Gold

Gold is a unique chemical element with the symbol Au, derived from the Latin word *aurum*. It is a transition metal and a member of group 11 on the periodic table.

As a noble metal, gold is one of the least reactive elements in existence. Only platinum is ranked as less reactive in the chemical reactivity series. This stability makes gold highly resistant to corrosion and most chemical attacks. In its pure form, it is a dense, soft, and bright metallic-yellow metal. It is also famously malleable and ductile, meaning it can be shaped easily.

The physical properties of gold allow for incredible transformations. Gold is the most malleable metal known to science. A single gram of gold can be beaten into a sheet covering 1 square meter. An entire ounce can be hammered into a sheet covering 30 square meters.

It is also extremely ductile. This means it can be drawn into a wire just one atom wide. These tiny nanowires can be stretched significantly before they eventually break. Even gold leaf can be beaten thin enough to become semi-transparent. When light passes through these ultra-thin sheets, it appears greenish-blue because gold reflects yellow and red light so strongly.

Gold is found in several different forms throughout the Earth. It often occurs in a native state as nuggets or grains. These can be found in rocks, veins, or alluvial deposits left by water.

Sometimes gold exists in a solid solution with silver, creating an alloy called electrum. It can also be naturally alloyed with metals like copper, platinum, or palladium. In some cases, gold is found as mineral inclusions within pyrite.

While rare, gold can also exist as compounds, such as gold tellurides.

Because gold is so unreactive, it requires specific methods to dissolve or refine. Most acids, such as nitric or hydrochloric acid, cannot dissolve pure gold. This property was historically used in the "acid test" to confirm if a metal was truly gold.

To dissolve gold, scientists use aqua regia. This is a specific mixture of nitric acid and hydrochloric acid. The mixture forms a soluble tetrachloroaurate anion. In mining, alkaline solutions of cyanide are used to dissolve gold for collection. Gold also dissolves in mercury to form an amalgam alloy. This process is a physical dissolution rather than a chemical reaction.

Humans have utilized gold for thousands of years in many ways. It has been used for coinage, jewelry, and fine works of art.

For a long time, many nations followed a gold standard for monetary policy. This meant the value of a currency was linked to gold. Most gold coins stopped circulating as regular money in the 1930s. Later, the global gold standard was abandoned following the Nixon shock of 1971. Today, gold remains a massive global commodity. In 2023, China was the largest producer, followed by Russia and Australia.

There is a finite amount of gold available above the ground. Approximately 201,296 tonnes of gold exist in the world today.

If you gathered all this gold into one cube, each side would be only 22 centimeters long. Despite this small volume, its uses are vast. About 50% of new gold production goes to jewelry. Another 40% is used for investments. The remaining 10% is used for industrial purposes.

In modern technology, gold serves critical roles due to its conductivity and resistance. It is an excellent conductor of both heat and electricity. This makes it essential for electrical connectors in computerized devices. Because it does not corrode, it protects these connections. Gold is also used for infrared shielding. Thin sheets reflect radiant heat, which is useful for space suit visors.

Beyond technology, gold is used in medicine, such as the drug auranofin for rheumatoid arthritis. It is even used in tooth restoration and the creation of colored glass.