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 RockThe 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 MarbleEven 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 MarbleThe 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 MarbleNatural 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 MarbleWarm 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. QuartzMarble 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.
