- Carbonate rock
Carbonate rocks are a class of
sedimentary rock s composed primarily ofcarbonate mineral s. The two major types arelimestone anddolomite , composed ofcalcite (CaCO3) and the mineraldolomite (CaMg(CO3)2) respectively.Chalk andtufa are also minor sedimentary carbonates.Calcite can be either dissolved by
groundwater or precipitated by groundwater, depending on several factors including the water temperature, pH, and dissolvedion concentrations. Calcite exhibits an unusual characteristic calledretrograde solubility in which it becomes less soluble in water as the temperature increases.When conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together or it can fill fractures.
Karst topography andcave s develop in carbonate rocks due to theirsolubility in diluteacid icgroundwater . Cooling groundwater or mixing of different groundwaters will also create conditions suitable for cave formation.Marble is the metamorphic carbonate rock. Rareigneous carbonate rocks exist asintrusive carbonatite s and even more rarevolcanic carbonatelava .
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