Dolomite ( /ˈdɒləmaɪt/) is an anhydrous carbonate mineral composed of calcium magnesium carbonate, ideally CaMg(CO3)2. The time period can be used for a sedimentary carbonate rock composed largely of the mineral dolomite. Another title generally used for the dolomitic rock kind is dolostone.
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Historical past[edit]
The mineral dolomite was in all probability first described by Carl Linnaeus in 1768.[6][non-primary source needed] In 1791, it was described as a rock by the French naturalist and geologist Déodat Gratet de Dolomieu (1750–1801), first in buildings of the outdated metropolis of Rome, and later as samples collected within the mountains now often called the Dolomite Alps of northern Italy. Nicolas-Théodore de Saussure first named the mineral (after Dolomieu) in March 1792.[7]
Properties[edit]
The mineral dolomite crystallizes within the trigonal-rhombohedral system. It varieties white, tan, grey, or pink crystals. Dolomite is a double carbonate, having an alternating structural association of calcium and magnesium ions. Except it’s in nice powder kind, it doesn’t quickly dissolve or effervesce (fizz) in chilly dilute hydrochloric acid as calcite does.[8] Crystal twinning is frequent.
Strong answer exists between dolomite, the iron-dominant ankerite and the manganese-dominant kutnohorite.[9] Small quantities of iron within the construction give the crystals a yellow to brown tint. Manganese substitutes within the construction additionally as much as about three p.c MnO. A excessive manganese content material provides the crystals a rosy pink coloration. Lead, zinc, and cobalt additionally substitute within the construction for magnesium. The mineral dolomite is carefully associated to huntite Mg3Ca(CO3)4.
As a result of dolomite might be dissolved by barely acidic water, areas of dolomite are necessary as aquifers and contribute to karst terrain formation.[10]
Formation[edit]
Fashionable dolomite formation has been discovered to happen underneath anaerobic circumstances in supersaturated saline lagoons alongside the Rio de Janeiro coast of Brazil, specifically, Lagoa Vermelha and Brejo do Espinho. It’s typically thought that dolomite will develop solely with the assistance of sulfate-reducing micro organism (e.g. Desulfovibrio brasiliensis).[11] Nonetheless, low-temperature dolomite could happen in pure environments wealthy in natural matter and microbial cell surfaces.[12] This happens because of magnesium complexation by carboxyl teams related to natural matter.[13]
Huge deposits of dolomite are current within the geological file, however the mineral is comparatively uncommon in fashionable environments. Reproducible, inorganic low-temperature syntheses of dolomite and magnesite had been printed for the primary time in 1999. These laboratory experiments confirmed how the preliminary precipitation of a metastable “precursor” (akin to magnesium calcite) will change step by step into increasingly of the secure section (akin to dolomite or magnesite) throughout periodical intervals of dissolution and re-precipitation. The final precept governing the course of this irreversible geochemical response has been coined “breaking Ostwald’s step rule”.[14]
There’s some proof for a biogenic prevalence of dolomite. One instance is that of the formation of dolomite within the urinary bladder of a Dalmatian canine, presumably as the results of an sickness or an infection.[15]
Makes use of[edit] – “calcium magnesium carbonate”
Dolomite is used as a decorative stone, a concrete mixture, and a supply of magnesium oxide, in addition to within the Pidgeon course of for the manufacturing of magnesium. It is a vital petroleum reservoir rock, and serves because the host rock for giant strata-bound Mississippi Valley-Sort (MVT) ore deposits of base metals akin to lead, zinc, and copper. The place calcite limestone is rare or too expensive, dolomite is usually used as a replacement as a flux for the smelting of iron and metal. Massive portions of processed dolomite are used within the manufacturing of float glass.
In horticulture, dolomite and dolomitic limestone are added to soils and soilless potting mixes as a pH buffer and as a magnesium supply.
Dolomite can be used because the substrate in marine (saltwater) aquariums to assist buffer adjustments within the pH of the water.
Calcined dolomite can be used as a catalyst for destruction of tar within the gasification of biomass at excessive temperature.[16] Particle physics researchers wish to construct particle detectors underneath layers of dolomite to allow the detectors to detect the best potential variety of unique particles. As a result of dolomite accommodates comparatively minor portions of radioactive supplies, it could possibly insulate in opposition to interference from cosmic rays with out including to background radiation ranges.[17]
Along with being an industrial mineral, dolomite is very valued by collectors and museums when it varieties giant, clear crystals. The specimens that seem within the magnesite quarry exploited in Eugui, Esteribar, Navarra (Spain) are thought-about among the many finest on this planet.[18]
See additionally[edit]
References[edit]