Dolomiittikivet

Dolomiittikivet, or dolostone, are carbonate sedimentary rocks composed predominantly of the mineral dolomite (CaMg(CO3)2). They form in marine settings when calcium-rich limestone is altered by magnesium-rich fluids, a process called dolomitization, or by direct precipitation of dolomite from seawater. Impurities such as calcite, quartz, clay minerals, and organic matter can give the rock variable textures and colors, ranging from gray and white to tan or pink in some cases.

Most dolomiittikivet are massive or crystalline in texture; grain size can vary from fine to coarse. The dolomite mineral itself is a double carbonate with a hardness around 3.5 to 4 on the Mohs scale and a specific gravity near 2.8 to 2.95.

Fresh dolostone may show little reaction to dilute acid, whereas a powdered sample or weathered surfaces may effervesce slowly due to the calcite impurities or residual carbonate; in practice, dolostone responds to acid only when crushed or powdered.

Geographically, dolostones occur on many continents and form major portions of ancient carbonate platforms, foreland basins and sedimentary sequences from the Paleozoic onward. They are widely used as crushed stone and construction aggregate, as decorative or dimension stone, and as a source of magnesium oxide in some industrial applications.

Related topics include dolostone, the process of dolomitization, and the broader class of carbonate rocks.