Uranium decay dating
Zircon also concentrates Uranium (You) and (although less so) Thorium (Th) and excludes lead (Pb), which means it has a very high You/Pb ratio. Since igneous rocks have no fossils, this makes zircon valuable in dating them.The half-life of the uranium series is 4.47 billion years, and the half-life of the actinium series is 710 million years.When a grain of mineral forms, the clock starts at zero. The oldest and most reliable method they use is called Uranium-lead (U-Pb) dating. Scientists have many ways to discover how old rocks and fossils are.
Also, zircons are magnetic so scientists can separate the finest pieces with magnets.Uranium-238, for example, will undergo 14 radioactive decays to eventually become lead-206 which is stable and no longer radioactive.Some of these radioactive decays will be alpha decays and some of these decays will be beta decays.They map out the area and collect samples of this type of rock; then they take samples.The samples can be anywhere from two pounds to more than 100 pounds.