The most abundant chemical element in the earth’s crust.

Iron is the most abundant chemical element in the earth’s crust. It is mainly present inside the Earth in the core, but this is the most common occurrence. This is followed by oxygen, followed by silicon.
Iron is a fairly common element in the universe, although it lags well behind hydrogen and helium. It is the last synthesis product to be exothermic. After iron, making heavier elements consumes more energy than is produced, so there really is no thermodynamic push towards heavier elements.