Gold is a heavy metal and one of Earth's rarer elements, formed in space when neutron stars collide. But just how rare is gold on Earth, and how much of it is there in the world now?
To answer these questions, it is easiest to start with the amount of gold that humans have mined to date. The U.S. Geological Survey (USGS) estimates that throughout history, humans have extracted about 206,000 tons (187,000 metric tons) of gold from rocks and rivers, with much of the gold mined and produced today used to make jewelry.
