<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (December 2015) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (December 2015) (Learn how and when to remove this template message) </Td> </Tr> <P> The iron catastrophe was a postulated major geological event early in the history of Earth . The original accretion of the Earth's material into a spherical mass is thought to have resulted in a relatively uniform composition . While residual heat from the collision of the material that formed the Earth was significant, heating from radioactive materials in this mass gradually increased the temperature until a critical condition was reached . As material became molten enough to allow movement, the denser iron and nickel, evenly distributed throughout the mass, began to migrate to the center of the planet to form the core . The gravitational potential energy released by the sinking of the dense NiFe globules, along with any cooler, denser solid material, is thought to have been a runaway process, increasing the temperature of the protoplanet above the melting point of most components, resulting in the rapid formation of a molten iron core covered by a deep global silicate magma . This event, an important process of planetary differentiation, occurred at about 500 million years into the formation of the planet . </P>

Approximately how much of earth’s mass sank to the center of the planet during the iron catastrophe