Characteristics and Properties of Gold
- Gold is the most malleable of all metals.
- It can be drawn into a wire of single-atom width.
- Gold can be beaten into a sheet of 1 square meter.
- Gold leaf can be beaten thin enough to become semi-transparent.
- Gold is a good conductor of heat and electricity.
- Gold is slightly reddish-yellow in color.
- The color is determined by plasma oscillations among the metals valence electrons.
- Relativistic effects affect the orbitals around gold atoms, giving it a golden hue.
- Different alloys can produce colored gold, such as rose gold, white gold, green gold, blue gold, and purple gold.
- Colloidal gold appears red when particles are small and blue when particles are larger.
- Gold has only one stable isotope, 197Au.
- Thirty-six radioisotopes of gold have been synthesised.
- The most stable radioisotope is 195Au with a half-life of 186.1 days.
- Gold's radioisotopes decay through various processes such as proton emission, alpha decay, beta decay, and electron capture.
- Gold also has nuclear isomers, with 198m2Au being the most stable.
- Gold often occurs in free elemental form as nuggets or grains.
- It is found in rocks, veins, and alluvial deposits.
- Gold can form solid solutions with silver and be naturally alloyed with other metals like copper and palladium.
- Gold compounds can occur in minerals, often with tellurium.
- Gold is a relatively rare element.
- Gold has been used for coinage, jewelry, and art throughout history.
- It was once used as a monetary standard.
- Gold is used in electrical connectors, infrared shielding, colored glass production, gold leafing, and tooth restoration.
- Certain gold salts have medical applications as anti-inflammatories.
- China is the world's largest gold producer, followed by Russia and Australia.

Synthesis and Chemistry of Gold
- Gold has three decay paths: β decay, isomeric transition, and alpha decay.
- No other isomer or isotope of gold has three decay paths.
- The first synthesis of gold was conducted by Japanese physicist Hantaro Nagaoka in 1924 by neutron bombardment of mercury.
- An American team conducted the same experiment in 1941, achieving the same result and showing that the isotopes of gold produced were all radioactive.
- In 1980, Glenn Seaborg transmuted several thousand atoms of bismuth into gold.
- Gold can be manufactured in a nuclear reactor, but it is highly impractical and costly.
- Gold forms diverse compounds with oxidation states ranging from -1 to +5.
- Au(I) compounds are typically linear and commonly encountered in mining.
- Au(III) compounds have square planar structures and can form mixed-valence complexes.
- Gold does not react with oxygen or most acids, but can react with halogens and form gold sulfide.
- Gold readily dissolves in mercury at room temperature and forms alloys with other metals.
- Gold can exhibit oxidation states of -1, +2, and +5.
- Aurides, compounds containing the auride anion, can have gold in the -1 oxidation state.
- Gold(II) compounds are usually diamagnetic and form Au-Au bonds.
- Gold(II) sulfate contains Au4+2 cations, similar to the mercury(I) ion.
- Gold(V) is represented by gold pentafluoride, its derivative anion, and gold heptafluoride.

Occurrence of Gold
- Gold is thought to have been produced in supernova nucleosynthesis and from the collision of neutron stars.
- It is also believed to have been present in the dust from which the Solar System formed.
- Traditionally, gold in the universe is thought to have formed by the r-process in supernova nucleosynthesis.
- Recent studies suggest that gold and other heavy elements may also be produced in neutron star mergers.
- Spectroscopic signatures of gold and other heavy elements were observed in the GW170817 neutron star merger event.
- Gold in Earth's crust and mantle may have been delivered by asteroid impacts during the Late Heavy Bombardment.
- The asteroid that formed the Vredefort impact structure is associated with the richest gold deposits in the Witwatersrand basin.
- The gold-bearing Witwatersrand rocks were laid down before the Vredefort impact.
- The impact distorted the Witwatersrand basin, bringing the gold-bearing rocks to the surface.
- The discovery of the deposit in 1886 led to the Witwatersrand Gold Rush.
- Gold on Earth is thought to have been incorporated into the planet since its formation.
- Scientists found evidence of gold coming from the mantle at Deseado Massif in Argentina.
- Further research is needed for clarification.
- Gold is found in ores in rock formed from the Precambrian time onward.
- It often occurs as a native metal or in gold/silver alloys.
- Native gold is found in lode deposits or as free flakes, grains, or nuggets in alluvial deposits.
- Gold can occur with tellurium minerals and in rare alloys with copper, lead, and mercury.
- Microbes and earthquakes can also play a role in forming gold deposits.
- Gold is present in the world's oceans, but at very low concentrations.
- Gold concentrations in the Atlantic and Northeast Pacific are 50-150 femtomol/L.
- Mediterranean deep waters have slightly higher concentrations.
- Claims of economically recovering gold from seawater have been proven to be false.
- Previous data on gold concentrations in seawater were contaminated.

Historical Significance of Gold
- The oldest recorded gold artifacts date back to the late Paleolithic period, around 40,000 BC.
- The Varna Necropolis in Bulgaria contains the oldest well-dated gold artifacts, dating back to the 5th millennium BC.
- Gold artifacts also appeared in Ancient Egypt and Lower Mesopotam