The application of Raman spectroscopy to the study of the mixed cationic Pb-Cu and Pb-Cu-Ag minerals: boléite, cumengéite and diaboléite has enabled their molecular structures to be compared. Each of these three minerals shows different hydroxyl-stretching vibrational patterns, but some similarity exists in the Raman spectra of the hydroxyl-deformation modes. The low-wavenumber region is characterized by the bands assigned to the cation-chloride stretching and bending modes. Phosgenite is also a mixed chloride-carbonate mineral and a comparison is made with the molecular structure of the aforementioned minerals. Raman spectroscopy lends itself to the study of these types of minerals in complex mineral systems of secondary mineral formation.