Cave rainwater and groundwater charged with HCO (carbonic acid) and naturally occurring organic acids. The dissolution process produces a distinctive landform known as "karst", characterized by sinkholes and underground drainage. Limestone caves are often adorned with calcium carbonate formations produced through slow precipitation. These include flowstones, stalactites, stalagmites, helictites, soda straws and columns. These secondary mineral deposits in caves are called "speleothems". The portions of a solutional cave that are below the water table or the local level of the groundwater will be flooded. Lechuguilla Cave in New Mexico and nearby Carlsbad Cavern are now believed to be examples of another
Calcium carbonate PCC used for paper filling and paper coatings is precipitated and prepared in a variety of shapes and sizes having characteristic narrow particle size distributions and equivalent spherical diameters of 0.4 to 3 micrometres. Calcium carbonate is widely used as an extender in paints, in particular matte emulsion paint where typically 30% by weight of the paint is either chalk or marble. It is also a popular filler in plastics. Some typical examples include around 15 to 20% loading of chalk in unplasticized polyvinyl chloride (uPVC) drain pipe, 5 to 15% loading of stearate coated chalk or marble in uPVC