They were formed in giant stars near the end of their lives and released during a super nova. Basically the early universe had a first generation of stars that were much bigger & brighter but didn't last long before exploding and helping to form the smaller stars of today. The big stars created all the heavy elements that the planets are made of.

Was Iron THe First Metal On Earth? If So THen I'd Say It Was Compounded with other stuff, it's just so far back we havn't been able to recognize the iron trait.

1) "There are a number of astrophysical processes which are believed to be responsible for nucleosynthesis in the universe. The majority of these occur within the hot matter inside stars. The successive nuclear fusion processes which occur inside stars are known as hydrogen burning (via the proton-proton chain or the CNO cycle), helium burning, carbon burning, neon burning, oxygen burning and silicon burning. These processes are able to create elements up to iron and nickel, the region of the isotopes having the highest binding energy per nucleon. Heavier elements can be assembled within stars by a neutron capture process known as the s process or in explosive environments, such as supernovae, by a number of processes. Some of the more important of these include the r process which involves rapid neutron captures, the rp process which involves rapid proton captures and the p process (sometimes known as the gamma process) which involves photodisintegration of existing nuclei." Source and further information: http://en.wikipedia.org/wiki/Nucleosynthesis 2) "The S-process or slow-neutron-capture-process is a nucleosynthesis process that occurs at relatively low neutron density and intermediate temperature conditions in stars. Under these conditions the rate of neutron capture by atomic nuclei is slow relative to the rate of radioactive beta-minus decay. A stable isotope captures another neutron; but a radioactive isotope decays to its stable daughter before the next neutron is captured. This process produces stable isotopes by moving along the valley of beta stability in the chart of isotopes. The S-process produces approximately half of the isotopes of the elements heavier than iron, and therefore plays an important role in the galactic chemical evolution. The S-process differs from the more rapid R-process of neutron-capture by its slow rate of neutron captures." Source and further information: http://en.wikipedia.org/wiki/S-process Further information: (other processes) http://en.wikipedia.org/wiki/R-process http://en.wikipedia.org/wiki/Rp-process http://en.wikipedia.org/wiki/P-process