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Onyx
Onyx is a typically black-and-white banded variety of agate, a silicate mineral. The bands can also be monochromatic with alternating light and dark bands. ''Sardonyx'' is a variety with red to brown bands alternated with black or white bands. The name "onyx" is also frequently used for level-banded (parallel-banded) agates, but in proper usage it refers to color pattern not band structure. Onyx, as a descriptive term, has also been incorrectly applied to parallel-banded varieties of alabaster, marble, calcite, obsidian, and opal, and misleadingly to materials with contorted banding, such as "cave onyx" and "Mexican onyx". Etymology ''Onyx'' comes through Latin (of the same spelling), from the Ancient Greek (), meaning or . Onyx with pink and white bands can sometimes resemble a fingernail. The English word "nail" is cognate with the Greek word. Varieties Onyx is formed of chalcedony bands in alternating colors. It is cryptocrystalline, consisting of fine intergrowths o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Onyx
Onyx is a typically black-and-white banded variety of agate, a silicate mineral. The bands can also be monochromatic with alternating light and dark bands. ''Sardonyx'' is a variety with red to brown bands alternated with black or white bands. The name "onyx" is also frequently used for level-banded (parallel-banded) agates, but in proper usage it refers to color pattern not band structure. Onyx, as a descriptive term, has also been incorrectly applied to parallel-banded varieties of alabaster, marble, calcite, obsidian, and opal, and misleadingly to materials with contorted banding, such as "cave onyx" and "Mexican onyx". Etymology ''Onyx'' comes through Latin (of the same spelling), from the Ancient Greek (), meaning or . Onyx with pink and white bands can sometimes resemble a fingernail. The English word "nail" is cognate with the Greek word. Varieties Onyx is formed of chalcedony bands in alternating colors. It is cryptocrystalline, consisting of fine intergrowths of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agate
Agate ( ) is a banded variety of chalcedony. Agate stones are characterized by alternating bands of different colored chalcedony and sometimes include macroscopic quartz. They are common in nature and can be found globally in a large number of different varieties. There are some varieties of chalcedony without bands that are commonly called agate ( moss agate, fire agate, etc.); however, these are more properly classified solely as varieties of chalcedony. Agates are primarily formed as nodules within volcanic rock, but they can also form in veins or in sedimentary rock. Agate has been popular as a gemstone in jewelry for thousands of years, and today it is also popular as a collector's stone. Some duller agates sold commercially are artificially dyed to enhance their color. Etymology Agate was given its name by Theophrastus, a Greek philosopher and naturalist. He discovered the stone c. 350 BCE along the shoreline of the River Achates (), now the Dirillo River, on the Italian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chalcedony
Chalcedony ( or ) is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic. Chalcedony's standard chemical structure (based on the chemical structure of quartz) is SiO2 (silicon dioxide). Chalcedony has a waxy luster, and may be semitransparent or translucent. It can assume a wide range of colors, but those most commonly seen are white to gray, grayish-blue or a shade of brown ranging from pale to nearly black. The color of chalcedony sold commercially is often enhanced by dyeing or heating. The name ''chalcedony'' comes from the Latin (alternatively spelled ) and is probably derived from the town of Chalcedon in Asia Minor. The name appears in Pliny the Elder's as a term for a translucent kind of jaspis. Another reference to a gem by the name of () is found in the Book of Revelation (21:19); however, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quartz
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of Silicon dioxide, SiO2. Quartz is, therefore, classified structurally as a Silicate mineral#Tectosilicates, framework silicate mineral and compositionally as an oxide mineral. Quartz is the second most abundant mineral in Earth's continental crust, 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 . Since the transformation is accompanied by a significant change in volume, it can easily induce microfracturing of ceramics or rocks passing through this temperature threshold. There are many different varieties of quartz, several of which are classifi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alabaster
Alabaster is a mineral and a soft Rock (geology), rock used for carvings and as a source of plaster powder. Archaeologists, geologists, and the stone industry have different definitions for the word ''alabaster''. In archaeology, the term ''alabaster'' includes objects and artefacts made from two different minerals: (i) the fine-grained, massive type of gypsum, and (ii) the fine-grained, banded type of calcite.''More About Alabaster and Travertine'': Brief Guide explains the different definitions used by geologists, archaeologists, and the stone trade. Oxford University Museum of Natural History, 2012/ref> Chemically, gypsum is a Water of crystallization, hydrous sulfate of calcium, whereas calcite is a carbonate of calcium. As types of alabaster, gypsum and calcite have similar properties, such as light color, translucence, and soft stones that can be sculpture, carved and sculpted; thus the historical use and application of alabaster for the production of carved, decorative art ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tectosilicate
Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, the crystalline forms of silica (silicon dioxide, ) are usually considered to be tectosilicates, and they are classified as such in the Dana system (75.1). However, the Nickel-Strunz system classifies them as oxide minerals (4.DA). Silica is found in nature as the mineral quartz, and its polymorphs. On Earth, a wide variety of silicate minerals occur in an even wider range of combinations as a result of the processes that have been forming and re-working the crust for billions of years. These processes include partial melting, crystallization, fractionation, metamorphism, weathering, and diagenesis. Living organisms also contribute to this geologic cycle. For example, a type of plankton known as diatoms construct their exoskeletons ("frustules") from silica extracted from sea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silica
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant families of materials, existing as a compound of several minerals and as a synthetic product. Examples include fused quartz, fumed silica, opal, and aerogels. It is used in structural materials, microelectronics, and as components in the food and pharmaceutical industries. All forms are white or colorless, although impure samples can be colored. Silicon dioxide is a common fundamental constituent of glass. Structure In the majority of silicon dioxides, the silicon atom shows Tetrahedral molecular geometry, tetrahedral coordination, with four oxygen atoms surrounding a central Si atomsee 3-D Unit Cell. Thus, SiO2 forms 3-dimensional network solids in which each silicon atom is covalently bonded in a tetrahedral manner to 4 oxygen atoms. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Onyx - Handicraft
Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–750 nanometres. It is a primary color in the RGB color model and a secondary color (made from magenta and yellow) in the CMYK color model, and is the complementary color of cyan. Reds range from the brilliant yellow-tinged scarlet and vermillion to bluish-red crimson, and vary in shade from the pale red pink to the dark red burgundy. Red pigment made from ochre was one of the first colors used in prehistoric art. The Ancient Egyptians and Mayans colored their faces red in ceremonies; Roman generals had their bodies colored red to celebrate victories. It was also an important color in China, where it was used to color early pottery and later the gates and walls of palaces. In the Renaissance, the brilliant red costumes for the nobility and wealthy were dyed with kermes and cochineal. The 19th century brought the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptocrystalline
Cryptocrystalline is a rock microstructure, rock texture made up of such minute crystals that its crystalline nature is only vaguely revealed even microscopically in thin section by transmitted polarized light. Among the sedimentary rocks, chert and flint are cryptocrystalline. carbonado (diamond), Carbonado, a form of diamond, is also cryptocrystalline. Volcanic rocks, especially of the felsic type such as felsites and rhyolites, may have a cryptocrystalline matrix (geology), groundmass as distinguished from pure obsidian (felsic) or tachylyte (mafic), which are natural rock glasses. Agate and onyx are examples of cryptocrystalline silica (chalcedony). The quartz crystals in chalcedony are so tiny that they cannot be distinguished with the naked eye. See also * List of rock textures * Macrocrystalline * Microcrystalline * Nanocrystalline * Rock microstructure References Crystals Lithics Petrology {{Petrology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heidelberg
Heidelberg (; ; ) is the List of cities in Baden-Württemberg by population, fifth-largest city in the States of Germany, German state of Baden-Württemberg, and with a population of about 163,000, of which roughly a quarter consists of students, it is List of cities in Germany by population, Germany's 51st-largest city. Located about south of Frankfurt, Heidelberg is part of the densely populated Rhine-Neckar, Rhine-Neckar Metropolitan Region which has its centre in Mannheim. Heidelberg is located on the Neckar River, at the point where it leaves its narrow valley between the Oden Forest and the Kleiner Odenwald, Little Oden Forest, and enters the wide Upper Rhine Plain. The old town lies in the valley, the end of which is flanked by the Königstuhl (Odenwald), Königstuhl in the south and the Heiligenberg (Heidelberg), Heiligenberg in the north. The majority of the population lives in the districts west of the mountains in the Upper Rhine Plain, into which the city has expan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Springer Science+Business Media
Springer Science+Business Media, commonly known as Springer, is a German multinational publishing company of books, e-books and peer-reviewed journals in science, humanities, technical and medical (STM) publishing. Originally founded in 1842 in Berlin, it expanded internationally in the 1960s, and through mergers in the 1990s and a sale to venture capitalists it fused with Wolters Kluwer and eventually became part of Springer Nature in 2015. Springer has major offices in Berlin, Heidelberg, Dordrecht, and New York City. History Julius Springer founded Springer-Verlag in Berlin in 1842 and his son Ferdinand Springer grew it from a small firm of 4 employees into Germany's then second-largest academic publisher with 65 staff in 1872.Chronology ". Springer Science+Business Media. In 1964, Springer expanded its business internationally, op ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
