Green is the color between blue and yellow on the spectrum of visible light. It is evoked by light with a predominant wavelength of roughly 495–570 nm, the modern English word green comes from the Middle English and Anglo-Saxon word grene, from the same Germanic root as the words grass and grow. It is the color of living grass and leaves and as a result is the color most associated with springtime, growth, by far the largest contributor to green in nature is chlorophyll, the chemical by which plants photosynthesize and convert sunlight into chemical energy. Many creatures have adapted to their environments by taking on a green hue themselves as camouflage. Several minerals have a color, including the emerald, which is colored green by its chromium content. In surveys made in Europe and the United States, green is the color most commonly associated with nature, health, spring and envy. In Europe and the U. S. green is associated with death, sickness, or the devil. In the Middle Ages and Renaissance, when the color of clothing showed the social status, green was worn by merchants, bankers.
The Mona Lisa by Leonardo da Vinci wears green, showing she is not from a noble family, Green is the traditional color of safety and permission, a green light means go ahead, a green card permits permanent residence in the United States. It is the most important color in Islam and it was the color of the banner of Muhammad, and is found in the flags of nearly all Islamic countries, and represents the lush vegetation of Paradise. It is associated with the culture of Gaelic Ireland. Because of its association with nature, it is the color of the environmental movement, political groups advocating environmental protection and social justice describe themselves as part of the Green movement, some naming themselves Green parties. This has led to campaigns in advertising, as companies have sold green, or environmentally friendly. The word green comes from the Middle English and Old English word grene, like the German word grün, has the same root as the words grass and grow. It is from a Common Germanic *gronja-, which is reflected in Old Norse grænn, Old High German gruoni, ultimately from a PIE root *ghre- to grow.
The first recorded use of the word as a term in Old English dates to ca. Latin with viridis has a genuine and widely used term for green, related to virere to grow and ver spring, it gave rise to words in several Romance languages, French vert, Italian verde. Likewise the Slavic languages with zelenъ, Ancient Greek had a term for yellowish, pale green – χλωρός, cognate with χλοερός verdant and χλόη the green of new growth
A mineral is a naturally occurring chemical compound, usually of crystalline form and abiogenic in origin. A mineral has one specific chemical composition, whereas a rock can be an aggregate of different minerals or mineraloids, the study of minerals is called mineralogy. There are over 5,300 known mineral species, over 5,070 of these have been approved by the International Mineralogical Association, the silicate minerals compose over 90% of the Earths crust. The diversity and abundance of species is controlled by the Earths chemistry. Silicon and oxygen constitute approximately 75% of the Earths crust, which translates directly into the predominance of silicate minerals, minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish the various species, changes in the temperature, pressure, or bulk composition of a rock mass cause changes in its minerals. Minerals can be described by their various properties, which are related to their chemical structure.
Common distinguishing characteristics include crystal structure and habit, lustre, colour, tenacity, fracture, more specific tests for describing minerals include magnetism, taste or smell and reaction to acid. Minerals are classified by key chemical constituents, the two dominant systems are the Dana classification and the Strunz classification, the silicate class of minerals is subdivided into six subclasses by the degree of polymerization in the chemical structure. All silicate minerals have a unit of a 4− silica tetrahedron—that is, a silicon cation coordinated by four oxygen anions. These tetrahedra can be polymerized to give the subclasses, disilicates, inosilicates, other important mineral groups include the native elements, oxides, carbonates and phosphates. The first criterion means that a mineral has to form by a natural process, stability at room temperature, in the simplest sense, is synonymous to the mineral being solid. More specifically, a compound has to be stable or metastable at 25 °C, modern advances have included extensive study of liquid crystals, which extensively involve mineralogy.
Minerals are chemical compounds, and as such they can be described by fixed or a variable formula, many mineral groups and species are composed of a solid solution, pure substances are not usually found because of contamination or chemical substitution. Finally, the requirement of an ordered atomic arrangement is usually synonymous with crystallinity, crystals are periodic, an ordered atomic arrangement gives rise to a variety of macroscopic physical properties, such as crystal form and cleavage. There have been recent proposals to amend the definition to consider biogenic or amorphous substances as minerals. The formal definition of an approved by the IMA in 1995, A mineral is an element or chemical compound that is normally crystalline. However, if geological processes were involved in the genesis of the compound, Mineral classification schemes and their definitions are evolving to match recent advances in mineral science
Red is the color at the longer-wavelengths end of the spectrum of visible light next to orange, at the opposite end from violet. Red color has a predominant light wavelength of roughly 620–740 nanometers, light with a longer wavelength than red but shorter than terahertz radiation and microwave is called infrared. Red is one of the secondary colors, resulting from the combination of yellow. Traditionally, it was viewed as a primary colour, along with yellow and blue, in the RYB color space and traditional color wheel formerly used by painters. Reds can vary in shade from light pink to very dark maroon or burgundy. Red is the color of cyan. In nature, the red color of blood comes from hemoglobin, the red color of the Grand Canyon and other geological features is caused by hematite or red ochre, both forms of iron oxide. It causes the red color of the planet Mars, the color of autumn leaves is caused by pigments called anthocyanins, which are produced towards the end of summer, when the green chlorophyll is no longer produced.
One to two percent of the population has red hair, the color is produced by high levels of the reddish pigment pheomelanin. Since red is the color of blood, it has historically been associated with sacrifice, modern surveys in the United States and Europe show red is the color most commonly associated with heat, passion, anger and joy. In China and many other Asian countries it is the color of symbolizing happiness, since the 19th century, red has been associated with socialism and communism. The word red is derived from the Old English rēad, the word can be further traced to the Proto-Germanic rauthaz and the Proto-Indo European root rewdʰ-. In Sanskrit, the word means red or blood. In the Akkadian language of Ancient Mesopotamia and in the modern Inuit language of Inuit, the words for colored in Latin and Spanish both mean red. In Portuguese the word for red is vermelho, which comes from Latin vermiculus, in the Russian language, the word for red, Кра́сный, comes from the same old Slavic root as the words for beautiful—красивый and excellent—прекрасный.
Thus Red Square in Moscow, named long before the Russian Revolution, in heraldry, the word gules is used for red. Red can vary in hue from orange-red to violet-red, and for each hue there is a variety of shades and tints. Red hematite powder was found scattered around the remains at a grave site in a Zhoukoudian cave complex near Beijing
India, officially the Republic of India, is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and it is bounded by the Indian Ocean on the south, the Arabian Sea on the southwest, and the Bay of Bengal on the southeast. It shares land borders with Pakistan to the west, China and Bhutan to the northeast, in the Indian Ocean, India is in the vicinity of Sri Lanka and the Maldives. Indias Andaman and Nicobar Islands share a border with Thailand. The Indian subcontinent was home to the urban Indus Valley Civilisation of the 3rd millennium BCE, in the following millennium, the oldest scriptures associated with Hinduism began to be composed. Social stratification, based on caste, emerged in the first millennium BCE, early political consolidations took place under the Maurya and Gupta empires, the peninsular Middle Kingdoms influenced cultures as far as southeast Asia. In the medieval era, Zoroastrianism and Islam arrived, much of the north fell to the Delhi sultanate, the south was united under the Vijayanagara Empire.
The economy expanded in the 17th century in the Mughal empire, in the mid-18th century, the subcontinent came under British East India Company rule, and in the mid-19th under British crown rule. A nationalist movement emerged in the late 19th century, which later, under Mahatma Gandhi, was noted for nonviolent resistance, in 2015, the Indian economy was the worlds seventh largest by nominal GDP and third largest by purchasing power parity. Following market-based economic reforms in 1991, India became one of the major economies and is considered a newly industrialised country. However, it continues to face the challenges of poverty, malnutrition, a nuclear weapons state and regional power, it has the third largest standing army in the world and ranks sixth in military expenditure among nations. India is a constitutional republic governed under a parliamentary system. It is a pluralistic and multi-ethnic society and is home to a diversity of wildlife in a variety of protected habitats. The name India is derived from Indus, which originates from the Old Persian word Hindu, the latter term stems from the Sanskrit word Sindhu, which was the historical local appellation for the Indus River.
The ancient Greeks referred to the Indians as Indoi, which translates as The people of the Indus, the geographical term Bharat, which is recognised by the Constitution of India as an official name for the country, is used by many Indian languages in its variations. Scholars believe it to be named after the Vedic tribe of Bharatas in the second millennium B. C. E and it is traditionally associated with the rule of the legendary emperor Bharata. Gaṇarājya is the Sanskrit/Hindi term for republic dating back to the ancient times, hindustan is a Persian name for India dating back to the 3rd century B. C. E. It was introduced into India by the Mughals and widely used since and its meaning varied, referring to a region that encompassed northern India and Pakistan or India in its entirety
Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the group on the periodic table and is a highly reactive nonmetal. By mass, oxygen is the third-most abundant element in the universe, after hydrogen, at standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. This is an important part of the atmosphere and diatomic oxygen gas constitutes 20. 8% of the Earths atmosphere, additionally, as oxides the element makes up almost half of the Earths crust. Most of the mass of living organisms is oxygen as a component of water, oxygen is continuously replenished by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. Oxygen is too reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. Another form of oxygen, strongly absorbs ultraviolet UVB radiation, but ozone is a pollutant near the surface where it is a by-product of smog.
At low earth orbit altitudes, sufficient atomic oxygen is present to cause corrosion of spacecraft, the name oxygen was coined in 1777 by Antoine Lavoisier, whose experiments with oxygen helped to discredit the then-popular phlogiston theory of combustion and corrosion. One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium. In his work Pneumatica, Philo observed that inverting a vessel over a burning candle, Philo incorrectly surmised that parts of the air in the vessel were converted into the classical element fire and thus were able to escape through pores in the glass. Many centuries Leonardo da Vinci built on Philos work by observing that a portion of air is consumed during combustion and respiration, Oxygen was discovered by the Polish alchemist Sendivogius, who considered it the philosophers stone. In the late 17th century, Robert Boyle proved that air is necessary for combustion, English chemist John Mayow refined this work by showing that fire requires only a part of air that he called spiritus nitroaereus.
From this he surmised that nitroaereus is consumed in both respiration and combustion, Mayow observed that antimony increased in weight when heated, and inferred that the nitroaereus must have combined with it. Accounts of these and other experiments and ideas were published in 1668 in his work Tractatus duo in the tract De respiratione. Robert Hooke, Ole Borch, Mikhail Lomonosov, and Pierre Bayen all produced oxygen in experiments in the 17th and the 18th century but none of them recognized it as a chemical element. This may have been in part due to the prevalence of the philosophy of combustion and corrosion called the phlogiston theory, which was the favored explanation of those processes. Established in 1667 by the German alchemist J. J. Becher, one part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, or calx. The fact that a substance like wood gains overall weight in burning was hidden by the buoyancy of the combustion products
Chromium is a chemical element with symbol Cr and atomic number 24. It is the first element in Group 6 and it is a steely-grey, lustrous and brittle metal which takes a high polish, resists tarnishing, and has a high melting point. The name of the element is derived from the Greek word χρῶμα, chrōma, meaning color, Chromium metal is of high value for its high corrosion resistance and hardness. A major development was the discovery that steel could be highly resistant to corrosion and discoloration by adding metallic chromium to form stainless steel. Stainless steel and chrome plating together comprise 85% of the commercial use, trivalent chromium ion is an essential nutrient in trace amounts in humans for insulin and lipid metabolism, although the issue is debated. While chromium metal and Cr ions are not considered toxic, hexavalent chromium is toxic and carcinogenic, abandoned chromium production sites often require environmental cleanup. Chromium is remarkable for its properties, it is the only elemental solid which shows antiferromagnetic ordering at room temperature.
Above 38 °C, it changes to paramagnetic, Chromium metal left standing in air is passivated by oxidation, forming a thin, surface layer. This layer is a structure only a few molecules thick. It is very dense, and prevents the diffusion of oxygen into the underlying metal and this is different from the oxide that forms on iron and carbon steel, through which elemental oxygen continues to migrate, reaching the underlying material to cause incessant rusting. Passivation can be enhanced by short contact with oxidizing acids like nitric acid, passivated chromium is stable against acids. Passivation can be removed with a reducing agent that destroys the protective oxide layer on the metal. Chromium metal treated in this way readily dissolves in weak acids, unlike such metals as iron and nickel, does not suffer from hydrogen embrittlement. However, it suffer from nitrogen embrittlement, reacting with nitrogen from air. Chromium is the 22nd most abundant element in Earths crust with a concentration of 100 ppm.
Chromium compounds are found in the environment from the erosion of chromium-containing rocks, Chromium is mined as chromite ore. About two-fifths of the ores and concentrates in the world are produced in South Africa, while Kazakhstan, Russia. Untapped chromite deposits are plentiful, but geographically concentrated in Kazakhstan, although rare, deposits of native chromium exist
In the field of mineralogy, fracture is the texture and shape of a rocks surface formed when a mineral is fractured. Minerals often have a highly distinctive fracture, making it a feature used in their identification. Fracture differs from cleavage in that the latter involves clean splitting along the planes of the minerals crystal structure. All minerals exhibit fracture, but when very strong cleavage is present, conchoidal fracture breakage that resembles the concentric ripples of a mussel shell. It often occurs in amorphous or fine-grained minerals such as flint, opal or obsidian, subconchoidal fracture is similar to conchoidal fracture, but with less significant curvature. Earthy fracture is reminiscent of freshly broken soil and it is frequently seen in relatively soft, loosely bound minerals, such as limonite and aluminite. Hackly fracture is jagged and not even and it occurs when metals are torn, and so is often encountered in native metals such as copper and silver. Splintery fracture comprises sharp elongated points and it is particularly seen in fibrous minerals such as chrysotile, but may occur in non-fibrous minerals such as kyanite.
Uneven fracture is a surface or one with random irregularities. It occurs in a range of minerals including arsenopyrite and magnetite. Rudolf Duda and Lubos Rejl, Minerals of the World http, //www. galleries. com/minerals/property/fracture. htm
Silicon is a chemical element with symbol Si and atomic number 14. A hard and brittle crystalline solid with a metallic luster. It is a member of group 14 in the table, along with carbon above it and germanium, lead. It is not very reactive, although more reactive than germanium, Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure element in the Earths crust. It is most widely distributed in dusts, planetoids, over 90% of the Earths crust is composed of silicate minerals, making silicon the second most abundant element in the Earths crust after oxygen. Most silicon is used commercially without being separated, and often with little processing of the natural minerals, such use includes industrial construction with clays, silica sand, and stone. Silicate is used in Portland cement for mortar and stucco, and mixed with sand and gravel to make concrete for walkways, foundations. Silicates are used in whiteware ceramics such as porcelain, and in traditional quartz-based soda-lime glass, Silicon compounds such as silicon carbide are used as abrasives and components of high-strength ceramics.
Elemental silicon has an impact on the modern world economy. Most free silicon is used in the refining, aluminium-casting. Silicon is the basis of the widely used synthetic polymers called silicones, Silicon is an essential element in biology, although only tiny traces are required by animals. However, various sea sponges and microorganisms, such as diatoms and radiolaria, silica is deposited in many plant tissues, such as in the bark and wood of Chrysobalanaceae and the silica cells and silicified trichomes of Cannabis sativa and many grasses. Silicon is a solid at room temperature, with a point of 1,414 °C. Like water, it has a density in a liquid state than in a solid state and it expands when it freezes. With a relatively high conductivity of 149 W·m−1·K−1, silicon conducts heat well. In its crystalline form, pure silicon has a gray color, like germanium, silicon is rather strong, very brittle, and prone to chipping. Silicon, like carbon and germanium, crystallizes in a cubic crystal structure with a lattice spacing of 0.5430710 nm.
The outer electron orbital of silicon, like that of carbon, has four valence electrons, the 1s, 2s, 2p and 3s subshells are completely filled while the 3p subshell contains two electrons out of a possible six
Violet is the color of amethyst and beautyberries. It takes its name from the violet flower, Violet is the color at the end of the visible spectrum of light between blue and the invisible ultraviolet. Violet color has a predominant light wavelength of roughly 380-450 nanometers, light with a shorter wavelength than violet but longer than X-rays and gamma rays is called ultraviolet. In the color wheel used by painters, it is located between blue and purple. This is not true violet, since it is composed of multiple longer wavelengths rather than a wavelength shorter than that of blue light. Violet and purple look very similar, but violet is a color, with its own set of wavelengths on the spectrum of visible light, while purple is a composite color, made by combining blue. In history and purple have long associated with royalty and majesty. The emperors of Rome wore purple togas, as did the Byzantine emperors, during the Middle Ages violet was worn by bishops and university professors and was often used in art as the color of the robes of the Virgin Mary.
According to surveys in Europe and the United States, violet is the people most often associate with extravagance and individualism, the unconventional, the artificial. In Chinese painting, the color represents the harmony of the universe because it is a combination of red. In Hinduism and Buddhism violet is associated with the Crown Chakra, from the Middle English and old French violette, and from the Latin viola, the names of the violet flower. The first recorded use of violet as a name in English was in 1370. Violet can refer to the first violas which were painted a similar color. In the traditional color used by painters and purple are both placed between red and blue. Purple occupies the space closer to red, between crimson and violet, Violet is closer to blue, and usually less intense and bright than purple. The range of purples is created by combining blue and red light of any intensities, Violet is one of the oldest colors used by man. It has found in the cave of Altamira and Lascaux. It was sometimes used an alternative to black charcoal, sticks of manganese, used for drawing, have been found at sites occupied by Neanderthal man in France and Israel
Minas Gerais is a state in the north of Southeastern Brazil. It ranks as the second most populous, the third by gross domestic product, Minas Gerais is the state with the largest number of Brazilian presidents. With an area of 586,528 square kilometres —larger than Metropolitan France—it is the fourth most extensive state in Brazil. In the south, the tourist points are the mineral spas, such as Caxambu, Lambari, São Lourenço, Poços de Caldas, São Thomé das Letras, Monte Verde. The landscape of the State is marked by mountains, valleys, in the Serra do Cipó, Sete Lagoas and Lagoa Santa, the caves and waterfalls are the attractions. Some of Brazils most famous caverns are located there, in recent years, the state has emerged as one of the largest economic forces of Brazil, exploring its great economic potential. Two interpretations are given for the origin of the name Minas Gerais and it comes from Minas dos Matos Gerais, the former name of the colonial province. Another explanation is that this ignores the two large geographical spaces which conformed the state in its history, the region of the mines, and these corresponded to the areas of Sertão which were farther and hard to access from the mining spots.
The confusion comes from the fact that the term Gerais is taken as an adjective to Minas in the first version, Minas Gerais is in the north of the southeastern subdivision of Brasil, which contains the states of São Paulo, Rio de Janeiro and Espírito Santo. It borders on Bahia, Goiás, Mato Grosso do Sul, the states of São Paulo and Rio de Janeiro and it shares a short boundary with the Distrito Federal. Minas Gerais is situated between 14°1358 and 22°5400 S latitude and between 39°5132 and 51°0235 W longitude and it is larger in area than Metropolitan France or Spain. Minas Gerais features some of the longest rivers in Brazil, most notably the São Francisco, the Paraná and to a lesser extent, the state holds many hydroelectric power plants, including Furnas. The most notable one is the Pico da Bandeira, the third highest mountain in Brazil at 2890 m, the state has huge reserves of iron and sizeable reserves of gold and gemstones, including emerald and aquamarine mines. Emeralds found in location are comparable to the best Colombia-origin emeralds.
Each region of the state has a character, geographically. The central and eastern area of the state is hilly and rocky, around Lagoa Santa and Sete Lagoas a typical Karst topography with caves and lakes is found. Some of the mountains are almost entirely iron ore, which led to extensive mining, recent advances in environmental policy helped to put limits to mining. Vale do Aços largest cities are Ipatinga, Coronel Fabriciano and Timóteo, now that mining is restricted large areas of forest are being removed for timber, charcoal and to clear land for cattle ranching
A thin sliver of rock is cut from the sample with a diamond saw and ground optically flat. It is mounted on a slide and ground smooth using progressively finer abrasive grit until the sample is only 30 μm thick. The method involved using the Michel-Lévy interference colour chart, typically quartz is used as the gauge to determine thickness as it is one of the most abundant minerals. As different minerals have different optical properties, most rock forming minerals can be easily identified, plagioclase for example can be seen in the photo on the right as a clear mineral with multiple parallel twinning planes. The large blue-green minerals are clinopyroxene with some exsolution of orthopyroxene, thin sections are prepared in order to investigate the optical properties of the minerals in the rock. This work is a part of petrology and helps to reveal the origin, a photograph of a rock in thin section is often referred to as a photomicrograph. Fine-grained rocks, particularly those containing minerals of high birefringence, such as calcite, are prepared as ultra-thin sections.
An ordinary 30 μm thin section is prepared as described above, the section is polished on both sides using a fine diamond paste until it has a thickness in the range of 2-12 μm. This technique has been used to study the microstructure of fine-grained carbonates such as the Lochseitenkalk mylonite in which the grains are less than 5 μm in size. Ceramography, thin sections of ceramics Shelley, D
Grey or gray is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is a color without color and this means that there are equal components of red and blue. The variations in intensity of these colors uniformly produce different shades of grey and it is the color of a cloud-covered sky, of ash and of lead. The first recorded use of grey as a name in the English language was in AD700. Grey is the dominant spelling in European and Commonwealth English, although remained in common usage in the UK until the second half of the 20th century. Gray has been the preferred American spelling since approximately 1825, although grey is an accepted variant, in Europe and the United States, surveys show that grey is the color most commonly associated with neutrality, boredom, old age and modesty. Only one percent of respondents chose it as their favorite color, Grey comes from the Middle English grai or grei, from the Anglo-Saxon graeg, and is related to the Dutch grauw and grijs and German grau.
The first recorded use of grey as a name in the English language was in AD700. In antiquity and the Middle Ages, grey was the color of undyed wool, and thus was the color most commonly worn by peasants and the poor. It was the color worn by monks of the Franciscan order, Cistercian Order, Franciscan monks in England and Scotland were commonly known as the Grey friars, and that name is now attached to many places in Great Britain. During the Renaissance and the Baroque, grey began to play an important role in fashion, Black became the most popular color of the nobility, particularly in Italy and Spain, and grey and white were harmonious with it. Grey was used for the drawing of oil paintings. The painting would first be composed in grey and white, and the colors, made with thin transparent glazes, the grisaille beneath would provide the shading, visible through the layers of color. Sometimes the grisaille was simply left uncovered, giving the appearance of carved stone, Grey was a particularly good background color for gold and for skin tones.
It became the most common background for the portraits of Rembrandt Van Rijn and for many of the paintings of El Greco, the palette of Rembrandt was composed almost entirely of somber colors. Over this he put a layer of glaze made of mixture of blue smalt, red ochre. Using these ingredients and many others, he made greys which had, according to art historian Philip Ball, the warm and rich greys and browns served to emphasize the golden light on the faces in the paintings. Grey became a fashionable color in the 18th century, both for womens dresses and for mens waistcoats and coats