Minerals gypsum

Finally, there is a major flux of sulfur through the atmosphere in both seasalt particles ( 140 Tg S/yr) and terrestrial dust ( 20 Tg S/ yr). In each case, the form of sulfur is sulfate, originating mostly as the mineral gypsum in the... 

It will be noted that the term gypsum is used by Theophrastus, as indeed by later ancient writers, to indicate the dehydrated sulphate of lime (plaster of Paris), rather than the mineral (gypsum) from which it is obtained, though he elsewhere alludes somewhat vaguely to certain natural earths under that name. 

ALABASTER. A fine-grained variety of the mineral gypsum, formerly much used for vases and statuary. It is usually white in color or may be of other light, pleasing tints. 

Sulfate is principally derived from the weathering of CaS04 minerals (gypsum and anhydrite) in sedimentary rocks. Some sulfate in rivers, however, comes from the weathering of magnesium sulfate salts in sedimentary rocks and from oxidation of sulfides (primarily FeS2. pyrite) in sedimentary and crystalline rocks. The latter process also liberates small amounts of the cations Ca2+, Mg2+, Na+, and K+ by reactions like ... 

Composition of a Crystal Hydrate. The mineral gypsum contains, besides calcium sulphate, also a certain proportion of water. The latter may be completely driven off by heat, leaving anhydrous calcium sulphate. 

The most abundant source of calcium sulphate is the mineral gypsum CaS04-2H20. We desire anhydrous CaS04 as our start-... 

Calcium sulfate occurs in nature as the mineral gypsum, CaS04 2H20. 

The mineral gypsum has the formula CaS04 2H20, its solubility product being 2.4 X I0 Calculate the solubility of calcium sulfate in... 

CaS04.2 H2O. This hydrate, the mineral gypsum, has a rather complex layer structure (Fig. 15.22) in which the layers are bound together by hydrogen... 

The data from Ehrlich and Wygal also showed that the alkalinity loss by calcium sulfate minerals (gypsum, anhydrite) was one or two orders of magnitude higher than that by other minerals, which was not seen from Mohnot and Bae (1989) data. The alkalinity loss reported by kaolinite from Ehrlich and Wygal was one order of magnitude lower than that from Mohnot and Bae. This may have been caused by the test temperature difference (room temperature versus 82°C) because Johnson et al. (1988) showed the consumption of alkali by kaolinite and quartz increased considerably with increasing temperature. 

Sulfur occurs mostly in the solid Earth reservoirs and in oceans and is only a minor component of the atmosphere. Volcanic, sulfur-bearing gases emitted into the atmosphere have only a short residence time and are quickly transferred into the oceans. Because sulfur occurs in both the oxidized form -chiefly as the sulfate mineral gypsum, and in a reduced state - principally as the sulfide... 

On the other hand, the alkaline earths often are found in nature as sulfates (S04)—unlike transition and post-transition metals, which are much less commonly found as sulfates. Familiar examples of alkaline earth sulfates include the minerals gypsum (calcium sulfate), epsomite (magnesium sulfate), and barite (barium sulfate). 

After transformation, the equation 15.1 to calculate the saturation index of the mineral gypsum reads ... 

In all samples studied, of pyrite is the most depleted. The OM sulfur is on average 10%c heavier a very small amount of the sulfate minerals gypsum and anhydrite for the Nabi Musa location indicates evaporative conditions and sulfate closed system. Despite the same Senonian Ghareb Formation sedimentary rock for aU of the Dead Sea area samples studied, the values recorded for different sites show wide variability. This indicates that small differences in sub-basin conditions have a significant imprint on sulfur isotope distribution. 

Figure 1. Pictures of Desert rose, Satin Spar, Selenite, and Alabaster. These pictures were obtained from http //gwydir.demon.co.uk/jo/minerals/gypsum.htm.

From a pure, saturated solution of calcium sulfate the dihydrate CaSO ZHjO crystallizes if the temperature is below 60°G. If the crystaUization occurs at a higher temperature the anhydrous salt GaSO is formed. From common seawater, with its high content of sodium chloride, anhydrous calcium sulfate may also be formed at temperatures down to 30°G [14.3]. During geological periods these processes have occurred in nature and formed the minerals gypsum, the dihydrate, and anhydrite, anhydrous calcium sulfate. 

The mineral gypsum has the chemical name calcium sulfate dihydrate. What is the chemical formula of this substance ... 

Due to its inherent brittleness, hydroxyapatite is often combined with calcium sulfate (CaS04 2H20, denoted as plaster of Paris) to form a more durable ceramic material. Calcium sulfate is biocompatible and bioactive, being resorbed after 30-60 days. Calcium sulfate is mostly used in its partially hydrated form when mixed with water, an exothermic reaction leads to reciystallization into the dihydrate final form shared by the mineral gypsum (Eq. 57) ... 

Calcium sulfate, gypsum type has the formula, CaS04.2H20, and is the synthetic analogue of the calciinn sidfate hydrate mineral gypsum (q.v). 

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