Zn release from fluid inclusions in a natural sphalerite

The type, size, and compositions of fluid inclusions in a natural sphalerite were investigated and the total concentration of Zn released from the fluid inclusions was measured. To compare the total concentration of Zn released from the fluid inclusions with that dissolved from the sphalerite itself, dissolution experiments and theoretical calculations for the dissolution equilibrium of the sphalerite were also performed. The results indicate that large numbers of fluid inclusions with various sizes exist in the sphalerite, which can be divided into four types, i.e., pure gaseous inclusions, pure liquid inclusions, gas-liquid inclusions, and gas-liquid inclusions containing solid minerals. These inclusions were broken open during the grinding process, and their compositions were released to the solution. The total concentration of Zn released from these inclusions reaches 18.35×10⁻⁶ mol/L, which is much higher than that of Zn dissolved from the sphalerite itself (1.93×10⁻⁶ mol/L) and the theoretical calculation value (2.73×10⁻⁸ mol/L).