In condensed matter physics and materials science, an amorphous or non-crystalline solid is a solid that lacks the long-range order, characteristic of a crystal. In some older books, the term has been used synonymously with glass. Nowadays, "glassy solid" or "amorphous solid" is considered to be the overarching concept, glass the more special case: Glass is an amorphous solid that exhibits a glass transition. Polymers are amorphous. Other types of amorphous solids include gels, thin films, nanostructured materials such as glass doors and windows. Amorphous materials have an internal structure made of interconnected structural blocks; these blocks can be similar to the basic structural units found in the corresponding crystalline phase of the same compound. Whether a material is liquid or solid depends on the connectivity between its elementary building blocks so that solids are characterized by a high degree of connectivity whereas structural blocks in fluids have lower connectivity. In pharmaceutical industry, the amorphous drugs were shown to have higher bioavailability than their crystalline counterparts due to the high solubility of amorphous phase.
Moreover, certain compounds can undergo precipitation in their amorphous form in vivo, they can decrease each other's bioavailability if administered together. Amorphous materials have some shortrange order at the atomic length scale due to the nature of chemical bonding. Furthermore, in small crystals a large fraction of the atoms are the crystal; the most advanced structural characterization techniques, such as x-ray diffraction and transmission electron microscopy, have difficulty in distinguishing between amorphous and crystalline structures on these length scales. Amorphous phases are important constituents of thin films, which are solid layers of a few nanometres to some tens of micrometres thickness deposited upon a substrate. So-called structure zone models were developed to describe the micro structure and ceramics of thin films as a function of the homologous temperature Th, the ratio of deposition temperature over melting temperature. According to these models, a necessary condition for the occurrence of amorphous phases is that Th has to be smaller than 0.3, the deposition temperature must be below 30% of the melting temperature.
For higher values, the surface diffusion of deposited atomic species would allow for the formation of crystallites with long range atomic order. Regarding their applications, amorphous metallic layers played an important role in the discussion of a suspected superconductivity in amorphous metals. Today, optical coatings made from TiO2, SiO2, Ta2O5 etc. and combinations of them in most cases consist of amorphous phases of these compounds. Much research is carried out into thin amorphous films as a gas separating membrane layer; the technologically most important thin amorphous film is represented by few nm thin SiO2 layers serving as isolator above the conducting channel of a metal-oxide semiconductor field-effect transistor. Hydrogenated amorphous silicon, a-Si:H in short, is of technical significance for thin-film solar cells. In case of a-Si:H the missing long-range order between silicon atoms is induced by the presence by hydrogen in the percent range; the occurrence of amorphous phases turned out as a phenomenon of particular interest for studying thin-film growth.
Remarkably, the growth of polycrystalline films is used and preceded by an initial amorphous layer, the thickness of which may amount to only a few nm. The most investigated example is represented by thin multicrystalline silicon films, where such as the unoriented molecule. An initial amorphous layer was observed in many studies. Wedge-shaped polycrystals were identified by transmission electron microscopy to grow out of the amorphous phase only after the latter has exceeded a certain thickness, the precise value of which depends on deposition temperature, background pressure and various other process parameters; the phenomenon has been interpreted in the framework of Ostwald's rule of stages that predicts the formation of phases to proceed with increasing condensation time towards increasing stability. Experimental studies of the phenomenon require a defined state of the substrate surface and its contaminant density etc. upon which the thin film is deposited. R. Zallen; the Physics of Amorphous Solids.
Wiley Interscience. S. R. Elliot; the Physics of Amorphous Materials. Longman. N. Cusack; the Physics of Structurally Disordered Matter: An Introduction. IOP Publishing. N. H. March. A. Street. P. Tosi, eds.. Amorphous Solids and the Liquid State. Springer. D. A. Adler. B. Schwartz. C. Steele, eds.. Physical Properties of Amorphous Materials. Springer. A. Inoue. Amorphous and Nanocrystalline Materials. Springer. Journal of non-crystalline solids
Fulgurites are natural tubes, clumps, or masses of sintered, and/or fused soil, rock, organic debris and other sediments that can form when lightning discharges into ground. They can therefore be referred to as petrified lightning, they are classified as a variety of the mineraloid lechatelierite, although their absolute chemical composition is dependent on the physical and chemical properties of the granular-crystalline material providing an electrically and thermally conductive dissipation network for lightning-facilitated energy transfer. They are hollow and/or branching assemblages of glassy and heterogeneously microcrystalline tubes, slags, vesicular masses, clusters of refractory materials that form during the discharge phase of lightning strikes propagating into silica-rich quartzose sand, mixed soil, clay, or other sediments. Fulgurites are homologous to Lichtenberg figures, which are the branching patterns produced on surfaces of insulators during dielectric breakdown by high-voltage discharges, such as lightning.
Fulgurites are formed when lightning strikes the ground and vitrifying mineral grains. Peak temperatures within a lightning channel are known to exceed 30,000 K, with sufficient pressure to produce planar deformation features, or "shock lamellae," in SiO2, a kind of polymorphism; this is known colloquially as shocked quartz. "Artificial fulgurites" can be produced when the controlled arcing of electricity into an appropriate medium. Downed high voltage power lines have produced fulgurite-like lechatelierites colored by copper from the power lines themselves; the primary SiO2 phase in common tube fulgurites is lechatelierite, a silica glass found in impactites, but many other glasses may result from the processes involved with the production of fulgurites given their chemical context. Because their groundmass is amorphous in structure, fulgurites are classified as mineraloids; the optical properties of fulgurites vary depending on bulk composition, refractory inclusions, interface dynamics, chemical "impurities," among other possible sources of variation.
Most natural fulgurites fall on a spectrum from colorless, to white, to black. More colorful variants are synthetic and reflect incorporation of synthetic materials; the interior of Type I fulgurites is smooth or lined with fine bubbles, while other types are both vesicular and dense pore-free, or scoria-like. Branching fulgurites display fractal-like self-similarity and structural scale invariance as a macroscopic or microscopic network of root-like branches, can display this texture without central channels or obvious divergence from morphology of context or target. Fulgurites formed in sand or loose soil are mechanically fragile, making the field collection of large specimens difficult. Other fulgurite classes are very durable and may withstand a long residence in the geologic record, an issue of some contention in planetary sciences, such as impact geology. Fulgurites can exceed tens of centimeters in diameter and can penetrate deep into the subsoil, sometimes occurring as far as 15 m below the surface, struck, but may form directly on appropriate sedimentary surfaces.
One of the longest fulgurites to have been found in modern times was a little over 4.9 m in length, was found in northern Florida. The Yale University Peabody Museum of Natural History displays one of the longest known preserved fulgurites 4 m in length. Charles Darwin in The Voyage of the Beagle recorded that tubes such as these found in Drigg, Cumberland, UK reached a length of 9.1 m. The Winans Lake fulgurite, extended discontinuously throughout a 30 m range, arguably includes the largest reported fulgurite mass recovered and described - its largest section extending 16 ft in length by 1 ft in diameter. Fulgurites have been classified by Pasek et al. into five types related to the type of sediment in which the fulgurite formed, as follows: Type I - sand fulgurites with tubaceous structure.
Quartz is a mineral composed of silicon and oxygen atoms in a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2. Quartz is the second most abundant mineral behind feldspar. Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral; the transformation from α-quartz to β-quartz takes place abruptly at 573 °C. Since the transformation is accompanied by a significant change in volume, it can induce fracturing of ceramics or rocks passing through this temperature threshold. There are many different varieties of quartz. Since antiquity, varieties of quartz have been the most used minerals in the making of jewelry and hardstone carvings in Eurasia; the word "quartz" is derived from the German word "Quarz", which had the same form in the first half of the 14th century in Middle High German in East Central German and which came from the Polish dialect term kwardy, which corresponds to the Czech term tvrdý.
The Ancient Greeks referred to quartz as κρύσταλλος derived from the Ancient Greek κρύος meaning "icy cold", because some philosophers believed the mineral to be a form of supercooled ice. Today, the term rock crystal is sometimes used as an alternative name for the purest form of quartz. Quartz belongs to the trigonal crystal system; the ideal crystal shape is a six-sided prism terminating with six-sided pyramids at each end. In nature quartz crystals are twinned, distorted, or so intergrown with adjacent crystals of quartz or other minerals as to only show part of this shape, or to lack obvious crystal faces altogether and appear massive. Well-formed crystals form in a'bed' that has unconstrained growth into a void. However, doubly terminated crystals do occur where they develop without attachment, for instance within gypsum. A quartz geode is such a situation where the void is spherical in shape, lined with a bed of crystals pointing inward. Α-quartz crystallizes in the trigonal crystal system, space group P3121 or P3221 depending on the chirality.
Β-quartz belongs to space group P6222 and P6422, respectively. These space groups are chiral. Both α-quartz and β-quartz are examples of chiral crystal structures composed of achiral building blocks; the transformation between α- and β-quartz only involves a comparatively minor rotation of the tetrahedra with respect to one another, without change in the way they are linked. Although many of the varietal names arose from the color of the mineral, current scientific naming schemes refer to the microstructure of the mineral. Color is a secondary identifier for the cryptocrystalline minerals, although it is a primary identifier for the macrocrystalline varieties. Pure quartz, traditionally called rock crystal or clear quartz, is colorless and transparent or translucent, has been used for hardstone carvings, such as the Lothair Crystal. Common colored varieties include citrine, rose quartz, smoky quartz, milky quartz, others; these color differentiation's arise from chromophores which have been incorporated into the crystal structure of the mineral.
Polymorphs of quartz include: α-quartz, β-quartz, moganite, cristobalite and stishovite. The most important distinction between types of quartz is that of macrocrystalline and the microcrystalline or cryptocrystalline varieties; the cryptocrystalline varieties are either translucent or opaque, while the transparent varieties tend to be macrocrystalline. Chalcedony is a cryptocrystalline form of silica consisting of fine intergrowths of both quartz, its monoclinic polymorph moganite. Other opaque gemstone varieties of quartz, or mixed rocks including quartz including contrasting bands or patterns of color, are agate, carnelian or sard, onyx and jasper. Amethyst is a form of quartz that ranges from a dull purple color; the world's largest deposits of amethysts can be found in Brazil, Uruguay, France and Morocco. Sometimes amethyst and citrine are found growing in the same crystal, it is referred to as ametrine. An amethyst is formed. Blue quartz contains inclusions of fibrous crocidolite. Inclusions of the mineral dumortierite within quartz pieces result in silky-appearing splotches with a blue hue, shades giving off purple and/or grey colors additionally being found.
"Dumortierite quartz" will sometimes feature contrasting light and dark color zones across the material. Interest in the certain quality forms of blue quartz as a collectible gemstone arises in India and in the United States. Citrine is a variety of quartz whose color ranges from a pale yellow to brown due to ferric impurities. Natural citrines are rare. However, a heat-treated amethyst will have small lines in the crystal, as opposed to a natural citrine's cloudy or smokey appearance, it is nearly impossible to differentiate between cut citrine and yellow topaz visually, but they differ in hardness. Brazil is the leading producer of citrine, with much
Coesite is a form of silicon dioxide SiO2, formed when high pressure, moderately high temperature, are applied to quartz. Coesite was first synthesized by Loring Coes Jr. a chemist at the Norton Company, in 1953. In 1960, a natural occurrence of coesite was reported by Edward C. T. Chao, in collaboration with Eugene Shoemaker, from Barringer Crater, in Arizona, US, evidence that the crater must have been formed by an impact. After this report, the presence of coesite in unmetamorphosed rocks was taken as evidence of a meteorite impact event or of an atomic bomb explosion, it was not expected. In metamorphic rocks, coesite was described in eclogite xenoliths from the mantle of the Earth that were carried up by ascending magmas. In metamorphic rocks, coesite is now recognized as one of the best mineral indicators of metamorphism at high pressures; such UHP metamorphic rocks record subduction or continental collisions in which crustal rocks are carried to depths of 70 km or more. Coesite is formed at pressures above about 2.5 GPa and temperature above about 700 °C.
This corresponds to a depth of about 70 km in the Earth. It can be preserved as mineral inclusions in other phases because as it reverts to quartz, the quartz rim exerts pressure on the core of the grain, preserving the metastable grain as tectonic forces uplift and expose these rock at the surface; as a result, the grains have a characteristic texture of a polycrystalline quartz rim. Coesite has been identified in UHP metamorphic rocks around the world, including the western Alps of Italy at Dora Maira, the Erzgebirge of Germany, the Lanterman Range of Antarctica, in the Kokchetav Massif of Kazakhstan, in the Western Gneiss region of Norway, the Dabie-Shan Range in Eastern China, the Himalayas of Eastern Pakistan. Coesite is a tectosilicate with each silicon atom surrounded by four oxygen atoms in a tetrahedron; each oxygen atom is bonded to two Si atoms to form a framework. There are two crystallographically distinct Si atoms and five different oxygen positions in the unit cell. Although the unit cell is close to being hexagonal in shape, it is inherently monoclinic and cannot be hexagonal.
The crystal structure of coesite is similar to that of feldspar and consists of four silicon dioxide tetrahedra arranged in Si4O8 and Si8O16 rings. The rings are further arranged into chains; this structure is metastable within the stability field of quartz: coesite will decay back into quartz with a consequent volume increase, although the metamorphic reaction is slow at the low temperatures of the Earth's surface. The crystal symmetry is monoclinic C2/c, No.15, Pearson symbol mS48. Stishovite, a higher-pressure polymorph Seifertite, forming at higher pressure than stishovite Coesite page Barringer Meteor Crater science education page
Conquistador is a term used to refer to the knights and explorers of the Spanish Empire and the Portuguese Empire. During the Age of Discovery, conquistadors sailed beyond Europe to the Americas, Oceania and Asia, conquering territory and opening trade routes, they colonized much of the world for Spain and Portugal in the 16th, 17th, 18th centuries. After Columbus's discovery of the West Indies in 1492, the Spanish conquistadors, who were poor nobles from the impoverished west and south of Spain, began building up an American empire in the Caribbean, using islands such as Cuba, Puerto Rico, Hispaniola as bases. Florida fell to Juan Ponce de León after 1513. From 1519 to 1521, Hernán Cortés waged a campaign against the Aztec Empire, ruled by Moctezuma II. From the territories of the Aztec Empire conquistadors expanded Spanish rule to northern Central America and parts of what is now southern and western United States. Other conquistadors took over the Inca Empire after crossing the Isthmus of Panama and sailing the Pacific to northern Peru.
As Francisco Pizarro subdued the empire in a manner similar to Cortés other conquistadores used Peru as base for conquering much of Ecuador and Chile. In Colombia and Argentina conquistadors from Peru linked up with other conquistadors arriving more directly from the Caribbean and Río de la Plata-Paraguay respectively. Conquistadors founded numerous cities many of them on locations with pre-existing pre-colonial settlements including the capitals of most Latin American countries. Besides conquests, Spanish conquistadors made significant explorations into the Amazon Jungle, the interior of North America, the Pacific Ocean. Portugal established a route to China in the early 16th century, sending ships via the southern coast of Africa and founding numerous coastal enclaves along the route. Following the discovery in 1492 by Spaniards of the New World with Christopher Columbus's first voyage there and the first circumnavigation of the world by Ferdinand Magellan and Juan Sebastián Elcano in 1521, expeditions led by conquistadors in the 16th century established trading routes linking Europe with all these areas.
Human infections gained worldwide transmission vectors for the first time: from Africa and Eurasia to the Americas and vice versa. The spread of old-world diseases, including smallpox and typhus, led to the deaths of many indigenous inhabitants of the New World. In the 16th century 240,000 Europeans entered American ports. By the late 16th century gold and silver imports from America provided one-fifth of Spain's total budget; the conquistadors were professional warriors, using European tactics and cavalry. Their units would specialize in forms of combat that required long periods of training that were too costly for informal groups, their armies were composed of Iberian and other European soldiers. Native allied troops were infantry equipped with armament and armour that varied geographically; some groups consisted of young men without military experience, Catholic clergy which helped with administrative duties, soldiers with military training. These native forces included African slaves and Native Americans.
They not only fought in the battlefield but served as interpreters, servants, teachers and scribes. India Catalina and Malintzin were Native American women slaves. Castilian law prohibited non-Catholics from settling in the New World. However, not all conquistadors were Castilian. Many foreigners Hispanicised their names and/or converted to Catholicism to serve the Castilian Crown. For example, Ioánnis Fokás was a Castilian of Greek origin who discovered the strait that bears his name between Vancouver Island and Washington State in 1592. German-born Nikolaus Federmann, Hispanicised as Nicolás de Federmán, was a conquistador in Venezuela and Colombia; the Venetian Sebastiano Caboto was Sebastián Caboto, Georg von Speyer Hispanicised as Jorge de la Espira, Eusebio Francesco Chini Hispanicised as Eusebio Kino, Wenceslaus Linck was Wenceslao Linck, Ferdinand Konščak, was Fernando Consag, Amerigo Vespucci was Américo Vespucio, the Portuguese Aleixo Garcia was known as Alejo García in the Castilian army.
The origin of many people in mixed expeditions was not always distinguished. Various occupations, such as sailors, fishermen and nobles employed different languages, so that crew and settlers of Iberian empires recorded as Galicians from Spain were using Portuguese, Catalan and Languedoc languages, which were wrongly identified. Castilian law banned Spanish women from travelling to America unless they were married and accompanied by a husband. Women who travelled thus include María de Escobar, María Estrada, Marina Vélez de Ortega, Marina de la Caballería, Francisca de Valenzuela, Catalina de Salazar; some conquistadors had illegitimate children. European young men enlisted in the army. Catholic priests instructed the soldiers in mathematics, theology, Latin and history, wrote letters and official documents for them. King's army officers taught military arts. An uneducated young recruit could become a military leader, elected by their fellow professional soldiers based on merit. Others were born into hidalgo families, as such they were members of the Spanish nobility with some studies but without economic resources.
Some rich nobility families' members became soldiers or missionaries, but not the fi
Flint is a hard, sedimentary cryptocrystalline form of the mineral quartz, categorized as a variety of chert. It occurs chiefly as nodules and masses such as chalks and limestones. Inside the nodule, flint is dark grey, green, white or brown in colour, has a glassy or waxy appearance. A thin layer on the outside of the nodules is different in colour white and rough in texture. From a petrological point of view, "flint" refers to the form of chert which occurs in chalk or marly limestone. "common chert" occurs in limestone. Flint is durable and can be found along streams and beaches, its use to make stone tools dates back millions of years. Due to some properties of flint it breaks into sharp edged pieces making it useful for knife blades and other sharp tools. During the Stone Age access to flint was so important for survival that people would travel or trade to obtain flint. Flint Ridge in eastern Ohio was an important source of flint and Native Americans extracted the flint from hundreds of quarries along the ridge.
This "Ohio Flint" was traded across the eastern United States and has been found as far west as the Rocky Mountains and south around the Gulf of Mexico. The exact mode of formation of flint is not yet clear, but it is thought that it occurs as a result of chemical changes in compressed sedimentary rock formations, during the process of diagenesis. One hypothesis is that a gelatinous material fills cavities in the sediment, such as holes bored by crustaceans or molluscs and that this becomes silicified; this hypothesis explains the complex shapes of flint nodules that are found. The source of dissolved silica in the porous media could be the spicules of silicious sponges. Certain types of flint, such as that from the south coast of England, contain trapped fossilised marine flora. Pieces of coral and vegetation have been found preserved like amber inside the flint. Thin slices of the stone reveal this effect. Puzzling giant flint formations known as paramoudra and flint circles are found around Europe but in Norfolk, England on the beaches at Beeston Bump and West Runton.
Flint sometimes occurs in large flint fields for example, in Europe. The "Ohio flint" is the official gemstone of Ohio state, it is formed from limey debris, deposited at the bottom of inland Paleozoic seas hundreds of millions of years ago that hardened into limestone and became infused with silica. The flint from Flint Ridge is found in many hues like red, pink, blue and gray, with the color variations caused by minute impurities of iron compounds. Flint was used in the manufacture of tools during the Stone Age as it splits into thin, sharp splinters called flakes or blades when struck by another hard object; this process is referred to as knapping. The process of making tools this way is called "flintknapping". In Europe, some of the best toolmaking flint has come from Belgium, the coastal chalks of the English Channel, the Paris Basin, Thy in Jutland, the Sennonian deposits of Rügen, Grimes Graves in England, the Upper Cretaceous chalk formation of Dobruja and the lower Danube, the Cenomanian chalky marl formation of the Moldavian Plateau and the Jurassic deposits of the Kraków area and Krzemionki in Poland, as well as of the Lägern in the Jura Mountains of Switzerland.
Flint mining became more common since the Neolithic. In 1938, a project of the Ohio Historical Society, under the leadership of H. Holmes Ellis began to study the flintknapping "methods and techniques" of Native Americans. Like past studies, this work involved experimenting with actual flintknapping techniques by creation of stone tools through the use of techniques like direct freehand percussion, freehand pressure and pressure using a rest. Other scholars who have conducted similar experiments and studies include William Henry Holmes, Alonzo W. Pond, Sir Francis H. S. Knowles and Don Crabtree; when struck against steel, a flint edge produces. The hard flint edge shaves off a particle of the steel that exposes iron, which reacts with oxygen from the atmosphere and can ignite the proper tinder. Prior to the wide availability of steel, rocks of pyrite would be used along with the flint, in a similar way; these methods are popular in woodcraft and amongst people practising traditional fire-starting skills.
A major use of flint and steel was in the flintlock mechanism, used in flintlock firearms, but used on dedicated fire-starting tools. A piece of flint held in the jaws of a spring-loaded hammer, when released by a trigger, strikes a hinged piece of steel at an angle, creating a shower of sparks and exposing a charge of priming powder; the sparks ignite the priming powder and that flame, in turn, ignites the main charge, propelling the ball, bullet, or shot through the barrel. While the military use of the flintlock declined after the adoption of the percussion cap from the 1840s onward, flintlock rifles and shotguns remain in use amongst recreational shooters. Flint and steel used to strike sparks were superseded by ferrocerium; this man-made material, when scraped with any hard, sharp edge, produces sparks that are much hotter than obtained with natural flint and steel, allowing use of a wider range of tinders. Because it can produce sparks when wet and can start fires
Shocked quartz is a form of quartz that has a microscopic structure, different from normal quartz. Under intense pressure, the crystalline structure of quartz is deformed along planes inside the crystal; these planes, which show up as lines under a microscope, are called planar deformation features, or shock lamellae. Shocked quartz was discovered following underground nuclear bomb testing, which generated the intense pressures required to alter the quartz lattice. Eugene Shoemaker showed that shocked quartz is found inside craters created by meteor impact, such as the Barringer Crater and Chicxulub crater; the presence of shocked quartz supports that such craters were formed by impact, because a volcanic eruption would not generate the required pressure. Lightning is now known to contribute to the surface record of shocked quartz grains, complicating identification of hypervelocity impact features. Shocked quartz is associated in nature with two high-pressure polymorphs of silicon dioxide: coesite and stishovite.
These polymorphs have a crystal structure different from standard quartz. This structure can be formed only at moderate temperatures. Coesite and stishovite are viewed as indicative of impact events, eclogite facies metamorphism, but are found in sediments prone to lightning strikes and in fulgurites. Shocked quartz is found worldwide, occurs in the thin Cretaceous–Paleogene boundary layer, which occurs at the contact between Cretaceous and Paleogene rocks; this is further evidence that the transition between the two geologic periods was caused by a large impact. Lightning generates planar deformation features in quartz and is capable of propagating appropriate pressure/temperature gradients in rocks and sediments alike; this common mechanism may contribute to the accumulation of shocked quartz in the geologic record. Mantle xenoliths and sediments derived from them may contain stishovite. Though shocked quartz is only recognized, Eugene Shoemaker discovered it prior to its crystallographic description in building stones in the Bavarian town of Nördlingen, derived from shock-metamorphic rocks, such as breccia and pseudotachylite, of Ries crater.
Lechatelierite Seifertite Shatter cone Shock metamorphism Shocked quartz page Coesite page Stishovite page