One important turning point in history has been the discovery of Crude gypsum crystal which is used for its variety of benefits and properties provided in different shapes and qualities for sale online. Examples of its wide range of use include usage as a fluxing agent, fertilizer, filler in paper and textiles, and retarder in Portland Cement. About three-fourths of the entire production is calcined for utilization as plaster of Paris and as construction materials in plaster, Keene's cement, board products, tiles, and blocks. Because of its worldwide occurrence and massive potential reserves, however, its uses are not considered basic to sustain in a national emergency, and gypsum is not considered a strategic mineral rock. This has allowed natural economic factors to pay off in the development of the mineral worldwide, which overall is a healthy situation that should go on to prevail. 
Gypsum is fairly water-soluble (~2.0–2.5 g/l at 25 °C) and, in contrast to most other salts, it shows retrograde solubility, becoming less soluble at higher temperatures. When gypsum is heated in air it loses water and changes first to calcium sulfate hemihydrate, (bassanite, usually simply called "plaster") and, if it is heated further, to anhydrous calcium sulfate (anhydrite). As with anhydrite, the solubility of gypsum in saline solutions and in brines is also widely dependent on NaCl (common table salt) concentration. Regarding such benefits it is widely believed that gypsum crystal discovery has marked a turning point in the history of crystal extraction from the earth. Also, these matters will be discussed,
- Occurrence:
2. Desulfurization 3. Desalination 4. Refinery waste
Gypsum Crystals Meaning
Gypsum is a mineral mostly found in crystal as well as masses named gypsum and quartzite rock. It is a very gentle mineral and it can form very beautifully, and sometimes so much large colored crystals. Massive gypsum rock is produced within layers of sedimentary stones, typically found in thick beds or layers under-ground. The mineral gypsum is the most usual sulfate mineral found mostly in sedimentary rocks. Its chemical formula contains, CaSO4 2H2O, describes its chemistry as a hydrated calcium sulfate mineral. Gypsum has a variety of colors ranging from white, colorless, yellowish white, greenish white, or brown and also it has a white streak color. Its pearly luster gives it a beautiful glow, and some forms of gypsum would produce nice jewelry if it was stronger, as its hardness is two. When gypsum is heated it transforms to a powder form. If water is then added to this powder, it can become hard when drying and set to the form it is molded in. Gypsum has wide area of uses in our every day life that we usually overlook. It is used to produce plaster-of-Paris, which has many reasons, but it's also utilized to make floor underlayments, plasters and cements for art and casting industry, soil fertilizer, fake snow in Hollywood together with scenery, road and surface fixing, as well as dry wall. 
Companies like USG, in the United States Gypsum mabufacturer, sell different forms of the minerals for all sorts of various projects requiring plaster. USG might purchase its source of gypsum from Germany, because there are several cities in Germany that mine Gypsum. The cities of Heimkenie, Wald Schmiede, Seefrotte, Nixsee Valley, Slazaspring, Rhumequw, and also the Cave of Segberg are all mines in Germany. One of the locations in the USA, the Alablaster Caverns in Okalahoma City, form the largest gypsum cave in the world. The Caverns are such a great environment for gypsum to grow because the fine soil produces clear crystals. The clay in the soil gives the formations an exciting hourglass form. This gave is so special since it is open to the public and they are allowed to look for crystals.
Gypsum Crystal Benefits
In manufacturing the fire-resistant gypsum wallboards, different properties of GWB like thermal, physical, chalk chemical and mechanical features are to be studied which plays a major role in controlling the distribution of fire in buildings. Gypsum wallboard consists majorly of gypsum i.e. calcium sulfate dihydrate with the formula, CaSO4.2H2O. Calcium sulfate in nature is highly available in two forms: Calcium sulfate dihydrate is usually referred as gypsum, which is one of the oldest building materials. It naturally takes place in sedimentary deposits from ancient sea beds. The most distinguishing characteristic of Gypsum is that it is moderately soluble in water at room temperature and shows a special feature of retrograde solubility i.e. gypsum becomes less soluble at elevated degrees. 
Another derivative of calcium sulfate is the calcium sulfate anhydrite. At a temperature of around 58’C Gypsum and Anhydrite coexist together, also the anhydrite exhibits the firm retrograde property but it does not revert back to gypsum as its solubility reduces with increasing temperature. Gypsum wallboard is utilized to make interior walls and ceilings in residential and commercial applications that usually require specific fire rated assemblies.
Gypsum Crystal Properties
Various types of gypsum wallboard are produced, with the most common variety and special varieties like fire resistant, water resistant, and plaster lath. Combination of beta hemihydrates stucco, water and other additions form slurry which is used in the production of the gypsum wallboard. Additives like asphalt emulsion, vermiculite, chopped fiberglass composite and paper fiber impart to the wallboard characteristics such as water resistance, fire resistance and strength as two important factors. The fire resistance property is mainly connected to the absorption of energy related with the loss of hydrate water going from the dihydrate (CaSo4.2H2O) and from the hemihydrates to the anhydrous shape (CaSo4). Impinging the heat of gypsum wallboards originally operates to change the hydration reaction resulting in controlling the spread of fire and penetration of flame in set gypsum structures. 
Fire resistance can be gained by using appropriate additives like fiber, glass textile fibers, vermiculite, which expands when it is heated, which acts against the gypsum shrinkage. Plan of procedure (Outline the initial approach to the difficulty and its feasibility. Point out creative features, relate it to previous work including pertinent references, and refer how this plan might contribute to the solution of the broader problem proposed. Gypsum manufacturing process include three main steps (1) rock preparation process, (2) calcining (3) formulating and manufacturing. Though we begin with buying the gypsum material from one of the providers so the next crucial step ahead is the calcination process. Gypsum is often referred to be CaSO4.2H2O. Calcium sulfate dIiydrate undergoes calcination to produce hemihydrate (CaSO41/2H2O) or anhydrous form (CaSO4). Basically, the calcination process was gained by heating the raw gypsum material in an open environment, later on with the growth in science calcination was gained by heating the gypsum material in a kiln. 
Kinetic studies of calcination process play a major role in determining the gypsum product parameters. We are interested in recognizing the time, temperature and rate at which the calcination process can be gained. Initially a small proportion of the gypsum material is taken and X- Ray diffraction studies are led on it to figure out its composition i.e. CaSO4.2H2O or CaSO41/2 H2O or CaSO4 . Later after determining the shape of gypsum material, thermogravimetric researches (used for the determination of weight change at different temperatures and time) are done on the CaSO4.2H2O to determine the temperature and time needed to convert from dihydrate form to hemihydrate and anhydrite form. Again the achieved product is first subjected to XRD and SEM studies to investigate the mode of gypsum i.e. dihydrate, hemihydrate or anhydrous shape. 
This can be studied by interpreting the achieved results with the earlier established results. Later gypsum powder is subjected to various temperatures at different time intervals to specify the time and temperature required for the calcination process to finalize by using Thermogravimetric Analysis Instrument together with Differential Scanning Calorimetry (which determines the melting and boiling temperatures) studies are also led to know the melting temperatures of the product Until present time the calcination process is studied by using a highly small amount of the sample in a laboratory environment, the obtained results from these examines is used to correlate with the calcination procedure which is done in hot air oven by using a huge amount of samples. The temperature obtained from the thermogravimetric researches is used as basis for the calcination process in hot air oven. These studies are conducted to recognize the reproducibility for large scale samples. This encompasses the first stage in our research. The importance of these kinetic researches related to calcination is very beneficial to determine the conditions for achieving the hemi hydride from calcium sulfate which is subject to rehydration process i.e is addition of water molecules to the hemi hydride form in order to form the gypsum wallboard. 
Calcium sulfate hemihydrate (CaSO41/2H2O) or Calcium sulfate anhydrite (CaSO4) is subject to rehydration in the presence of water. Rehydration plays an important role as it permits to add the additives like glass material, vermiculite etc. to the slurry which is referred as stucco. Chemically stucco is referred to as the hemihydrate form of CaSO4. These additives are added to raise the fire-resistant property in addition to the power of the wallboards. The kinetic studies connected to the rehydration process are studied similar to the calcination step. These kinetic studies give us scope for better understanding the process of gypsum wallboard. i.e the amount of water needed for rehydration and also the amount of additives that can be added to the gypsum mix to retain the chemical stability of the gypsum composition needed for the wallboard manufacturing. 
Like the first step this step is studied for the time, temperature and rate of reaction through the open environment and later in the laboratory environment by utilizing kettle. In the kettle the hemihydrate and hydride variants of calcium are reacted with the water and the gained product is subjected to the XRD and SEM studies to specify the state of product. This is the second step in our study. The final stage in our research is the lab scale preparation of gypsum wallboard which involves the dihydrate form of calcium sulfate react with the sufficient proportion of water to form slurry. Theoretically about 18.6 parts of water is needed to react with the 100 parts of gypsum but to get a slurry, excessive amount of water (about 80 to 85 parts) is reacted with 100 parts of gypsum. In this step water together with 10-30 wt. % of starch such as corn starch is applied to obtain milk of starch. Next about 0.1 -1.5 wt.% of amolytic enzyme like α amylase based on the starch is included and heated up to the decomposition point of the starch with stirring. After the heating is paused enzyme deactivating agent based on the starch is added in the amount of 0.8 to 1.0 wt. % and mixed with water to gain a starch paste. To the provided starch material, the calcination product is added along with water and vermiculite, glass materials which develop the fire resistance feature of the gypsum wallboard. This mixture is agitated in slow motion to gain a slurry. This slurry form of gypsum is poured into a paper sheets like paper boards. 
The edges of the paper is carefully folded upwards to retain the slurry form of gypsum. The other end part of the product is covered with another paper material which contributes to retain the structure of the gypsum board. This mixture is subjected to heating by utilizing hot air press which is practical to remove the excess water and to obtain a specific structure of the gypsum board. This process goes on until all the excess water is removed. It is finally dried in the temperature range of 50 ËšC-200 ËšC. Starch paste such as denatured starch and dextrin is utilized as an auxiliary adhesive to limit calcination of the crystal of gypsum dihydrate and dehydrated to provide a gypsum hemihydrate in drying at higher temperatures. Also to limit separation of the gypsum core member from both paper board, hardening modifier are applied to the raw material of the gypsum core part. 
It is effective that starch paste together with water in the gypsum core member and both paper boards is transferred during drying at high temperatures, and cover the crystal of gypsum dihydrate because water retention ability of the starch paste which is developed into the fiber of the paper boards is so as to prevent the calcination and dehydration of these crystals. The obtained wallboard is subjected to various analytical techniques such as Thermogravimetric analysis, Thermomechanical analysis, XRD, SEM and Different scanning calorimetry as discussed thoroughly in the calcination and rehydration step. Gypsum is a gentle sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. [4] It is widely mined and is utilized as a fertilizer and as the main constituent in various forms of plaster, blackboard or sidewalk chalk, and drywall. A huge fine-grained white or lightly tinted variety of gypsum, called alabaster, has been applied for sculpture production by many cultures including Ancient Egypt, Mesopotamia, Ancient Rome, the Byzantine Empire, and the Nottingham alabasters of Medieval era in England. Gypsum also crystallizes itself as translucent crystals of selenite. It forms as an evaporite mineral and also as a hydration product of anhydrite. The word gypsum comes from the Greek word γύψος (gypsos), "plaster". [5] since the quarries of the Montmartre region of Paris have long furnished burnt gypsum (calcined gypsum) used for different purposes, this dehydrated gypsum became known as plaster of Paris. Upon adding water to it, after a few dozen minutes, plaster of Paris turns into a regular gypsum (dihydrate) again, causing the material to get hard or "set" in ways that are useful for casting and construction. [6] Gypsum was recognized in Old English as spærstān, "spear stone", referring to its widely crystalline projections. (Thus, the word spar in mineralogy is by means of comparison to gypsum, referring to any non-ore mineral or crystal that is produced in spearlike projections). 
during the mid-18th century, the German clergyman and agriculturalist Johann Friderich Mayer investigated and publicized gypsum's utilization as a fertilizer. [7] Gypsum might act as a source of sulfur for plant growth, and during the early 19th century, it was regarded as a rsther miraculous fertilizer. American farmers were so anxious to acquire it that a lively smuggling deal with Nova Scotia evolved, resulting in the well-known "Plaster War" of 1820. [8] The structure of gypsum includes layers of calcium (Ca2+) and sulfate (SO2−4) ions tightly bound together. These layers are bonded together by sheets of anion water molecules via weaker hydrogen bonding, which gives the crystal nice cleavage along the sheets. Gypsum occurs in nature as flattened and usually twinned crystals, and transparent, cleavable masses named selenite. Selenite contains no significant selenium; instead, both substances were named for the ancient Greek term for the Moon. Selenite might also occur in a silky, fibrous form, in which case it is commonly named "satin spar". Finally, it might also be granular or quite compact. In hand-sized samples, it could be anywhere from transparent to opaque. 
A much fine-grained white or lightly tinted variety of gypsum, called alabaster, is prized for ornamental work of different sorts. In arid areas, gypsum can occur in a flower-like form, typically opaque, with embedded sand grains called desert rose. It also forms some of the largest crystals found in nature, up to 12 m (39 ft) long, in the form of selenite.[11]
Occurrence
Gypsum is a common mineral, with thick and extensive evaporite beds in association with sedimentary rocks. Deposits are known to occur in strata from as far back as the Archaean eon. [12] Gypsum is deposited from lake and sea water, as well as in hot springs, from volcanic vapors, and sulfate solutions in veins. Hydrothermal anhydrite in veins is commonly hydrated to gypsum by groundwater in near-surface exposures. It is often associated with the minerals like halite and sulfur. Gypsum is the most commonly sulfate mineral. [13] Pure gypsum is white, but some other substances found as impurities may give a wider range of colors to localized deposits. Because gypsum dissolves over time in the water, gypsum is rarely found in the form of sand powder. However, the specific conditions of the White Sands National Park in the US state of New Mexico have produced a 710 km2 (270 sq mi) expanse of white gypsum sand, fully enough to supply the US building industry with a length drywall for 1,000 years. 
Commercial exploitation of the area, largely opposed by area residents, was permanently prevented in 1933 when President Herbert Hoover announced the gypsum dunes a protected national monument. Gypsum is also shaped as a by-product of sulfide oxidation, amongst others by pyrite oxidation, when the sulfuric acid produced reacts with calcium carbonate. Its existence indicates oxidizing conditions. Under reducing conditions, the sulfates it produced can be reduced back to sulfide by sulfate-reducing bacteria. This can result in accumulation of elemental sulfur in oil-bearing formations, [15] such asvarious salt domes, [16] where it can be mined and utilized by the Frasch process [17] Electric power stations burning coal with flue gas desulfurization and produce large amounts of gypsum as a byproduct derived from the scrubbers. Orbital images from the Mars Reconnaissance Orbiter (MRO) have shown the existence of gypsum dunes in the northern polar district of Mars,[18] which were later confirmed at ground level by the Mars Exploration Rover (MER) Opportunity. [19] Commercial quantities of gypsum are excavated widely in the areas of Araripina and Grajaú in Brazil; in Pakistan, Jamaica, Iran (world's second largest producer), Thailand, Spain (the main producer of gypsum in Europe), Germany, Italy, England, Ireland, Canada [21] and also the United States. 
Large open pit quarries are located in many places including Fort Dodge, Iowa, which sits on one of the biggest deposits of gypsum in the world, [22] and Plaster City, California, US, and East Kutai, Kalimantan, Indonesia. Several small mines also exist in places like Kalannie in Western Australia, where gypsum is sold to personal buyers for additions of calcium and sulfur as well as reduction of powder aluminum toxicities on earth for agricultural purposes. Crystals of gypsum up to 11 m (36 ft) long have been extracted in the caves of the Naica Mine of Chihuahua, Mexico. The crystals thrived in the cave's extremely scarce and stable natural environment. Temperatures stayed at 58 °C (136 °F), and the cave was piled with mineral-rich water that drove the crystals' growth. The largest of those crystals weighs around 55 tons.
Desulfurization
Flue gas desulfurization gypsum (FGDG) is recovered at a number of coal-fired power plants. The main contaminants include Mg, K, Cl, F, B, Al, Fe, Si, and Se. They come both from the limestone utilized in desulfurization and from the coal burned. This product is pure appropriate to replace natural gypsum in a wide range of fields including drywalls, water treatment, and cement set retarder. Improvements in flue gas desulfurization have greatly decreased the amount of toxic elements present.[24]
desalination
Gypsum precipitates into brackish water membranes, a phenomenon recognized as mineral salt scaling, such as during brackish water desalination of water with large concentrations of calcium and sulfate. Scaling reduces membrane life and productivity.[25] This is one of the main obstacles in brackish water membrane desalination procedures, like reverse osmosis or nanofiltration. Other forms of scaling, such as calcite scaling, relying on the water source, can also be essential considerations in distillation, as well as in heat exchangers, where either the salt solubility or concentration can change quickly. A recent study has suggested that the formation of gypsum starts as small crystals of a mineral called bassanite (CaSO4·0.5H2O). 
[26] This process occurs via a three-stages of pathway: homogeneous nucleation related to nanocrystalline bassanite; self-assembly of bassanite turning into aggregates, and transformation of bassanite into gypsum powder.
Refinery waste
The production of phosphate fertilizers needs breaking down calcium-containing phosphate stone with acid, producing calcium sulfate waste widely known as phosphogypsum (PG). This form of gypsum is contaminated by impurities mostly found in the rock, namely fluoride, silica, radioactive elements like radium, and heavy black metal elements such as cadmium. [27] Similarly, production of titanium dioxide results in titanium gypsum (TG) due to neutralization of excessive acid with lime. The product is contaminated with silica, fluorides, organic matters, and also alkalis.[28] Impurities included in refinery gypsum waste have, in many cases, limited them from being utilized as normal gypsum in fields such as construction. As a result, waste gypsum is maintained in stacks indefinitely, with significant risk of leaching their contaminants inside water and soil. [27] To decrease the accumulation and ultimately clear out these stacks, research is underway to discover more applications for such waste products. [28] People can be subject to gypsum in the workplace by breathing it in, skin contact, and eye contact too. Calcium sulfate per se is nontoxic and is even approved as a meal additive,[30] but as powdered gypsum, it could irritate skin and mucous membranes.[31] Gypsum, common sulfate mineral of high commercial importance, is composed of hydrated calcium sulfate (CaSO4·2H2O). 
In well-developed crystals the mineral usually has been called selenite. The fibrous massive variety has a silky luster and also is called satin spar; it is translucent and opalescent and is valued for works of ornaments and jewelry. The fine-grained massive variety called alabaster is carved and polished gently for statuary and ornamental utilization when pure and translucent. Gypsite is the earthy pulverulent variety. Gypsum occurs in extensive beds largely associated with other evaporite minerals (e.g., anhydrite and halite), particularly shown in Permian and Triassic sedimentary formations; it is deposited from ocean brine, which is followed by anhydrite and halite. It also takes place in considerable quantity in saline lakes and salt pans and is an essential constituent of cap rock, an anhydrite-gypsum stone forming a covering on salt domes, as in Texas and Louisiana. Very commonly it is shaped from the hydration of anhydrite by surface waters and groundwaters, and, therefore, many gypsiferous strata grade downward into anhydrite rocks. This replacement causes a 30 percent to 50 percent volume rise and results in intense, tight folding of the remaining anhydrite layers. Gypsum also occurs disseminated in limestones, dolomitic limestones, and some other forms of shales. Gypsum deposits take place in many countries, but Spain, Thailand, the United States, Turkey, and Russia are amongst the leading producers. 
The largest gypsum crystal was discovered in the Braden mine in Chile and exceeds 3 meters (about 10 feet) in terms of length and 0.4 meter (about 1.5 feet) in diameter. In the U.S., commercial sedimentary gypsum deposits mostly occur in New York and Michigan; other forms of economic importance occur widely in Virginia, Ohio, Iowa, Kansas, Texas, Nevada, and southern California. In Canada, gypsum is manufactured for export in Nova Scotia and New Brunswick. In France, gypsum is widely found in the marls and ball clays of the Paris Basin (hence the name plaster of Paris), especially in Montmartre.
6 Environmental Effects of Gypsum Application
Gypsum can be utilized in order to increase water infiltration, and furthermore reduce runoff rate and loss of nutrients through runoff (Watts and Dick, 2014). Gypsum has been tested and successfully utilized as a phosphorus sorbing material (McGrath et al., 2013; Penn and Bryant, 2006; Penn and McGrath, 2014). Soils lately fertilized by either commercial fertilizer or animal manure, and soils built up in soil test P, can be a good nutrient source to overland flow under special conditions. Many soils that received animal manure amendments according to crop N needs for many years have gone excessive in soil P concentrations thanks to the fact that the N:P ratio of manure is often less than crop N:P needs (Reddy et al., 2008). Excess nutrients accumulated at the soil level can move from treated fields to lakes and rivers, resulting in algal blooms and areas of hypoxia. Among manure types, poultry manure has the least N:P ratio (Kleinman et al., 2002). Poultry litter (manure which is mixed with bedding) is a by-product from poultry production, which is usual in the southeast USA (USDA-NASS, 2011) and elsewhere throughout the world (Boland et al., 2010). 
presently, most of the manure and litter produced by poultry industry is widely applied onto agricultural lands by surface broadcasting (Dou et al., 2001; Sheng et al. Torbert and Watts (2014) together performed an experiment on a Coastal Plain soil to assess the ability of FGD-gypsum to develop the quality of surface runoff from pastures that previously gained poultry litter applications. They found that FGD-gypsum application rating 8.9 Mg ha− 1 reduced soluble reactive phosphorus (SRP) in runoff by around 61%. besides, they highlighted that the rate of 4.4 Mg ha− 1 was also effective in reducing the amount of SRP. Gypsum is the most commonly utilized amendment for sodic soil reclamation and for decreasing the harmful effects of high-sodium irrigation waters for its solubility, low cost, and availability. Gypsum which is added to a sodic soil can cause permeability changes by rising EC and by cation exchange effects. The relative significance of the two effects is of interest for numerous reasons. If the electrolyte effect is sufficiently large to prevent dispersion and swelling of dirt soil clays, the surface application of gypsum might be worthwhile. In this case the proportion of gypsum required relies on the amount of high-quality water applied in it and the rate of gypsum dissolution. It is somewhat independent of the proportion of exchangeable Na in the soil profile. Conversely, in soils where the EC effect is not sufficient due to the high ESP level, or in order to gain permanent improvement, then the amount of gypsum required depends on the amount of exchangeable Na in a opted depth of soil. The benefit of gypsum for reclaiming sodic soils relies not only on the infiltration characteristics of the soil, but also on the gypsum-dissolution properties. 
The main mechanism through which gypsum affects the IR of soils exposed to rainwater is by its dissolution and letting out of electrolytes into the soil solution. The dissolution rate of gypsum is an essential factor in IR because of the short contact time between rainwater and gypsum seeds at the soil surface. Some of the factors that affect the dissolution rate of gypsum are the surface area of the gypsum particles, the soil water velocity throughout leaching, and the electrolyte composition of the soil solution. Gypsum source, application rate, and particle size all have their influence on crust formation and IR (Figure 2). Although the IR for soil without gypsum reduces sharply as the cumulative rainfall increases, the IR stays relatively high in the presence of phosphogypsum (PG), whereas the effectiveness of mined gypsum (MG) on IR is essentially less. The higher efficiency of PG in maintaining high IR is attributed to its increased rate of dissolution (Table 1). Application of gypsum on sodic calcareous soil is much effective in lowering surface runoff under field conditions (Table 2). Spreading the gypsum over the earth is more effective than mixing it in the upper 10 cm of soil. Although gypsum affects the ESP of the soil in the upper levels from 0- to 15-cm layer very little (Table 3), it has a large influence on IR (Figure 2). The gypsum has a significant effect on the amount of soil erosion occurring on the earth. The effectiveness is greater when the gypsum particles are distributed over the soil rather than mixed in the top 10 cm of soil. The presence of gypsum on the soil surface raises soil stability by increasing EC in the percolated solution and by reducing ESP. This effect of gypsum on soil erosion is for two reasons: (1) reducing runoff by increasing IR, and (2) changing the erodibility factor in gypsum. The erodibility of the soil is essentially connected to the stability of soil aggregates and to the cohesive powers holding the aggregates together. Sulfate poisoning of cattle was seen when appreciable levels of gypsum were added to a feed supplement for a large number of range cattle (Raisbeck, 1982). Excessive sulfate intake by ruminants could cause a severe disease, called polioencephalomalacia (Gould, 1998). Adherence of powdered gypsum on leaves through following surface application on pastures could permit increased amount of intake by grazing livestock, as could lead access to FGDG piles in a wide length of field. 
Thus, a waiting period for rainfall or forage increase should occur after surface application of highly powdered gypsum before ruminants may graze amended pastures, and ruminants must be fenced out of FGDG storage piles. The benefit of gypsum for reclaiming sodic soils relies not only on the infiltration characteristics of the soil, but also on the gypsum-dissolution properties in general. The main mechanism by which gypsum influences the IR of soils exposed to rainwater is by its dissolution and release of electrolytes inside the soil solution. The dissolution rate of gypsum is an essential factor in IR because of the short contact time between rainwater and gypsum seeds at the soil surface. Some of the factors that influence the dissolution rate of gypsum are the surface zone of the gypsum particles, the soil water speed during leaching, and the electrolyte composition of the soil solution. Gypsum karst is widespread and very well developed through the desert areas of southwestern USA (Nevada, Arizona, Utah, Wyoming, Colorado, New Mexico, and Texas), where it has shaped on outcrops of Permian evaporites. Gypsum largely resists erosion in these areas and typically caps ridges, mesas, and buttes in large amounts. Karst features are common, including caves, usually with scalloped walls for dissolution during high-flow events after flooding (Fig. 2B). Dolines, karren, disappearing streams, springs, and collapse structures are also widely seen (Hill, 1996; Johnson, 2003, 2008). Of more than 500 known gypsum caves in the USA, most of them are located in the southwestern part of the country (Quinlan et al., 1986). Gypsum karst is most conspicuous in outcrops of gypsum, but also takes place where the gypsum is up to 30 m below the land level As widely mentioned in the whole text, the discovery of gypsum crystal with its wide range of use include usage as a fluxing agent, fertilizer, filler in paper and textiles, and retarder in Portland Cement. Also about three-fourths of the entire production is calcined for utilization as plaster of Paris and as construction materials in plaster, Keene's cement, board products, tiles and blocks. My company is honored to have exceeded in recent years in both supply and export of gypsum crystal to all areas around the world. For all costumers and traders, a link is provided above to inter our variety of product world. All you need is to press the link to enjoy the best purchase of your life.