Dolomite
General
Category	Carbonate mineral
Chemical formula	CaMg(CO3)2
Identification
Color	white, gray to pink
Crystal habit	tabular crystals, often with curved faces, also columnar, stalactitic, granular, massive. Carbonate minerals are those Minerals containing the Carbonate Ion: CO32- A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the In Mineralogy, shape and size give rise to descriptive terms applied to the typical appearance or habit of Crystals The many terms used by mineralogists
Crystal system	trigonal - rhombohedral, bar3
Twinning	common as simple contact twins
Cleavage	rhombohedral cleavage (3 planes)
Fracture	brittle - conchoidal
Mohs Scale hardness	3. A crystal system is a category of Space groups which characterize Symmetry of structures in three dimensions with Translational symmetry in three directions In Crystallography, the rhombohedral (or trigonal) Crystal system is one of the seven lattice point groups named after the two-dimensional Crystal twinning occurs when two separate crystals share some of the same Crystal lattice points in a symmetrical manner Cleavage, in Mineralogy, is the tendency of crystalline materials to split along definite planes creating smooth surfaces of which there are several named types In the field of Mineralogy, fracture is a term used to describe the shape and texture of the surface formed when a Mineral is broken The Mohs scale of mineral hardness characterizes the scratch resistance of various Minerals through the ability of a harder material to scratch a softer material 5 to 4
Luster	vitreous to pearly
Refractive index	nω = 1. Lustre (or luster) is a description of the way light interacts with the surface of a Crystal, rock, or Mineral. The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium 679–1. 681 nε = 1. 500
Optical Properties	Uniaxial (-)
Birefringence	δ = 0. Birefringence, or double refraction, is the decomposition of a ray of Light into two rays (the ordinary ray and the extraordinary ray 179–0. 181
Streak	white
Specific gravity	2. The streak (also called powder color) of a Mineral is the Color of the powder produced when it is dragged across an unweathered surface Specific gravity is defined as the ratio of the Density of a given solid or liquid substance to the density of water at a specific temperature and pressure typically 84–2. 86
Solubility	Poorly soluble in dilute HCl unless powdered. Solubility is the characteristic Physical property referring to the ability of a given substance the Solute, to dissolve in a Solvent. Hydrochloric acid is the Solution of Hydrogen chloride ( H[[Chlorine Cl]] in water
Other Characteristics	May fluoresce white to pink under UV; triboluminescent.
References	[1][2][3][4]

Dolomite from Morocco. Morocco (المغرب "al-Maghrib" officially the Kingdom of Morocco (المملكة المغربية is a country located in North Africa

Dolomite.

Dolomite (pronounced /ˈdɒləmaɪt/) is the name of a sedimentary carbonate rock and a mineral, both composed of calcium magnesium carbonate CaMg(CO₃)₂ found in crystals. Sedimentary rock is one of the three main rock types (the others being igneous and Metamorphic rock) Carbonate rocks are a class of Sedimentary rocks composed primarily of Carbonate Minerals The two major types are Limestone and Dolomite A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 In Chemistry, a carbonate is a salt or Ester of Carbonic acid. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating

Dolomite rock (also dolostone) is composed predominantly of the mineral dolomite. Dolostone is a sedimentary Carbonate rock that contains a high percentage of the Mineral Dolomite. Limestone that is partially replaced by dolomite is referred to as dolomitic limestone, or in old U. Limestone is a Sedimentary rock composed largely of the Mineral Calcite ( Calcium carbonate: CaCO3 S. geologic literature as magnesian limestone. Dolomite was first described in 1791 as the rock by the French naturalist and geologist, Déodat Gratet de Dolomieu (1750–1801) for exposures in the Dolomite Alps of northern Italy. Legal residents and citizens To be French according to the first article of the Constitution is to be a citizen of France regardless of one's origin race or religion ( Natural history is the Scientific research of Plants or Animals leaning more towards the Observational than Experimental methods A geologist is a contributor to the Science of Geology, studying the physical structure and processes of the Earth and planets of the solar system Dieudonné Sylvain Guy Tancrède de Dolomieu usually known as Déodat de Dolomieu (Dolomieu near La Tour-du-Pin, June 23, 1750 - Chateauneuf The Dolomites (Dolomiti Dolomiten Dolomitis are a section of the Alps. Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest

Properties

The mineral dolomite crystallizes in the trigonal-rhombohedral system. In Crystallography, the rhombohedral (or trigonal) Crystal system is one of the seven lattice point groups named after the two-dimensional It forms white, gray to pink, commonly curved crystals, although it is usually massive. It has physical properties similar to those of the mineral calcite, but does not rapidly dissolve or effervesce (fizz) in dilute hydrochloric acid unless it is scratched or in powdered form. Calcite is a carbonate mineral and the most stable polymorph of Calcium carbonate ( Ca[[carbon C]] O 3 Hydrochloric acid is the Solution of Hydrogen chloride ( H[[Chlorine Cl]] in water The Mohs hardness is 3. The Mohs scale of mineral hardness characterizes the scratch resistance of various Minerals through the ability of a harder material to scratch a softer material 5 to 4 and the specific gravity is 2. Specific gravity is defined as the ratio of the Density of a given solid or liquid substance to the density of water at a specific temperature and pressure typically 85. Refractive index values are nω = 1. The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium 679 - 1. 681 and nε = 1. 500. Crystal twinning is common. Crystal twinning occurs when two separate crystals share some of the same Crystal lattice points in a symmetrical manner A solid solution series exists between dolomite and iron rich ankerite. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Ankerite is a Calcium, Iron, Magnesium, Manganese carbonate mineral of the group of rhombohedral carbonates with formula Ca Small amounts of iron in the structure give the crystals a yellow to brown tint. Manganese substitutes in the structure also up to about three percent MnO. Manganese (ˈmæŋgəniːz is a Chemical element, designated by the symbol Mn. A high manganese content gives the crystals a rosy pink color noted in the image above. A series with the manganese rich kutnohorite may exist. Kutnohorite is a rare calcium manganese magnesium iron Carbonate mineral with formula Ca ( Mn, Mg, Fe)( C[[oxygen O]]32 Lead and zinc also substitute in the structure for magnesium. Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly Zinc (ˈzɪŋk from Zink is a Metallic Chemical element with the symbol Zn and Atomic number 30

Formation

Pale pink crystals of dolomite with a slight pearly luster.

Vast deposits are present in the geological record, but the mineral is relatively rare in modern environments. However, laboratory synthesis of stoichiometric dolomite has been carried out only at temperatures of greater than 100 degrees Celsius, conditions typical of burial in sedimentary basins—even though much dolomite in the rock record appears to have formed in low-temperature conditions. The high temperature is likely to speed up the movement of calcium and magnesium ions so that they can find their places in the ordered structure within a reasonable amount of time. This suggests that the lack of dolomite that is being formed today is likely due to kinematic factors.

Modern dolomite does occur as a precipitating mineral in specialized environments on the surface of the earth today. In the 1950s and 60s, dolomite was found to be forming in highly saline lakes in the Coorong region of South Australia. South Australia is a state of Australia in the southern central part of the country Dolomite crystals also occur in deep-sea sediments, where organic matter content is high. This dolomite is termed "organogenic" dolomite.

Recent research has found modern dolomite formation under anaerobic conditions in supersaturated saline lagoons along the Rio de Janeiro coast of Brazil, namely, Lagoa Vermelha and Brejo do Espinho. For other uses of the term "hypoxia" see Hypoxia. Hypoxia or oxygen depletion is a phenomenon that occurs in aquatic environments The term supersaturation refers to a Solution that contains more of the dissolved material than could be dissolved by the Solvent under normal circumstances A lagoon is a body of comparatively shallow salt or Brackish water separated from the deeper Sea by a shallow or exposed sandbank, coral Rio de Janeiro ("River of January" ˈhiw dʒi ʒʌˈnejɾu in Brazilian Portuguese, /ˈriːoʊ di ʒəˈnɛroʊ/ in English is the second largest city of Brazil |utc_offset = -2 to -4 |time_zone_DST = BRST |utc_offset_DST = -2 to -5 |cctld One interesting reported case was the formation of dolomite in the kidneys of a Dalmatian dog. This was believed to be due to chemical processes triggered by bacteria. Dolomite has been speculated to develop under these conditions with the help of sulfate-reducing bacteria. Sulfate-reducing bacteria comprise several groups of bacteria that use Sulfate as an oxidizing agent reducing it to Sulfide. This joins other research in pointing out many new interesting links between large-scale geology and small-scale microbiology (see geomicrobiology). Geology (from Greek γη gê, "earth" and λόγος Logos, "speech" lit Microbiology (from Greek grc μῑκρος mīkros, "small" grc βίος bios, " Life " and grc -λογία Geomicrobiology is a subset of the scientific discipline Microbiology.

The actual role of bacteria in the low-temperature formation of dolomite remains to be demonstrated. The specific mechanism of dolomitization, involving sulfate-reducing bacteria, has not yet been demonstrated. ^[5]

Dolomite appears to form in many different types of environment and can have varying structural, textural and chemical characteristics. Some researchers have stated "there are dolomites and dolomites", meaning that there may not be one single mechanism by which dolomite can form. Much modern dolomite differs significantly from the bulk of the dolomite found in the rock record, leading researchers to speculate that environments where dolomite formed in the geologic past differ significantly from those where it forms today.

Reproducible laboratory syntheses of dolomite (and magnesite) leads first to the initial precipitation of a metastable "precursor" (such as magnesium calcite), to be changed gradually into more and more of the stable phase (such as dolomite or magnesite) during periodical intervals of dissolution and reprecipitation. Magnesite is not to be confused with Magnetite or Magnemite. Magnesite is Magnesium carbonate, Mg[[carbon The general principle governing the course of this irreversible geochemical reaction has been coined Ostwald's step rule. The field of geochemistry involves study of the chemical composition of the Earth and other Planets chemical processes and reactions that govern the composition Polymorphism in Materials science is the ability of a solid material to exist in more than one form or Crystal structure

For a very long time scientists had difficulties synthesizing dolomite. However, in a 1999 study, through a processes of dissolution alternating with the intervals of precipitation measurable levels of dolomite were synthesized at low temperatures and pressures. ^[6]

Uses

Dolomite is used as an ornamental stone, a concrete aggregate and as a source of magnesium oxide. An ornamental stone is a stone used as a decoration They differ from Gemstones in that they are not only used for Jewelry. Magnesium oxide, or magnesia, is a white solid Mineral that occurs naturally as Periclase and is a source It is an important petroleum reservoir rock, and serves as the host rock for large strata-bound Mississippi Valley-Type (MVT) ore deposits of base metals (that is, readily oxidized metals) such as lead, zinc, and copper. Petroleum ( L petroleum, from Greek πετρέλαιον, lit A petroleum reservoir or an oil and gas reservoir (or system) is a subsurface pool of Hydrocarbons contained in porous Carbonate-hosted lead-zinc ore deposits are important and highly valuable concentrations of lead and zinc sulfide Ores hosted within carbonate ( Limestone An ore is a volume of rock containing components or Minerals in a mode of occurrence that renders it valuable for mining In Chemistry, the term base metal is used informally to refer to a Metal that oxidizes or corrodes relatively easily and reacts variably with Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly Zinc (ˈzɪŋk from Zink is a Metallic Chemical element with the symbol Zn and Atomic number 30 Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Where calcite limestone is uncommon or too costly, dolomite is sometime used in its place as a flux (impurity remover) for the smelting of iron and steel. Calcite is a carbonate mineral and the most stable polymorph of Calcium carbonate ( Ca[[carbon C]] O 3 Limestone is a Sedimentary rock composed largely of the Mineral Calcite ( Calcium carbonate: CaCO3 In Metallurgy, a flux is a chemical cleaning agent which facilitates Soldering, Brazing, and Welding by removing Oxidation from Chemical reduction, or smelting, is a form of Extractive metallurgy.

In horticulture, dolomite and dolomitic limestone are added to soils and soilless potting mixes to lower their acidity ("sweeten" them). Home and container gardening are common examples of this use.

As nutritional supplement

In nutrition, dolomite is sold sometimes as a dietary supplement on the assumption that it should make a good simultaneous source of the two important elemental nutrients calcium and magnesium. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 However, since dolomites from Mississippi Valley-Type ore regions such as the Old Lead Belt and New Lead Belt in southeastern Missouri United States often include significant levels of lead and other toxic elements, users should always verify that such dolomite supplements are from non-ore regions before ingesting them. Carbonate-hosted lead-zinc ore deposits are important and highly valuable concentrations of lead and zinc sulfide Ores hosted within carbonate ( Limestone The Lead Belt is a Lead mining district in the southeastern part of Missouri. Missouri ( or) is a state in the Midwestern region of the United States bordered by Iowa, Illinois, Kentucky, Tennessee The United States of America —commonly referred to as the Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly Further, laboratory experiments conducted at the University of Alberta demonstrate that dolomite is practically insoluble in stomach acid and is eliminated from the body before significant magnesium or calcium can be absorbed. The University of Alberta (U of A is a public research University located in Edmonton, Alberta, Canada. A far safer strategy is to avoid using dolomite as a supplement altogether, and instead taking equivalent amounts of milk of magnesia and calcium supplements. Milk of Magnesia is an aqueous suspension of Magnesium hydroxide, Mg ( O[[hydrogen H]]2 in water Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 The chemical processes used to create such individual supplements effectively eliminate the risk of ingesting the toxic metals often associated with raw dolomite.

See also

• List of minerals
• Evaporite

References