On the primordial abundance of argon-40.

Argon trapped in graphite-diamond-kamacite inclusions from the Havero ureilite has a /sup 40/Ar//sup 36/Ar ratio of (1.4 +- 0.6) x 10/sup -3/, which is close to the estimated primordial abundance ratio of 2 x 10/sup -4/. Some implications are discussed. (AIP)