Mineralogical and Geochemical Characteristics of Siliceous Sinter in Japan

Abstract

To examine the relationship between siliceous sinter and epithexmal gold mineralization, sinter samples were collected from thirteen locations in Japan. The samples were analyzed by X-ray difltactometry and X-ray fluorescence spectrometry. The samples were also analyzed by inductively coupled plasma mass spectrometry (ICP-MS) for the quantitative determination of gold. The dominant silica minerals change from opal-A (younger than 10 ka), through opal-CT with quartz (10 ka to 1 Ma) and finally to quartz (older than 1 Ma). Most sinter in the distal location from the discharge site contains less than 0.02 wt % Ti02 and 0.5 wt % A1203. Higher concentrations of Ti02, A1203 and K20 can be explained by contamination of detrital materials. The concentration of gold in sinter ranges 0.1-827 ppb and shows a bimodal distribution, which corresponds to gold mineralization.