The Chelyabinsk meteor which exploded on 2013-02-15 at a height of around 29.7 km above the Russian city with a blast estimated between 400 and 500 kilotons of TNT deposited meteorites, one as massive as 540 kg, on the ground below. Analyses of the minerals in these fragments allow identification of two separate collision events which formed the impactor long before it encountered the Earth.