Chalk is a kind of limestone, made of the mineral calcite, or calcium carbonate.

Limestone - sedimentary rock composed largely of the mineral calcite (calcium carbonate: CaCO).

Limestone is a sedimentary rock composed of the mineral calcite (calcium carbonate).

Each of the spicules is a single crystal of mineral calcite.

The eggs of crocodilians and birds have a similar structure and are made of the mineral calcite.

Limestone is defined as a rock which contains at least 50 per cent, which nearly always occurs as the mineral calcite.

Calcium oxide is usually made by the thermal decomposition of materials such as limestone, that contain calcium carbonate (CaCO; mineral calcite) in a lime kiln.

The first is the mineral calcite, which is the most common and consists of cave fillings, such as stalactites, stalagmites, sinter deposits and valances.

As a piece of living tissue, a tusk is relatively soft; it is as hard as the mineral calcite.

Coquina is mainly composed of mineral calcite, often including some phosphate, in the form of seashells or coral.