We analysed standard zircon crystals using a 91500 zircon crystal (1065.4 ± 0.6 Ma determined by isotope dilution thermal ionization mass spectrometry (ID-TIMS)) as a bracketing standard.
Ages determined from TEMORA2, Prešovice, and OD-3 zircons compared very well with their reference ages determined by ID-TIMS and/or SHRIMP.
It is useful for geochronology because it contains relatively large amounts of uranium and thorium, which decay radioactively to lead.
Typically, there is negligible non-radiogenic lead in monazite.
Therefore, it is assumed that all lead found within a grain is due to radioactive decay of uranium and thorium.