Earth's oldest crystal. Astonishingly, this is a zircon crystal 4.4 billion years old. What's more, it carries internal chemical evidence that it formed in a relatively "normal" Earth crust, not the hellish, bombarded Earth we would have expected at this time. Either the evidence is somehow wrong, or Earth cooled much earlier than we had thought. If the crystal evidence is good, it allows more time for life to have evolved on the early Earth.
Last updated October 28, 2005.
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