Spherulitic growth of orpiment (As₂S₃) under hydrothermal condition

Abstract

Conditions and process of hydrothermal growth of As₂S₃ crystals were examined. Although it has been known that As₂S₃ is quite soluble only in alkaline solutions, it was found in this study that it is also soluble in weakly acid solution, as well as in neutral solution. As₂S₃ crystals usually grew in the form of spherulitic aggregation regardless of the growth conditions and the chemical species in the solvents. The process of spherulite formation is discussed. The crystals grown from an H₂0 solvent gave a=11.394±0.009Å, b=9.581±0.008Å, c=4.267±0.004Å, β=90°03′±6′, V=465.8±0.5ų.