Dolomite is both a mineral and a sedimentary rock, and the distinction in 2026 geology remains primarily about scale. The mineral dolomite is an anhydrous carbonate composed of calcium magnesium carbonate (CaMg(CO3)2). It forms as rhombohedral crystals and is often pinkish or white with a glassy luster. The rock dolomite (also sometimes called dolostone to avoid confusion) is a sedimentary carbonate rock consisting of more than 50% of the mineral dolomite. This rock is the primary component of the Dolomites mountain range in Italy. While it looks very similar to limestone, dolomite rock is harder and does not react (fizz) as readily with cold hydrochloric acid. In 2026, the term "dolostone" is increasingly used in academic circles to describe the rock, while "dolomite" is reserved for the specific mineral species, though in common conversation, the single term "dolomite" continues to serve as a descriptor for both the individual crystal and the massive mountain formations.