What is Marble?
Marble is a kind of metamorphic rock made of recrystallized Calcite or Dolomite. Metamorphic rocks mean the rocks that are transformed over the years from the existing rocks. The process is known as Metamorphism, which means a gradual change in the form. Foliation is the repetitive layering process in the metamorphic rocks. According to the studies in Geology, Marble is not a foliated rock but there are many contradictions to this theory. Marble is often referred to as metamorphosed Limestone. Marble is used in sculpturing and in the building process. Marble can be found in several regions all around the world but the most sought after ones are from Greece and Italy. It is famous for its purest color.
Marble: The Rock
The word Marble is derived from Greek terminology that means a crystalline and shining rock. The rock has the capability to gleam and shine. The metamorphism of pure limestone or dolomite results in the formation of Marble stone. The different colors and textures of Marble are due to the presence of impurities like sand, oxides of iron, clay and chert. The recrystallization of the impurities is due to high pressure and temperature over centuries since the formation of earth constituted in the process of metamorphism. Marbles are massive, instead of thin-layered, petrographically. It may consist of a mosaic of calcite that barely shows under the microscope. If the rock is severely deformed then it reflects elongated stripes on the surface that are the grains. The purest form of metamorphic Marbles like Carrara consists of accessory minerals and the common ones are quartz shaped in small round grains in colorless or pale mica, dark and shining particles of iron oxide, graphite, and pyrite.
Types of Marbles:
The most popular and extensively used types of commercial Marbles:
Pentelic Marble- This kind of Marble is pure white in color and is semi-translucent with fine grain like structures. (Greece country)
Creole Marble- It is available in blue, black and white colors. (United States)
Etowah Marble- It is available in pink, salmon and rose colors. (United States)
Makrana Marble- It is white. (India)Murphy Marble- It is white. (United States)
Proconnesian Marble- White. ( Turkey)
Wunsiedel Marble- White. (Germany)
Yule Marble- Uniform pure white color. (United States)
Vermont Marble- White. (United States)
Sylacauga Marble- White. (United States)
Swedish green Marble- Green in color. (Sweden)
Bianco Sivec Marble- White. (North Macedonia)
Ruscha Marble- Available in white, pink and red shades. (Romania)
Ruskeala Marble- White. (Russia)
Nero Marquina Marble- Black in color Chemical Formula of MarbleCaCo₃ is the chemical formula of Marble. Minerals that naturally occur like calcite and rocks like limestone and Marble are examples of inorganic crystalline solids. They depict the multiple faces of Calcium Carbonate. So, all these subclasses of Calcium Carbonate have the same chemical formula. The Marble chips are white limestones that have the same chemical formula CaCo₃. Marble is alkaline. For example, when it reacts with Hydrochloric acid, the reaction produces Calcium Chloride, water and Carbon dioxide.
Properties of Marble:
The color of Marble is generally in the light shades. Pure Marble will be white in color and Marble with impurities like clay and iron oxides will have pink, blue, yellow and black shades. High purity Marble of bright white shade is crushed and refined into a fine powder and all the impurities are almost removed. This process is known as Whiting.
As the Marble’s formula is Calcium carbonate, it will react with acids, thereby neutralizing them. Marble is one of the most effective acid neutralizing agents.
As the Marble has Calcite, on the scale of Mohs hardness scale, it ranges at the number It can be easily carved and its translucent property is also taken advantage of. Marble has high solubility and low hardness.
Marble can be polished with great efficiency giving it a fine luster. It has a good ability to accept polish positively.
Several Marbles also contain silicates of lime and magnesia while Diopside is common as pale green color or white.
The accessory minerals include actinolite and tremolite.
The texture of Marble is granular or granoblastic.
Porosity, density, solubility especially in water, and luster are the physical properties of Marble that are taken into consideration in the research. XRF and XRD tests are often conducted in the analysis of Marble and other stones. The mechanical properties like the combined strength, compressive strength, flexural strength, abrasion resistance, water absorption coefficient, polishing surface appearance and hardness gives an idea of the overall structure and composition of Marble. The morphology exam of Marble is conducted under the guidance of a scanning electron microscope.
Advantages of Marble:
The product of the process Whiting, the fine Marble powder is used as filler and coloring agent in industries like paper, cosmetics, plastic and putty etc.
Crushed Marble is used for acid neutralization in rivers, lakes, soils and ponds.
It is used as an inert filler in pills.
Marble powder is used in the pharmaceutical industry. Antacid medicines contain CaCo₃ of powdered Marble used to reduce acid reflux in patients.
Marble is used in making sculptures and ornaments.
Powdered Marble is also used in calcium addictive feeds to dairy animals like chickens and cows.
Marble is used in floor tiles, stair treads, window sills and panels used for decoration.
Marble is more affordable since it is available in abundance.
Disadvantages of Marble
Even though Marble is one of the most sought after rocks, it still has its drawbacks and they are as follows:
Using acid causes the Marble to lose its luster and shine. Hence it requires extra care and maintenance. It is a calcareous stone that is prone to acid etching.
The Marbles from Italy, even though very pure, are soft and prime to crack compared to the rest of the Marbles. Appropriate resins must be used to make the surface durable.
The weight of the stone is too much so it requires many people to lift it and move it.
It can be very cold during winters.
Distinctive Properties of Marble:
The present-day Marble rocks are denser, harder and colorful than the original stone due to years of metamorphosis.
The veining is a distinctive feature of Marble. These glistening veins are patterns made by the minerals that fill the cracks in the limestone, the origin of Marble.
The shades of the Marble depend on the region they originate from since the climatic and soil conditions differ from place to place.
Marble does not heat up quickly and does not absorb heat energy when compared to other materials like concrete and wood. Marble is used to cool the interiors of the spaces.
Taj Mahal and Pantheon structures are still going strong for generations due to the density and durability of Marble.
Marble is hypoallergenic as its density and porosity are low. It does not attract mold, dust and termites.
Marble has good reflective strength.
Effects of Atmosphere on the Marble
The atmospheric gasses combined with the rain can deteriorate the Marble. It decays the structure of the rock and causes the dissolution of Marble. Snow, rain and temperature are also responsible for generating the movement of saltwater in the cracks. The temperature rise can increase the chemical change in Marble and wind may cause erosion in the Marble. For example, The Taj Mahal has seen significant deterioration over the years due to the weather conditions in Delhi. The atmospheric changes and waste from the nearby factories cause staining of the Marble.
Problems of Marble
Natural agents can be responsible for the deterioration of Marble. Weathering effects and thermal change can affect the durability of the rock substantially. Because of its porosity, it does not absorb much water but even a little dissolution of water can deteriorate it since it is highly reactive to mildly acidic rainwater. Its inherent solubility of acid can affect the Marble.
Any kind of metal such as copper or bronze can cause the Marble to stain. The source could also be internal and structural components. It can also be caused due to water wash.
Travertines
The calcium carbonate that is present in the limestone when suspended in water, turns into travertine upon returning to the surface after the water evaporates. One characteristic feature of travertine is the precession of air bubbles formed by the hot water. Onyx can also be found along with it when the water is cold.
Best Way to Clean Marble
Warm water is best for cleaning the Marble along with mild dish soap that is pH neutral so it doesn’t affect the properties of the Marble since acidic cleaners can deteriorate the Marble. Microfiber cloths can be perfect for cleaning the residue of the soap and drying the surface of the Marble without scrubbing it too roughly.
Marble vs. Quartz
Marble is a soft stone while quartz is hard.
Marble can be damaged easily while quartz cannot be.
Marble is more porous than granite.
Marble is more natural-looking while quartz comes in a high array of colors.
Sealing of Marble:
Marble has fine pores or tiny holes as liquids and air is absorbed in the process of metamorphosis. Since there is a possibility of spilling on the Marble countertops, the surface of the Marble needs to be sealed. Sealing agents expire over a period of time and the process needs to be repeated. Non Abrasive soaps or PH neutral cleaners should be used to clean the Marble surfaces.
Polished Marble and Honed Marble:
The polished Marble has a shiny and highly reflective surface. It is very smooth but is easily prone to itching and scratching. The honed Marble is less reflective and has a flattened finish. But it is chosen over the polished Marble as it has a matte finish. Honed Marble will have the possibility of more stains as the pores of the stone are closer to the surface than the polished Marble. According to a quote by a famous scientist, “What sculpture is to a block of marble, education is to the soul.” This statement signifies the importance of Marble in the daily life of human beings.
FAQs on Uses of Marble
1. What is marble and what is its chemical formula?
Marble is a metamorphic rock that forms when limestone or dolomite is subjected to intense heat and pressure over a long period. This process, called metamorphism, recrystallizes the original carbonate minerals. The primary chemical component of marble is calcium carbonate, and its chemical formula is CaCO₃.
2. What are the main uses of marble in construction and industry?
Marble is a versatile material with numerous applications due to its aesthetic appeal and chemical properties. Its main uses include:
- Construction and Architecture: Used for flooring, decorative wall panels, stair treads, and window sills. It is famous for its use in iconic buildings and monuments.
- Sculpture and Ornaments: Its relative softness makes it ideal for carving intricate sculptures and decorative items.
- Industrial Applications: Crushed marble is used to make a fine powder called 'Whiting,' which serves as a filler in paper, paint, and plastics.
- Environmental Use: Powdered marble is used to neutralise acidity in soil, lakes, and rivers due to its alkaline nature.
- Pharmaceuticals: High-purity calcium carbonate from marble is used as an inert filler in pills and as the active ingredient in some antacid medications.
3. What are the key physical and chemical properties of marble?
Marble has distinct properties that define its uses. The key properties are:
- Chemical Properties: It is primarily composed of calcium carbonate (CaCO₃), making it alkaline. It reacts vigorously with acids, producing carbon dioxide gas.
- Physical Properties: Marble has a granular, crystalline texture. It is a relatively soft stone, ranking around 3 on the Mohs hardness scale. It is also porous and can be polished to a high, reflective lustre. It has low heat absorption, which is why it often feels cool to the touch.
4. How do impurities affect the colour and appearance of marble?
Pure marble is white. However, the wide variety of colours and the characteristic veining patterns are caused by mineral impurities present in the original limestone before metamorphism. For example, iron oxides can create red, pink, or yellow hues, clay minerals can result in a grey colour, and carbonaceous materials like graphite can produce black marble.
5. Why does an acidic substance like lemon juice damage a marble surface?
Marble is damaged by acids because it is made of calcium carbonate (CaCO₃), which is a base. When an acid comes into contact with the marble, a chemical neutralization reaction occurs. This reaction, known as etching, effectively dissolves a tiny layer of the stone's surface, leaving a dull, rough, or discoloured spot. This is physical damage to the stone, not just a stain.
6. What is the main difference between marble and granite?
The main difference lies in their geological formation and composition. Marble is a metamorphic rock made from calcium carbonate, which makes it softer and susceptible to acids. It typically features soft, vein-like patterns. In contrast, granite is an igneous rock formed from cooled magma, composed mainly of hard minerals like quartz and feldspar. This makes granite harder, more durable, and resistant to acid etching. Its appearance is typically granular or speckled rather than veined.
7. Why is marble a preferred material for creating sculptures and historical monuments?
Marble is favoured for sculpture and monuments for several reasons. Its relative softness (Mohs hardness of 3) makes it easy to carve with fine detail. Its crystalline structure gives it a slight translucency, which can mimic the appearance of human skin, adding realism to statues. Furthermore, its density and ability to be polished to a high lustre contribute to its beauty and longevity, allowing structures like the Taj Mahal to endure for centuries.
8. What causes marble to turn yellow over time?
The primary reason for marble, especially white marble, turning yellow is the oxidation of iron deposits naturally present within the stone. When the marble is exposed to water or moisture over extended periods, the iron minerals begin to rust, creating a yellow or brown discolouration from within. The process can be accelerated by the use of harsh, acidic, or bleach-based cleaners that damage the marble's surface and sealant.
