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Zircon radiometric dating

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This week, Cherry Lewis of the University of Bristol presented a talk about the history of dating the Earth as part of the BA Festival of Science in York, England.Before so-called radiometric dating, Earth's age was anybody's guess.But this sediment doesn't typically include the necessary isotopes in measurable amounts.Fossils can't form in the igneous rock that usually does contain the isotopes.Zircon should not be confused with cubic zirconia, which is a man-made material.Zircon is present in most soils and clastic sediments.

The four-sided crystals are prismatic with a square cross-section and terminate with a pyramid. Zircon is a popular gemstone that has been used for nearly 2000 years.Some of the isotopes used for this purpose are uranium-238, uranium-235 and potassium-40, each of which has a half-life of more than a million years.Unfortunately, these elements don't exist in dinosaur fossils themselves.Color differences in zircon are caused by impurities, some of which (like uranium) can be slightly radioactive.These gems are also treated with heat to stabilize the radioactivity.In 1898, Marie Curie discovered the phenomenon of radioactivity, in which unstable atoms lose energy, or decay, by emitting radiation in the form of particles or electromagnetic waves.