Magnesium siderite

Sellaite, see Magnesium fluoride Senarmontite, see Antimony(III) oxide Siderite, see Iron(II) carbonate Siderotil, see Iron(II) sulfate 5-water Silica, see Silicon dioxide Silicotungstic acid, see Silicon oxide—tungsten oxide—water (1/12/26)... 

Carbonates. The carbonate minerals, in general, vary widely in composition because of the extensive solid solution of calcium, magnesium, iron, manganese, etc. that is possible within them. There is also a wide range of mineral compositions for the carbonate minerals in coals. The relatively pure end members, calcite (CaC03) and siderite (FeC03),... 

The major cations found in the carbonate minerals in coals are calcium, magnesium, and iron. The rather pure end member calcite (CaC03) is dominant in some coals, whereas siderite (FeCO ) is dominant in others. Calcite and ankerite (a mixed crystal composed of Ca, Mg, and Fe carbonates) are abundant in some coals. 

The deposition of greenalite and its interrelationships with siderite are controlled by reactions (2.16) and (2.17), considered earlier. The line separating the field of deposition of Sid and Gree (Fig. 24) in the first approximation characterizes the conditions of joint deposition of Fe-Mg carbonates and silicates of variable composition. From the diagram it is seen that as the content of Fe in solution decreases and, apparently, the magnesium content of the minerals deposited increases somewhat, the buffer value of also decreases several times from 7- 10 to (l-2)- 10 bar. Inasmuch as in most Precambrian BIF magnesian silicates occur relatively rarely (the finding of talc in the unoxidized oxide facies of the BIF of the... 

Calcium carbonate (such as calcite, siderite, dolomite, and aragonite) is typically present in marine deposits and Pleistocene sediments deposited in river-banks and practically absent in deposits from ancient rivers and deposits of Miocene age. Calcium is generally the dominant exchangeable cation (56-82%) followed by magnesium (6-26%). An important parameter for behavior during aquifer transport is the calcite saturation index (SI = log[Ca ][C03 J/KcacOj)-... 

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