Natural Occurrence

• Seashells are made from calcium carbonate.Photos.com/Photos.com/Getty Images
  
  The most common form of carbonate naturally found is sedimentary rock such as limestone, marble and calcite. Aside from being found in the form of rock, calcium carbonate is also used by many animals. Calcium carbonate is often found dissolved in water in large enough quantities for aquatic invertebrates like snails, shellfish and other mollusks to use for their shells and internal structures, according to the Geology Rocks website.
  
  

Agricultural Use

• Calcium carbonate is a common agricultural conditioner.Hemera Technologies/AbleStock.com/Getty Images
  
  Calcium carbonate is an alkali, the opposite of an acid. It's used to balance acidic soil so more sensitive crops can grow in otherwise harsh conditions, the Physics Post website states. Calcium carbonate is powdered and spread over the ground where crops will be planted, much like fertilizer.
  
  

Building and Construction

• Carbonates are a common building material used in North American and Europe. Limestone is often used outdoors on houses and buildings, as well as sculpted into monuments and statues, the Minerals Zone website explains. Though more expensive than some other options, marble is a common material used for countertops and flooring in homes.
  
  

Use in Health Supplements

• Calcium carbonate is commonly used as a calcium supplement.Thinkstock/Comstock/Getty Images
  
  Calcium carbonate is the active ingredient in many brands of antacid to combat heartburn and upset stomach, according to Physics Post. Used as a health supplement, calcium carbonate is manufactured into pill form for people who need to increase their dietary intake of calcium.