Ask A Scientist Chemistry Archive

name         Robert L.
status       other
age          50s

Question -   Carbon 14 dating of Diamonds-----I recently saw some data that indicated that 
Canadian diamonds had been dated using the C-14 method and that the age of those diamonds was 
30,000+ years.
Please advise if C12 can be converted into c14 isotope in nature?
A formula and description of the natural process would really help me.
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I am not familiar with the work you site, however, the half life of carbon 14 is 5730 yrs., and 
it is created from nitrogen 14 interactions with cosmic rays and / or radiation from solar 
flares. It is "secular" equilibrium i.e. in a living, breathing plants/animals its 
concentration is at a steady state being incorporated and excreted at the same rate until 
the plant/animal dies at which time the amount of carbon 14 relative to carbon 12 begins to 
decrease because no more is being incorporated. Consequently, carbon 14 "dating" is only good 
for several half lives because measuring the decay rate becomes experimentally too difficult. 
Natural diamonds are probably much older than a few half lives of carbon 14 so I do not know 
what process(es) in nature would generate the isotope. If there is some processes that keeps 
even the "dead" plants/animals in contact with the rest of the world, e.g. bacterial actions 
then for purposes of carbon 14 dating it is not "dead" yet. Since carbon 14 dating was first 
described by Urey et. al. a lot more has been learned and the whole process is much more 
complicated and refined. For one thing cosmic rays and solar flares occur in cycles, and are 
not a steady background. As a result seldom is carbon 14 used alone in determining the age of 
artifacts. There are other isotopes with which it is used in conjunction. In addition, there 
are non-radioactive processes, for
example, tree rings, that are used to collectively determine the "best" estimate of the age of 
an artifact, mineral or whatever. I do not know of any way in nature that carbon 12 can be 
converted to carbon 14.

Vince Calder
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