Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3) . It is a very common mineral, particularly as a component of limestone, and is best recognized by its relatively low Mohs hardness (3) and its high reactivity with even weak acids, such as vinegar, plus its prominent rhombohedral cleavage in most varieties. Some key properties and uses of calcite include:
Properties:
- Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scratch hardness comparison.
- Calcite has a high reactivity with even weak acids, such as vinegar.
- Calcite is best recognized by its prominent rhombohedral cleavage in most varieties.
Uses:
- Calcite is the principal constituent of limestone and marble, which are extremely common and make up a significant portion of Earths crust.
- Calcite is used as a construction material, abrasive, agricultural soil treatment, construction aggregate, pigment, pharmaceutical, and more.
- Large calcite crystals are used in optical equipment, and limestone composed mostly of calcite has numerous uses.
Calcite is also a common constituent of sedimentary rocks, limestone in particular, much of which is formed from the shells of dead marine organisms. Approximately 10% of sedimentary rock is limestone. It is the primary mineral in metamorphic marble. It also occurs in deposits from hot springs as a vein mineral; in caverns as stalactites and stalagmites; and in volcanic or mantle-derived rocks such as carbonatites, kimberlites, or rarely in peridotites.
