Pisolite is a rock formed by agglomerated pisoliths, spherical concretions of 2 to 10 mm in diameter, made of calcium carbonate (calcite or more rarely aragonite) Calcitic pisolites are often formed in hot-spring environments. Other minerals may also form pisoliths, bauxite being a well-known example. Pisolite is not to be confused with oolite, in which the spheres are much smaller (under 2mm) The specimen here displayed originates from Ljubljana, Slovenia and actual height is 22 cm