dolostones

Dolostone is a sedimentary rock dominated by the mineral dolomite, CaMg(CO3)2. In most classifications, rocks in which dolomite is the principal carbonate mineral are called dolostones, whereas rocks with significant calcite are classified as limestones. Dolostones are typically fine- to medium-crystalline and can occur in a range of colors, commonly gray to tan or pink, forming massive units or well-developed beds.

Formation and composition: Dolostones form largely through dolomitization, a diagenetic process in which calcium in limestone is replaced by magnesium, often during burial or in the presence of magnesium-rich fluids. Some dolostones arise from direct precipitation of dolomite from seawater in restricted or particular environmental settings. The dolomite mineral features a lattice where magnesium substitutes for calcium, giving properties distinct from calcite.

Occurrence and environments: Dolostones are widespread in the geological record, especially in ancient carbonate platforms. Modern analogs occur in sabkha and shallow-marine environments with limited circulation of magnesium-rich brines. The diagenetic history of dolostones can either enhance or reduce porosity and permeability, influencing their role as reservoir rocks.

Physical properties and weathering: Dolostone generally reacts slowly with dilute acids compared with limestone; dissolution can require powdered samples or heated/stronger acids. Textures range from crystalline to finely crystalline, and porosity is highly variable, depending on diagenetic history and original sedimentary fabric.

Economic aspects: Dolostones are quarried for crushed stone and aggregate and serve as a source of magnesium ore in some applications. They are also used as decorative stone and, when processed, can contribute to cement and other industrial materials.