Recent technological advances in mass spectrometry make possible the use of isotopic tracers, present in rocks in very low concentrations, in order to determine the ages and the ultimate source of samples which originate in the mantle of the earth. These samples usually reach the surface as inclusions in lava flows which have been fractionally melted from the deep interior or in kimberlite pipes which have explosively brought material up from great depth. This project will assemble a mass spectrometer system that will combine the features of secondary ionization (ion gun) with laser resonance ionization in the sample source. The spectrometer is expected to be capable of accurately analyzing difficult tracer systems such as osmium isotope ratios of masses 187/186 in samples containing only 10 picograms of total osmium.
