Calcium carbonate
[CAS# 471-34-1]

Identification

• Classification: API >> Digestive system medication >> Acid and gastric mucosal protective drugs
• Name: Calcium carbonate
• Synonyms: Carbonic acid calcium salt; Limestone; Marble
• Molecular Formula: CaCO₃
• Molecular Weight: 100.09
• CAS Registry Number: 471-34-1
• EC Number: 207-439-9
• SMILES: C(=O)([O-])[O-].[Ca+2]

Properties

• Density: 2.93
• Melting point: 825 °C
• Water solubility: Insoluble

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H315-H319-H335
• Safety Statements: P261-P305+P351+P338

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Serious eye damage	Eye Dam.	1	H318
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Specific target organ toxicity - single exposure	STOT SE	3	H336
Specific target organ toxicity - repeated exposure	STOT RE	1	H372

Discovery and Applications

The discovery of calcium carbonate dates back to ancient civilizations, when people used limestone and marble for construction and artistic creation. Calcium carbonate is primarily found in geological formations such as limestone, chalk, and marble, and is also the structural basis of marine shells and coral reefs. Its natural abundance makes it a readily available resource with important uses.

In construction, calcium carbonate is an essential component of cement and mortar. When ground into a fine powder, it can be used as a filler in concrete, enhancing its properties and reducing costs. In addition, both marble and limestone are calcium carbonates, which are highly valued for their durability and beauty in building facades and interior design.

Calcium carbonate is widely used in the paper industry as a coating and filling material to increase brightness and opacity. In plastics, it can be used as a filler to enhance mechanical properties and reduce production costs. The paint industry uses calcium carbonate to extend pigments and improve the stability and finish of paints and coatings.

In agriculture, calcium carbonate (commonly known as agricultural lime) is applied to acidic soils to neutralize pH. This improves soil structure, increases nutrient availability, and promotes healthy plant growth. It is used as a calcium supplement in livestock feed to help animals develop strong bones and teeth.

Calcium carbonate is a common ingredient in antacids because of its ability to neutralize stomach acid. It quickly relieves heartburn and indigestion and is widely used in chewable tablets and liquid preparations. As a dietary supplement, calcium carbonate is used to prevent or treat calcium deficiency, support bone health, and prevent diseases such as osteoporosis. It is well absorbed when taken with meals, making it a popular choice among over-the-counter calcium supplements.

Calcium carbonate also plays a role in environmental protection. It is used in flue gas desulfurization to reduce sulfur dioxide emissions from power plants. In addition, it is involved in water treatment processes to adjust pH and remove impurities.

While calcium carbonate is generally safe to use, precautions need to be taken when handling fine powders to avoid respiratory irritation. Moderate intake as a supplement or antacid is safe, but excessive intake can lead to health problems such as kidney stones or hypercalcemia.

References

1991. Calcium supplementation: Effect on iron absorption. The American Journal of Clinical Nutrition, 53.
DOI: 10.1093/ajcn/53.1.106

1991. Aluminum accumulation during treatment with aluminum hydroxide and dialysis in children and young adults with chronic renal disease. The New England Journal of Medicine, 324.
DOI: 10.1056/nejm199102213240804