How old are diamonds ?
One of the major research efforts of the geochemistry group is the dating of diamond formation in different cratons. Because the carbon in diamond has no radiogenic decay scheme practical for use as a chronometer over millions of years, minerals trapped within the diamonds at the time of their growth have to be used. The rhenium-osmium isotope system is used to date the time of crystallisation of sulphides included by the diamonds, and hence the timing of diamond crystallisation. This work is carried out by Dr Graham Pearson, in collaboration with major industrial sponsors De Beers and the Diamond and Precious Metal Institute, Yakutsk, Russia and Collaborators Dr Jeff Harris (Glasgow) and Dr Galina Bulanova. Tiny sulphide inclusions weighing only 10 millionths of a gramme (Figure 1), are extracted from the host diamonds and processes using special chemistry techniques developed by Dr. Pearson. The amounts of rhenium and osmium are as low as 100 femtogrammes (100 * 10-15 grammes) and re
