Natural Isotopes
There are 3 naturally occurring isotopes of carbon: 12, 13, and 14. 12C and 13C are stable, occurring in a natural proportion of approximately 99:1. 14C is produced by thermal neutrons from cosmic radiation in the upper atmosphere, and is transported down to earth to be absorbed by living biological material. Isotopically the 14C constitutes a negligible part, but since it is radioactive with a half-life of 5700 years, it is radiometrically detectable. Since dead tissue doesn't absorb 14C, the amount of 14C is used for radiometric dating of biological material, among others within the field of archeology.
Read more about this topic: Carbon-16
Famous quotes containing the word natural:
“The aim of every political association is the preservation of the natural and imprescriptible rights of man. These rights are liberty, property, security and resistance to oppression.”
—French National Assembly. Declaration of the Rights of Man (drafted and discussed August 1789, published September 1791)