Physics and Chemistry of Water
Published Online: 15 JUL 2005
Copyright © 2005 by John Wiley & Sons, Inc.
How to Cite
Steele, K. F. 2005. Carbonate Geochemistry. Water Encyclopedia. 4:408–413.
- Published Online: 15 JUL 2005
Calcite (CaCO3) is one of the most common minerals at or near the surface of the earth and thus is one of the main contributors to carbonate geochemistry. Less common carbonate minerals include dolomite [MgCa (CO3)2]; aragonite, a calcite polymorph (mineral of the same composition as calcite but having a different atomic structure); azurite and malachite (copper hydroxycarbonate minerals); siderite (FeCO3); and rhodochrosite (MnCO3) which can be important spatially and economically.
Although calcite does occur in igneous and metamorphic rocks, the mineral is present dominantly in the sedimentary environment which is the focus of this article. Calcite may be precipitated to form a relatively pure monomineralic rock (limestone), be present as a cement binding sediments into indurated rock, occurs simply as a trace mineral in rocks, and composes many shells and fossils. Weathering of calcite is relatively easy and depends largely on the amount of carbonic acid present. Other carbonate minerals, except dolomite, generally are dissolved and precipitated in a manner geochemically similar to calcite.
- carbonate solubility;
- carbonic acid;
- effect of pressure;
- effect of temperature;
- effect of ionic strength