1. Primordial rocks
A rock is a piece of solid matter made up of minerals or with a composition that is fixed within certain limits. ‘Primordial rocks’ considers the first minerals that appeared some millions of years after the Big Bang, during the dramatic finale of supernovae. These comprised: carbon in the form of diamond; a few carbides and nitrides; a few oxides including corundum; and a form of olivine, a member of the silicate minerals that dominate the surface of Earth. The first rocks—asteroids—were a result of a second generation of stars. Remnants from the primordial planetary building processes are seen as meteorites, which are divided into ‘stony’ achondrites and ‘iron-rich’ chondrites.