Uranium-lead radiometric dating is most often performed on the mineral zircon.
Answer:
<em>A. 6,000 years</em>
Explanation:
Original sample N = 60 g
The half life of N/2 is 3000yrs
"""""""""""""""""""N/4 is 6000yrs
N/4 ===> 15 gram
it takes 6000yrs to decrease to 15grams
