Marble is a metamorphic rock consisting of carbonate minerals (most commonly calcite (CaCO<sub>3</sub>) or dolomite (CaMg(CO<sub>3</sub>)<sub>2</sub>) 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.
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 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. from (), "crystalline rock, shining stone", perhaps from the verb (), "to flash, sparkle, gleam"; R. S. P. Beekes has suggested that a "Pre-Greek origin is probable".
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
thumb|Folded and weathered marble at [[General Carrera Lake, Chile]]
thumb|Fossils on Marble floor tile
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 CO<sub>2</sub> and H<sub>2</sub>O) and other soluble salts :
:CaCO<sub>3</sub>(s) + 2H<sup>+</sup>(aq) → Ca<sup>2+</sup>(aq) + CO<sub>2</sub>(g) + H<sub>2</sub>O (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).
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
thumb|The [[Library of Celsus in Ephesus, Turkey. Turkey is the largest marble exporter in the world.]]
thumb|Marble wall of [[Ruskeala, Republic of Karelia, Russia]]
thumb|A piece of blue [[Calcite|calcite marble from the Precambrian period in New York State, United States]]
Examples of notable marble varieties and locations
{| class="wikitable mw-collapsible mw-collapsed"
|-
! 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 marble
| 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.
{| class="wikitable"
|+
!Colour
|White, Pink, Black etc
|-
!Texture
|granular
|-
!Grain size
|medium grained
|-
!Mineralogy
|calcite
|-
!Hardness
|hard
|-
!Other features
|generally gritty to touch
|-
!Uses
|building stone
|}
Uses
thumb|Marble products in [[Romblon province|Romblon, Philippines]]
thumb|[[Statue of Abraham Lincoln (Lincoln Memorial) sculpted by Daniel Chester French from Georgia Marble in 1920]]
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.
Construction
Construction marble is a stone which is composed of calcite, dolomite or serpentine that is capable of taking a polish. 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
thumb|right|Mining of Karibib Marble (2018)<br />
alt=Marble quarry in Jaipur, India. Large rock faces that have been cut to vertical angles, with heavy equipment such as excavators in the picture.|thumb|Marble quarry in [[Jaipur, India]]
thumb|right|Marble plant workers in [[Romblon, Philippines]]
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.
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.
Palestine
Marble in the geologic sense does not naturally outcrop in Palestine, and the vast majority of commercially labeled marble produced in Palestine would geologically be considered limestone.
Occupational safety
Particulate air pollution exposure has been found to be elevated in the marble production industry. Exposure to the dust produced by cutting marble could impair lung function or cause lung disease in workers, such as silicosis. Skin and eye problems are also a potential hazard. Mitigations such as dust filters, or dust suppression are suggested, but more research needs to be carried out on the efficacy of safety measures.
Dust, debris and temperature fluctuations from working marble can endanger the eye health of employees. For the staff involved in marble processing, it is necessary to provide eye protection equipment, and it is recommended to improve the education of all workers on occupational health risks and strengthen preventive measures.
Places named after the stone include Marblehead, Massachusetts; Marblehead, Ohio; Marble Arch, London; the Sea of Marmara; India's Marble Rocks; and the towns of Marble, Minnesota; Marble, Colorado; Marble Falls, Texas, and Marble Hill, Manhattan, New York. The Elgin Marbles are marble sculptures from the Parthenon in Athens that are on display in the British Museum.
Impact on the environment
thumb|Marble waste in [[Aliveri.]]
thumb|Marble bench in [[Warszawa Centralna railway station in Poland (1975).]]
Total world quarrying production in 2019 was approximately 316 million tonnes; however, quarrying waste accounted for 53% of this total production. Using ground calcium carbonate as a filler in paint production can improve the brightness, hiding power and application performance of paint, and can also replace expensive pigments such as titanium dioxide.
Preservation
- Marble surfaces are corroded by alcohol or acidic liquids.
- A mild, pH-neutral, non-abrasive soap is used for cleaning marble surfaces.