Amazing World of Limestone

From alkalinizing agents to mortar materials to sculptures, Limestone is as diverse as the parts of the world where it is found.

Description

There are a variety of types of limestone available, each with their own unique looks and use. Generally, however, most typically come in small, clastic (although some are non-clastic), hard rock formations. The color of limestone varies from rock to rock, though most are light in color, and usually having hints or grey or yellow.

Limestone is a sedimentary rock, although it has a hardness of 3-4 Mohs and a density of 2.5 to 2.7 grams per cubic centimeter. The rock is primarily composed of calcite or calcium carbonate, with most of these rocks being around 95% calcium carbonate. Being so high in calcium makes limestone rock polish and smooth better.

Location

Limestone forms in various ways, most commonly forming in shallow, calm, and warm marine waters. These buildups of limestone can be found between 30 degrees North Latitude and 30 degrees South Latitude of the globe. Such deposits are found in the Caribbean Sea, the Indian Ocean, the Persian Gulf, and the Gulf of Mexico. Another way limestone forms is through evaporation, with this type of limestone growing in caves around the world. China, the US, Russia, Japan, India, Brazil, Germany, Mexico, and Italy are some of the world’s largest limestone producers today. Some of the biggest quarries in the world, however, are in the U.S. state of Michigan, specifically near the Great Lakes’ coastlines.

Formation

When limestone forms in water, the rock becomes a collection of calcium carbonate shells and skeletons from previous life forms who have died on the ocean floor, and are mixed up with other rock sediments over time. This enables the rock to accumulate debris which includes said shells and skeletons, and eventually this causes a buildup of calcium carbonate. Another formation process of Limestone occurs through evaporation. In this manner, droplets on cave walls seep down from the entrances of the cave through fractures, and this water then evaporates, leaving a calcium carbonate deposit behind, which forms limestone.

Uses

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, 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 are 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.

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.
  • It is used in sculptures because of its suitability for carving.

Production

The mining of limestone begins with its extraction from deposits in mines and quarries, with many of these mines being located in the United States, as well as in parts of the African and South American continents. After extraction, limestone is tested for its chemical composition. Limestone that meets the required calcium carbonate levels is then put into a “lime kiln”, and heated to 1000 degrees Celsius (1,832o Fahrenheit). Depending on the type of limestone begin produced, it may be hydrated by adding water to its composition, which is how we quicklime and slaked lime are formed.

Limestone is One of the Most Popular Stones in the World

Unfortunately, though, many of us don’t know the full extent to which limestone has played a role in our world’s history. From courthouses, to pyramids, to temples, all the way to your home, limestone has shaped architecture in many ways with its natural beauty. Here are some interesting ways that limestone has been used to create architectural and artistic masterpieces throughout history.

1. The Great Sphinx

Remember that mythical creature that appeared to have the body of a lion and a human’s head when you learned about Egypt as a kid? It’s the largest monolith statue in the entire world (over 240 feet long, 63 feet wide, and 66ft tall!) built by the Egyptians over four thousand years ago. What many people don’t know about the Great Sphinx is that it was actually constructed out of limestone: the same stone that is used in interior designs all across the world.

2. The Parthenon

The Ancient Greeks were also quite fond of limestone, incorporating it into many facets of their architecture, most notably, the Parthenon, in which we see early uses of limestone columns, which people are still incorporating all across the world today. Architects used to have to oversee every part of the building process, from planning, to cutting, to construction!

3. The Great Pyramid

The Great Pyramid is one of the Seven Wonders of the Ancient World. While the pyramid is not made solely from limestone, (granite and mortar paid a big role too!) for the most part, the Great Pyramid was made up of limestone. The surface “casing stone” is made from highly polished white limestone that had to be carefully cut to give the correct dimensions and precise slant needed to construct the pyramid’s unique design.

4. The Lincoln Memorial

Built in the style of the Greek Temple, the interiors walls and columns of the Lincoln Memorial were constructed from natural Indiana limestone. This incredible monument is made up of many different materials, including marble, granite, and more, but they made a classic choice by incorporating limestone columns which are always an elegant choice.

5. The Empire State Building

One of the tallest, most impressive buildings in the United States, the Empire State Building is constructed mostly from Indiana limestone. This monument is visited by people from all over the world for its fantastic views from the observation deck and history being named after New York’s nickname, “The Empire State”.

6. The Reconstruction of the Pentagon

On September 11, 2011, a hijacked plane crashed into the western side of the massive Pentagon. Showing true American resilience, the reconstruction was made with “The Nation’s Building Stone”, natural Indiana limestone. Since then, it’s been a symbol of the true American toughness to carry on through tragedy.

7. The Charminar

The Charminar (“Four Minarets”), constructed in 1591, is a monument and mosque located in Hyderabad, Telangana, India. The landmark has become a global icon of Hyderabad, listed among the most recognized structures of India. Charminar has been a historical place with Mosque on the top floor for over 400 years and also known for its surrounding markets. The structure is made of granite, limestone, mortar and pulverized marble and it weighs approximately 14000 tones. Initially the monument with its four arches was so proportionately planned that when the fort was opened one could catch a glimpse of the bustling Hyderabad city, as these Charminar arches were facing the most active royal ancestral streets.

8. The Victoria Terminus

Chhatrapati Shivaji Maharaj Terminus, formerly known as Victoria Terminus, is a historic railway station and a UNESCO World Heritage Site in Mumbai, Maharashtra, India which serves as the headquarters of the Central Railways. The station was designed by Frederick William Stevens according to the concept of Victorian Italianate Gothic Revival architecture and meant to be a similar revival of Indian Goth (classical era) architecture. The station was built in 1887 in the Bori Bunder area of Mumbai to commemorate the Golden Jubilee of Queen Victoria. The new railway station was built to the south of the old Bori Bunder railway station. It is one of the busiest railway stations in India, serving as a terminal for both long-distance trains and suburban trains. The station’s name was changed from Victoria Terminus to Chhatrapati Shivaji Terminus in March 1996 in honour of Emperor Chhatrapati Shivaji, founder of the Maratha Empire. In 2017, the station was again renamed Chhatrapati Shivaji Maharaj Terminus. However, both the former name “VT” and the current name “CST” are popularly used. The main structure is built from a blend of India sandstone and limestone, while high-quality Italian marble was used for the key decorative elements.

9. Khajuraho Group of Monuments

The Khajuraho Group of Monuments is a group of Hindu temples and Jain temples made of limestone in Chhatarpur, Madhya Pradesh, India, about 175 kilometres (109 mi) southeast of Jhansi. They are one of the UNESCO World Heritage Sites. The temples are famous for their nagara-style architectural symbolism and their erotic sculptures. Most Khajuraho temples were built between 950 and 1050 by the Chandela dynasty. Historical records note that the Khajuraho temple site had 85 temples by the 12th century, spread over 20 square kilometers Of these, only about 25 temples have survived, spread over six square kilometers. Of the surviving temples, the Kandariya Mahadeva Temple is decorated with a profusion of sculptures with intricate details, symbolism and expressiveness of ancient Indian art. The Khajuraho group of temples were built together but were dedicated to two religions, Hinduism and Jainism, suggesting a tradition of acceptance and respect for diverse religious views among Hindus and Jains in the region.

10. Western Wall

The Western Wall, Wailing Wall, or Kotel, known in Islam as the Buraq Wall, is an ancient limestone wall in the Old City of Jerusalem. It is a relatively small segment of a far longer ancient retaining wall, known also in its entirety as the “Western Wall”. The wall was originally erected as part of the expansion of the Second Jewish Temple begun by Herod the Great, which resulted in the encasement of the natural, steep hill known to Jews and Christians as the Temple Mount, in a large rectangular structure topped by a huge flat platform, thus creating more space for the Temple itself and its auxiliary buildings. For Muslims, it is the site where the Islamic Prophet Muhammad tied his steed, al-Buraq, on his night journey to Jerusalem before ascending to paradise, and constitutes the Western border of al-Haram al-Sharif. The Western Wall is considered holy due to its connection to the Temple Mount. Because of the Temple Mount entry restrictions, the Wall is the holiest place where Jews are permitted to pray, though the holiest site in the Jewish faith lies behind it. The original, natural, and irregular-shaped Temple Mount was gradually extended to allow for an ever-larger Temple compound to be built at its top. This process was finalised by Herod, who enclosed the Mount with an almost rectangular set of retaining walls, built to support extensive substructures and earth fills needed to give the natural hill a geometrically regular shape. On top of this box-like structure Herod built a vast paved esplanade which surrounded the Temple. Of the four retaining walls, the western one is considered to be closest to the former Temple, which makes it the most sacred site recognised by Judaism outside the former Temple Mount esplanade. Just over half the wall’s total height, including its 17 courses located below street level, dates from the end of the Second Temple period, and is commonly believed to have been built around 19 BCE by Herod the Great, although recent excavations indicate that the work was not finished by the time Herod died in 4 BCE. The very large stone blocks of the lower courses are Herodian, the courses of medium-sized stones above them were added during the Umayyad era, while the small stones of the uppermost courses are of more recent date, especially from the Ottoman period.

 

 

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