SEM Study of the Surface of Arsenopyrite and Pyrite from the Natalkinskoe Deposit, Northeastern Russia

Abstract

The paper presents newly acquired data on the mineral and chemical composition of the crystal surface layers of arsenopyrite and pyrite from the Natalkinskoe gold deposit, northeastern Russia. Data on arsenopyrite and pyrite grains from metasomatites and from quartz veins and veinlets were obtained using a scanning electron microscope equipped with an energy dispersive X-ray spectrometer (SEM-EDX). The surface layers of the sulfide crystals from the metasomatites contain no admixtures, except only As (up to 2.48 wt %) in the pyrite. The surface layers of arsenopyrite crystals from the vein and veinlets contains the following admixtures (wt %): Pt (up to 2.11), U (up to 2.03), Hg (up to 1.11), Au (up to 0.96), and more rarely Ru (up to 1.44), Ir (up to 0.67), Os (up to 0.64), Ag (up to 0.71), and Cu (up to 0.56). The surface layers of the pyrite crystals contain (wt %): As (up to 2.24), Pt (up to 2.88), and Cu (up to 0.69). The detected elevated concentrations of the admixtures are thought to be explained primarily by the presence of nonautonomous phases.