Calcite

**Chemical name:** Calcium carbonate

**Formula:** CaCO₃

**Molar mass of compound CaCO₃:** 100,087 g/mol

**Hardness:** 3

**Crystal system:** Rhombohedral system

**Arrangement of atoms:** Planar coordination group CO₃ and calcium ions in a six-membered coordination with oxygen.

**Crystal habit:** Columnar, rhombohedral or scalenohedral type

**Information:** Calcite is a mineral formed by crystallization of magma and hydrothermal fluids. Calcite forms a rock limestone (marble) or travertine. Depending on the mixture it has different colours. Limpid calcite is called Icelandic limestone.

**Use:** It is used for the production of lime, cement or as a building block. Icelandic limestone is used as a polarizing prism.