Primitive Helium in Diamonds

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Science  04 Mar 1983:
Vol. 219, Issue 4588, pp. 1067-1068
DOI: 10.1126/science.219.4588.1067


Thirteen diamond stones from various unspecified mines in South Africa were analyzed for the isotopic ratio of helium-3 to helium-4. Values of the ratio ranged from less than 10–7 to (3.2 ± 0.25) x 10–4. The latter value is higher than the primordial helium-3/helium-4 ratio in meteorites and close to the ratio for solar-type helium. Such extremely high values may represent primitive helium that evolved very little (that is, showed very little increase in radiogenic helium-4) since the formation of the earth.