Marble is a metamorphic rock consisting of carbonate minerals (most commonly calcite (CaCO3) or dolomite (CaMg(CO3)2) that have recrystallized under the influence of heat and pressure. It has a crystalline texture, and is typically not foliated (layered), although there are exceptions.
In geology, the term marble refers to metamorphosed limestone, but its use in stonemasonry more broadly encompasses unmetamorphosed limestone.Kearey, Philip (2001). Dictionary of Geology, Penguin Group, London and New York, p. 163.
Pure white marble arises from very clean limestone or from dolomite rock. However, its signature veins and swirls result from impurities, for example clay, sand, iron oxides, or chert that were originally present in the protolith—magnesium-rich varieties may show green tones due to serpentine. These impurities are redistributed and recrystallized during metamorphism. Due to its hardness, durability and resistance to temperature, marble is often used in sculpture and construction. In sculpture, marble is ideal for fine detail due to its uniform grain, moderate hardness, and ability to scatter light beneath the surface (subsurface scattering), lending the sculpture a lifelike, waxy appearance. In architecture marble is valued for its polishable surface, hardness, and wear resistance. In stonemasonry, "marble" may broadly include similar crystalline rocks, even if not true geological marble.
The extraction of marble is performed by quarrying. Marble production is dominated by four countries: China, Italy, India and Spain, which account for almost half of world production of marble and decorative stone.
Etymology
The word "marble" derives from the Ancient Greek (), from (), "crystalline rock, shining stone",μάρμαρος , Henry George Liddell, Robert Scott, A Greek–English Lexicon, on Perseus Digital Library. Askoxford.com. Retrieved on 2011-09-30. perhaps from the verb (), "to flash, sparkle, gleam";μαρμαίρω , Henry George Liddell, Robert Scott, A Greek–English Lexicon, on Perseus Digital Library R. S. P. Beekes has suggested that a "Pre-Greek origin is probable".R. S. P. Beekes, Etymological Dictionary of Greek, Brill, 2009, p. 907.
This stem is also the ancestor of the English word "marmoreal", meaning "marble-like." While the English term "marble" resembles the French , most other European languages (with words like "marmoreal") more closely resemble the original Ancient Greek.
Geology
Marble is a rock resulting from metamorphism of sedimentary carbonate rocks, most commonly limestone or dolomite. Metamorphism causes variable re-crystallization of the original carbonate mineral grains. The resulting marble rock is typically composed of an interlocking mosaic of carbonate crystals. Primary sedimentary textures and structures of the original carbonate rock (protolith) have typically been modified or destroyed.
Pure white marble is the result of metamorphism of a very pure (silicate-poor) limestone or dolomite protolith. The characteristic swirls and veins of many colored marble varieties, sometimes called striations, are usually due to various mineral impurities such as clay, silt, sand, iron oxides, or chert which were originally present as grains or layers in the limestone. Green coloration is often due to serpentine resulting from originally magnesium-rich limestone or dolomite with silica impurities. These various impurities have been mobilized and recrystallized by the intense pressure and heat of the metamorphism.
Chemistry
Degradation by acids Acids react with the calcium carbonate in marble, producing carbonic acid (which decomposes quickly to CO2 and H2O) and other soluble salts : CaCO3(s) + 2H+(aq) → Ca2+(aq) + CO2(g) + H2O (l)
Outdoor marble statues, gravestones, or other marble structures are damaged by acid rain whether by carbonation, sulfation or the formation of "black-crust" (accumulation of calcium sulphate, nitrates and carbon particles). Vinegar and other acidic solutions should be avoided in the cleaning of marble products.
Crystallization Crystallization refers to a method of imparting a glossy, more durable finish on to a marble floor (CaCO3). It involves polishing the surface with an acidic solution and a steel wool pad on a flooring machine. The chemical reaction below shows a typical process using magnesium fluorosilicate (MgSiF6) and hydrochloric acid (HCl) taking place.
CaCO3(s) + MgSiF6(l) + 2HCl (l) → MgCl2(s) + CaSiF6(s) + CO2(g) + H2O(l)
The resulting calcium hexafluorosilicate (CaSiF6) is bonded to the surface of the marble. This is harder, more glossy and stain resistant compared to the original surface.
The other often used method of finishing marble is to polish with oxalic acid (H2C2O4), an organic acid. The resulting reaction is as follows:
CaCO3(s) + H2C2O4(l) → CaC2O4(s) + CO2(g) + H2O(l)
In this case the calcium oxalate (CaC2O4) formed in the reaction is washed away with the slurry, leaving a surface that has not been chemically changed.
Microbial degradation The haloalkaliphilic methylotrophic bacterium Methylophaga murata was isolated from deteriorating marble in the Kremlin. Bacterial and fungal degradation was detected in four samples of marble from Milan Cathedral; black Cladosporium attacked dried acrylic resin using melanin.
Types and features
Examples of notable marble varieties and locations Marble Color Location Country Bianco Sivec white near Prilep (Прилеп), Pelagonia (Пелагониски) North Macedonia Carrara marble white or blue-gray Carrara, Tuscany Italy Statuario marble white, golden, black Carrara, Apuan Alps Italy Creole marble white and blue/black Pickens County, Georgia United States Etowah marble pink, salmon, rose Pickens County, Georgia United States Hanbaiyu marble white Quyang County, Hebei China Makrana marble white Makrana, Nagaur district, Rajasthan India Murphy marble white Pickens and Gilmer Counties, Georgia United States Nero Marquina marble black Markina-Xemein, Bizkaia, Basque County Spain Parian marble pure-white, fine-grained Island of Paros (Πάρος), South Aegean (Νοτίου Αιγαίου) Greece Pentelic marblePentelic marble , Britannica Online Encyclopaedia. Britannica.com. Retrieved on 2011-09-30. pure-white, fine-grained semitranslucent Mount Pentelicus (Πεντελικό όρος), Attica (Ἀττική) Greece Prokonnesos marble white Marmara Island, Sea of Marmara Turkey Ruskeala marble white near Ruskeala (Рускеала), Karelia (Карелия) Russia Rușchița marble white, pinkish, reddish Poiana Ruscă Mountains, Caraș-Severin County Romania Swedish green marble green near Kolmården, Södermanland Sweden Sylacauga marble white Talladega County, Alabama United States Venčac marble white Venčac mountain near Aranđelovac Serbia Vermont marble white Proctor, Vermont United States Wunsiedel marble white Wunsiedel, Bavaria Germany Yule marble uniform pure white near Marble, Colorado United States
Features Marble is a rock composed of calcium and magnesium carbonate, mostly white and pink. Common marble varieties are granular limestone or dolomite. The hardness of marble is very high, because the internal structure of the rock is very uniform after long-term natural aging, and the internal stress disappears, so the marble will not be deformed due to temperature, and has strong wear resistance. It is a popular building material.
The following table is a summary of the features of marble. +ColourWhite, Pink, Black etcTexturegranularGrain sizemedium grainedMineralogycalciteHardnesshardOther featuresgenerally gritty to touchUsesbuilding stone
Uses
Sculpture White marble has been prized for its use in sculptures since classical times. This preference has to do with its softness, which made it easier to carve, relative isotropy and homogeneity, and a relative resistance to shattering. Also, the low index of refraction of calcite allows light to penetrate 12.7 to 38 millimeters into the stone before being scattered out, resulting in the characteristic waxy look which brings a lifelike luster to marble sculptures of any kind, which is why many sculptors preferred and still prefer marble for sculpting the human form."Marble", Britannica Online Encyclopaedia. Britannica.com.; Clarke, Michael, The Concise Oxford Dictionary of Art Terms, p.148, 2001, Oxford University Press,
Construction Construction marble is a stone which is composed of calcite, dolomite or serpentine that is capable of taking a polish.Marble Institute of America pp. 223 Glossary More generally in construction, specifically the dimension stone trade, the term marble is used for any crystalline calcitic rock (and some non-calcitic rocks) useful as building stone. For example, Tennessee marble is really a dense granular fossiliferous gray to pink to maroon Ordovician limestone, that geologists call the Holston Formation.
Ashgabat, the capital city of Turkmenistan, was recorded in the 2013 Guinness Book of Records as having the world's highest concentration of white marble buildings.
Production
The extraction of marble is performed by quarrying. Blocks are favoured for most purposes, and can be created through various techniques, including drilling and blasting, water jet and wedge methods. Limestones are often commercially and historically referred to as marble, which differs from the geological definition.
Locations Marble production was dominated by 4 countries that accounted for almost half of world production of marble and decorative stone. China and Italy were the world leaders, each representing 34% and 19% of world production respectively, followed by India and Spain produced 16% and 13% respectively.Country wise production of stones in percentages
In 2018 Turkey was the world leader in marble export, with 42% share in global marble trade, followed by Italy with 18% and Greece with 10%. The largest importer of marble in 2018 was China with a 64% market share, followed by India with 11% and Italy with 5%.
Ancient times White marbles throughout the Mediterranean basin were widely utilized during the Roman period. Extraction centers were unevenly distributed across the Italian Peninsula, mainland Greece, the Aegean Islands, Asia Minor, and smaller hubs like those in the Iberian Peninsula. The need for extensive trade arose due to this imbalance, leading to the widespread exchange of marble objects, including building elements, sculptures, and sarcophagi. There was a significant increase in the distribution of white marble from the late 1st century BC to the end of the 2nd century AD. A gradual decline in distribution started in the third century AD.
United States According to the United States Geological Survey, U.S. domestic marble production in 2006 was 46,400 tons valued at about $18.1 million, compared to 72,300 tons valued at $18.9 million in 2005. Crushed marble production (for aggregate and industrial uses) in 2006 was 11.8 million tons valued at $116 million, of which 6.5 million tons was finely ground calcium carbonate and the rest was construction aggregate. For comparison, 2005 crushed marble production was 7.76 million tons valued at $58.7 million, of which 4.8 million tons was finely ground calcium carbonate and the rest was construction aggregate. U.S. dimension marble demand is about 1.3 million tons. The DSAN World Demand for (finished) Marble Index has shown a growth of 12% annually for the 2000–2006 period, compared to 10.5% annually for the 2000–2005 period. The largest dimension marble application is tile.
Occupational safety