A method for determining a composition of a cement-lime masonry mortar involving the following stages: a) determination of the % atomic ratio of cement/lime in the binder, including: i) mechanical collection of a mortar fragment, ii) drying the sample from stage i) at a temperature not lower than 40 °C for at least 8 hours, then immersing the cooled sample in epoxy resin under vacuum, exposing the surface of the cross-section of the mortar by grinding and polishing, as well as sputtering it with a conductive material selected from a group including gold, platinum, palladium, osmium and carbon, with the thickness of the layer formed by sputtering being at least 1 nm; iii) determining the cement/lime ratio in the binder mass based on the Si/Ca content ratio, by microscopic examination of the sample from stage ii) using a scanning microscope with an accelerating voltage of not less than 10 kV and an aperture of not less than 1 μm b) determination of the aggregate content in the mortar: iii) cutting out a fragment of cement-lime mortar and drying it at a temperature not lower than 40 °C for at least 8 hours, followed by its grinding in entirety to obtain grains measuring less than 0.125 mm. iv) determination of the aggregate content in the cement-lime mortar on the basis of the quantity of insoluble residue in aqueous HCI and Na 2 CO 3 solutions in the sample prepared in stage iv), in accordance with the standard PN-EN 196-2: 2013-11. characterized in that the microscopic examination of the prepared sample is the examination of the binder mass in the sample alone, omitting the aggregate grain, with a SEM scanning electron microscope integrated with an EDS X-ray energy dispersion spectrometer. a) determination of the % atomic ratio of cement/lime in the binder, including: i) mechanical collection of a mortar fragment, ii) drying the sample from stage i) at a temperature not lower than 40 °C for at least 8 hours, then immersing the cooled sample in epoxy resin under vacuum, exposing the surface of the cross-section of the mortar by grinding and polishing, as well as sputtering it with a conductive material selected from a group including gold, platinum, palladium, osmium and carbon, with the thickness of the layer formed by sputtering being at least 1 nm; iii) determining the cement/lime ratio in the binder mass based on the Si/Ca content ratio, by microscopic examination of the sample from stage ii) using a scanning microscope with an accelerating voltage of not less than 10 kV and an aperture of not less than 1 μm i) mechanical collection of a mortar fragment, ii) drying the sample from stage i) at a temperature not lower than 40 °C for at least 8 hours, then immersing the cooled sample in epoxy resin under vacuum, exposing the surface of the cross-section of the mortar by grinding and polishing, as well as sputtering it with a conductive material selected from a group including gold, platinum, palladium, osmium and carbon, with the thickness of the layer formed by sputtering being at least 1 nm; iii) determining the cement/lime ratio in the binder mass based on the Si/Ca content ratio, by microscopic examination of the sample from stage ii) using a scanning microscope with an accelerating voltage of not less than 10 kV and an aperture of not less than 1 μm b) determination of the aggregate content in the mortar: iii) cutting out a fragment of cement-lime mortar and drying it at a temperature not lower than 40 °C for at least 8 hours, followed by its grinding in entirety to obtain grains measuring less than 0.125 mm. iv) determination of the aggregate content in the cement-lime mortar on the basis of the quantity of insoluble residue in aqueous HCI and Na 2 CO 3 solutions in the sample prepared in stage iv), in accordance with the standard PN-EN 196-2: 2013-11. characterized in that the microscopic examination of the prepared sample is the examination of the binder mass in the sample alone, omitting the aggregate grain, with a SEM scanning electron microscope integrated with an EDS X-ray energy dispersion spectrometer. iii) cutting out a fragment of cement-lime mortar and drying it at a temperature not lower than 40 °C for at least 8 hours, followed by its grinding in entirety to obtain grains measuring less than 0.125 mm. iv) determination of the aggregate content in the cement-lime mortar on the basis of the quantity of insoluble residue in aqueous HCI and Na 2 CO 3 solutions in the sample prepared in stage iv), in accordance with the standard PN-EN 196-2: 2013-11.