If a rock sample contains uranium and lead, and lead-204 is present, then
A) both radiogenic and primordial lead are present.
B) all the lead is primordial.
C) neither radiologic nor primordial lead is present.
D) all the lead is radiogenic.

Question

Quizplus · Accepted Answer

Lead-204 is a non-radiogenic isotope, indicating primordial lead (present since the formation of the Earth). The presence of uranium suggests that radiogenic lead (formed from the radioactive decay of uranium) could also be present. Thus, both radiogenic and primordial lead are present.

If a Rock Sample Contains Uranium and Lead, and Lead-204