CaCO3rich

CaCO3rich is a descriptive term used in geology, soil science, and related fields to describe materials or environments with high calcium carbonate content, usually expressed as a percentage of CaCO3 by weight. The term is not a strict mineralogical category but indicates carbonate predominance.

Common CaCO3-rich materials include carbonate rocks such as limestone, chalk, travertine, and marble (in terms of CaCO3 content; marble is metamorphosed limestone). In soils, calcareous soils have high CaCO3 and often high pH. In natural waters, hardness and alkalinity reflect dissolved CaCO3.

Formation of CaCO3-rich deposits occurs by precipitation of calcium carbonate from seawater or freshwater, biological precipitation by organisms like coccolithophores, foraminifera, and corals, and by diagenetic replacement. Weathering of carbonate rocks also enriches soils and sediments with CaCO3.

Properties and implications include the fact that CaCO3 is readily dissolved by acids, releasing CO2 and contributing to buffering capacity, which raises pH. Calcination of CaCO3 yields lime (CaO) or quicklime, a process used in cement production and other industrial applications. In agriculture, calcareous soils influence nutrient availability and lime requirements.

Quantification of CaCO3 content is typically done by acid digestion (acid-neutralization titration), loss on ignition methods, or X-ray diffraction to determine mineral fractions; results are expressed as weight percent CaCO3 or CaCO3-equivalent.

See also: carbonate rock, limestone, chalk, calcareous soil, calcination.