Carbonate Calcite

Calcium carbonate (calcite) scale formation in hard water can be prevented by the addition of a small amount of soluble polyphosphate in a process known as threshold treatment. The polyphosphate sorbs to the face of the calcite nuclei and further growth is blocked. Polyphosphates can also inhibit the corrosion of metals by the sorption of the phosphate onto a thin calcite film that deposits onto the metal surface. When the polyphosphate is present, a protective anodic polarization results. 

Principal gangue minerals in base-metal vein-type deposits are quartz, chlorite, Mn-carbonates, calcite, siderite and sericite (Shikazono, 1985b). Barite is sometimes found. K-feldspar, Mn-silicates, interstratified mixed layer clay minerals (chlorite/smectite, sericite/smectite) are absent. Vuggy, comb, cockade, banding and brecciated textures are commonly observed in these veins. 

The predominant gangue minerals vary with different types of ore deposits quartz, chalcedonic quartz, adularia, calcite, smectite, interstratified mica/smectite, interstratified chlorite/smectite, sericite, zeolites and kaolinite in Au-Ag rich deposits chlorite, quartz, sericite, carbonates (calcite, rhodoehrosite, siderite), and rare magnetite in Pb-Zn rich deposits chlorite, serieite, siderite, hematite, magnetite and rare epidote in Cu-rich deposits (Sudo, 1954 Nagasawa et al., 1976 Shikazono, 1985b). 

Wettability measurements show that most soil constituents are water wettable or hydrophilic,28 although calcium carbonates [calcite, CaC03, and dolomite, CaMg(C03)2] are slightly hydrophobic for example, the contact angle of water and heptane is 100 to 105°. Therefore, carbonaceous reservoirs are usually oil-wet. 

In arid and semi-arid soils, calcite, dolomite, leonhardite (Ca2Al4Si8024.7H20) and lawsonite (CaAl2Si208.2H20) can be possible minerals. Calcium carbonate strongly influences soil properties in arid and semi-arid soils. Most calcareous soils have soil a pH in the range of 7.3-8 5. When sodium is predominant in soils, soil pH is above 8.5. In most arid and semi-arid soils, calcium carbonates (calcite and dolomite) generally accumulate and are most likely to control the Ca2+ and Mg2+ solubility in these soils (Lindsay, 1979). 

Calcium carbonate (calcite, aragonite, Exoskeletons (mollusc and egg shells ... 

The calcium ion is of such a size that it may enter 6-fold coordination to produce the rhombohedral carbonate, calcite, or it may enter 9-fold coordination to form the orthorhombic carbonate, aragonite. Cations larger than Ca2+, e.g., Sr2+, Ba2+, Pb2+, and Ra2 only form orthorhombic carbonates (at earth surface conditions) which are not, of course, isomorphous with calcite. Therefore these cations are incapable of isomorphous substitution in calcite, but may participate in isodimorphous or "forced isomorphous" substitution (21). Isodimorphous substitution occurs when an ion "adapts" to a crystal structure different from its own by occupying the lattice site of the appropriate major ion in that structure. For example, Sr2+ may substitute for Ca2 in the rhombohedral lattice of calcite even though SrC03, strontianite, forms an orthorhombic lattice. Note that the coordination of Sr2 to the carbonate groups in each of these structures is quite different. Very limited miscibility normally characterizes such substitution. 

Other Aluminosilicates - Mica, Feldspar, Chlorite, Quartz Sulfate - Fe Sulfate, Gypsum Carbonate - Calcite, Siderite, Dolomite Fe Altered - Oxides, Sulfate... 

Curing of wetted coal ash results in carbona-tion to form calcite and possibly other metal carbonates. Calcite surfaces have been shown by Zachara et al. (1991) to preferentially sorb certain metals through adsorption followed by recrystallization (Zn, Co, Ni) or surface precipitation (Cd, Mn), but the total adsorption capacity of calcite for these metals is minor compared to their adsorption by other phases. 

Bones, teeth, and shells. Living organisms are able to induce the formation of over 60 inorganic compounds.681 Most of these are formed by animals. Two forms of calcium carbonate, calcite and aragonite, predominate.682 These minerals form shells, exoskeleton bones, bones, teeth, and other specialized structures. 

Lorcher, K., and Newesely, H. Calcium carbonate (calcite) as a separate phase besides calcium phosphate apatite in medullary bone of laying hens. Calc. Tiss. Res. 3, 358-362 (1969). 

Calcium carbonate (calcite, CaC03) is calcined to lime (CaO) during high-temperature ashing, and carbon dioxide is evolved, resulting in a 44% reduction in weight from the original calcite ... 

Some coal samples contain a high amount of carbonates (calcite, CaC03) or pyrite (FeS2) or both. In such cases, sulfur retained as sulfates may be both unduly high and nonuniform between duplicate samples. Sulfate sulfur in the ash can be determined (ASTM D-1757) and the requisite correction made, and the ash yield should be reported and designated both as determined and corrected. 

Suspended solid surfaces (particles or colloids) in waters play a prominent role in controlling the concentration of dissolved trace elements. Most of these elements are eliminated by sedimentation after incorporation on to or into particles, generally by complexation with the surface sites. The most common inorganic particles and colloids are non-clay silicates (quartz, potash feldspar, plagioclase, opaline silica (diatoms)) clays (illite, smectite) carbonates (calcite, dolomite) Fe-Mn oxides (goethite, magnetite) phosphates (apatite) sulfides (mackinawite). Particles and colloids in a water body may be classified as a function of their origin ... 

The minerals calcite and aragonite are polymorphs of calcium carbonate. Calcite is the more stable of the two, and aragonite is most often seen in objects made of speleothems, the rocks formed in solution caverns. Aragonite is also an important constituent in many materials of organic origin, such as mollusk shells and the outer skeletons of sand dollars and coral. Calcite is the major component of the rocks limestone and marble, and as such is found in collections as sculpture, building stone, in mosaics, and in inlay or in tarsia. 

When forming, limestone may contain both the polymorphs of calcium carbonate, calcite and aragonite. But aragonite is the least stable of the two minerals, and most older carbonate deposits will contain only calcite. Since limestone is a marine deposit that forms in quiet seas, it often contains visible fossils of marine organisms such as coral, mollusks, and foraminifera. 

What happens when not only pure calcium carbonate (calcite) but also magnesium calcium carbonate (dolomite) exists Present your results graphically. How is this kind of reaction called [For simulation use mineral phase dolomite(d) = dispersive distributed dolomite]... 

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