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, 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: 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 colours 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.
Types of Marbles:
The most popular and extensively used types of commercial marbles:
Pentelic marble- This kind of marble is pure white in colour and is semi-translucent with a fine grain like structures. (Greece country)
Creole marble- It is available in blue, black and white colours. (United States)
Etowah marble- It is available in pink, salmon and rose colours. (United States)
Makrana marble- It is white in colour. (India)
Murphy marble- It is white in colour. (United States)
Prokonnesos marble- White in colour. ( Turkey)
Wunsiedel marble- White in colour. (Germany)
Yule marble- Uniform pure white colour. (United States)
Vermont marble- White in colour. (United States)
Sylacauga marble- White in colour. (United States)
Swedish green marble- Green in colour.(Sweden)
Bianco Sivec marble- White in colour. (North Macedonia)
Ruschita marble- Available in white, pink and red shades. (Romania)
Ruskeala marble- White in colour. (Russia)
Nero Marquina marble- Black in colour. (Spain)
The Chemical Formula of Marble
CaCo₃ is the chemical formula of marble. Minerals that naturally occur like calcite and rocks like limestone and marble are the 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 basically white lime stones that have the same chemical formula CaCo₃. Marble is alkaline in nature. For example, when it reacts with Hydrochloric acid, the reaction produces Calcium Chloride, water and Carbon dioxide.
Properties of Marble:
The colour of marble is generally in the light shades. Pure marble will be white in colour 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 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 3. 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 in a positive way.
Porosity, density, solubility especially in water, 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 in the guidance of scanning electron microscope.
Advantages of Marble:
The product of the process Whiting, the fine marble powder is used as filler and colouring 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 inert filler in pills.
The marble powder is used in 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 diary animals like chickens and cows.
Marble is used in floor tiles, stair treads, window sills and panels used for decoration.
Distinctive Properties of Marble:
The present day marble rocks are denser, harder and colourful than the original stone due to years of metamorphosis.
The veining is a distinctive feature of marble. These glistening veins are basically 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 the 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 since generations due to the density and durability of marble.
Marble is hypoallergenic as its density and porosity is low. It does not attract mold, dust and termites.
Marble has good reflective strength.
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 again. Nonabrasive soaps or PH neutral cleaners should be used to clean the marble surfaces.
Polished Marble and Honed Marble:
The polished marble has shiny and highly reflective surface. It is very smooth but is easily prone to etching and scratching. The honed marble is less reflective and has a flattered 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 polishes 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.
1. State the Differences Between Marble and Granite
Answer: Both the stones have some visible particles on their surface and can be differentiated based on their appearance. Granite has a granular appearances and marble has veining on its surface. The stones in the nature are classified into two main categories. One type of the stones is mainly made up of Silica or Quartz. These types of stones last long and are durable. They can also be cleaned and maintained easily. Granite, sandstone and slate fall in this category. The other types of stones are mainly made of Calcium Carbonate. Cleaning these types of stones is difficult and requires special techniques. They cannot be cleaned using the acid based products. Marble, limestone, onyx and travertine come under this category of stones.
2. Will Marble have Visible Seams?
Answer: During the installation of most of the stones, the process requires a seam. Even marble will require seam during its installation process. Coordinating with the fabricator in the initial stages of design and layout processes, the number of seams can be reduced and they can be installed in such a way that the seams are located in minimal view or in less conspicuous areas.
3. Explain the Etching Process.
Answer: When any type of acid reacts with the marble stone, a corrosive chemical reaction occurs and that is known as etching. The Calcium Carbonate present in the marble is eaten away by the acid during the chemical reaction. This is not just temporary discolouration; the marble stone is actually damaged in the process. These look like dull spots on the surface but cannot be cleaned and repaired. The unsealed areas in the marble can etch if simple ingredients of cooking like lemon juice get penetrated and remain un-cleaned for a longer period of time. Polishing or refinishing the area of etching can help to cover the damage to some extent.
4. Can Extreme Hot Dishes or Pans be Placed on the Marble Countertops Directly?
Answer: The marble stone has high tolerance of high, but that does not mean that hot pots or cookers can be placed directly on the surface of the marble. In some cases, the heat may cause thermal shock due to which cracks will appear. There will also be change in the colour of the marble stone and a burnt mark kind of stain will appear in the spot where the hot utensil is placed.