One might be surprised to learn how many products contain limestone. Inorganic remains are compressed over a very long period of time to form limestone. Calcium carbonate is the main element in limestone, but it can also contain magnesium or iron, which determines its whiteness and hardness. In addition to being used in construction materials, limestone is also used in a variety of other ways in daily life. A wide range of plastics and rubber products include lime powder as a filler material. Cement is formed when lime powder is mixed with clay and heated. Sand and water are added to the cement to form mortar