A Neutron Activation Analysis Technique for Determination of the Precious Metals and its Application to a Study of their Geochemistry

Abstract

<p> A neutron activation analysis procedure for the simultaneous determination of Ru, Pd, Os, Ir, Pt and Au has been developed. It consists principally of distillation, anion exchange, solvent extraction and precipitation steps and was used to determine all of these metals in meteorites as well as Pd, Ir and Au in sulphide minerals from the Sudbury Nickel Irruptive. The accuracy of the method was checked against G-1 and W-1 and a sulphide standard. A literature survey of the geology of the Sudbury Nickel Irruptive and a description of the geology of the Strathcona mine are presented. A detailed description of the inorganic chemistr! and its bearing on the geochemistry of the precious metals, with special reference to basic rocks is given. Analytical results for Pd, Ir and Au in a large number of pyrrhotite and chalcopyrite samples and a smaller number of sulphide and oxide minerals and an ultramafic xenolith are presented. Arsenic was determined in 15 of the sulphide samples and found to be highly correlated with Pd. The genesis of the Strathcona ores is discussed and the differential behaviour of the precious metals during fractionation or a sulphide-rich basic magma is described. </p> <p> Seven carbonaceous and two enstatite chondrites were analysed and the data evaluated with respect to estimation of the cosmic abundances of these metals. </p>