dolostoon

Dolostoon is a sedimentary carbonate rock in the dolomite family, characterized by a predominant dolomite (CaMg(CO3)2) composition with minor impurities of calcite, silica, and clay. It forms primarily through diagenetic dolomitization, in which magnesium-rich fluids alter limestone, replacing calcium with magnesium during burial or early diagenesis, often in warm, shallow-marine environments.

The texture is typically fine- to medium-grained, ranging from microcrystalline to interlocking dolomite grains. The rock is usually gray to tan, occasionally pinkish or reddish due to iron oxide stains. It shows rhombohedral cleavage and a vitreous to dull luster. It is moderately hard and dense, with Mohs hardness around 3.5–4 and a tendency to effervesce weakly in cold hydrochloric acid when powdered.

Distribution: Dolostoon is found in carbonate platforms and basins worldwide, often forming continuous units that can extend for kilometers. It commonly occurs with other carbonates such as limestone and evaporites.

Formation and diagenesis: Dolostoon forms when dolomitization proceeds to substantial depth, either through reflux of magnesium-rich formation waters or seawater intrusion in restricted basins, producing a rock that is more resistant to dissolution than limestone.

Economic and industrial relevance: It is used as crushed stone and aggregate in construction, and when sufficiently pure, as decorative stone for architecture. Some deposits also serve as sources of magnesium or as reservoir rocks in hydrocarbon systems.

See also: dolomite, dolostone, carbonate rock.