Difference Between Calcite and Dolomite

Calcite vs Dolomite

Dolomite and calcite are minerals containing calcium carbonate. Both of these are hard to distinguish from each other except for few properties.

Calcite

Calcite is a mineral, which contains calcium carbonate (CaCO₃). This is an abundant mineral on the earth surface. Calcite can form rocks, and they may grow up to large sizes. They are found in all three types of rocks, which are sedimentary, igneous and metamorphic rocks. Different varieties of calcites can be formed due to variations in the distribution and environments. They can exist as colorless crystals, or sometimes can have white, pink, yellow or brownish colors. The crystals can be transparent, translucent or opaque, depending on the substances it has incorporated within when forming. The amount of calcium carbonate containing in the rock can vary. Sometimes, there are calcite minerals, which contain about 99% calcium carbonate. Calcite has unique optical properties. When a ray of light goes through a calcite mineral, it reflects the light double. Furthermore, calcite has fluorescence, phosphorescence, thermo luminescence and triboluminescence properties. Depending on the calcite variety, the extent of showing these properties may vary. Calcites react with acids and produce carbon dioxide gas. Especially in water, it becomes less soluble as the temperature increases, which allow calcite to precipitate and form more massive crystals. Calcites are relatively less hard, so they can be scratched by a fingernail. Calcite can be mainly found in Ohio, Illinois, New Jersey, Tennessee, Kansas in USA and Germany, Brazil, Mexico, England, Iceland, many African countries etc.

Dolomite

Dolomite is a mineral which contains calcium magnesium carbonate CaMg(CO₃)₂mainly. Dolomites can grow up to large sizes forming mineral beds, and this is a sedimentary rock forming mineral. Dolomite is widely distributed all over the world and commonly found in sedimentary rocks. Dolomite can react with acids (but very weakly). When hot acids are used or when powdered dolomite is used, the reaction can be fast. Dolomite has a pearly luster, which is unique. There can be several colors in dolomites, but mainly there are colorless, pink and white forms. Crystals can be transparent or translucent. Dolomite crystals have a unique crystal habit with sharp rhombohedrons or some with curved faces. Dolomite has a perfect cleavage from three directions as calcites. Based on a Mohs’ scale, the hardness of dolomite is around 3.5-4. Dolomite is abundant in Canada, Switzerland, Mexico, Spain and in Midwestern quarries of USA. Dolomite is added to agricultural soils, to increase the magnesium content and lower the acidity. It is also used as an ornamental stone and a concrete aggregate.

What is the difference between Calcite and Dolomite?

• Calcite mainly contains calcium carbonate and dolomite contains calcium magnesium carbonate. Dolomite differs from calcite because of the presence of magnesium.

• Calcite reacts quickly with acids and produce carbon dioxide bubbles. But dolomite is weakly reacts with acids producing bubbles very slowly. When hot acids or powdered dolomite is used they may react quickly.

• Dolomite is slightly harder and denser than calcite.

• Calcites form scalenohedrons but dolomites never form scalenohedrons. Dolomite crystal habit represents rhombohedrons or curved faces.