ABSTRACT

Pb/Ba ratios of barite from various origins (hot springs, banks in the Japan Sea and Kuroko-type or vein-type ore mines) vary from 10^-5 to 10^-1. When they are plotted against chloride concentrations of the barite-precipitating solutions, both expressed in logarithms, the ratios increase almost linearly with a decrease in those of the solutions. For their chloride concentrations except those of hot spring waters, NaCl-equivalent salinities of fluid inclusions in the barite were used as an approximation. This fact is possibly elucidated in terms of chloro-complexing of lead in thermal solutions.