This substance is a chemical element with the symbol “Au”, from the Latin ‘aurum’. It is a bright, slightly orange-yellow, dense, soft, malleable and ductile metal in a pure form. It is also one of the least reactive chemical elements and is solid under standard conditions. Gold often occurs in its elemental or native form as nuggets or grains in rocks, veins and alluvial deposits. It occurs in a solid solution series with the native element silver (as electrum), naturally alloyed with other metals like copper and palladium and mineral inclusions such as within pyrite. It occurs less commonly in minerals as gold compounds, often with tellurium (gold tellurides). Gold is resistant to most acids, though it does dissolve in aqua regia, a mixture of nitric acid and hydrochloric acid, forming a soluble, but it is insoluble in nitric acid, which dissolves silver and base metals, a property long used to refine gold and confirm the presence of gold in metallic substances, giving rise to the term ‘acid test’. Gold dissolves in alkaline solutions of cyanide, which are used in mining and electroplating. It dissolves in mercury forming amalgam alloys, and as the gold acts simply as a solute, this is not a chemical reaction. A relatively rare element, gold is classed as a precious metal that has been used for coinage, jewellery and other arts throughout recorded history. In the past, a gold standard was often implemented as a monetary policy but gold coins ceased to be minted as a circulating currency in the 1930s, and the world gold standard was abandoned for a flat currency system after 1971. In 2017 the world’s largest gold producer by far was China, with 440 tonnes per year and as of 2020, a total of around 201,296 tonnes of gold exists above ground. This is equal to a cube with each side measuring roughly 21.7 metres (71ft). The world consumption of new gold produced is about 50% in jewellery, 40% in investments and 10% in industry. The high malleability, ductility, resistance to corrosion and most other chemical reactions and conductivity of electricity of gold has led to its continued use in corrosion-resistant electrical connectors in all types of computerised devices, its chief industrial use. It is also used in infra-red shielding, coloured glass production, gold-leafing and tooth restoration. Certain gold salts are still used as anti-inflammatories in medicine. A gold nugget of 5mm (0.20in) in size can be hammered into a gold foil of about 0.5 square metres, 5.4 square feet in area. Gold can be drawn into a wire of single-atom width, and then stretched considerably before it breaks. Such nanowires distort via formation, reorientation and migration of dislocations and crystal twins without noticeable hardening. Gold leaf can be beaten thin enough to become semi-transparent and the transmitted light appears greenish blue, because gold strongly reflects yellow and red. Such semi-transparent sheets also strongly reflect infra-red light, making them useful as infrared (radiant heat) shields in visors of heat-resistant suits, and in sun-visors. Whilst most metals are grey or silvery white, gold is slightly reddish-yellow, the colour 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 coloured gold alloys include the distinctive eighteen-carat rose gold, which is created by the addition of copper. Also alloys containing palladium or nickel are important in commercial jewellery as these produce white gold alloys. Fourteen-carat gold-copper alloy is nearly identical in colour to certain bronze alloys, and both may be used to produce police and other badges. Fourteen and eighteen-carat gold alloys with silver alone appear greenish-yellow and are referred to as green gold, whilst blue gold can be made by alloying it with iron and purple gold can be made by alloying with aluminium. Although less common, the addition of manganese, indium and other elements can produce more unusual gold colours for various applications. The possible production of gold from a more common element such as lead has long been a subject of human enquiry, and the ancient and medieval discipline of alchemy often focussed on it. However, the transmutation of the chemical elements did not become possible until the understanding of nuclear physics in the 20th century. It can be manufactured in a nuclear reactor, but doing so is highly impractical and would cost far more than the value of the gold that is produced. Medicinal applications of gold and its complexes have a long history dating back thousands of years and several gold complexes have been applied to treat rheumatoid arthritis. Also some of its compounds have been investigated as possible anti-cancer drugs.

Gold is thought to have been produced in supernova nucleosynthesis and from the collision of neutron stars, therefore being present in the dust from which the Solar System was formed. Because the Earth was molten when it was formed, almost all of the gold present in the early Earth probably sank into the planetary core. Therefore, most of the gold that is in the Earth’s crust and mantle has, according to one theory, thought to have been delivered to Earth later by asteroid impacts about 4 billion years ago. The gold which is reachable by humans has therefore been associated with a particular asteroid impact and the asteroid that formed the Vredefort crater around two billion years ago is often credited with seeding the Witwatersrand basin in South Africa with the richest gold deposits on earth. However, this scenario is now questioned, as these gold-bearing rocks were laid down between 700 and 950 million years before the Vredefort impact. These gold-bearing rocks had also been covered by a thick layer of Ventersdorp lavas and the Transvaal Supergroup of rocks before the meteor struck, and thus the gold did not actually arrive in the asteroid/meteorite. What the Vredefort impact achieved, however, was to distort the Witwatersrand basin in such a way that the gold-bearing rocks were brought to the present erosion surface in Johannesburg, just inside the rim of the original 300km (190 mile) diameter crater caused by the meteor strike. It was the discovery of the deposit in 1886 that launched the Witwatersrand Gold Rush. Some 22% of all the gold that is ascertained to exist today on Earth has been extracted from these rocks. However, besides that much of the rest of the gold on Earth is thought to have been incorporated into the planet since its very beginning, as planetesimals formed the planet’s mantle early in Earth’s creation. In 2017 an international group of scientists established that gold ‘came to the Earth’s surface from the deepest regions of our planet’, the mantle, and this is said to have been evidenced by their findings at the Deseado Massif in the Argentinian region of Patagonia. Perhaps surprisingly, the world’s oceans also contain gold and measured concentrations estimate that they would hold 15,000 tonnes. A number of people have claimed to be able to economically recover gold from sea water, but they were either mistaken or acted in an intentional deception. There was one man who ran a gold-from-seawater swindle in the United States in the 1890s, as did an English fraudster in the early 1900s. Another man did research on the extraction of gold from sea water in an effort to help pay Germany’s reparations following World War I and based on the published values of gold in seawater a commercially successful extraction seemed possible. But after analysis of 4,000 water samples, it became clear that extraction would not be possible and he ended the project.

Grave offerings on exposition in the Varna museum, Bulgaria, thought to be the oldest golden artefacts in the world (4600 BC – 4200 BC).

The earliest recorded metal employed by humans appears to be gold. Small amounts of natural gold have been found in Spanish caves used during the late Palaeolithic period, c. 40,000 BC. The oldest gold artefacts in the world are from Bulgaria and date back to around 4,600 BC to 4,200 BC, such as those found in the Varna Necropolis near Lake Varna and the Black Sea coast, thought to be the earliest ‘well-dated’ finding of gold artefacts in history. Such items probably made their first appearance in Ancient Egypt at the very beginning of the pre-dynastic period, at the end of the fifth millennium BC and the start of the fourth, and smelting was developed during the course of the 4th millennium. The oldest known map of a gold mine was drawn in the 19th Dynasty of Ancient Egypt (1320–1200 BC), and the first written reference to gold was recorded in the 12th Dynasty around 1900 BC. Egyptian hieroglyphs from as early as 2600 BC describe gold and one of the earliest known maps, known as the Turin Papyrus Map, shows the plan of a gold mine in Nubia together with indications of the local geology. Large mines were also present across the Red Sea in what is now Saudi Arabia. Gold is mentioned frequently in the Old Testament of the Bible, starting with Genesis. In the New Testament it is included with the gifts of the Magi in the first chapters of Matthew. The book of Revelation describes the city of New Jerusalem as having streets ‘made of pure gold, clear as crystal’. Exploitation of gold in the south-east corner of the Black Sea is said to date from the time of King Midas and this gold was important in the establishment of what is probably the world’s earliest coinage in Lydia, around 610 BC. The legend of the Golden Fleece, dating from eighth century BCE may refer to the use of fleeces to trap gold dust from deposits in the ancient world. In Roman metallurgy, new methods for extracting gold on a large scale were developed from 25 BC onwards. The European exploration of the Americas was fuelled in no small part by reports of the gold ornaments displayed in great profusion by Native American peoples. The Aztecs regarded gold as the product of the gods, calling it literally ‘god excrement’ but after Moctezuma II was killed, much of this gold was shipped to Spain. However, for the indigenous peoples of North America gold was considered useless and they saw much greater value in other minerals which were directly related to their use, such as obsidian, flint and slate. Gold has played a role in western culture as a cause for desire and of corruption, for example in children’s fables where Rumpelstiltskin turns hay into gold for the peasant’s daughter in return for her child when she becomes a princess, and the stealing of the hen that lays golden eggs in Jack and the Beanstalk. The top prize at the Olympic Games and many other sports competitions is the gold medal. The main goal of alchemists has been to produce gold from other substances such as lead, perhaps by the interaction with a mythical substance called the philosopher’s stone. Trying to produce gold led the alchemists to systematically find out what can be done with substances and this laid the foundation for today’s chemistry.

Minoan jewellery from 2300–2100 BC in the Metropolitan Museum of Art, New York City.

Apart from chemistry, gold is mentioned in a variety of expressions, most often associated with intrinsic worth. As already mentioned, great achievements are frequently rewarded with gold in the form of medals as well as trophies and other decorations. Winners of athletic events and other graded competitions are usually awarded a gold medal. Many awards such as the Nobel Prize are made from gold. Other award statues and prizes are depicted in gold or are gold-plated, such as the Academy Awards, the Golden Globe Awards, the Emmy awards and the British Academy of Film and Television Awards (BAFTA) .Gold is associated with the wisdom of ageing and fruition, hence the fiftieth wedding anniversary is golden. A person’s most valued or most successful latter years are sometimes considered their ‘golden years’ and the height of a civilisation is referred to as a golden age. In some religions gold has been associated both with holiness and evil, for example in the Bible’s Book of Exodus the Golden Calf is a symbol of idolatry, whilst in the Book of Genesis Abraham was said to be rich in gold and silver, also Moses was instructed to cover the Mercy Seat of the Ark of the Covenant with pure gold. In Islam gold, along with silk, is often cited as being forbidden for men to wear. Wedding rings are typically made of gold as it is long lasting and unaffected by the passage of time and may aid in the ring symbolism of eternal vows before God and the perfection the marriage signifies. In August 2020, Israeli archaeologists discovered a trove of early Islamic gold coins near the central city of Yavneh, Israel and analysis of the extremely rare collection of 425 gold coins indicated that they were from the late 9th century.

Golden coins from the Scandinavian Monetary Union. To the left is Swedish and the right is Danish.

Gold has been widely used throughout the world as money, for efficient indirect exchange as opposed to bartering and to store wealth in hoards. For exchange purposes, mints produce standardised gold bullion coins, bars and other units of fixed weight and purity. The first known coins containing gold were struck in Lydia, Asia Minor, around 600 BC. The talent coin of gold in use during the periods of Grecian history both before and during the time of the life of Homer weighed between 8.42 and 8.75 grams. From an earlier preference in using silver, European economies re-established the minting of gold as coinage during the thirteenth and fourteenth centuries. In preparation for World War I the warring nations moved to fractional gold standards, inflating their currencies to finance the war effort. Post-war, the victorious countries, most notably Britain, gradually restored gold-convertibility, but international flows of gold via bills of exchange remained embargoed and international shipments were made exclusively for bilateral trades or to pay war reparations. After World War II, gold was replaced by a system of nominally convertible currencies related by fixed exchange rates following the Bretton Woods system of monetary management, which established the rules for commercial and financial relations among the countries of the United States, Canada, Australia, Japan and Western European countries after the 1944 Bretton Woods Agreement. This system was the first example of a fully negotiated monetary order intended to govern monetary relations among independent states. It required countries to guarantee convertibility of their currencies into U.S. dollars to within 1% of fixed parity rates, with the dollar convertible to gold bullion for foreign governments and central banks at 35 US dollars per troy ounce of fine gold, or 0.88867 gram fine gold per dollar. It also envisioned greater cooperation among countries in order to prevent future competitive devaluations and thus established the International Monetary Fund (IMF) to monitor exchange rates and lend reserve currencies to nations with balance of payments deficits. I must admit to smiling when I first came across the name ‘Bretton Woods system’, as I was brought up in Peterborough and a township of that fine city is named Bretton, where you will find the Bretton Woods Community School! But I am certain they played no part in establishing this monetary system. But back to the story. Gold standards and direct convertibility of currencies to gold have been abandoned by world governments, led in 1971 by the United States’ refusal to redeem its dollars in gold. Flat currency now fills most monetary roles. Switzerland was the last country to tie its currency to gold, it backed 40% of its value until the Swiss joined the IMF in 1999. Central banks continue to keep a portion of their liquid reserves as gold in some form, and metals exchanges such as the London Bullion Market Association still clear transactions denominated in gold, including future delivery contracts. Today, gold mining output is declining, so with the sharp growth of economies in the 20th century along with increasing foreign exchange, the world’s gold reserves and their trading market have become a small fraction of all markets, and fixed exchange rates of currencies to gold have been replaced by floating prices for gold. Though the gold stock grows by only 1 or 2% per year, very little metal is irretrievably consumed. Inventory above ground would satisfy many decades of industrial and even artisan uses at current prices. The gold proportion or fineness of alloys is measured by carat, with pure gold (commercially termed ‘fine’ gold) designated as 24 carat. English gold coins intended for circulation from 1526 into the 1930s was typically a standard 22-carat alloy called crown gold for hardness, whilst American gold coins for circulation after 1837 contain an alloy of 0.900 fine gold, or 21.6 carat. Only 10% of the world consumption of new gold produced goes to industry, but by far the most important industrial use for new gold is in fabrication of corrosion-free electrical connectors in computers and other electrical devices. Gold is a valuable commodity.

A mirror for the James Webb Space Telescope, coated in gold to reflect infrared light.

This week…
You might already know that the collective noun for crows is a murder and for lapwings it is a deceit. You might even be aware that for hawks it is an aerie. But an ambush is the collective term for both tigers and widows!

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