The study was focused upon fluid inclusions in zoisite from the Merelani Hills deposit (Northern Tanzania) - they are characterized by the unique composition. The Raman spectroscopy has detected there mostly the system H ₂ S) (N ₂ )) (CH ₄ ), together with remarked presence of liquid H ₂ O and the ion HS ^- . Solid phases in inclusions are identified as graphite, calcite, quartz, dickite, micas, and the native sulfur (S ₈ ). The average temperature of partial homogenization corresponds for gas-liquid inclusions, according to authors, is equal to 60-70 °C, complete homogenization and dissolution of solid phases occurs at temperature about 400 °C (Malisa et al., 1986). Physical-chemical parameters of the zoisite formation were estimated with techniques of chemical thermodynamic calculation: Eh 7 -0.2; pH 7 6.4.