page_title: Limestone
section_title: Uses
hierarchical_section_title: Limestone / Uses
caption_attribution_description: Facade du temple principal de Hagar Qim This media is about Maltese cultural property with inventory number 25.
context_page_description: Limestone is a carbonate sedimentary rock that is often composed of the skeletal fragments of marine organisms such as coral, foraminifera, and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate. A closely related rock is dolomite, which contains a high percentage of the mineral dolomite, CaMg(CO₃)₂. In old USGS publications, dolomite was referred to as magnesian limestone, a term now reserved for magnesium-deficient dolomites or magnesium-rich limestones.
  About 10% of sedimentary rocks are limestones. The solubility of limestone in water and weak acid solutions leads to karst landscapes, in which water erodes the limestone over thousands to millions of years. Most cave systems are through limestone bedrock.
  Limestone has numerous uses: as a building material, an essential component of concrete, as aggregate for the base of roads, as white pigment or filler in products such as toothpaste or paints, as a chemical feedstock for the production of lime, as a soil conditioner, and as a popular decorative addition to rock gardens.
context_section_description: Limestone is very common in architecture, especially in Europe and North America. Many landmarks across the world, including the Great Pyramid and its associated complex in Giza, Egypt, were made of limestone. So many buildings in Kingston, Ontario, Canada were, and continue to be, constructed from it that it is nicknamed the 'Limestone City'. On the island of Malta, a variety of limestone called Globigerina limestone was, for a long time, the only building material available, and is still very frequently used on all types of buildings and sculptures. Limestone is readily available and relatively easy to cut into blocks or more elaborate carving. Ancient American sculptors valued limestone because it was easy to work and good for fine detail. Going back to the Late Preclassic period (by 200–100 BCE), the Maya civilization (Ancient Mexico) created refined sculpture using limestone because of these excellent carving properties. The Maya would decorate the ceilings of their sacred buildings (known as lintels) and cover the walls with carved limestone panels. Carved on these sculptures were political and social stories, and this helped communicate messages of the king to his people. Limestone is long-lasting and stands up well to exposure, which explains why many limestone ruins survive. However, it is very heavy (density 2.6), making it impractical for tall buildings, and relatively expensive as a building material.
  Limestone was most popular in the late 19th and early 20th centuries. Train stations, banks and other structures from that era were normally made of limestone. It is used as a facade on some skyscrapers, but only in thin plates for covering, rather than solid blocks. In the United States, Indiana, most notably the Bloomington area, has long been a source of high-quality quarried limestone, called Indiana limestone. Many famous buildings in London are built from Portland limestone. Houses built in Odessa in Ukraine in the 19th century were mostly constructed from limestone and the extensive remains of the mines now form the Odessa Catacombs.
  Limestone was also a very popular building block in the Middle Ages in the areas where it occurred, since it is hard, durable, and commonly occurs in easily accessible surface exposures. Many medieval churches and castles in Europe are made of limestone. Beer stone was a popular kind of limestone for medieval buildings in southern England.
  Limestone and (to a lesser extent) marble are reactive to acid solutions, making acid rain a significant problem to the preservation of artifacts made from this stone. Many limestone statues and building surfaces have suffered severe damage due to acid rain. Likewise limestone gravel has been used to protect lakes vulnerable to acid rain, acting as a pH buffering agent.  Acid-based cleaning chemicals can also etch limestone, which should only be cleaned with a neutral or mild alkali-based cleaner.
  Other uses include:
  It is the raw material for the manufacture of quicklime (calcium oxide), slaked lime (calcium hydroxide), cement and mortar.
  Pulverized limestone is used as a soil conditioner to neutralize acidic soils (agricultural lime).
  Is crushed for use as aggregate—the solid base for many roads as well as in asphalt concrete.
  Geological formations of limestone are among the best petroleum reservoirs;
  As a reagent in flue-gas desulfurization, it reacts with sulfur dioxide for air pollution control.
  Glass making, in some circumstances, uses limestone.
  It is added to toothpaste, paper, plastics, paint, tiles, and other materials as both white pigment and a cheap filler.
  It can suppress methane explosions in underground coal mines.
  Purified, it is added to bread and cereals as a source of calcium.
  Calcium levels in livestock feed are supplemented with it, such as for poultry (when ground up).
  It can be used for remineralizing and increasing the alkalinity of purified water to prevent pipe corrosion and to restore essential nutrient levels.
  Used in blast furnaces, limestone binds with silica and other impurities to remove them from the iron.
  
caption: The Megalithic Temples of Malta such as Ħaġar Qim are built entirely of limestone. They are among the oldest freestanding structures in existence.[12]
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