Schreibersite is a rare iron nickel phosphide mineral, 3P, though common in iron-nickel meteorites. The only known occurrence of the mineral on Earth is located on Disko Island in Greenland. Another name used for the mineral is rhabdite, it forms tetragonal crystals with perfect 001 cleavage. Its color ranges from bronze to brass yellow to silver white, it has a density of 7.5 and a hardness of 6.5 – 7. It is opaque with a dark gray streak, it was named after the Austrian scientist Carl Franz Anton Ritter von Schreibers, one of the first to describe it from iron meteorites. Schreibersite is reported from Slovak Republic. In 2007, researchers reported that schreibersite and other meteoric phosphorus bearing minerals may be the ultimate source for the phosphorus, so important for life on Earth. In 2013, researchers reported that they had produced pyrophosphite, a possible precursor to pyrophosphate, the molecule associated with ATP, a co-enzyme central to energy metabolism in all life on Earth, their experiment consisted of subjecting a sample of schreibersite to a warm, acidic environment found in association with volcanic activity, activity, far more common on the primordial Earth.
They hypothesized that their experiment might represent what they termed "chemical life", a stage of evolution which may have led to the emergence of biological life as exists today. Glossary of meteoritics List of minerals List of minerals named after people
Moissanite is occurring silicon carbide and its various crystalline polymorphs. It has the chemical formula SiC and is a rare mineral, discovered by the French chemist Henri Moissan in 1893. Silicon carbide is useful for commercial and industrial applications due to its hardness, optical properties and thermal conductivity. Efforts to synthesize silicon carbide in a laboratory began in the early 1900s. Mineral moissanite was discovered by Henri Moissan while examining rock samples from a meteor crater located in Canyon Diablo, Arizona, in 1893. At first, he mistakenly identified the crystals as diamonds, but in 1904 he identified the crystals as silicon carbide. Artificial silicon carbide had been synthesized in the lab by Edward G. Acheson just two years before Moissan's discovery; the mineral form of silicon carbide was named moissanite in honor of Moissan on in his life. The discovery in the Canyon Diablo meteorite and other places was challenged for a long time as carborundum contamination from man-made abrasive tools.
Until the 1950s, no other source for moissanite than meteorites had been encountered. In 1958, moissanite was found in the Green River Formation in Wyoming and, the following year, as inclusions in kimberlite from a diamond mine in Yakutia, yet the existence of moissanite in nature was questioned as late as 1986 by the American geologist Charles Milton. Moissanite, in its natural form, remains rare, it has been discovered only from upper mantle rock to meteorites. Discoveries show that it occurs as inclusions in diamonds and such ultramafic rocks as kimberlite and lamproite, it has been identified as presolar grains in carbonaceous chondrite meteorites. Analysis of silicon carbide grains found in the Murchison meteorite has revealed anomalous isotopic ratios of carbon and silicon, indicating an origin from outside the solar system. 99% of these silicon carbide grains originate around carbon-rich asymptotic giant branch stars. Silicon carbide is found around these stars, as deduced from their infrared spectra.
All applications of silicon carbide today use synthetic material, as the natural material is scarce. Silicon carbide was first synthesized by Jöns Jacob Berzelius, best known for his discovery of silicon. Years Edward Goodrich Acheson produced viable minerals that could substitute for diamond as an abrasive and cutting material; this was possible, as moissanite is one of the hardest substances known, with a hardness below that of diamond and comparable with those of cubic boron nitride and boron. Pure synthetic moissanite can be made from thermal decomposition of the preceramic polymer poly, requiring no binding matrix, e.g. cobalt metal powder. The crystalline structure is held together with strong covalent bonding similar to diamonds, that allows moissanite to withstand high pressures up to 52.1 gigapascals. Colors vary and are graded from D to K range on the diamond color grading scale. Moissanite was introduced to the jewelry market in 1998 after Charles & Colvard known as C3 Inc. received patents to create and market lab-grown silicon carbide gemstones, becoming the first firm to do so.
Charles & Colvard makes and distributes moissanite jewelry and loose gems under the trademarks Forever One, Forever Brilliant and Forever Classic. Other manufacturers market silicon carbide gemstones under trademarked names such as Amora and Berzelian. Moissanite is regarded as a diamond alternative, with some optical properties exceeding those of diamond, its lower price and less exploitative mining practices necessary to obtain it make it a popular alternative to diamonds. Due in part to the similar thermal conductivity of moissanite and diamond, it is a popular target for scams. In addition, thermochromism is exhibited in moissanite, such that heating it will cause it to change color starting at around 65 °C; this color change can be diagnostic for distinguishing diamond from moissanite, although birefringence and electrical conductivity differential are more practical diagnostic differentiators. On the Mohs scale of mineral hardness it is a 9.5, with a diamond being a 10. In many developed countries, the use of moissanite in jewelry was controlled by the patents held by Charles & Colvard.
Because of its hardness, it can be used as a replacement for diamond. Since large diamonds are too expensive to be used as anvils, synthetic moissanite is more used in large-volume experiments. Synthetic moissanite is interesting for electronic and thermal applications because its thermal conductivity is similar to that of diamonds. High power silicon carbide electronic devices are expected to find use in the design of protection circuits used for motors and energy storage or pulse power systems, it exhibits thermoluminescence, making it useful in radiation dosimetry. Glossary of meteoritics Engagement ring Fair trade Charles & Colvard Diamond Cubic zirconia Nassau, Kurt. "Moissanite: a new synthetic gemstone material". Journal of Gemmology. 26: 425–438. Doi:10.15506/JoG.19184.108.40.2065
Widmanstätten patterns called Thomson structures, are figures of long nickel-iron crystals, found in the octahedrite iron meteorites and some pallasites. They consist of a fine interleaving of kamacite and taenite ribbons called lamellae. In gaps between the lamellae, a fine-grained mixture of kamacite and taenite called plessite can be found. Widmanstätten patterns describe features in modern steels and zirconium alloys. In 1808, these figures were named after Count Alois von Beckh Widmanstätten, the director of the Imperial Porcelain works in Vienna. While flame heating iron meteorites, Widmanstätten noticed color and lustre zone differentiation as the various iron alloys oxidized at different rates, he did not publish his findings. The discovery was acknowledged by Carl von Schreibers, director of the Vienna Mineral and Zoology Cabinet, who named the structure after Widmanstätten. However, it is now believed that full credit for the discovery should be assigned to the English mineralogist William Thomson, as he published the same findings four years earlier.
Working in Naples in 1804, Thomson treated a Krasnojarsk meteorite with nitric acid in an effort to remove the dull patina caused by oxidation. Shortly after the acid made contact with the metal, strange figures appeared on the surface, which he detailed as described above. Civil wars and political instability in southern Italy made it difficult for Thomson to maintain contact with his colleagues in England; this was demonstrated in his loss of important correspondence. As a result, in 1804, his findings were only published in French in the Bibliothèque Britannique. At the beginning of 1806, Napoleon invaded the Kingdom of Naples and Thomson was forced to flee to Sicily and in November of that year, he died in Palermo at the age of 46. In 1808, Thomson's work was again published posthumously in Italian in Atti dell'Accademia Delle Scienze di Siena; the Napoleonic wars obstructed Thomson's contacts with the scientific community and his peregrinations across Europe, in addition to his early death, obscured his contributions for many years.
The most common names for these figures are Widmanstätten pattern and Widmanstätten structure, however there are some spelling variations: Widmanstetter Widmannstätten Widmanstatten Moreover, due the discover priority of G. Thomson, several authors suggested to call these figures Thomson structure or Thomson-Widmanstätten structure. Iron and nickel form homogeneous alloys at temperatures below the melting point. At temperatures below 900 to 600 °C, two alloys with different nickel content are stable: kamacite with lower Ni-content and taenite with high Ni. Octahedrite meteorites have a nickel content intermediate between the norm for taenite; the formation of Ni-poor kamacite proceeds by diffusion of Ni in the solid alloy at temperatures between 700 and 450 °C, can only take place during slow cooling, about 100 to 10,000 °C/Myr, with total cooling times of 10 Myr or less. This explains; the crystalline patterns become visible when the meteorites are cut and acid etched, because taenite is more resistant to the acid.
In the picture shown, the broad white bars are kamacite, the thin line-like ribbons are taenite. The dark mottled areas are called plessite; the dimension of kamacite lamellae ranges from coarsest to finest as the nickel content increases. This classification is called structural classification. Since nickel-iron crystals grow to lengths of some centimetres only when the solid metal cools down at an exceptionally slow rate, the presence of these patterns is the proof of the extraterrestrial origin of the material and can be used to determine if a piece of iron comes from a meteorite; the methods used to reveal the Widmanstätten pattern on iron meteorites vary. Most the slice is ground and polished, etched with a chemical such as nitric acid or ferric chloride and dried. Cutting the meteorite along different planes affects the shape and direction of Widmanstätten figures because kamacite lamellae in octahedrites are arranged. Octahedrites derive their name from the crystal structure paralleling an octahedron.
Opposite faces are parallel so, although an octahedron has 8 faces, there are only 4 sets of kamacite plates. Iron and nickel-iron form crystals with an external octahedral structure only rarely, but these orientations are still plainly detectable crystallographically without the external habit. Cutting an octahedrite meteorite along different planes will result in one of these cases: perpendicular cut to one of the three axes: two sets of bands at right angles each other parallel cut to one of the octahedron faces: three sets of bands running at 60° angles each other any other angle: four sets of bands with different angles of intersection The term Widmanstätten structure is used on non-meteoritic material to indicate a structure with a geometrical pattern resulting from the formation of a new phase along certain crystallographic planes
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. Octahedrites derive their name from the crystal structure paralleling an octahedron. Opposite faces are parallel so, although an octahedron has 8 faces, there are only 4 sets of kamacite plates. Due to a long cooling time in the interior of the parent asteroids, these alloys have crystallized into intermixed millimeter-sized bands; when polished and acid etched the classic Widmanstätten patterns of intersecting lines of lamellar kamacite, are visible. In gaps between the kamacite and taenite lamellae, a fine-grained mixture called plessite is found. An iron nickel phosphide, schreibersite, is present in most nickel-iron meteorites, as well as an iron-nickel-cobalt carbide, cohenite. Graphite and troilite occur in rounded nodules up to several cm in size. Octahedrites can be grouped by the dimensions of kamacite lamellae in the Widmanstätten pattern, which are related to the nickel content: Coarsest octahedrites, lamellae width >3.3 mm, 5-9% Ni, symbol Ogg Coarse octahedrites, lamellae 1.3-3.3 mm, 6.5-8.5% Ni, symbol Og Medium octahedrites, lamellae 0.5-1.3 mm, 7-13% Ni, symbol Om Fine octahedrites, lamellae 0.2-0.5 mm, 7.5-13% Ni, symbol Of Finest octahedrites, lamellae <0.2 mm, 17-18% Ni, symbol Off Plessitic octahedrites, kamacite spindles, a transitional structure between octahedrites and ataxites, 9-18% Ni, symbol Opl Octahedrite is an obsolete synonym for anatase, one of the three known titanium dioxide minerals.
Glossary of meteoritics Webmineral Meteorites Australia
Eugene Merle Shoemaker
Eugene Merle Shoemaker known as Gene Shoemaker, was an American geologist and one of the founders of the field of planetary science. He is best known for co-discovering the Comet Shoemaker–Levy 9 with his wife Carolyn S. Shoemaker and David H. Levy; this comet hit Jupiter in July 1994: the impact was televised around the world. Shoemaker was well known for his studies of terrestrial craters, such as Barringer Meteor Crater in Arizona. Shoemaker was the first director of the United States Geological Survey's Astrogeology Research Program. Shoemaker was born in Los Angeles, the son of Muriel May, a teacher, George Estel Shoemaker, who worked in farming, business and motion pictures, his parents were natives of Nebraska. During Gene's childhood they moved between Los Angeles, New York City, New York and Wyoming, as George worked on a variety of jobs. George hated living in big cities, was quite satisfied to take a job as director of education for a Civilian Conservation Corps camp in Wyoming, his wife soon found life in a remote cabin quite unsatisfactory.
They compromised. She could teach in the Buffalo School of Practice of the State Teachers College at Buffalo during the school year while keeping Gene with her both would return to Wyoming during the summers. Gene's passion for studying rocks was ignited by the science education courses offered by the Buffalo Museum of Education, he enrolled in the School of Practice in the fourth grade, began collecting samples of minerals. Within a year, he was taking high-school-level evening courses; the family moved back to Los Angeles in 1942, where Gene enrolled in Fairfax High School at the age of thirteen. He completed high school in three years. During that time he played violin in the school orchestra, excelled in gymnastics, got a summer job as an apprentice lapidary. Gene enrolled in the Caltech at the age of sixteen, his classmates were older, more mature and on a fast track to graduate before serving in World War II. Gene earned his bachelor's degree in 1948, at age nineteen, he undertook the study of Precambrian metamorphic rocks in northern New Mexico, earning his M. Sc. degree from Caltech in 1949.
While Shoemaker was attending Caltech, his roommate was Richard Spellman, a young man from Chico, California. Although Shoemaker had enrolled in a doctoral program at Princeton University, Gene returned to California, to serve as best man at Richard's wedding in 1950, he met Richard's sister, for the first time on that occasion. Carolyn had been born in Gallup, New Mexico in 1929, but the Spellman family had moved to Chico soon afterward. Carolyn had earned degrees from Chico State College in history and political science, she had never exhibited any interest in scientific subjects while growing up, had taken one geology course in college, which she had found quite boring. The couple formed a "pen pal" relationship while Gene spent the next year in Princeton, followed by a two-week vacation touring the Colorado Plateau, she told others that,"listening to Gene explaining geology made what she had thought was a boring subject into an exciting and interesting pursuit of knowledge." The couple married on August 17, 1951.
The Shoemakers had three children: one son. Carolyn saw her work as keeping house and raising the children after they settled in Flagstaff in the 1960s, she had tried teaching school before they found the work unsatisfying. She traveled sometimes with Gene, but stopped after she noticed that her absence affected the children. After their children were grown, Carolyn wanted something meaningful to combat the "empty nest" feeling. By Gene Shoemaker suggested that she take up astronomy and join his team looking for asteroids approaching Earth. A student working at Lowell Observatory commenced teaching her astronomy, she showed great potential and launched her career as a planetary astronomer at age 51. She continues the work to the present; the United States Geological Survey hired Shoemaker in 1950. His first assignment was to search for uranium deposits in Colorado, his next mission was to study volcanic processes, since other investigators had noticed that uranium deposits were located in the vents of ancient volcanoes.
This study led him to explore the Hopi Buttes of Northern Arizona, which happened to be near Meteor Crater. Daniel Barringer, an entrepreneur and mining engineer who had discovered Meteor Crater in 1891, had postulated that it had been caused by the impact of a meteor. About the same time, G. K. Gilbert, the chief geologist of the USGS, examined the crater and announced that it had been created by an explosive venting of volcanic steam. A majority of scientists accepted Gilbert's explanation of the cause of the crater, This theory remained as conventional wisdom until Shoemaker's investigations a half century later. For his Ph. D. degree at Princeton, under the guidance of Harry Hammond Hess, Shoemaker studied the impact dynamics of Barringer Meteor Crater. Shoemaker noted Meteor Crater had the same form and structure as two explosion craters created from atomic bomb tests at the Nevada Test Site, notably Jangle U in 1951 and Teapot Ess in 1955. In 1960, Edward C. T. Chao and Shoemaker identified shocked quartz at Meteor Crater, proving the crater was formed from an impact generating high temperatures and pressures.
They followed this discovery with the identification of coesite within suevite at Nördlinger Ries, proving its impact origin. In 1960, Shoemaker directed a team at the USGS center in Menlo Park, California, to generate the first geol
Arizona is a state in the southwestern region of the United States. It is part of the Western and the Mountain states, it is the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona shares the Four Corners region with Utah and New Mexico. Arizona is the 48th state and last of the contiguous states to be admitted to the Union, achieving statehood on February 14, 1912, coinciding with Valentine's Day. Part of the territory of Alta California in New Spain, it became part of independent Mexico in 1821. After being defeated in the Mexican–American War, Mexico ceded much of this territory to the United States in 1848; the southernmost portion of the state was acquired in 1853 through the Gadsden Purchase. Southern Arizona is known for its desert climate, with hot summers and mild winters. Northern Arizona features forests of pine, Douglas fir, spruce trees. There are ski resorts in the areas of Flagstaff and Tucson. In addition to the Grand Canyon National Park, there are several national forests, national parks, national monuments.
About one-quarter of the state is made up of Indian reservations that serve as the home of 27 federally recognized Native American tribes, including the Navajo Nation, the largest in the state and the United States, with more than 300,000 citizens. Although federal law gave all Native Americans the right to vote in 1924, Arizona excluded those living on reservations in the state from voting until the state Supreme Court ruled in favor of Native American plaintiffs in Trujillo v. Garley; the state's name appears to originate from an earlier Spanish name, derived from the O'odham name alĭ ṣonak, meaning "small spring", which applied only to an area near the silver mining camp of Planchas de Plata, Sonora. To the European settlers, their pronunciation sounded like "Arissona"; the area is still known as alĭ ṣonak in the O'odham language. Another possible origin is the Basque phrase haritz ona, as there were numerous Basque sheepherders in the area. A native Mexican of Basque heritage established the ranchería of Arizona between 1734 and 1736 in the current Mexican state of Sonora, which became notable after a significant discovery of silver there, c.
1737. There is a misconception. For thousands of years before the modern era, Arizona was home to numerous Native American tribes. Hohokam and Ancestral Puebloan cultures were among the many that flourished throughout the state. Many of their pueblos, cliffside dwellings, rock paintings and other prehistoric treasures have survived, attracting thousands of tourists each year; the first European contact by native peoples was with Marcos de Niza, a Spanish Franciscan, in 1539. He explored parts of the present state and made contact with native inhabitants the Sobaipuri; the expedition of Spanish explorer Coronado entered the area in 1540–1542 during its search for Cíbola. Few Spanish settlers migrated to Arizona. One of the first settlers in Arizona was José Romo de Vivar. Father Kino was the next European in the region. A member of the Society of Jesus, he led the development of a chain of missions in the region, he converted many of the Indians to Christianity in the Pimería Alta in the 1690s and early 18th century.
Spain founded presidios at Tubac in 1752 and Tucson in 1775. When Mexico achieved its independence from the Kingdom of Spain and its Spanish Empire in 1821, what is now Arizona became part of its Territory of Nueva California known as Alta California. Descendants of ethnic Spanish and mestizo settlers from the colonial years still lived in the area at the time of the arrival of European-American migrants from the United States. During the Mexican–American War, the U. S. Army occupied the national capital of Mexico City and pursued its claim to much of northern Mexico, including what became Arizona Territory in 1863 and the State of Arizona in 1912; the Treaty of Guadalupe Hidalgo specified that, in addition to language and cultural rights of the existing inhabitants of former Mexican citizens being considered as inviolable, the sum of US$15 million dollars in compensation be paid to the Republic of Mexico. In 1853, the U. S. acquired the land south below the Gila River from Mexico in the Gadsden Purchase along the southern border area as encompassing the best future southern route for a transcontinental railway.
What is now known as the state of Arizona was administered by the United States government as part of the Territory of New Mexico until the southern part of that region seceded from the Union to form the Territory of Arizona. This newly established territory was formally organized by the Confederate States government on Saturday, January 18, 1862, when President Jefferson Davis approved and signed An Act to Organize the Territory of Arizona, marking the first official use of the name "Territory of Arizona"; the Southern territory supplied the Confederate government with men and equipment. Formed in 1862, Arizona scout companies served with the Confederate States Army duri
Kamacite is an alloy of iron and nickel, found on Earth only in meteorites. The proportion iron:nickel is between 90:10 and 95:5; 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 sometimes called balkeneisen. The name was coined in 1861 and is derived from the Greek root καμακ- "kamak" or κάμαξ "kamaks", meaning vine-pole, it is a major constituent of iron meteorites. In the octahedrites it is found in bands interleaving with taenite forming Widmanstätten patterns. In hexahedrites, fine parallel lines called Neumann lines are seen, which are evidence for structural deformation of adjacent kamacite plates due to shock from impacts. At times kamacite can be found so intermixed with taenite that it is difficult to distinguish them visually, forming plessite; the largest documented kamacite crystal measured 92×54×23 cm. Kamacite has many unique physical properties including Thomson structures and high density.
Kamacite is opaque, its surface displays varying shades of gray streaking, or "quilting" patterns. Kamacite has a metallic luster. Kamacite can vary in hardness based on the extent of shock it has undergone, but ranks a four on the mohs hardness scale. Shock increases kamacite hardness, but this is not 100% reliable in determining shock histories as there is a myriad of other reasons the hardness of kamacite could increase. Kamacite has a measured density of 7.9 g/cm3. It has a massive crystal habit but individual crystals are indistinguishable in natural occurrences. There are no planes of cleavage present in kamacite. Kamacite is magnetic, isometric which makes it behave optically isometrically. Kamacite occurs with taenite and a mixed area of kamacite and taenite referred to as plessite. Taenite contains more nickel than kamacite; the increase in nickel content causes taenite to have a face-centered unit cell, whereas kamacite's higher iron content causes its unit cell to be body centered. This difference is caused by nickel and iron having a similar size but different interatomic magnetic and quantum interactions.
There is evidence of a tetragonal phase, observed in X-ray powder tests and under a microscope. When tested two meteorites gave d-values that could "be indexed on the basis of a tetragonal unit cell, but not on the basis of a cubic or hexagonal unit cell", it has been speculated to be a hexagonal polymorph of iron. Thomson structures referred to as Widmanstätten patterns are textures seen in meteorites that contain kamacite; these are bands which are alternating between kamacite and taenite. G. Thomson stumbled upon these structures in 1804 after cleaning a specimen with nitric acid he noticed geometric patterns, he published his observations in a French journal but due to the Napoleonic wars the English scientists, who were doing much of the meteorite research of the time, never saw his work. It was not until four years after in 1808 the same patterns were discovered by Count Alois von Beckh Widmanstätten, heating iron meteorites when he noticed geometric patterns caused by the differing oxidation rates of kamacite and taenite.
Widmanstätten told many of his colleagues about these patterns in correspondence leading to them being referred to as Widmanstätten patterns in most literature. Thomson structures or Widmanstätten patterns are created; when the meteorite is formed it starts out as molten taenite and as it cools past 723 °C the primary metastable phase of the alloy changes into taenite and kamacite begins to precipitate out. It is in this window where the meteorite is cooling below 723 °C where the Thomson structures form and they can be affected by the temperature and composition of the meteorite. Kamacite can be observed only in reflected light microscopy, it therefore behaves isotropically. As the meteorite cools below 750 °C iron becomes magnetic as it moves into the kamacite phase. During this cooling the meteorite takes on non-conventional thermoremanent magnetization. Thermoremanent magnetization on Earth gives iron minerals formed in the Earth's crust, a higher magnetization than if they were formed in the same field at room temperature.
This is a non-conventional thermoremanent magnetization because it appears to be due to a chemical remanent process, induced as taenite is cooled to kamacite. What makes this interesting is this has been shown to account for all of the ordinary chondrites magnetic field, shown to be as strong as 0.4 Os. Kamacite is an isometric mineral with a body centered unit cell. Kamacite is not found in large crystals. With large crystals being so rare crystallography is important to understand plays an important role in the formation of Thomson structures. Kamacite forms isometric, hexoctahedral crystals this causes the crystals to have many symmetry elements. Kamacite falls under the 4/m32/m class in the Hermann–Mauguin notation meaning it has three fourfold axes, four threefold axes, six twofold axes and nine mirror planes. Kamacite has a space group of F m3m. Kamacite is made up of a repeating unit of α-; the interatomic magnetic and qu