Could meteors have been been formed with lead, and mislead radiometric dating? The age of the Earth has been determined by radiometric dating of meteorites, by seeing how much uranium has decayed into lead. How do we know the meteor samples weren't formed with lead already in them, and thus confuse the radiometric dating? Links to references for further research would be much appreciated. I'd just like to know in depth how the process worked and how there's so much certainty in it.

Radio-isotope dating is not just performed on meteorites, but also on terrestrial rocks. The dates obtained are consistent, with meteorites slightly older than the earth. Are you suggesting the earth was also formed with lead already present?

Isochron dating avoids contamination problems. Meteorites are often dated by iscohron lead-lead methods, and hence are not affected by contamination.