"When unstable radioactive minerals are trapped in a mineral, they begin to decay. The mineral is like a tiny hour glass collecting products of decay and can be age-dated. The rate of decay varies with the radioactive element but is a constant. As an element such as uranium decays, it may lose protons and thus its atomic number and chemical identity changes. The new element created by the radioactive decay is called a daughter element. For example: uranium, the parent, element spontaneously decays to lead, the daughter element."
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