The conventional dating method uses the Thermal Ionization Mass Spectrometer (TIMS). Geochronologists using this technique take "a small fraction of (zircons) and then treat them chemically and (then) separate the uranium and lead." The next step is to "run the uranium and lead separates on the TIMS." According to Dr. Cox, "that, undoubtedly, produces the most precise ages; typically we get down to something in the region of a million years or thereabouts on relatively old material."