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
Carbonate hardness given in ppm. The term "carbonate hardness" is also sometimes used as a synonym for temporary hardness, in which case it refers to that portion of hard water that can be removed by processes such as boiling or lime softening, and then separation of water from the resulting precipitate. Carbonate hardness Carbonate hardness, is a measure of the water hardness caused by the presence of carbonate () and bicarbonate () anions. Carbonate hardness is usually expressed either in degrees KH (dKH) (from the German ""Karbonathärte""), or in "parts per million calcium carbonate" ( ppm or grams per litre|mg/l). One dKH