Calcite from the Quaternary spring waters at Tylicz, Krynica, Polish Carpathians

At Tylicz, near Krynica Spa (Polish Carpathians), spelean deposits fill fissures and caverns in Eocene flysch rocks. They occur as: (1) clastic cave sediments transformed into hard crusts due to cementation by finely crystalline low‐Mg calcite, (2) drusy calcite that covers crust surfaces and fills voids in the crust and (3) colloform calcite. Two varieties of drusy calcite are distinguished: acicular and columnar. The acicular calcite is built up of crystallites forming spherulitic fans or cones. In places it is syntaxially covered with colloform calcite. The drusy calcite is low‐Mg ferroan calcite with non‐ferroan subzones, whereas the colloform calcite is a low‐Mg non‐ferroan variety. The columnar calcite crystals form fan‐like bundles. Cross‐sections cut perpendicular to the c‐axes of columnar crystals are equilateral triangular in shape, although some have slightly curved edges. The columnar crystals have steep rhombic terminations and most have curved triangular faces, i.e. gothic‐arch calcite. Saddle crystals have also been observed. The columnar crystals are composed of radially orientated crystallites whose long dimension is parallel to the c ‐axis. The curved crystal faces of such polycrystals are interpreted as a result of differential growth rates of the crystallites. The spelean calcites precipitated from CO 2 ‐saturated water. The high rate of CaCO 3 precipitation is thought to be responsible for the formation of radial structures. Finely crystalline calcite formed within pore spaces of clastic sediments close to the water‐air interface, drusy calcite crystallized beneath the water‐air interface, and colloform calcite precipitated from thin films of water.