murray, Carter County, Oklahoma, Siderite (CN = + 0970,341)." La Paz, L. Meteoritics and Planetary Science, Vol. 1, pp. 109–113 (1953).

[ResourcefulOK-2] 1 2 "Rare Meteorite Found, Exhibited In State Park." Resourceful Oklahoma. Volume 3, Number 10, October,1952. Retrieved July 25, 2014.

[3] Meteorite.fr – All about Meteorites. December 9, 2012. Retrieved July 28, 2014.

[manoa-4] 1 2 "Lake Murray, Oklahoma, U.S.A." Handbook of Iron Meteorites. Volume 2. Buchwald V. F. 1975. pp. 752–754. Retrieved July 26, 2014.

[5] "Lake Murray Restoration and Preservation Images." November 2000. Retrieved July 26, 2014.