If iron-60 has a half life of 2.6 million years, how can the iron in earth’s core be billions of years old?

5 Answers

  • Mike
    Lv 7
    1 month ago

    Not all the iron in the Earth's core is iron-60.

  • Bill-M
    Lv 7
    1 month ago

    Your talking about TWO Completely different elements.

    Iron-60  is NOT iron.

  • 1 month ago

    The simple answer is that it is because it is not iron 60.  That mostly self-destructed long ago if it ever existed to begin with.

    Clearly, if there is iron in abundance throughout the earth (it is generally a couple weight percent of any rock or soil you can look at), and iron 60 cannot exist and persist, the obvious conclusion is that the iron is not iron 60 if there is no continuous re-making of iron 60 in nature (Which there really isn't).

  • 1 month ago

    Because normal Iron is mostly Iron-56 and that is totally stable.

    (As are Iron 57 & Iron 58).

    Plus a small amount of iron-54, which is either stable or has a half life of something like 10^20 years - billions of times more than the age of the universe.


    Iron 60 decays to cobalt 60 then nickel 60 over time. The iron 60 on Earth has all been deposited from space over the last few million years.


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  • Jim
    Lv 7
    1 month ago

    Maybe there was a lot more, or new iron was formed from other decay, or we had an asteroid hit.

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