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
Calcium carbonate equilibrium pressure must exceed total atmospheric pressure of 101 kPa, which happens at 898 °C. Calcium carbonate is poorly soluble in pure water (47 mg/L at normal atmospheric CO partial pressure as shown below). The equilibrium of its solution is given by the equation (with dissolved calcium carbonate on the right): where the solubility product for [Ca] [CO] is given as anywhere from "K" = 3.7×10 to "K" = 8.7×10 at 25 °C, depending upon the data source. What the equation means is that the product of molar concentration of calcium ions (moles of dissolved Ca per liter of solution)