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Line 15: − To avoid this problem, scientists focus on rocks that do not contain the decay product originally. For example, in uranium-lead dating, they use rocks containing [[zircon]] (ZrSiO<sub>4</sub>), though it can be used on other materials, such as [[baddeleyite]].<ref>{{Cite journal|doi=10.2113/104.1.13 |title=SHRIMP baddeleyite and zircon ages for an Umkondo dolerite sill, Nyanga Mountains, Eastern Zimbabwe |year=2001 |first=M.T.D. |last=Wingate |journal=South African Journal of Geology |volume=104|issue=1 |pages=13–22}}</ref> Zircon and baddeleyite incorporate uranium atoms into their crystalline structure as substitutes for [[zirconium]], but strongly reject lead. Zincon has a very high closure temperature, is very chemically inert, and is resistant to mechanical weathering. For these reasons, if a rock strata contains zircon, running a uranium-lead test on a zircon sample will give produce a radiometric dating result that is not subject to the initial quantity problem.+
→Initial quantities: copy edit
In the case of carbon dating, it is not the initial quantity that is important, but the initial ratio of C<sup>14</sup> to C<sup>12</sup>, but the same principle otherwise applies.
In the case of carbon dating, it is not the initial quantity that is important, but the initial ratio of C<sup>14</sup> to C<sup>12</sup>, but the same principle otherwise applies.
Recognizing this problem, scientists try to focus on rocks that do not contain the decay product originally. For example, in uranium-lead dating, they use rocks containing [[zircon]] (ZrSiO<sub>4</sub>), though it can be used on other materials, such as [[baddeleyite]].<ref>{{Cite journal|doi=10.2113/104.1.13 |title=SHRIMP baddeleyite and zircon ages for an Umkondo dolerite sill, Nyanga Mountains, Eastern Zimbabwe |year=2001 |first=M.T.D. |last=Wingate |journal=South African Journal of Geology |volume=104|issue=1 |pages=13–22}}</ref> Zircon and baddeleyite incorporate uranium atoms into their crystalline structure as substitutes for [[zirconium]], but strongly reject lead. Zincon has a very high closure temperature, is very chemically inert, and is resistant to mechanical weathering. For these reasons, if a rock strata contains zircon, running a uranium-lead test on a zircon sample will produce a radiometric dating result that is less dependent on the initial quantity problem.
=== Rate of decay ===
=== Rate of decay ===