The Mariovo basin in North Macedonia is an important karst area in the Balkans, home to dolomite and calcite marble formations. The Melnica Pestera hypogene karst proves a hydrothermal driven speleogenesis, which shows relation to alteration shown on dolomite marble bodies around the cave. The correlation of these two phenomena is followed in this study, using previously collected samples for thin sectioning and stable isotope composition measurements, and physical observations made in a fieldwork in the study area.