If a scientist found a sample of crystal, which had a large amount of
lead surrounding it, how would you describe the age of this crystal? Very young, old, or is the amount of lead not related to the age?

I believe the lead would not matter to the age

the precambrian aged rocks could be found in australia. australia is a region that has a lot of ancient civilization history from million years ago. in this region, there are a lot of recognizable fossils buried in its land which is considered a precambrian-aged rocks