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 carbonate expressed as if calcium carbonate were the sole source of carbonate ions. An aqueous solution containing 120 mg NaHCO (baking soda) per litre of water will contain 1.4285 mmol/l of bicarbonate, since the molar mass of baking soda is 84.007 g/mol. This is equivalent in carbonate hardness to a solution containing 0.71423 mmol/L of (calcium) carbonate, or 71.485 mg/l of calcium carbonate (molar mass 100.09 g/mol). Since one degree KH = 17.848 mg/L CaCO, this solution has a KH of 4.0052 degrees. Carbonate hardness should not be confused with a similar measure Carbonate Alkalinity which is expressed in either