Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. At room temperature and pressure, another solid form of carbon known as graphite is the chemically stable form, but diamond never converts to it. Diamond has the highest hardness and thermal conductivity of any natural material, properties that are utilized in major industrial applications such as cutting and polishing tools, they are the reason that diamond anvil cells can subject materials to pressures found deep in the Earth. Because the arrangement of atoms in diamond is rigid, few types of impurity can contaminate it. Small numbers of defects or impurities color diamond blue, brown, purple, orange or red. Diamond has high optical dispersion. Most natural diamonds have ages between 1 billion and 3.5 billion years. Most were formed at depths between 150 and 250 kilometers in the Earth's mantle, although a few have come from as deep as 800 kilometers. Under high pressure and temperature, carbon-containing fluids dissolved minerals and replaced them with diamonds.
Much more they were carried to the surface in volcanic eruptions and deposited in igneous rocks known as kimberlites and lamproites. Synthetic diamonds can be grown from high-purity carbon under high pressures and temperatures or from hydrocarbon gas by chemical vapor deposition. Imitation diamonds can be made out of materials such as cubic zirconia and silicon carbide. Natural and imitation diamonds are most distinguished using optical techniques or thermal conductivity measurements. Diamond is a solid form of pure carbon with its atoms arranged in a crystal. Solid carbon comes in different forms known as allotropes depending on the type of chemical bond; the two most common allotropes of pure carbon are graphite. In graphite the bonds are sp2 orbital hybrids and the atoms form in planes with each bound to three nearest neighbors 120 degrees apart. In diamond they are sp3 and the atoms form tetrahedra with each bound to four nearest neighbors. Tetrahedra are rigid, the bonds are strong, of all known substances diamond has the greatest number of atoms per unit volume, why it is both the hardest and the least compressible.
It has a high density, ranging from 3150 to 3530 kilograms per cubic metre in natural diamonds and 3520 kg/m³ in pure diamond. In graphite, the bonds between nearest neighbors are stronger but the bonds between planes are weak, so the planes can slip past each other. Thus, graphite is much softer than diamond. However, the stronger bonds make graphite less flammable. Diamonds have been adapted for many uses because of the material's exceptional physical characteristics. Most notable are its extreme hardness and thermal conductivity, as well as wide bandgap and high optical dispersion. Diamond's ignition point is 720 -- 800 °C in 850 -- 1000 °C in air; the equilibrium pressure and temperature conditions for a transition between graphite and diamond is well established theoretically and experimentally. The pressure changes linearly between 1.7 GPa at 0 K and 12 GPa at 5000 K. However, the phases have a wide region about this line where they can coexist. At normal temperature and pressure, 20 °C and 1 standard atmosphere, the stable phase of carbon is graphite, but diamond is metastable and its rate of conversion to graphite is negligible.
However, at temperatures above about 4500 K, diamond converts to graphite. Rapid conversion of graphite to diamond requires pressures well above the equilibrium line: at 2000 K, a pressure of 35 GPa is needed. Above the triple point, the melting point of diamond increases with increasing pressure. At high pressures and germanium have a BC8 body-centered cubic crystal structure, a similar structure is predicted for carbon at high pressures. At 0 K, the transition is predicted to occur at 1100 GPa; the most common crystal structure of diamond is called diamond cubic. It is formed of unit cells stacked together. Although there are 18 atoms in the figure, each corner atom is shared by eight unit cells and each atom in the center of a face is shared by two, so there are a total of eight atoms per unit cell; each side of the unit cell is 3.57 angstroms in length. A diamond cubic lattice can be thought of as two interpenetrating face-centered cubic lattices with one displaced by 1/4 of the diagonal along a cubic cell, or as one lattice with two atoms associated with each lattice point.
Looked at from a <1 1 1> crystallographic direction, it is formed of layers stacked in a repeating ABCABC... pattern. Diamonds can form an ABAB... structure, known as hexagonal diamond or lonsdaleite, but this is far less common and is formed under different conditions from cubic carbon. Diamonds occur most as euhedral or rounded octahedra and twinned octahedra known as macles; as diamond's crystal structure has a cubic arrangement of the atoms, they have many facets that belong to a cube, rhombicosidodecahedron, tetrakis hexahedron or disdyakis dodecahedron. The crystals can be elongated. Diamonds are found coated in nyf, an opaque gum-like skin; some diamonds have opaque fibers. They are referred to as opaque if the fibers
Kimberley, Northern Cape
Kimberley is the capital and largest city of the Northern Cape Province of South Africa. It is located 110 km east of the confluence of the Vaal and Orange Rivers; the city has considerable historical significance due to its diamond mining past and the siege during the Second Boer War. British businessmen Cecil Rhodes and Barney Barnato made their fortunes in Kimberley, Rhodes established the De Beers diamond company in the early days of the mining town. On September 2, 1882, Kimberley was the first city in the Southern Hemisphere and the second in the world after Philadelphia, Pennsylvania in the United States to integrate electric street lights into its infrastructure; the first Stock Exchange in Africa was built in Kimberley, as early as 1881. In 1866, Erasmus Jacobs found a small brilliant pebble on the banks of the Orange River, on the farm De Kalk leased from local Griquas, near Hopetown, his father's farm, he showed the pebble to his father. The pebble was purchased from Jacobs by Schalk van Niekerk, who sold it.
It proved to be a 21.25-carat diamond, became known as the Eureka. Three years in 1869, an 83.5-carat diamond, which became known as the Star of South Africa, was found nearby. This diamond was sold by van Niekerk for £11,200 and resold in the London market for £25,000. Henry Richard Giddy recounted how Esau Damoense, the cook for prospector Fleetwood Rawstone's "Red Cap Party", found diamonds in 1871 on Colesberg Kopje after he was sent there to dig as punishment. Rawstorne took the news to the nearby diggings of the De Beer brothers — his arrival there sparking off the famous "New Rush" which, as historian Brian Roberts puts it, was a stampede. Within a month 800 claims were cut into the hillock which were worked frenetically by two to three thousand men; as the land was lowered so the hillock became a mine – in time, the world-renowned Kimberley Mine. The Cape Colony, Orange Free State and the Griqua leader Nicolaas Waterboer all laid claim to the diamond fields; the Free State Boers in particular wanted the area as it lay inside the natural borders created by Orange and Vaal Rivers.
Following the mediation, overseen by the governor of Natal, the Keate Award went in favour of Waterboer, who placed himself under British protection. The territory known as Griqualand West was proclaimed on 27 October 1871. Colonial Commissioners arrived in New Rush on 17 November 1871 to exercise authority over the territory on behalf of the Cape Governor. Digger objections and minor riots led to Governor Barkly's visit to New Rush in September the following year, when he revealed a plan instead to have Griqualand West proclaimed a Crown Colony. Richard Southey would arrive as Lieutenant-Governor of the intended Crown Colony in January 1873. Months passed however without any sign of the proclamation or of the promised new constitution and provision for representative government; the delay was in London where Secretary of State for the Colonies, Lord Kimberley, insisted that before electoral divisions could be defined, the places had to receive "decent and intelligible names. His Lordship declined to be in any way connected with such a vulgarism as New Rush and as for the Dutch name, Vooruitzigt … he could neither spell nor pronounce it."
The matter was passed to Southey who gave it to his Colonial Secretary J. B. Currey. Roberts writes, he made quite sure that Lord Kimberley would be able both to spell and pronounce the name of the main electoral division by, as he says, calling it'after His Lordship'." New Rush became Kimberley, by Proclamation dated 5 July 1873. Digger sentiment was expressed in an editorial in the Diamond Field newspaper when it stated "we went to sleep in New Rush and waked up in Kimberley, so our dream was gone."Following agreement by the British government on compensation to the Orange Free State for its competing land claims, Griqualand West was annexed to the Cape Colony in 1877. The Cape Prime Minister John Molteno had serious doubts about annexing the indebted region, after striking a deal with the Home Government and receiving assurances that the local population would be consulted in the process, he passed the Griqualand West Annexation Act on 27 July 1877; as miners arrived in their thousands the hill disappeared and subsequently became known as the Big Hole or, more formally, Kimberley Mine.
From mid-July 1871 to 1914, 50,000 miners dug the hole with picks and shovels, yielding 2,722 kg of diamonds. The Big Hole is 463 metres wide, it was excavated to a depth of 240 m, but partially infilled with debris reducing its depth to about 215 m. Beneath the surface, the Kimberley Mine underneath the Big Hole was mined to a depth of 1097 metres. A popular local myth claims that it is the largest hand-dug hole on the world, however Jagersfontein Mine appears to hold that record; the Big Hole is the principal feature of a May 2004 submission which placed "Kimberley Mines and associated early industries" on UNESCO's World Heritage Tentative Lists. By 1873 Kimberley was the second largest town in South Africa, having an approximate population of 40,000; the various smaller mining companies were amalgamated by Cecil Rhodes and Charles Rudd into De Beers, The Kimberley under Barney Barnato. In 1888, the two companies merged to form De Beers Consolidated Mines, which once had a monopoly over the world's diamond market.
Kimberley became the largest city in the area due to a massive African migration to the area from all over t
Lamproite is an ultrapotassic mantle-derived volcanic or subvolcanic rock. It has low CaO, Al2O3, Na2O, high K2O/Al2O3, a high MgO content and extreme enrichment in incompatible elements. Lamproites are volumetrically insignificant. Unlike kimberlites, which are found in Archaean cratons, lamproites are found in terrains of varying age, ranging from Archaean in Western Australia, to Palaeozoic and Mesozoic in southern Spain, they vary in age, from Proterozoic to Pleistocene, the youngest known example being 56,000 ± 5,000 years old. Lamproite volcanology is varied, with cone edifices known. Lamproites form from melted mantle at depths exceeding 150 km; the molten material is forced to the surface in volcanic pipes, bringing with it xenoliths and diamonds from the harzburgitic peridotite or eclogite mantle regions where diamond formation is stabilized. Recent research, for example on the lamproites at Gaussberg in Antarctica, lead-lead isotope geochemistry have revealed that the source of lamproites may be transition zone melts of subducted lithosphere which has become trapped at the base of the lithospheric mantle.
This observation reconciles the depth of melting with the peculiar geochemistry, most explained by melting of felsic material under deep mantle conditions. The mineralogy of lamproites is controlled by their peculiar geochemistry, with a predominance of rare silica-deficient mineral species and rare, mantle-derived minerals predominating. Minerals typical of lamproites include: forsteritic olivine. A variety of rare trace minerals occur; the rocks are high in potassium with 6 to 8% potassium oxide. High chromium and nickel content is typical; the rocks are altered to talc with carbonate or serpentine and magnetite. Zeolites and quartz may occur. Lamproites are characterized by the presence of varying amounts of the following primary phases: titanian, aluminium-poor phenocrystic phlogopite titanian groundmass poikilitic "tetraferriphlogopite" titanian potassium richterite forsteritic olivine aluminium-poor, sodium-poor diopside nonstoichiometric iron-rich leucite, iron-rich sanidine ); the presence of all the above phases is not required in order to classify a rock as a lamproite.
Any one mineral may be dominant, this, together with the two or three other major minerals present, suffices to determine the petrographic name. The presence of the following minerals precludes a rock from being classified as a lamproite: primary plagioclase, monticellite, nepheline, Na-rich alkali feldspar, nosean, melanite, schorlomite or kimzeyite. Lamproites conform to the following chemical characteristics: molar K2O/Na2O > 3, i.e. ultrapotassic molar K2O/Al2O3> 0.8 and > 1 molar K2O + Na2O/ Al2O3 > 1 i.e. peralkaline <10 wt% each of FeO and CaO, TiO2 1-7 wt%, >2000 and >5000 ppm Ba, >500 ppm Zr, >1000 ppm Sr and >200 ppm La. The economic significance of lamproite became known with the 1979 discovery of the Argyle diamond pipe in Western Australia; this discovery led to the intense study and re-evaluation of other known lamproite occurrences worldwide. The Argyle diamond mine remains the only economically viable source of lamproite diamonds; this deposit differs markedly by having a high content of diamonds but low quality of most stones.
Research at Argyle diamond have shown. The Argyle diamond mine is the main source of rare pink diamonds. Olivine lamproite pyroclastic rocks and dikes are sometimes hosts for diamonds; the diamonds occur as xenocrysts that have been carried to the surface or to shallow depths by the lamproite diapiric intrusions. The diamonds of Crater of Diamonds State Park near Murfreesboro, Arkansas are found in a lamproite host. Lamproites, as a group, were known by a variety of localised names due to the fact their mineralogy is quite variable and because of their rarity few examples of the following lamproite variants were known. Modern terminology classes all as lamproites but modifies this term with the mineral abundances as per the standard IUGS rules. Kimberlite – An igneous rock which sometimes contains diamonds Lamprophyre Ultrapotassic igneous rocks Bergman, S. C.. In: Alkaline Igneous rocks, Fitton, J. G. and Upton, B. G. J, Geological Society of London special publication No. 30. Pp. 103–19. Mitchell, R. H..
C.. Petrology of Lamproites. New York: Plenum Press. ISBN 978-0-306-43556-0. Murphy, D. T.. S.. "Lamproites from Gaussberg, Antarctica: Possible Transition Zone Melts of Archaean Subducted Sediments". Journal of Petrology. 43: 981–1001. Bibcode:2002JPet...43..981M. Doi:10.1093/petrology/43.6.981. Woolley, A. R. Bergman, S. C. Edgar, A. D, Le Bas, M. J. Mitchell, R. H. Rock, N. M. S. & Scott Smith, B. H. 1996. Classification of lamprophyres, lamproites and the kalsilitic and leucitic rocks; the Canadian Mineralogist, Vol 34, Part 2. Pp. 175–186. Müller, Groves, David I.: Potassic igneous rocks and associated gold-copper mine
Nashville is a city in Howard County, United States. The population was 4,627 at the 2010 census; the estimated population in 2015 was 4,479. The city is the county seat of Howard County. Nashville is situated at the base of the Ouachita foothills and was once a major center of the peach trade in southwest Arkansas. Today the land is given over to cattle and chicken farming; the world's largest dinosaur trackway was discovered near the town in 1983. Mine Creek Baptist Church was built along the banks of Mine Creek by the Rev. Isaac Cooper Perkins in the area where Nashville now stands around 1835. Settlers established a post stop along the settlement roads in 1840, a post office incorporated in 1848. Michael Womack, a Tennessee native reputed to have killed the British general Edward Packenham during the War of 1812, settled in the area with his family in 1849; the area was known by locals as "Mine Creek", but was called "Hell's Valley" and "Pleasant Valley". Settlement in the area progressed but though industry declined during the Civil War.
Following the war, the village's prospects improved and settlement picked up, the town was incorporated as Nashville on 18 October 1883, with D. A. Hutchinson serving as the first mayor. Womack called the town after Nashville, Tennessee; the following year and Hope were connected via railroad, spurring further growth, the county seat was relocated from Center Point to Nashville. With the establishment of county government in the town, due to the increased trade and access brought by the railroad, Nashville continued to grow; the town had a population of 928 in 1900, boasted "a cotton-compress and gin" and a "bottling-works". In the years before the Great Depression, Nashville was a prosperous, if small, town. According to author Dallas Tabor Herndon, Nashville was "a banking town, with electric lights, waterworks, an ice and cold storage plant, a canning factory, machine shops, a flour mill, two newspapers, a brick factory, fruit box and crate factory, mercantile concerns... well-kept streets, modern public schools."An EF2 tornado struck the town on May 10, 2015, killed two people.
Nashville is located in southeastern Howard County at 33°56′31″N 93°50′53″W. U. S. Routes 278 and 371 run concurrently through the northern side of the city. US 371 leads west 19 miles to Lockesburg. US 278 leads northwest 19 miles to Dierks and southeast 28 miles to Hope. Arkansas Highway 27 joins US 278 in a bypass around the eastern side of Nashville. According to the United States Census Bureau, Nashville has a total area of 5.7 square miles, of which 0.04 square miles, or 0.76%, are water. The city is in the valley of a south-flowing tributary of the Saline and Little rivers; as of the census of 2000, there were 4,878 people, 1,857 households, 1,179 families residing in the city. The population density was 1,067.7 people per square mile. There were 2,136 housing units at an average density of 467.5 per square mile. The racial makeup of the city was 59.96% White, 30.21% Black or African American, 5.25% Native American, 1.23% Asian, 0.02% Pacific Islander, 4.39% from other races, 0.94% from two or more races.
6.99% of the population were Hispanic or Latino of any race. There were 1,857 households out of which 33.0% had children under the age of 18 living with them, 41.6% were married couples living together, 18.5% had a female householder with no husband present, 36.5% were non-families. 32.8% of all households were made up of individuals and 14.9% had someone living alone, 65 years of age or older. The average household size was 2.45 and the average family size was 3.12. In the city, the population was spread out with 27.6% under the age of 18, 9.6% from 18 to 24, 27.0% from 25 to 44, 19.2% from 45 to 64, 16.6% who were 65 years of age or older. The median age was 35 years. For every 100 females, there were 89.2 males. For every 100 females age 18 and over, there were 83.4 males. The median income for a household in the city was $23,480, the median income for a family was $28,611. Males had a median income of $24,494 versus $17,480 for females; the per capita income for the city was $13,258. About 18.7% of families and 21.4% of the population were below the poverty line, including 29.4% of those under age 18 and 16.3% of those age 65 or over.
Peach farming sustained Nashville during the Depression. The peach industry came to the Nashville area in the late nineteenth century. Peak years of production lasted from the 1920s until the 1950s. Nashville's peak peach production was 1950, with over 400,000 bushels collected from 425 orchards. "Up to 175 boxcars, each carrying 396 bushel baskets, were shipped from Nashville each day during peak production years." Late freezes and early thaws in 1952 and 1953 led to the devastation of the peach harvests. Two-thirds of the crops were destroyed, production sank to 150,000 bushels. "The Arkansas growers lost the market, the impact was devastating. For Howard County growers, the only option was to pull up the trees and convert the land for other purposes pasture for cattle, or to raise chickens," which remain the dominant agricultural products in the Nashville area to this day; the peach industry in the area continued to decline as industrial farming in the Sun Belt and shifting production patterns made southwest Arkansas less attractive to larger produce companies.
However, many small peach orchards still remain and a
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate. The Mohs scale of mineral hardness, based on scratch hardness comparison, defines value 3 as "calcite". Other polymorphs of calcium carbonate are the minerals vaterite. Aragonite will change to calcite over timescales of days or less at temperatures exceeding 300 °C, vaterite is less stable. Calcite is derived from the German Calcit, a term coined in the 19th century from the Latin word for lime, calx with the suffix -ite used to name minerals, it is thus etymologically related to chalk. When applied by archaeologists and stone trade professionals, the term alabaster is used not just as in geology and mineralogy, where it is reserved for a variety of gypsum. In publications, two different sets of Miller indices are used to describe directions in calcite crystals - the hexagonal system with three indices h, k, l and the rhombohedral system with four indices h, k, l, i. To add to the complications, there are two definitions of unit cell for calcite.
One, an older "morphological" unit cell, was inferred by measuring angles between faces of crystals and looking for the smallest numbers that fit. A "structural" unit cell was determined using X-ray crystallography; the morphological unit cell has approximate dimensions a = 10 Å and c = 8.5 Å, while for the structural unit cell they are a = 5 Å and c = 17 Å. For the same orientation, c must be multiplied by 4 to convert from morphological to structural units; as an example, the cleavage is given as "perfect on " in morphological coordinates and "perfect on " in structural units. Twinning and crystal forms are always given in morphological units. Over 800 forms of calcite crystals have been identified. Most common are scalenohedra, with faces in the hexagonal directions or directions. Habits include acute to tabular forms, prisms, or various scalenohedra. Calcite exhibits several twinning types adding to the variety of observed forms, it may occur as fibrous, lamellar, or compact. A fibrous, efflorescent form is known as lublinite.
Cleavage is in three directions parallel to the rhombohedron form. Its fracture is difficult to obtain. Scalenohedral faces are chiral and come in pairs with mirror-image symmetry. Rhombohedral faces are achiral, it has a defining Mohs hardness of 3, a specific gravity of 2.71, its luster is vitreous in crystallized varieties. Color is white or none, though shades of gray, orange, green, violet, brown, or black can occur when the mineral is charged with impurities. Calcite is transparent to opaque and may show phosphorescence or fluorescence. A transparent variety called. Acute scalenohedral crystals are sometimes referred to as "dogtooth spar" while the rhombohedral form is sometimes referred to as "nailhead spar". Single calcite crystals display; this strong birefringence causes objects viewed through a clear piece of calcite to appear doubled. The birefringent effect was first described by the Danish scientist Rasmus Bartholin in 1669. At a wavelength of ≈590 nm calcite has ordinary and extraordinary refractive indices of 1.658 and 1.486, respectively.
Between 190 and 1700 nm, the ordinary refractive index varies between 1.9 and 1.5, while the extraordinary refractive index varies between 1.6 and 1.4. Calcite, like most carbonates, will dissolve with most forms of acid. Calcite can be either dissolved by groundwater or precipitated by groundwater, depending on several factors including the water temperature, pH, dissolved ion concentrations. Although calcite is insoluble in cold water, acidity can cause dissolution of calcite and release of carbon dioxide gas. Ambient carbon dioxide, due to its acidity, has a slight solubilizing effect on calcite. Calcite exhibits an unusual characteristic called retrograde solubility in which it becomes less soluble in water as the temperature increases; when conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together or it can fill fractures. When conditions are right for dissolution, the removal of calcite can increase the porosity and permeability of the rock, if it continues for a long period of time may result in the formation of caves.
On a landscape scale, continued dissolution of calcium carbonate-rich rocks can lead to the expansion and eventual collapse of cave systems, resulting in various forms of karst topography. Ancient Egyptians carved many items out of calcite, relating it to their goddess Bast, whose name contributed to the term alabaster because of the close association. Many other cultures have used the material for similar carved applications. High-grade optical calcite was used in World War II for gun sights in bomb sights and anti-aircraft weaponry. Experiments have been conducted to use calcite for a cloak of invisibility. Microbiologically precipitated calcite has a wide range of applications, such as soil remediation, soil stabilization and concrete repair. Calcite, obtained from an 80 kg sample of Carrara marble, is used as the IAEA-603 isotopic standard in mass spectrometry for the calibration of δ18O and δ13C. Calcite is a common constituent
The Strawn-Wagner Diamond is one of a few colorless, internally flawless diamonds found so far in the world, weighing 3.09 carat. It was found in 1990 by Shirley Strawn of Murfreesboro, Arkansas, in the Crater of Diamonds State Park public search field, it was cut to 1.09 carats in 1997, graded a "perfect" 0/0/0 by the American Gem Society in 1998 and graded perfect by the Gemological Institute of America, making it the first diamond from Arkansas to receive such an AGS grading. The diamond is considered one-in-a-billion, according to the AGS Laboratory Director; the diamond is on exhibit at the Crater of Diamonds State Park in Murfreesboro, Arkansas after the park purchased it for $34,700
The United States of America known as the United States or America, is a country composed of 50 states, a federal district, five major self-governing territories, various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U. S. is the third most populous country. The capital is Washington, D. C. and the largest city by population is New York City. Forty-eight states and the capital's federal district are contiguous in North America between Canada and Mexico; the State of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The State of Hawaii is an archipelago in the mid-Pacific Ocean; the U. S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The diverse geography and wildlife of the United States make it one of the world's 17 megadiverse countries.
Paleo-Indians migrated from Siberia to the North American mainland at least 12,000 years ago. European colonization began in the 16th century; the United States emerged from the thirteen British colonies established along the East Coast. Numerous disputes between Great Britain and the colonies following the French and Indian War led to the American Revolution, which began in 1775, the subsequent Declaration of Independence in 1776; the war ended in 1783 with the United States becoming the first country to gain independence from a European power. The current constitution was adopted in 1788, with the first ten amendments, collectively named the Bill of Rights, being ratified in 1791 to guarantee many fundamental civil liberties; the United States embarked on a vigorous expansion across North America throughout the 19th century, acquiring new territories, displacing Native American tribes, admitting new states until it spanned the continent by 1848. During the second half of the 19th century, the Civil War led to the abolition of slavery.
By the end of the century, the United States had extended into the Pacific Ocean, its economy, driven in large part by the Industrial Revolution, began to soar. The Spanish–American War and World War I confirmed the country's status as a global military power; the United States emerged from World War II as a global superpower, the first country to develop nuclear weapons, the only country to use them in warfare, a permanent member of the United Nations Security Council. Sweeping civil rights legislation, notably the Civil Rights Act of 1964, the Voting Rights Act of 1965 and the Fair Housing Act of 1968, outlawed discrimination based on race or color. During the Cold War, the United States and the Soviet Union competed in the Space Race, culminating with the 1969 U. S. Moon landing; the end of the Cold War and the collapse of the Soviet Union in 1991 left the United States as the world's sole superpower. The United States is the world's oldest surviving federation, it is a representative democracy.
The United States is a founding member of the United Nations, World Bank, International Monetary Fund, Organization of American States, other international organizations. The United States is a developed country, with the world's largest economy by nominal GDP and second-largest economy by PPP, accounting for a quarter of global GDP; the U. S. economy is post-industrial, characterized by the dominance of services and knowledge-based activities, although the manufacturing sector remains the second-largest in the world. The United States is the world's largest importer and the second largest exporter of goods, by value. Although its population is only 4.3% of the world total, the U. S. holds 31% of the total wealth in the world, the largest share of global wealth concentrated in a single country. Despite wide income and wealth disparities, the United States continues to rank high in measures of socioeconomic performance, including average wage, human development, per capita GDP, worker productivity.
The United States is the foremost military power in the world, making up a third of global military spending, is a leading political and scientific force internationally. In 1507, the German cartographer Martin Waldseemüller produced a world map on which he named the lands of the Western Hemisphere America in honor of the Italian explorer and cartographer Amerigo Vespucci; the first documentary evidence of the phrase "United States of America" is from a letter dated January 2, 1776, written by Stephen Moylan, Esq. to George Washington's aide-de-camp and Muster-Master General of the Continental Army, Lt. Col. Joseph Reed. Moylan expressed his wish to go "with full and ample powers from the United States of America to Spain" to seek assistance in the revolutionary war effort; the first known publication of the phrase "United States of America" was in an anonymous essay in The Virginia Gazette newspaper in Williamsburg, Virginia, on April 6, 1776. The second draft of the Articles of Confederation, prepared by John Dickinson and completed by June 17, 1776, at the latest, declared "The name of this Confederation shall be the'United States of America'".
The final version of the Articles sent to the states for ratification in late 1777 contains the sentence "The Stile of this Confederacy shall be'The United States of America'". In June 1776, Thomas Jefferson wrote the phrase "UNITED STATES OF AMERICA" in all capitalized letters in the headline of his "original Rough draught" of the Declaration of Independence; this draft of the document did not surface unti