Iron is the fourth largest element in the earth's crust. Its abundance on rocky planets like Earth is due to the large amount of production resulting from the reactions of large mass stars. Chemical compounds have many benefits. Iron oxide with aluminum powder can be ignited to create a thermite reaction, which is often used in welding and refining of ores. Iron forms binary compounds with calcium and halogens. Its metal organ compound is ferocene, the first sandwich compound to be discovered.
