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Oldest piece of the planet Earth.

  1. Apr 8, 2005 #1

    GENIERE

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    A speck of crystal is the oldest bit of Earth found according to this article:

    http://www.foxnews.com/story/0,2933,152930,00.html

    How in the world (pun intended) does one set out looking for the oldest bits?


     
  2. jcsd
  3. Apr 8, 2005 #2

    SpaceTiger

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    It's the usual radioactive dating method. You look for crystal structures that are known to have radioactive elements in them and then you look at the ratios of the product and the original radioactive element. In this case, Zircon crystals have uranium incorporated into their structure, so if you look at the ratio of uranium to lead (the decay product) in the crystal, you can determine roughly how long its been since the crystal was formed.
     
  4. Apr 9, 2005 #3

    DaveC426913

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    Come to Canada. The Canadian Shield (the place is lousy with it - you can't spit without hitting it) is 4 billion years old.
     
  5. Apr 9, 2005 #4

    matthyaouw

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    As much as I love geology, even to me, the prospect of going to see "A tiny speck of zircon crystal that is barely visible to the eye" seems somewhat silly. I'd much rather take a trip to see the Canadian Shield as Dave suggests.
     
  6. Apr 10, 2005 #5
    Are there any other molecules that are this old or is it just the one molecule?
     
  7. Apr 10, 2005 #6
    I tried to go to the site, and got bombarded with spam pop-ups. That site sucks
     
  8. Apr 10, 2005 #7
    What radioactive element would they use to determine the age of something that was 1 million years old, or 1 billion?. I know carbon 14 is used for carbon dating but the half life for that is like 5700 years. Would there be a measurable amount left after such a long amount of time?

    Huck
     
  9. Apr 17, 2005 #8

    SpaceTiger

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    Carbon-14 is better for much shorter timescales (such as for anthropology). There would be very little of the radioactive parent left after millions or billions of years (remember, exponential decay). For longer timescales, they use things like uranium and potassium-40.
     
  10. Apr 17, 2005 #9

    SpaceTiger

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    It's much bigger than a molecule (a small shard of crystal) and I'm sure that there are many more rocks that old. However, we can only date them if they contain radioactive elements, so for most rocks, we wouldn't know if they were very old.
     
  11. Apr 17, 2005 #10

    Chronos

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    Just to clarify, the Rubidium-Strontium method is used to date minerals. Carbon dating is used for organic matter.
     
  12. Apr 18, 2005 #11
    Let's say that carbon dating needs carbon and can be used for instance to date limestone as well. However, since the halftime of radioactive 14C is only 5700 years, the dating range is limited to about 50,000 years.
     
  13. Apr 18, 2005 #12
    GET MOZILLA
    it is free and popup free tooo
    [if you turn on the popup blocker]
    you will not see a popup

    when I clicked to that foxnews site
    I saw no popups at all

    :approve:
     
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