dolomiitilla

Dolomite refers to both a carbonate mineral and the rock known as dolostone. The mineral dolomite has the chemical formula CaMg(CO3)2 and typically crystallizes in the rhombohedral system. It is commonly white, gray, or color-tinted pink or brown, and its crystals range from grainy to well-formed rhombohedra. The related rock, dolostone, is largely composed of the dolomite mineral and forms the bulk of many sedimentary sequences.

The name dolomite honors the 18th‑century French geologist Déodat de Dolomieu. Dolomite occurs in a variety of geological settings, but most dolostones form through diagenetic alteration of limestone. In this process, magnesium-rich fluids or ion-rich waters progressively replace calcium with magnesium in the original limestone, a reaction called dolomitization. Dolomite can also form directly from seawater under suitable chemical conditions and evaporite environments.

Physically, dolomite has a Mohs hardness of about 3.5–4 and a vitreous to pearly luster. It may occur as coarse crystals or as fine-grained rock. It typically shows a pale, duller color than calcite and can display a weathered rind on exposure. Compared with calcite, dolomite dissolves in acid more slowly and often requires powdered samples or heated acid to observe a noticeable reaction.

Economically, dolomite is quarried for use as a source of magnesium oxide and lime, as an aggregate, and as a decorative or architectural stone. In geology, dolostone can serve as a reservoir rock in petroleum systems and provides important information about past environmental conditions in carbonate platforms.