Tsumoite in the Dashuigou tellurium deposit shows features of both ubiquitous metasomatism and exsolution by its occurrence and graphic-myrmekitic textures it contains. The graphic-myrmekitic pyrrhotites of the tsumoite have compositions similar to those of early stages, but their spatial elongation and size change are in contradiction with experiments and theoretical models. This suggests that the graphic-myrekitic textures be essentially metasomatic products of earlier pyrrhotites altered by Te-, Bi-rich fluids. The minor variation of the textures is dependent on variant metasomatic intensity and closeness of the corresponding environments. Week alteration without mobility of iron will produce tsumoites with typical metasomatic features, whereas complete alteration in a stable environment can dissolve early minerals in the fluids, which produce exsolution-oriented graphic-myrmekitic texture.