The compositional dependence of the Raman spectra of GexS1−xglasses has been investigated in comparison with the Raman spectra of crystalline GeS2and GeS. The results reveal that the appearance of minority configurations, (−S2−)nand GeS, is stoichiometry‐sensitive. Discussion is given on the basis of the phase diagram. The stoichiometry‐sensitive properties of ESR, luminescence and internal friction corresponds to the structural characteristics.