The Grand Cross of the Iron Cross was an award intended for senior Generals of the German Army and dated back to 1870. It was the senior most decoration of the Iron Cross award series.
During the Second World War, Hermann Göring was the only recipient of the Grand Cross of the Iron Cross, awarded the decoration on July 19, 1940.
An even higher decoration, the Star of the Grand Cross of the Iron Cross, was intended to have been presented to the most successful German General of the Second World War, once Germany had achieved victory. The decoration was obviously never bestowed.
The IronCross was awarded not only for bravery in the face of the enemy, but also for successful war planing and general merit.
Actually, the ribbon on the War Merit Cross had the colors of the IronCross reversed, as was the tradition of the non-combatant version of the IronCross.
The Knights Cross was much sought after by members of the armed forces, wearing it meant that they had been crowned as aces and their peers gave this distinction the appropriate respect.
Iron (along with nickel) are notable for being the final elements produced by stellar nucleosynthesis, and thus the heaviest elements which do not require a supernova or similarly cataclysmic event for formation.
Iron is also the second most abundant element by mass, making up 34% of the mass of the Earth; the concentration of iron in the various layers of the Earth ranges from high at the inner core to about 5% in the outer crust.
A newer variant of grey iron, referred to as ductile iron is specially treated with trace amounts of magnesium to alter the shape of graphite to sheroids, or nodules, vastly increasing the toughness and strength of the material.