Gold will be oxidized when it meets mercury. The simple substance of gold, commonly known as gold, is a precious metal, which has been used as currency, value preservation and jewelry for 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. Gold is solid at room temperature, with high density, softness, brightness and corrosion resistance. Gold is a simple form of chemical element gold (Au), which is a soft, golden yellow and corrosion-resistant precious metal. Gold is a rarer, more precious and more valuable metal. Generally speaking, gold in the world is measured in ounces. In ancient China, gold was measured in ounces, which was a very important metal. It is not only a special currency for reserve and investment, but also an important material for jewelry industry, electronics industry, modern communication and aerospace industry.