Raman spectra of 17 fahlore samples (tetrahedrite-tennantite solid solution series) and 3 samples of the pyrargyrite-proustite solid solution series were recorded. The fundamental stretching and bending vibrations of the pyramidal (Sb, As)S3 groups occur between 200 and 400 cm−1. The position, shape, relative intensity and appearance of the bands vary depending upon the Sb/(Sb+As) ratios of both mineral series. The symmetric stretching mode (ν1) shows a two-mode behavior in the tetrahedrite-tennantite solid solution series, whereas one-mode behavior is observed in all other cases. The excellent correlations between the positions of the vibrational modes and the Sb/(Sb+As) ratio, can be applied to determine the composition of the investigated sample by at least one band in the Raman spectrum of the mineral.