Groundwater, geothermal water and underground steam may contain dissolved calcium bicarbonate and other minerals. The chemical deposits along the spring pool edge or in cracks are called sinters. Sinters have strange shapes with many colours, so they have high ornamental value. Sinters and the associated spring pools form a sinter landscape. Based on the composition, sinter can be classified into calcareous sinter, sulphurous sinter, siliceous sinter, salt sinter and metallic mineral sinter. Calcareous sinter (travertine) is most common.