Solutional cave and most abundant solutional caves are located in limestone. Limestone caves are often adorned with calcium carbonate formations produced through slow precipitation. These include flowstones, stalactites, stalagmites, helictites, soda straws, calcite rafts and columns. These secondary mineral deposits in caves are called "speleothems". Limestone dissolves under the action of 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. Solutional caves in this landform—topography are often called karst caves. Lechuguilla Cave in New Mexico and nearby Carlsbad Cavern are now believed
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