United States Sesquicentennial coinage
The United States Sesquicentennial coin issue consisted of a commemorative half dollar and quarter eagle struck in 1926 at the Philadelphia Mint for the 150th anniversary of American independence. The obverse of the half dollar features portraits of the first president, George Washington, the president in 1926, Calvin Coolidge, making it the only American coin to depict a president in his lifetime. By the March 1925 Act of Congress, by which the National Sesquicentennial Exhibition Commission was chartered, Congress allowed it to purchase 1,000,000 specially designed half dollars and 200,000 quarter eagles, which could be sold to the public at a premium; the Commission had trouble agreeing on a design with Mint Chief Engraver John R. Sinnock, asked Philadelphia attorney, arts patron and numismatist John Frederick Lewis to submit sketches; these were adapted by Sinnock, without giving credit to Lewis, whose involvement would not be known for forty years. Both the quarter eagle, designed by Sinnock, the half dollar were struck in the maximum number authorized, but many were returned to the Mint for melting when they failed to sell.
The Liberty Bell reverse for the half dollar was reused by Sinnock, again without giving Lewis credit, on the Chief Engraver's Franklin half dollar, first minted in 1948. Legislation for a commemorative coin to mark the 150th anniversary of American independence was introduced on behalf of the United States National Sesquicentennial Exhibition Commission, charged with organizing what became known as the Sesquicentennial Exposition in Philadelphia. In the Act of March 3, 1925, Congress both chartered the Commission and allowed one million half dollars and 200,000 quarter eagles to be struck in commemoration of the Sesquicentennial of American Independence; these coins would be sold only at face value. Profits would go to financing the Exposition; the original version of the bill, introduced in the House of Representatives on February 16, 1925 by Pennsylvania Congressman George P. Darrow and in the Senate by that state's George W. Pepper, called for a $1.50 gold coin for the 150th anniversary, for commemorative half dollars, for a $1 bill honoring the Declaration of Independence.
A hearing was held before the House Committee on Industrial Arts and Expositions two days at which Congressman Darrow predicted that the $1.50 gold pieces would not be opposed by either the Treasury or the Committee on Coinage and Measures, but he was incorrect. The Commission hoped to have commemoratives depicting the enlargement of the country through acquisitions such as the Louisiana Purchase and the Annexation of Texas, but these were not included in the final version of the bill; the Commission continued to pursue congressional approval of the $1.50 piece and the other proposed commemoratives at least through August 1925. In May, H. P. Caemmerer, secretary of the Commission of Fine Arts, a body charged with making recommendations on the approval of coinage design, wrote to the Sesquicentennial Commission, asking what they proposed to do about the coins. Having received no reply, he wrote again in late August, this time to Milton Medary, a member of the Fine Arts Commission, asking what progress had been made.
Medary replied that the Sesquicentennial Commission was in touch with the new Chief Engraver at the Philadelphia Mint, John R. Sinnock, but that Sinnock had not yet submitted satisfactory designs. Dissatisfied with Sinnock's work, the Sesquicentennial Commission hired John Frederick Lewis to create designs. Lewis, who served as president of the Pennsylvania Academy of Fine Arts from 1906 until his death in 1932, was known as a numismatist, but not as an artist. On December 8, 1925, Sesquicentennial Commission director Asher C. Baker submitted Lewis's sketches, which appear much like the present half dollar, to Fine Arts Commission chairman Charles Moore. Baker referred to Lewis's "designs for the coins", which may mean that he submitted sketches for the quarter eagle as well, but if so, they are not extant and were not acted upon by the Fine Arts Commission; the half dollar designs were approved by the Fine Arts Commission, on condition the sketches were converted into models by a competent sculptor, Moore sent them on December 11 to Mint Director Robert J. Grant.
The resultant plaster models, made by Sinnock, were submitted to the Fine Arts Commission on March 13, 1926, were undoubtedly endorsed, but the approval letter is lost. Sinnock's sketches for the quarter eagle were sent to the Fine Arts Commission on February 27, 1926, were forwarded to sculptor member Lorado Taft for his views. Moore sent his commission's approval to Grant on March 26, with several recommendations, including that the motto E Pluribus Unum, present on the obverse in Sinnock's sketches, the sun's rays on the reverse, be omitted; the rays were not removed, the motto was moved to the reverse. Approval of the models followed in April, again with minor suggestions; the obverse of the half dollar features jugate busts of George Washington, first president of the United States, Calvin Coolidge, the president in 1926. According to Anthony Swiatek and Walter Breen, "both were mistakes. Washington was not president of the Continental Congress in 1776, Coolidge's likeness was illegal. By an 1866 Act of Congress, no living person could be portrayed on U.
S. coins or currency. Although Sinnock had not designed a coin showing a president, he had created presidential medals under Chief Engraver
James Monroe was an American statesman, lawyer and Founding Father who served as the fifth president of the United States from 1817 to 1825. A member of the Democratic-Republican Party, Monroe was the last president of the Virginia dynasty, his presidency coincided with the Era of Good Feelings, he is best known for issuing the Monroe Doctrine, a policy of opposing European colonialism in the Americas. He served as the governor of Virginia, a member of the United States Senate, the U. S. ambassador to France and Britain, the seventh Secretary of State, the eighth Secretary of War. Born into a planter family in Westmoreland County, Monroe served in the Continental Army during the American Revolutionary War. After studying law under Thomas Jefferson from 1780 to 1783, he served as a delegate in the Continental Congress; as a delegate to the Virginia Ratifying Convention, Monroe opposed the ratification of the United States Constitution. In 1790, he won election to the Senate, he left the Senate in 1794 to serve as President George Washington's ambassador to France, but was recalled by Washington in 1796.
Monroe won election as Governor of Virginia in 1799 and supported Jefferson's candidacy in the 1800 presidential election. As President Jefferson's special envoy, Monroe helped negotiate the Louisiana Purchase, through which the United States nearly doubled in size. Monroe fell out with his long-time friend, James Madison, after the latter rejected the Monroe–Pinkney Treaty that Monroe negotiated with Britain, he unsuccessfully challenged Madison in the 1808 presidential election, but in April 1811 he joined Madison's administration as Secretary of State. During the stages of the War of 1812, Monroe served as Madison's Secretary of State and Secretary of War, his war-time leadership established him as Madison's heir apparent, he defeated Federalist Party candidate Rufus King in the 1816 presidential election. Monroe's presidency was coterminous with the Era of Good Feelings, as the Federalist Party collapsed as a national political force; as president, Monroe signed the Missouri Compromise, which admitted Missouri as a slave state and banned slavery from territories north of the parallel 36°30′ north.
In foreign affairs and Secretary of State John Quincy Adams favored a policy of conciliation with Britain and a policy of expansionism against the Spanish Empire. In the 1819 Adams–Onís Treaty with Spain, the United States secured Florida and established its western border with New Spain. In 1823, Monroe announced the United States' opposition to any European intervention in the independent countries of the Americas with the Monroe Doctrine, which became a landmark in American foreign policy. Monroe was a member of the American Colonization Society, which supported the colonization of Africa by freed slaves, Liberia's capital of Monrovia is named in his honor. Following his retirement in 1825, Monroe was plagued by financial difficulties, he died in New York City on July 4, 1831. He has been ranked as an above-average president. James Monroe was born on April 28, 1758, in his parents' house located in a wooded area of Westmoreland County, Virginia; the marked site is one mile from the unincorporated community known today as Virginia.
The James Monroe Family Home Site was listed on the National Register of Historic Places in 1979. His father Spence Monroe was a moderately prosperous planter who practiced carpentry, his mother Elizabeth Jones married Spence Monroe in 1752 and they had five children: Elizabeth, Spence and Joseph Jones. His paternal 2nd great grandfather Patrick Andrew Monroe emigrated to America from Scotland in the mid-17th century, was part of an ancient Scottish clan known as Clan Munro. In 1650 he patented a large tract of land in Westmoreland County, Virginia. Monroe's mother was the daughter of a wealthy immigrant by the name of James Jones, who immigrated from Wales and had settled in nearby King George County, Virginia. Jones was an architect. Among James Monroe's ancestors were French Huguenot immigrants, who came to Virginia in 1700. At age eleven, Monroe was enrolled in the lone school in the county. Monroe attended this school for only eleven weeks a year. During this time, Monroe formed a lifelong friendship with John Marshall.
Monroe's mother died in 1772, his father died two years later. Though he inherited property from both of his parents, the sixteen-year-old Monroe was forced to withdraw from school to support his younger brothers, his childless maternal uncle, Joseph Jones, became a surrogate father to his siblings. A member of the Virginia House of Burgesses, Jones took Monroe to the capital of Williamsburg and enrolled him in the College of William and Mary. Jones introduced Monroe to important Virginians such as Thomas Jefferson, Patrick Henry, George Washington. In 1774, opposition to the British government grew in the Thirteen Colonies in reaction to the "Intolerable Acts," and Virginia sent a delegation to the First Continental Congress. Monroe became involved in the opposition to Lord Dunmore, the colonial governor of Virginia, he took part in the storming of the Governor's Palace. In early 1776, about a year and a half after his enrollment, Monroe dropped out of college and joined the 3rd Virginia Regiment in the Continental Army.
As the fledgling army valued literacy in its officers, Monroe was commissioned with the rank of lieutenant, serving under Captain William Washington. After months of training and seven hundred Virginia infantrymen were called north to
Daniel Boone was an American pioneer, explorer and frontiersman, whose frontier exploits made him one of the first folk heroes of the United States. Boone is most famous for his settlement of what is now Kentucky, it was still considered part of Virginia but was on the western side of the Appalachian Mountains from most European-American settlements. As a young adult, Boone supplemented his farm income by hunting and trapping game, selling their pelts in the fur market. Through this occupational interest, Boone first learned the easy routes to the area. Despite some resistance from American Indian tribes such as the Shawnee, in 1775, Boone blazed his Wilderness Road from North Carolina and Tennessee through Cumberland Gap in the Cumberland Mountains into Kentucky. There, he founded the village of Boonesborough, one of the first American settlements west of the Appalachians. Before the end of the 18th century, more than 200,000 Americans migrated to Kentucky/Virginia by following the route marked by Boone.
Boone served as a militia officer during the Revolutionary War, which, in Kentucky, was fought between the American settlers and British-allied Native Americans, who hoped to expel the Americans. Boone was captured by Shawnee warriors in 1778, he alerted Boonesborough that the Shawnee were planning an attack. Although outnumbered, Americans repelled the Shawnee warriors in the Siege of Boonesborough. Boone was elected to the first of his three terms in the Virginia General Assembly during the Revolutionary War, he fought in the Battle of Blue Licks in 1782. Blue Licks, a Shawnee victory over the Patriots, was one of the last battles of the Revolutionary War, coming after the main fighting ended in October 1781. Following the war, Boone worked as a surveyor and merchant, but fell into debt through failed Kentucky land speculation. Frustrated with the legal problems resulting from his land claims, in 1799, Boone emigrated to eastern Missouri, where he spent most of the last two decades of his life.
Boone remains an iconic figure in American history. He was a legend in his own lifetime after an account of his adventures was published in 1784, framing him as the typical American frontiersman. After his death, he was the subject of heroic tall tales and works of fiction, his adventures—real and legendary—were influential in creating the archetypal frontier hero of American folklore. In American popular culture, he is remembered as one of the foremost early frontiersmen; the epic Daniel Boone mythology overshadows the historical details of his life. Daniel Boone was of English West Welsh ancestry; because the Gregorian calendar was adopted during his lifetime, Boone's birth date is sometimes given as November 2, 1734, although Boone used the October date. The Boone family belonged to the Religious Society of Friends, called "Quakers", were persecuted in England for their dissenting beliefs. Daniel's father, Squire Boone emigrated from the small town of Bradninch, Devon to Pennsylvania in 1713, to join William Penn's colony of dissenters.
Squire Boone's parents, George Boone III and Mary Maugridge, followed their son to Pennsylvania in 1717, in 1720 built a log cabin at Boonecroft. In 1720, Squire Boone, who worked as a weaver and a blacksmith, married Sarah Morgan. Sarah's family were Quakers from Wales, had settled in 1708 in the area which became Towamencin Township of Montgomery County. In 1731, the Boones moved to Exeter Township in the Oley Valley of Berks County, near the modern city of Reading. There they built a log cabin preserved today as the Daniel Boone Homestead. Daniel Boone was born there, the sixth of eleven children; the Daniel Boone Homestead is four miles from the Mordecai Lincoln House, making the Squire Boone family neighbors of Mordecai Lincoln, the great-great-grandfather of future president Abraham Lincoln. Mordecai's son named Abraham, married Ann Boone, a first cousin of Daniel. Daniel Boone spent his early years on what was the edge of the frontier. Several Lenape Indian villages were nearby; the pacifist Pennsylvania Quakers had good relations with the Native Americans, but the steady growth of the white population compelled many Indians to move further west.
Boone was given his first rifle at the age of 12. He learned to hunt from the Lenape. Folk tales have emphasized Boone's skills as a hunter. In one story, the young Boone was hunting in the woods with some other boys, when the howl of a panther scattered all but Boone, he calmly shot the predator through the heart just as it leaped at him. The validity of this claim is contested, but the story was told so that it became part of his popular image. In Boone's youth, his family became a source of controversy in the local Quaker community when two of the oldest children married outside the endogamous community, in present-day Lower Gwynedd Township, Pennsylvania. In 1742, Boone's parents were compelled to apologize publicly after their eldest child, married John Willcockson, a "worldling"; because the young couple had "kept company", they were considered "married without benefit of clergy". When the Boones' oldest son Israel married a "worldling" in 1747, Squire Boone stood by him. Both men were expelled from the Quakers.
In 1750, Squire Boone moved the family to North Carolina. Daniel Boone did not attend church again, he had all of his children baptized. The Boones
John Calvin Coolidge Jr. was an American politician and lawyer who served as the 30th president of the United States from 1923 to 1929. A Republican lawyer from New England, born in Vermont, Coolidge worked his way up the ladder of Massachusetts state politics becoming governor, his response to the Boston Police Strike of 1919 thrust him into the national spotlight and gave him a reputation as a man of decisive action. The next year, he was elected vice president of the United States, he succeeded to the presidency upon the sudden death of Warren G. Harding in 1923. Elected in his own right in 1924, he gained a reputation as a small government conservative and as a man who said little and had a rather dry sense of humor. Coolidge restored public confidence in the White House after the scandals of his predecessor's administration, left office with considerable popularity; as a Coolidge biographer wrote: "He embodied the spirit and hopes of the middle class, could interpret their longings and express their opinions.
That he did represent the genius of the average is the most convincing proof of his strength". Scholars have ranked Coolidge in the lower half of those presidents, he is praised by advocates of smaller government and laissez-faire economics, while supporters of an active central government view him less favorably, though most praise his stalwart support of racial equality. John Calvin Coolidge Jr. was born in Plymouth Notch, Windsor County, Vermont, on July 4, 1872, the only US president to be born on Independence Day. He was the elder of the two children of John Calvin Coolidge Sr. and Victoria Josephine Moor. Coolidge Junior was called by his middle name, Calvin. Coolidge Senior engaged in many occupations and developed a statewide reputation as a prosperous farmer and public servant, he held various local offices, including justice of the peace and tax collector and served in the Vermont House of Representatives as well as the Vermont Senate. Coolidge's mother was the daughter of a Plymouth Notch farmer.
She was chronically ill and died from tuberculosis, when Coolidge was twelve years old. His younger sister, Abigail Grace Coolidge, died at the age of 15 of appendicitis, when Coolidge was 18. Coolidge's father married a Plymouth schoolteacher in 1891, lived to the age of 80. Coolidge's family had deep roots in New England. Another ancestor, Edmund Rice, arrived at Watertown in 1638. Coolidge's great-great-grandfather named John Coolidge, was an American military officer in the Revolutionary War and one of the first selectmen of the town of Plymouth, his grandfather Calvin Galusha Coolidge served in the Vermont House of Representatives. Coolidge was a descendant of Samuel Appleton, who settled in Ipswich and led the Massachusetts Bay Colony during King Philip's War. Coolidge attended Black River Academy and St. Johnsbury Academy, before enrolling at Amherst College, where he distinguished himself in the debating class; as a senior, he graduated cum laude. While at Amherst, Coolidge was profoundly influenced by philosophy professor Charles Edward Garman, a Congregational mystic, with a neo-Hegelian philosophy.
Coolidge explained Garman's ethics forty years later: here is a standard of righteousness that might does not make right, that the end does not justify the means, that expediency as a working principle is bound to fail. The only hope of perfecting human relationships is in accordance with the law of service under which men are not so solicitous about what they shall get as they are about what they shall give, yet people are entitled to the rewards of their industry. What they earn is theirs, no matter how small or how great, but the possession of property carries the obligation to use it in a larger service... At his father's urging after graduation, Coolidge moved to Northampton, Massachusetts to become a lawyer. To avoid the cost of law school, Coolidge followed the common practice of apprenticing with a local law firm, Hammond & Field, reading law with them. John C. Hammond and Henry P. Field, both Amherst graduates, introduced Coolidge to law practice in the county seat of Hampshire County.
In 1897, Coolidge was admitted to the Massachusetts bar. With his savings and a small inheritance from his grandfather, Coolidge opened his own law office in Northampton in 1898, he practiced commercial law. As his reputation as a hard-working and diligent attorney grew, local banks and other businesses began to retain his services. In 1903, Coolidge met Grace Anna Goodhue, a University of Vermont graduate and teacher at Northampton's Clarke School for the Deaf, they married on October 4, 1905 at 2:30 p.m. in a small ceremony which took place in the parlor of Grace's family's house, following a vain effort at postponement by Grace's mother. The newlyweds went on a honeymoon trip to Montreal planned for two weeks but cut short by a week at Coolidge's request. After 25 years he wrote of Grace, "for a quarter of a century she has borne with my infirmities and I have rejoiced in her graces"; the Coolidges had two sons: John and Calvin Jr.. Calvin Jr. died at age 16 from blood poisoning. On June 30, 1924 Calvin Jr had played tennis with his brother on the White House tennis courts without putting on socks and developed a blister on one of his toes.
The blister subsequently
Thomas Jonathan "Stonewall" Jackson served as a Confederate general during the American Civil War, became one of the best-known Confederate commanders after General Robert E. Lee. Jackson played a prominent role in nearly all military engagements in the Eastern Theater of the war until his death, played a key role in winning many significant battles. Born in what was part of Virginia, Jackson received an appointment to the United States Military Academy at West Point, served in the U. S. Army during the Mexican–American War of 1846–1848 and distinguished himself at Chapultepec. From 1851 to 1863 he taught at the Virginia Military Institute, where he was unpopular with his students. During this time, he married twice, his first wife died. When Virginia seceded from the Union in May 1861 after the attack on Fort Sumter, Jackson joined the Confederate Army, he distinguished himself commanding a brigade at the First Battle of Bull Run the following month, providing crucial reinforcements and beating back a fierce Union assault.
In this context Barnard Elliott Bee Jr. compared him to a "stone wall", hence his enduring nickname. Jackson performed well in the campaigns in the Shenandoah Valley during 1862. Despite an initial defeat due to faulty intelligence, through swift and careful maneuvers Jackson was able to defeat three separate Union armies and prevent any of them from reinforcing General George B. McClellan's Army of the Potomac in its campaign against Richmond. Jackson quickly moved his three divisions to reinforce General Lee's Army of Northern Virginia in defense of Richmond, his performance in the subsequent Seven Days Battles against George B. McClellan's Army of the Potomac was poor, but did not inhibit Confederate victory in the battles. During the Northern Virginia Campaign that summer, Jackson's troops captured and destroyed an important supply depot for General John Pope's Army of Virginia, withstood repeated assaults from Pope's troops at the Second Battle of Bull Run in August 1862. Jackson's troops played a prominent role in September's Maryland Campaign, capturing the town of Harpers Ferry, a strategic location, providing a defense of the Confederate Army's left at Antietam on September 17, 1862.
At Fredericksburg in December, Jackson's corps buckled but beat back an assault by the Union Army under Major General Ambrose Burnside. In late April and early May 1863, faced with a larger Union army now commanded by Joseph Hooker at Chancellorsville, Lee divided his force three ways. On May 2, Jackson took his 30,000 troops and launched a surprise attack against the Union right flank, driving the opposing troops back about two miles; that evening he was accidentally shot by Confederate pickets. The general lost his left arm to amputation. Military historians regard Jackson as one of the most gifted tactical commanders in U. S. history. His tactics are studied today, his death proved a severe setback for the Confederacy, affecting not only its military prospects, but the morale of its army and the general public. After Jackson's death, his military exploits developed a legendary quality, becoming an important element of the ideology of the "Lost Cause". Thomas Jonathan Jackson was the great-grandson of Elizabeth Cummins.
John Jackson was an Irish Protestant from County Londonderry, Ireland. While living in London, England, he was convicted of the capital crime of larceny for stealing £170. Elizabeth, a strong, blonde woman over 6 feet tall, born in London, was convicted of felony larceny in an unrelated case for stealing 19 pieces of silver and fine lace, received a similar sentence, they both were transported on the merchant ship Litchfield, which departed London in May 1749 with 150 convicts. John and Elizabeth met on board and were in love by the time the ship arrived at Annapolis, Maryland. Although they were sent to different locations in Maryland for their bond service, the couple married in July 1755; the family migrated west across the Blue Ridge Mountains to settle near Moorefield, Virginia in 1758. In 1770, they moved farther west to the Tygart Valley, they began to acquire large parcels of virgin farming land near the present-day town of Buckhannon, including 3,000 acres in Elizabeth's name. John and his two teenage sons, were early recruits for the American Revolutionary War, fighting in the Battle of Kings Mountain on October 7, 1780.
While the men were in the Army, Elizabeth converted their home to a haven, "Jackson's Fort", for refugees from Indian attacks. John and Elizabeth had eight children, their second son was Edward Jackson, Edward's third son was Jonathan Jackson, Thomas's father. Jonathan's mother died on April 17, 1796. Three years on October 13, 1799, his father married Elizabeth Wetherholt, they had nine more children. Thomas Jackson was the third child of an attorney. Both of Jackson's parents were natives of Virginia; the family had two young children and were living in Clarksburg, in what is now West Virginia, when Thomas was born. He was named for his maternal grandfather. There is some dispute about the actual location of Jackson's birth. A historical marker on the floodwall in
Gold is a chemical element with symbol Au and atomic number 79, making it one of the higher atomic number elements that occur naturally. In its purest form, it is a bright reddish yellow, soft and ductile metal. Chemically, gold is a group 11 element, it is solid under standard conditions. Gold occurs in free elemental form, as nuggets or grains, in rocks, in veins, in alluvial deposits, it occurs in a solid solution series with the native element silver and naturally alloyed with copper and palladium. Less it occurs in minerals as gold compounds with tellurium. Gold is resistant to most acids, though it does dissolve in aqua regia, a mixture of nitric acid and hydrochloric acid, which forms a soluble tetrachloroaurate anion. Gold is insoluble in nitric acid, which dissolves silver and base metals, a property that has long been used to refine gold and to confirm the presence of gold in metallic objects, giving rise to the term acid test. Gold dissolves in alkaline solutions of cyanide, which are used in mining and electroplating.
Gold dissolves in mercury, forming amalgam alloys. A rare element, gold is a precious metal, used for coinage and other arts throughout recorded history. In the past, a gold standard was implemented as a monetary policy, but gold coins ceased to be minted as a circulating currency in the 1930s, the world gold standard was abandoned for a fiat currency system after 1971. A total of 186,700 tonnes of gold exists above ground, as of 2015; the world consumption of new gold produced is about 50% in jewelry, 40% in investments, 10% in industry. Gold's high malleability, resistance to corrosion and most other chemical reactions, conductivity of electricity have led to its continued use in corrosion resistant electrical connectors in all types of computerized devices. Gold is used in infrared shielding, colored-glass production, gold leafing, tooth restoration. Certain gold salts are still used as anti-inflammatories in medicine; as of 2017, the world's largest gold producer by far was China with 440 tonnes per year.
Gold is the most malleable of all metals. It can be drawn into a monoatomic wire, stretched about twice before it breaks; such nanowires distort via formation and migration of dislocations and crystal twins without noticeable hardening. A single gram of gold can be beaten into a sheet of 1 square meter, an avoirdupois ounce into 300 square feet. Gold leaf can be beaten thin enough to become semi-transparent; the transmitted light appears greenish blue, because gold reflects yellow and red. Such semi-transparent sheets strongly reflect infrared light, making them useful as infrared shields in visors of heat-resistant suits, in sun-visors for spacesuits. Gold is a good conductor of electricity. Gold has a density of 19.3 g/cm3 identical to that of tungsten at 19.25 g/cm3. By comparison, the density of lead is 11.34 g/cm3, that of the densest element, osmium, is 22.588±0.015 g/cm3. Whereas most metals are gray or silvery white, gold is reddish-yellow; this color is determined by the frequency of plasma oscillations among the metal's valence electrons, in the ultraviolet range for most metals but in the visible range for gold due to relativistic effects affecting the orbitals around gold atoms.
Similar effects impart a golden hue to metallic caesium. Common colored gold alloys include the distinctive eighteen-karat rose gold created by the addition of copper. Alloys containing palladium or nickel are important in commercial jewelry as these produce white gold alloys. Fourteen-karat gold-copper alloy is nearly identical in color to certain bronze alloys, both may be used to produce police and other badges. White gold alloys can be made with nickel. Fourteen- and eighteen-karat gold alloys with silver alone appear greenish-yellow and are referred to as green gold. Blue gold can be made by alloying with iron, purple gold can be made by alloying with aluminium. Less addition of manganese, aluminium and other elements can produce more unusual colors of gold for various applications. Colloidal gold, used by electron-microscopists, is red. Gold has only one stable isotope, 197Au, its only occurring isotope, so gold is both a mononuclidic and monoisotopic element. Thirty-six radioisotopes have been synthesized, ranging in atomic mass from 169 to 205.
The most stable of these is 195Au with a half-life of 186.1 days. The least stable is 171Au. Most of gold's radioisotopes with atomic masses below 197 decay by some combination of proton emission, α decay, β+ decay; the exceptions are 195Au, which decays by electron capture, 196Au, which decays most by electron capture with a minor β− decay path. All of gold's radioisotopes with atomic masses above 197 decay by β− decay. At least 32 nuclear isomers have been characterized, ranging in atomic mass from 170 to 200. Within that range, only 178Au, 180Au, 181Au, 182Au, 188Au do not have isomers. Gold's most stable isomer is 198m2Au with a half-life of 2.27 days. Gold's least stable isomer is 177m2Au with a half-life of only 7 ns. 184m1Au has three decay paths: β+ decay, isomeric