17 samples were selected from the surface of the sculptures, decorative elements and pedestals of 9 fountains of Peterhof. The results of XRD and scanning electron microscopy showed that in the majority of samples are present by aragonite and monohyrocalcite, on one of the marble fountains - nesquehonit and lansfordite. Carbonates are produced in the western \"Rome\" fountain besides calcium contain lead (up to 29 wt.% PbO) and strontium (up to 43 wt.% SrO), ie are solid solutions in the system of aragonite (Ca) - cerussite (Pb) - strontianite (Sr). The fact that all the layers, irrespective of the underlying substrate (marble, granite, polyester resin, gilding) are carbonates, indicating that their formation is not related to the transformation of the material of the monument.
Keywords: carbonates, monohyrocalcite, Peterhof