Home >> Science & Nature >> Rocks & Minerals

The Differences Between Dolomite & Limestone

The Dolomites are a mountain range in Italy, and dolomite gives the mountains their characteristic shapes and color. The mountains were previously called the pale mountains. You can see dolomite rocks under Bristlecone pine in the White Mountains in California. After the Great Chicago Fire, many buildings were covered with Indiana limestone. Limestone also covers the Empire State Building and the Pentagon.

Formation of Dolomite and Limestone
- Limestone and dolomite are formed by an accumulation of sediments.The best sources of dolomite formations are in magnesium rich ground waters with a high salinity; for example, dolomite is formed in highly saline lakes in the Coorong region in South Australia. Laboratory tests suggest that dolomite needs temperatures above 212 F to form. Yet it is unclear how exactly dolomite is formed. Limestone is formed of remains of tiny shells coral, algal, fecal debris and microskeletons, which are deposited on the seabed. The shells and skeletons are compressed to form solid rock. Limestone is formed in layers and contains vertical cracks. The layers and the cracks make the rock permeable, allowing water to flow through. Water dripping from the roofs of limestone caves can leave behind particles and form icicle-shaped stalactites. Water that drips onto the floor of caves can lead to the formation of stalagmites.
Characteristics
- Dolomite has a pearly luster. Colorless and white dolomite is common, but you can find yellow, gray, brown and black dolomite. Black dolomite indicates the presence of iron in the crystals. High manganese content gives dolomite crystals a pink color. Limestone is often light gray, and there are often streaks, fossils or shell formations in the stone. The shells and fossils mean that it has a high concentration of calcium.
Bubble Tests
- It is difficult to distinguish dolomite from the more common calcite. Calcite bubbles when acid is put on it. In contrast dolomite only weakly bubbles in contact with warm acid. Dolomite also bubbles when it is in powered form. Rainwater contains a week carbonic acid, which reacts with and dissolves limestone. Limestone bubbles and forms gas when a cold solution of 5% hydrochloric acid is added to it.
Uses
- Dolomite is often used in ornamental stone and to produce concrete and asphalt. Processed dolomite is used in the production of float glass, which is a sheet of glass. Dolomite can be added to soils and potting mixtures to lower the acidity and enrich the soil with magnesium, a component of dolomite. There are several different forms of lime, which varies in hardiness. Chalk is a soft, fine limestone that is usually white or light gray. Lithographic limestone is a dense limestone that was used to make prints. Limestone can also be crushed and used as construction material, for example, road base.

Rocks & Minerals