Gold is the most ductile and malleable of all metals, with an attractive yellow color and very high resistance to corrosion. It can be mined from veins or gathered by sluicing or using pans from alluvial deposits. This noble metal doesn't react with air and most chemical compounds. Gold has very useful properties, as an excellent conductor of heat and electricity. Since it is very soft in pure form, most applications of gold use alloys that improve its strength. It is a traditional material for jewellery and the production of coins, being considered a monetary standard. Gold plating is used on various mechanical and electrical parts, as well as for decorative purposes. Carats have been traditionally used to indicate the purity of gold, with 24 carats being the purest form. It has the chemical symbol Au and the atomic number 79.
Gold is a solid metal that is famous for its stability, being one of the least reactive of all elements. Since it rarely forms bonds with other compounds, gold is often found in pure form in nature. It occurs in alluvial deposits, as well as in rocks, veins or as nuggets or grains. Sometimes it is naturally alloyed with other elements, especially with silver (the alloy is known as electrum), palladium or copper. Gold compounds are rarely found, the most common being gold tellurides.
Most acids have no effect on gold. A mixture of nitric acid and hydrochloric acid, known as aqua regia, is famously able to dissolve gold, the result being a tetrachloroaurate anion that is soluble in water. Pure nitric acid is not able to react with gold but dissolves silver and most other metals. As a result, it is used in the so-called acid test, which confirms if an object is made of gold and can also refine this noble metal from ores. Alkaline cyanide solutions also dissolve gold and are commonly used in electroplating techniques and the mining industry. Combining gold with mercury creates an amalgam, but this is not a chemical reaction but rather an alloy.
Due to its rarity and attractive aspect, gold has always been considered a precious metal. It is a valuable material used to produce coins, as well as jewellery and various art objects since ancient times. Gold has been for a long time the base of a monetary standard, but it was gradually abandoned. Actual circulation gold coins were not minted after the 1930s, while the standard itself was replaced in 1971 with the so-called fiat currency system.
Today, gold remains the most important metal used in jewellery, which consumes 78% of the world output. Most cultures have used gold for their jewellery and these items are the most common way to come in contact with gold. Gold jewellery is considered to be both very attractive and very valuable at the same time. In some countries, such as India, gold is a very important symbol of social status and wealth.
Gold has also been used for medicinal purposes and the oldest evidence for such practices has been discovered in the ancient Egyptian town of Alexandria. It was ingested by Egyptians as early as 5000 years ago, since they believed it could purify the body from the inside. They thought gold improved positive inner vibrations, boosting life force.
Alexandrian alchemists later used liquid gold to produce an elixir that was said to have miraculous powers. Since gold was considered the perfect metal, ingesting it was believed to be extremely beneficial. The ancients claimed gold could grant perfect health, restore youth, cure multiple diseases and rejuvenate the body in general.
Gold was also used by Egyptians for dental works, the earliest evidence dating from 4500 years ago. Archeologists have discovered several spectacular examples of such an early use. Approximately 13 tons of gold are used in dentistry every year to produce bridges, inlays, dentures and crowns, because this noble metal remains an ideal material for them. It is perfect in this role because it is not affected by corrosion and is not toxic, while being very malleable.
Of the earliest mentions of arthritis is related to gold. In the Middle Ages, drinks with a content of gold powder were sold by alchemists as a remedy for sore limbs. Various types of "gold water" and pills including gold were popular in that time.
Another alchemist, Paracelsus (1493-1541), is considered the inventor of pharmacology. He used a number of minerals, including precious gold, to produce the first effective medicines in history during the Renaissance period. He is listed among the greatest chemists of all times, as well as the founder of Iatrochemistry, or medical chemistry, which is pharmacology's direct ancestor.
Gold was also used as a treatment against inflammation. During surgery, small gold pieces were implanted near inflamed joints. The procedure was said to be effective, eliminating or significantly reducing pain.
Gold is still believed to have important health benefits in rural regions of China. Peasants cook rice alongside a gold coin, in order to increase the amount of this noble metal in their bodies. It is even included as gold leafs made of pure gold in some expensive dishes served in luxury Chinese restaurants.
Colloidal gold is produced using extremely small gold particles, with a diameter between one and one hundred billionths of a meter. These are placed in a solution, so the particles remain permanently in a suspended form. Since the exposed surface is a lot larger in this case, colloidal gold has different chemical properties. It is also known as activated gold and has many practical uses. It was discovered by English chemist Michael Faraday, who prepared it for the first time in 1857.
Colloidal gold was considered to be the best cure for alcoholism in the United States during the nineteenth century. This condition was known at the time as dipsomania. It is still employed in the management of various addictions, from alcohol and caffeine to tobacco or even the consumption of carbohydrates. In the same period, gold was believed to improve blood circulation and to provide important benefits to heart health. The use of gold in the treatment of arthritis dates from the 19th century.
Gold has been used as medicine in Europe for a very long time. Pills covered in a gold coating and water that contains gold has been available in pharmacies for more than a decade.
Modern medicine used gold in multiple ways, due to the special properties of this metal. It can repair ruptured bones, tissues and blood vessels and is used for this purpose in surgery. Injecting a solution that includes tiny gold particles is a known treatment for prostate cancer and other forms of tumours. Colloidal gold can cure women who suffer from ovarian cancer. Some types of laser use vapours of gold to destroy mutated cells, while not harming the healthy ones around them.
Gold instruments are widely used in surgical procedures, especially when cleaning clogged arteries. Many forms of tumours as well as very serious heart conditions can be cured with golden lasers.
This precious metal has become increasingly important in biomedicine and is used by scientists to investigate the human body. Tiny gold pieces can be marked at a molecular level and then tracked as they move inside the body. Electron microscopes are powerful enough to identify gold particles, which are even visible when inside very small human cells.
The same principle is used in DNA research, in order to study the genetics of cells. The cell response to various external factors, such as stress, toxins or extreme heat, can also be investigated using gold. This metal is absolutely harmless, so it can be used by scientists to combine with proteins and form new drugs. Since ancient times, people were aware that gold was beneficial for cardiovascular health. It is particularly effective at improving blood flow. A better circulation of blood has many positive effects, such as improving coordination and treating nervous congestion. If more blood reaches the brain and other internal organs, they can become rejuvenated.
Gold plays a role in the internal temperature stabilizing mechanism of the human body. This is very important for people who suffer from night sweating, chills or hot flashes.
In colloidal form, this precious metal is said to have an overall beneficial effect on human health. The strongest effect is on the mind, balancing emotions and relieving stress. It is also believed to have various other effects, such as improving libido, focus, energy and willpower.
The effects of colloidal gold on concentration and focus have been confirmed by modern scientific studies. While the exact mechanism remains unknown, scientists suspect that gold improves the connection between the brain and the nerve network, making the brain more effective.
Gold is well tolerated by the human body and no toxic effects of any kind are known. Due to its low reactivity, it doesn't seem to influence the effect of other drugs.
Radioactive gold isotopes exist and some of them are useful in the treatment of cancer. They are inserted in tissues, where they serve as a source of radiation.
Lagophthalmos is a disease that prevents people from closing their eyes completely. It can be treated using small quantities of gold, which are implanted in the eyelid tissue. In this case, gold is useful due to its remarkable density. The natural weight of gold helps the eyelid close fully by weighting it down through the force of gravity.
Another use for radioactive gold isotopes is in diagnostic tools. A colloidal solution that includes the isotopes is injected and the beta emissions allow it to be tracked through the body. Small gold quantities are also found in various items such as life-support machines, surgical instruments or electronic devices. Since gold doesn't react with any chemicals, these items are extremely reliable.
For thousands of years, gold and its compounds have been used in medicine. One of the earliest uses is in the treatment of inflammation, especially rheumatoid arthritis. Several gold compounds, such as aurothioglucose, auranofin and aurothiomalate, are still used for this purpose. Other compounds are tested as possible drugs against cancer. There is also considerable research on using physiological conditions to reduce gold (III) complexes to gold (0/I). The power of stable gold compounds has already been validated by in vitro tests. They can be synthesized from various types of bi-, tri-, and tetradentate ligand systems.
Due to its excellent electrical conducting qualities, gold can transmit even the smallest power charges. This property makes it extremely useful in electronics and it is included in small quantities in almost all devices like TVs, GPS units or modern cell phones. For the same reason, it is found in small amounts in all types of computers, since it allows information to travel at the best speed.