Cronstedtite from the Salsigne mine, France, has long been known to mineralogists and collectors but has not been characterized previously. The current study is the first thorough investigation of cronstedtite from this locality, using electron microprobe analysis, laser ablation inductively coupled plasma mass spectroscopy, Mössbauer spectroscopy, scanning electron microscopy, and single crystal X-ray diffraction. The chemical and structural features of cronstedtite from Salsigne were compared with those of cronstedtites from other localities. The results showed that the chemical/structural signature of cronstedtite from Salsigne could help to distinguish it from cronstedtites found elsewhere. All analyzed polytypes from Salsigne belong to the subfamily A and are mostly 1M and 3T polytypes showing various degrees of disorder. The only exception is the 1T polytype (subfamily C), which was found not as an isolated crystal but allotwinned with a 3T crystal. Other allotwins were also observed in this study: 3T + 1M, 3T + 2M1, 3T + 6T2, and 2M1 + 6T2. Chemical data indicate that cronstedtite from Salsigne contains the most iron in the tetrahedral sites (x = 0.73–0.90) of any known cronstedtite, although previous studies reported that the iron in tetrahedral coordination is greater in polytypes of subfamily D. The octahedral sites are not fully occupied, and the Mössbauer results suggest the presence of a small amount of vacancies. Although the Salsigne mine is known for the extraction of Au and other metals (Ag, Cu, As, Bi, Pb), no traces of these were detected. Traces of Cl and S are present, which seems to be a common feature for cronstedtite.