Uranium-lead dating
Uranium-lead dating is usually performed on the mineral zircon (ZrSiO4), though it can be used on other minerals. Zircon incorporates uranium and thorium atoms into its crystalline structure, but strongly rejects lead. Therefore, we can assume that the entire lead content of the zircon is radiogenic. Where this is not the case, a correction must be applied. Uranium-lead dating techniques have also been applied to other minerals such as calcite/aragonite and other carbonate minerals. These minerals often produce lower precision ages than igneous and metamorphic minerals traditionally used for age dating, but are more common in the geologic record.