dolomite


Also found in: Dictionary, Thesaurus, Medical, Acronyms, Wikipedia.
Related to dolomite: Dolomite rock

dolomite

(dō`ləmīt', dŏl`ə–). 1 Mineral, calcium magnesium carbonate, CaMg (CO3)2. It is commonly crystalline and is white, gray, brown, or reddish in color with a vitreous to pearly luster. The magnesium is sometimes replaced in part by iron or manganese. 2 Carbonate rock composed chiefly of the mineral dolomite, similar to limestone but somewhat harder and heavier. The rock may be metamorphosed into dolomitic marble. Most dolomites probably originated from the partial replacement of the calcium in limestone by magnesium. Its chief uses are as a building stone, for the manufacture of refractory furnace linings, and as basic magnesium carbonate for pipe coverings. Formations of dolomite are very widespread (occurring in Europe, the United States, Africa, Brazil, and Mexico) and notably in the region of the Alps now called the Dolomites, where the rock was first studied by Dolomieu.

dolomite

Limestone consisting principally of the mineral dolomite. See also: Stone

Dolomite

 

(named after the French geologist D. Dolomieu [1750-1801]).

(1) A mineral from the carbonate group. In terms of chemical composition, dolomite is a double carbonate of calcium and magnesium: CaMg [CO3]2. It crystallizes in the trigonal system, forming well-defined rhombohedral crystals. In nature, dolomite is encountered in macrocrystalline, finely crystalline, and cryptocrystalline aggregates and sometimes as a rock-forming mineral in oolitic, reniform, alveolar, and other habits. The large crystalline aggregates are usually encountered in hydrothermal formations as well as in carbonate layers that have undergone substantial recrystallization and metamorphism.

Dolomite has a grayish-white color, sometimes with a yellowish, brownish, or greenish cast. Its hardness on the mineralogical scale is 3.5-4, and its density is 2,800-2,900 kg/m3. In contrast to calcite, it does not effervesce in cold hydrochloric acid but does dissolve upon heating.

(2) A sedimentary rock, composed principally of the mineral dolomite (at least 90 percent). If the rock contains 50-90 percent dolomite, it is called limestone dolomite; if it contains even less dolomite, then the rock is known as dolomitized limestone. The most common admixture is calcite, often anhydrite or gypsum, and sometimes authigenic silica. In structure and porosity, dolomite may be compact with a predominance of the basic mineral mass or cavernous and porous with a predominance of cementing material. In terms of origin, dolomite is divided into two genetic groups: exogenous and endogenous. The principal mass of dolomite was formed exogenously in the seas, lagoons, and salty lakes (not connected with seas) with the diagenetic transformation of lime mud under the conditions of increased water salinity. These dolomites usually occur within limestone sequences in the form of beds—sometimes as very extensive, bedlike lenses and crystal accumulations—and also in clays and in detrital and sulfate rocks (anhydrites). The exogenous dolomites also arise as a result of the epigenic dolomitization of limestones. The endogenous dolomites are formed as a result of hydrothermal and hydrothermal-metasomatic processes. This results in the formation of veins, irregularly shaped bodies, and stockworks.

Dolomites have been discovered in the sedimentary sequences of all geological periods, but they are particularly widespread in Precambrian and Paleozoic deposits. Dolomite deposits are extremely numerous both in the USSR and abroad.

Dolomite has extensive practical use. It is used in burnt form as a refractory for lining metallurgical furnaces, is part of the charge for glass of increased hardness and strength, and is used in the production of refractory glaze and magnesia alba and as ashlar, rubblestone, and gravel for concrete. Dolomite and particularly dolomitized limestones are used in blast furnace smelting as fluxes and in agriculture as additives neutralizing acid soils. Abroad (in the United States), dolomite is raw material for obtaining magnesium.

REFERENCES

Strakhov, N. M. “O tipakh i genezise dolomitovykh porod.” Trudy Geologicheskogo in-ta AN SSSR, issue 4. Moscow, 1956.
Kurs mestorozhdenii ne metallic he skikh poleznykh iskopaemykh. Moscow, 1969.

G. I. TEODOROVICH

dolomite

[′dō·lə‚mīt]
(mineralogy)
CaMg(CO3)2 The carbonate mineral; white or colorless with hexagonal symmetry and a structure similar to that of calcite, but with alternate layers of calcium ions being completely replaced by magnesium.

dolomite

1. A mineral form of calcium-magnesium carbonate; a constituent of some building limestones.
2. Limestone consisting principally of the mineral dolomite; dolostone.

dolomite

1. a white mineral often tinted by impurities, found in sedimentary rocks and veins. It is used in the manufacture of cement and as a building stone (marble). Composition: calcium magnesium carbonate. Formula: CaMg(CO3)2. Crystal structure: hexagonal (rhombohedral)
2. a sedimentary rock resembling limestone but consisting principally of the mineral dolomite. It is an important source of magnesium and its compounds, and is used as a building material and refractory
References in periodicals archive ?
The following Companies as the Key Players in the Global Dolomite Market Research Report:
WITH signposted cycling routes, challenging and panoramic mountain passes, and adventurous alpine and valley roads, the Swiss region of Valais has great potential to develop into a well-known cycling destination like the Dolomites. Traveling by bike is one of the best ways to experience the Valais, both for leisure riders, mountain bikers, road racers and gravel riders.
Mail: BLM Las Cruces District Office, ATTN: Foothill Dolomite Mine EA, 1800 Marquess Street, Las Cruces, NM 88005
The calcite to dolomite conversion increases the porosity by 13% which is very good for the storage of petroleum (Chilingar and Terry, 1964).
But though road signs are posted in two or three languages, the otherworldly beauty of the Dolomites needs no translation.
Dolomite powder was prepared from dolomite rocks of the Neoproterozoic Dengying Formation in the Sichuan Basin, Southwest China.
Dolomite (22%) with a grain size of 80um to 200um wasidentified as another essential mineral.
Pure magnesite (MgC[O.sub.3]), dolomite (CaMg(C[O.sub.3])2), serpentine ([Mg.sub.6][[Si.sub.4][O.sub.10]][(OH).sub.8]]), and quartz (Si[O.sub.2]) ore samples were obtained from Haicheng, Liaoning Province, China.
The system is also compatible with a range of microscope systems for straightforward imaging and recording and Dolomite's optional Mitos PPump Remote Chambers, which allow up to 30 ml of fluid to be conveniently located in a pressurised, sterile environment for easy temperature control or agitation, ensuring you can develop a set-up to meet your application needs.
To counteract soil acidification, farmers usually apply lime and dolomite, which not only leads to an increase in soil pH, but also influences the concentrations and transformation processes of ammonia (N[H.sub.3]), (N[H.sub.4.sup.+]) and (N[O.sub.3.sup.-]) in the soil (Kirchmann and Witter 1989; Thangarajan et al.
Table 2 provides geometric (FI and SI) and strength (SZ and LA) quality indexes of granite and dolomite. Statistical data of gravel aggregate quality index are provided in the Table 3, but (due to insufficient data of the flakiness index FI) statistical calculations were made only for the shape index SI and strength indexes SZ and LA.
Rothon has identified the examples of mineral filler that are commonly used as filler in composites in variety application nowadays are natural calcium carbonate, talc, magnesium hydroxide and dolomite [4].