The simple substance (free form) of gold, commonly known as gold, is a precious metal, which has been used as currency, preservation and jewelry for many centuries. In nature, gold exists in the form of simple substance in gold nuggets or rocks, underground veins and alluvium. Gold is also one of the currency metals. Solid at room temperature, high density, soft, bright and corrosion resistant. It is the metal with the best ductility, which is second only to platinum.

Gold is a transition metal, which can form +3 and+1 valence compounds. Gold is chemically inactive, but it can be corroded by chlorine, fluorine, aqua regia and cyanide. Gold can be dissolved by mercury to form gold amalgam, while nitric acid which can dissolve silver cannot dissolve gold. The above two properties become the basis of gold refining technology, which are called adding silver to divide gold and gold and silver to divide gold respectively.

Gold introduction

As an international reserve, it is determined by the monetary commodity attribute of gold. Because of its excellent characteristics, gold has played a role as a currency in history, such as a measure of value, a means of circulation, a means of storage, a means of payment and a world currency. Since the decoupling of gold and the dollar in 1970s, the gold function of money has also weakened, but it still maintains a certain monetary function. Gold still occupies a very important position in the international reserves of many countries, including major western countries.

Used as jewelry decoration, gorgeous gold ornaments have always been a symbol of one's social status and wealth. In the application of industry and science and technology, gold has extremely high corrosion resistance and stability because of its unique good performance. Good electrical conductivity and thermal conductivity, the nucleus of gold has a large effective cross section to capture neutrons, and its infrared reflection ability is close to 100%. Among the alloys of gold, it has various catalytic properties. Gold has good manufacturability and is easy to be processed into ultra-thin gold foil, micron gold thread, gold powder and so on.