Dolomite group

carbonate mineral – CaMg(CO₃)₂

sedimentary carbonate rock

Ankerite, also known as brown spar () is a calcium, iron, magnesium, manganese carbonate mineral of the group of rhombohedral carbonates with the chemical formula . In composition it is closely related to dolomite, but differs from this in having magnesium replaced by varying amounts of iron(II) and manganese. It forms a series with dolomite and kutnohorite.

Kutnohorite is a rare calcium manganese carbonate mineral with the formula in the dolomite group of minerals. It forms a solid solution with the other group members dolomite and ankerite. The mineral was originally spelt "kutnahorite" but "kutnohorite" is the current IMA-approved spelling.

thumb|Sedimentary layers of dolomitized limestone in an outcrop in the [[Philippines]] thumb|Mountains with dolomite rock formations in northern Italy Dolomitization is a geological process where magnesium ions replace calcium ions in the mineral calcite, resulting in the formation of dolomite.