NANOSCALE CHARACTERIZATION OF Au2Te GRAINS FROM THE SANDAOWANZI GOLD DEPOSIT, NORTHEAST CHINA

Au2Te has previously been reported as a new mineral, although without adequate mineralogical data. Examination of Au2Te grains from the Sandaowanzi gold deposit, utilizing optical microscope, EPMA, SEM backscattered electron, and X-ray images revealed an apparently homogeneous composition leading to its examination as a possible new mineral. However, high resolution SEM, TEM, and micro-zone XRD analyses demonstrate that the Au2Te phase gives a false stoichiometry and is not a new mineral species, but a mixture of native gold and calaverite with a nanographic texture that is highly comparable to that of the Turing pattern. This finding implies that the nanographic textures of Au2Te composed of alternating growth layers of native gold (Au) and calaverite (AuTe2) are attributable to decomposition or breakdown of the previous metastable phases during cooling.