As of 2014, research suggests that colliding neutron stars created gold by fusing various elements during massive explosions. Neutron stars are the extremely dense cores of dead stars that are left after the stars explode as supernovae.
Gold is not usually formed when normal stars, composed of materials such as carbon and iron, collide. Because the neutron stars are so incredibly dense, when they orbit each other and eventually crash, they create a black hole in space. The resulting fused mass of dense neutron star material collapsed into the black hole.
Scientists have observed a gamma-ray burst that lasted for only two-tenths of a second, making it a short- duration burst. The burst occurred 3.9 billion light years away from the Earth. The burst is believed to have been the merging of two neutron stars spitting out radioactive material, which underwent radioactive decay and left behind infrared light. Gold was one of the elements formed. Approximately 10 moon masses of gold was created and ejected during the collision.
Other elements created by this type of explosion include platinum and uranium. The material travels as a gas throughout the universe, eventually turning into new stars and objects. The gold that became part of the Earth's structure sank to the core initially, but it was brought back close to the surface by meteors striking the Earth's surface.