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39-1203: Georgiaite has been found only in the eastern part of central Georgia with only between 1,000 and 2,500 known specimens as of 2018. They are most commonly found as splash-form tektites. Georgiaite specimens that have been found typically have a round shape and pock marked surfaces caused from the extreme conditions of its formation. Georgiaite most commonly is translucent with an olive green color. The size of Georgiaite can vary but most samples collected average around 2 inches (51 mm) at most. Georgiaite, like other tektites , are silicate glass and most closely resemble obsidian . Unlike other North American tektites, Georgiaite contains silica and potassium while showing no traces of any other major elements . Georgiaite has been confirmed to be found only in central and eastern counties in Georgia . The majority of all Georgiaite that has been collected has been from Bleckley County, Georgia and Dodge County, Georgia but other surrounding counties have also found samples in smaller quantities. There are several known collections of Georgiaites used for educational purposes, geological study, and for

78-415: A Mr. Pringle examined them and attempted to classify them. Pringle was unable to assign the specimens to a known mineral species and submitted them to Teall. After analyzing the specimens, Teall concluded that the mineral was mainly composed of titanic acid and magnesia , with an incidental mixture of protoxide of iron . Geikielite has the composition of MgTiO 3 . Teall and Pringle decided to name

117-595: A chunky, blocky appearance, exhibit a layered structure with abundant vesicles, and contain mineral inclusions, such as zircon, baddeleyite , chromite , rutile , corundum , cristobalite , and coesite. Microtektites, the fourth group of tektites, are less than 1 mm in size. They exhibit a variety of shapes ranging from spherical to dumbbell, disc, oval, and teardrop. Their colors range from colorless and transparent to yellowish and pale brown. They frequently contain bubbles and lechatelierite inclusions. Microtektites are typically found in deep-sea sediments that are of

156-439: A few tektites contain partly melted inclusions of shocked and unshocked mineral grains, i.e. quartz , apatite , and zircon , as well as coesite . The difference in water content can be used to distinguish tektites from terrestrial volcanic glasses. When heated to their melting point, terrestrial volcanic glasses turn into a foamy glass because of their content of water and other volatiles. Unlike terrestrial volcanic glass,

195-524: A tektite produces only a few bubbles at most when heated to its melting point, because of its much lower water and other volatiles content. On the basis of morphology and physical characteristics, tektites have traditionally been divided into four groups. Those found on land have traditionally been subdivided into three groups: (1) splash-form (normal) tektites, (2) aerodynamically shaped tektites, and (3) Muong Nong-type (layered) tektites. Splash-form and aerodynamically shaped tektites are only differentiated on

234-734: A type of tektite found in the Czech Republic , was determined to be 14 million years, which agrees well with the age determined for the Nördlinger Ries crater (a few hundred kilometers away in Germany) by radiometric dating of Suevite (an impact breccia found at the crater). Similar agreements exist between tektites from the North American strewnfield and the Chesapeake Bay impact crater and between tektites from

273-521: A volcanic origin. At one time, theories advocating the lunar origin of tektites enjoyed considerable support as part of a spirited controversy about the origin of tektites that occurred during the 1960s. Starting with the publication of research concerning lunar samples returned from the Moon, the consensus of Earth and planetary scientists shifted in favor of theories advocating a terrestrial impact versus lunar volcanic origin. For example, one problem with

312-402: Is a refractory mineral, with a melting point of 2700 °C. Hafnium is a substituting impurity and may be present in quantities ranging from 0.1 to several percent. It can be found in igneous rocks containing potassium feldspar and plagioclase . Baddeleyite is commonly not found with zircon (ZrSiO 4 ), because it forms in silica-undersaturated rocks, such as mafic rocks. This

351-1016: Is because, when silica is free in the system (silica-saturated/oversaturated), zircon is the dominating phase, not baddeleyite. It belongs to the monoclinic-prismatic class , of the P2 1 /c crystal system . It has been used for geochronology . Baddeleyite was first found in Sri Lanka in 1892. It can be found in numerous terrestrial and extraterrestrial rocks. Some of these terrestrial rocks are carbonatite , kimberlite , alkaline syenite , some rocks of layered mafic intrusions , diabase dikes , gabbroid sills and anorthosite . Some examples of extraterrestrial rocks are tektites , meteorites and lunar basalt . Studies have shown that zircon and baddeleyite can be recovered from some anorthositic rocks in Proterozoic anorthosite complexes. Places where these Proterozoic anorthosite complexes can be found are:

390-451: Is black in color with a submetallic lustre. It has a 6.5 hardness, and a brownish-white streak. Baddeleyite can also be brown, brownish black, green, and greenish brown. Its streak is white, or brownish white. It has a distinct cleavage along {001} and tends to twin along (100). It belongs to the monoclinic system and is part of the P21/c group. It was named for Joseph Baddeley. The mineral

429-478: Is extremely rare. Baddeleyite belongs to the oxide group, having a composition of ZrO 2 . Similar minerals belonging to the same group are the rutile group: rutile (TiO 2 ), pyrolusite (MnO 2 ), cassiterite (SnO 2 ), uraninite (UO 2 ) and thorianite (ThO 2 ). Baddeleyite is chemically homogeneous, but it may contain impurities such as Ti, Hf, and Fe. Higher concentrations of Ti and Fe are restricted to mafic - ultramafic rocks . Baddeleyite

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468-413: Is interpreted as indicating that the proposed Central American strewn field likely covers Belize, Honduras , Guatemala , Nicaragua , and possibly parts of southern Mexico . The hypothesized Pantasma Impact Crater in northern Nicaragua might be the source of these tektites. The ages of tektites from the four strewnfields have been determined using radiometric dating methods. The age of moldavites ,

507-466: Is that tektites consist of terrestrial debris that was ejected during the formation of an impact crater . During the extreme conditions created by a hypervelocity meteorite impact, near-surface terrestrial sediments and rocks were either melted, vaporized, or some combination of these, and ejected from an impact crater. After ejection from the impact crater, the material formed millimeter- to centimeter-sized bodies of molten material, which as they re-entered

546-475: The Moon . In addition, some tektites contain relict mineral inclusions ( quartz , zircon , rutile , chromite , and monazite ) that are characteristic of terrestrial sediments and crustal and sedimentary source rocks. Also, three of the four tektite strewnfields have been linked by their age and chemical and isotopic composition to known impact craters. A number of different geochemical studies of tektites from

585-485: The 1950s to the 1990s, O'Keefe argued for the lunar origin of tektites based upon their chemical, i.e. rare-earth, isotopic, and bulk, composition and physical properties. Chapman used complex orbital computer models and extensive wind tunnel tests to argue that the so-called Australasian tektites originated from the Rosse ejecta ray of the large crater Tycho on the Moon's near side. O'Keefe, Povenmire, and Futrell claimed on

624-475: The Australasian strewn field, are splash-form tektites (buttons) which display a secondary ring or flange. The secondary ring or flange is argued as having been produced during the high-speed re-entry and ablation of a solidified splash-form tektite into the atmosphere. Muong Nong tektites are typically larger, greater than 10 cm in size and 24 kg in weight, irregular, and layered tektites. They have

663-421: The Australasian strewnfield concluded that these tektites consist of melted Jurassic sediments, or sedimentary rocks that were weathered and deposited about 167 Mya . Their geochemistry suggests that the source of Australasian tektites is a single sedimentary formation with a narrow range of stratigraphic ages close to 170 Mya, more or less. This effectively refutes multiple impact hypotheses. Although

702-515: The Australasian, Central European, Ivory Coast, and North American. As summarized by Koeberl, the tektites within each strewn field are related to each other with respect to the criteria of petrological, physical, and chemical properties, as well as their age. In addition, three of the four strewn fields have been clearly linked with impact craters using those same criteria. Recognized types of tektites, grouped according to their known strewn fields, their associated craters, and ages are: Comparing

741-653: The Ivory Coast strewnfield and the Lake Bosumtwi Crater. Ages of tektites have usually been determined by either the K-Ar method, fission-track dating, the Ar-Ar technique, or combination of these techniques. Tektites in geological and archaeological deposits have been used as age markers of stratified deposits, but this practice is controversial. The overwhelming consensus of Earth and planetary scientists

780-1067: The Laramie Anorthosite Complex in Wyoming, the Nain and Grenville provinces of Canada, the Vico Volcanic Complex in Italy, and Minas Gerais and Jacupiranga , São Paulo , Brazil . Baddeleyite forms in igneous rocks low in silica, it can be found in rocks containing potassium feldspar and plagioclase. It has been observed in thin section that baddeleyite forms within plagioclase grains. Associated minerals include ilmenite , zirkelite , apatite , magnetite , perovskite , fluorite , nepheline , pyrochlore and allanite . Because of their refractory nature and stability under diverse conditions, baddeleyite grains, along with zircon , are used for uranium-lead radiometric age determinations. There has been some dispute in

819-640: The Moon. Verbeek's proposal of an extraterrestrial origin for tektites was soon seconded by the Austrian geologist Franz E. Suess. Subsequently, it was argued that tektites consist of material that was ejected from the Moon by major hydrogen-driven lunar volcanic eruptions and then drifted through space to later fall to Earth as tektites. The major proponents of the lunar origin of tektites include NASA scientist John A. O'Keefe , NASA aerodynamicist Dean R. Chapman , meteorite and tektite collector Darryl Futrell, and long-time tektite researcher Hal Povenmire. From

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858-422: The atmosphere, rapidly cooled to form tektites that fell to Earth to create a layer of distal ejecta hundreds or thousands of kilometers away from the impact site. The terrestrial source for tektites is supported by well-documented evidence. The chemical and isotopic composition of tektites indicates that they are derived from the melting of silica -rich crustal and sedimentary rocks , which are not found on

897-439: The basis of behavior of glass melts that the homogenization, which is called "fining", of silica melts that characterize tektites could not be explained by the terrestrial-impact theory. They also argued that the terrestrial-impact theory could not explain the vesicles and extremely low water and other volatile content of tektites. Futrell also reported the presence of microscopic internal features within tektites, which argued for

936-414: The basis of their appearance and some of their physical characteristics. Splash-form tektites are centimeter-sized tektites that are shaped like spheres, ellipsoids, teardrops, dumbbells, and other forms characteristic of isolated molten bodies. They are regarded as having formed from the solidification of rotating liquids, and not atmospheric ablation. Aerodynamically shaped tektites, which are mainly part of

975-473: The bulk chemical and isotopic composition of tektites is closer to those of shales and similar sedimentary rocks and quite different from the bulk chemical and isotopic composition of terrestrial volcanic glasses. Third, tektites contain virtually no water (<0.02 wt%), unlike terrestrial volcanic glasses. Fourth, the flow-banding within tektites often contains particles and bands of lechatelierite , which are not found in terrestrial volcanic glasses. Finally,

1014-551: The chemical, i.e. rare-earth, isotopic, and bulk composition evidence as decisively demonstrating that tektites are derived from terrestrial crustal rock, i.e. sedimentary rocks, that are unlike any known lunar crust. Baddeleyite Baddeleyite is a rare zirconium oxide mineral (ZrO 2 or zirconia ), occurring in a variety of monoclinic prismatic crystal forms. It is transparent to translucent, has high indices of refraction , and ranges from colorless to yellow, green, and dark brown. See etymology below . Baddeleyite

1053-426: The formation and widespread distribution of tektites is widely accepted to require the intense (superheated) melting of near-surface sediments and rocks at the impact site and the following high-velocity ejection of this material from the impact crater, the exact processes involved remain poorly understood. One possible mechanism for the formation of tektites is by the jetting of highly shocked and superheated melt during

1092-487: The initial contact/compression stage of impact crater formation. Alternatively, various mechanisms involving the dispersal of shock-melted material by an expanding vapor plume, which is created by a hypervelocity impact, have been used to explain the formation of tektites. Any mechanism by which tektites are created must explain chemical data that suggest that parent material from which tektites were created came from near-surface rocks and sediments at an impact site. In addition,

1131-733: The late 1970s suggested either Zhamanshin or Elgygytgyn as the source of the Australasian strewnfield . Povenmire and others have proposed the existence of an additional tektite strewn field, the Central American strewn field. Evidence for this reported tektite strewn field consists of tektites recovered from western Belize in the area of the villages of Bullet Tree Falls, Santa Familia, and Billy White. This area lies about 55 km east-southeast of Tikal, where 13 tektites, two of which were dated as being 820,000 years old, of unknown origin were found. A limited amount of evidence

1170-462: The lunar origin theory is that the arguments for it that are based upon the behavior of glass melts use data from pressures and temperatures that are vastly uncharacteristic of and unrelated to the extreme conditions of hypervelocity impacts. In addition, various studies have shown that hypervelocity impacts are likely quite capable of producing low- volatile melts with extremely low water content. The consensus of Earth and planetary scientists regards

1209-609: The new mineral geikielite , naming it after Sir  Archibald Geikie , then the Director General of the Geological Survey. Baddeley sent more specimens to Teall, in order to provide an exemplary specimen for display at the Museum of Practical Geology. While trying to find the specimens, Teall noticed that one of them was different from the rest: This new mineral was black in color, with a submetallic lustre, and

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1248-435: The number of known impact craters versus the number of known strewn fields, Natalia Artemieva considered essential factors such as the crater must exceed a certain diameter to produce distal ejecta, and that the event must be relatively recent. Limiting to diameters 10 km or more and younger than 50 Ma , the study yielded a list of 13 candidate craters, of which the youngest eight are given below. Preliminary papers in

1287-967: The public to view. One such collection can be found at the Smithsonian Natural History Museum in Washington, D.C. There is also a large donated collection at the Fernbank Museum of Natural History in Atlanta, GA . This article about a specific mineral or mineraloid is a stub . You can help Misplaced Pages by expanding it . This glass material related article is a stub . You can help Misplaced Pages by expanding it . Tektite Tektites (from Ancient Greek τηκτός ( tēktós )  'molten') are gravel -sized bodies composed of black, green, brown or grey natural glass formed from terrestrial debris ejected during meteorite impacts . The term

1326-577: The same ages as those of the four known strewn fields. Microtektites of the Australasian strewn field have also been found on land within Chinese loess deposits, and in sediment-filled joints and decimeter-sized weathering pits developed within glacially eroded granite outcrops of the Victoria Land Transantarctic Mountains, Antarctica. Most tektites have been found within four geographically extensive strewn fields:

1365-587: The scarcity of known strewn fields relative to the number of identified impact craters indicate that very special and rarely met circumstances are required for tektites to be created by a meteorite impact. Though the meteorite impact theory of tektite formation is widely accepted, there has been considerable controversy about their origin in the past. As early as 1897, the Dutch geologist Rogier Diederik Marius Verbeek (1845–1926) suggested an extraterrestrial origin for tektites: he proposed that they fell to Earth from

1404-440: The seven shortest Zr-O, ranging from 2.04 to 2.26 Å, and the second Zr-O separation is 3.77 Å. Because of this, the coordination of baddeleyite was determined to be sevenfold. Baddeleyite's structure is a combination of tetrahedrally coordinated oxide ions parallel to (100) with triangular coordinated oxide ions. This explains baddeleyite's tendency to twin along the (100) planes. It has been observed that baddeleyite without twinning

1443-506: The structure of baddeleyite. Originally, the mineral was assigned to the 8-fold coordination by Naray Szabo. This structure was ruled out due to the inaccuracy of the data used to establish it. Baddeleyite has the group symmetry P2 1 /c with four ZrO 2 in the unit cell . It has unit cell dimensions of: a = 5.169 b = 5.232 c = 5.341 Å (all ± 0.008 Å), β = 99˚15ˊ ± 10ˊ. The coordination number for ZrO 2 has been found to be 7. The mineral has two types of separations. The first being

1482-604: Was coined by Austrian geologist Franz Eduard Suess (1867–1941), son of Eduard Suess . They generally range in size from millimetres to centimetres. Millimetre-scale tektites are known as microtektites . Tektites are characterized by: Although tektites are superficially similar to some terrestrial volcanic glasses ( obsidians ), they have unusual distinctive physical characteristics that distinguish them from such glasses. First, they are completely glassy and lack any microlites or phenocrysts , unlike terrestrial volcanic glasses. Second, although high in silica (>65 wt%),

1521-718: Was discovered in Rakwana , Ceylon (now Sri Lanka ). Baddeley was a superintendent of a railroad project in Rakwana. As recounted by J.J.H. Teall – director of the British Geological Survey in the early 1900s – baddeleyite was discovered consequent to the discovery of geikielite . Baddeley sent specimens of several pebbles from the Rakwana railroad excavations to the Museum of Practical Geology in London , where

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