[ RadSafe ] 4.4 billion year old crystal
Kulp, Jeffrey (DOH)
Jeffrey.Kulp at DOH.WA.GOV
Mon Feb 24 16:58:07 CST 2014
I have a question about a news story I just read; it said that
scientists in Australia had discovered a 4.4 billion year old zircon
The article went on to say that they had dated it using uranium decay to
My question is how do they know what concentration of uranium the
crystal started with? At present the concentration of uranium in the
earth's crust varies
quite a bit (two orders of magnitude or more?). Was the U concentration
more uniform back when the crust just formed?
Given that the half-life of U-238 is roughly 4.4 billion years, how can
they be so sure of its age?
Thanks in advance for the information
Jeffrey Kulp, RRPT
Radiation Health Physicist
Washington State Department of Health - ORP
16201 E. Indiana Ave. Suite 1500
Spokane Valley, WA 99216
(509) 329-2138 (Office)
(509) 329-2154 (Fax)
"Public Health - Always Working for a Safer and Healthier Washington"
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