Last updated

Gypse Caresse.jpg
Category Sulfate minerals
(repeating unit)
IMA symbol Gp [1]
Strunz classification 7.CD.40
Crystal system Monoclinic
Crystal class Prismatic (2/m)
H-M symbol: (2/m)
Space group Monoclinic
Space group: I2/a
Unit cell a = 5.679(5), b = 15.202(14)
c = 6.522(6) Å; β = 118.43°; Z = 4
ColorColorless (in transmitted light) to white; often tinged other hues due to impurities; may be yellow, tan, blue, pink, dark brown, reddish brown or gray
Crystal habit Massive, flat. Elongated and generally prismatic crystals
Twinning Very common on {110}
Cleavage Perfect on {010}, distinct on {100}
Fracture Conchoidal on {100}, splintery parallel to [001]
Tenacity Flexible, inelastic
Mohs scale hardness1.5–2 (defining mineral for 2)
Luster Vitreous to silky, pearly, or waxy
Streak White
Diaphaneity Transparent to translucent
Specific gravity 2.31–2.33
Optical propertiesBiaxial (+)
Refractive index nα = 1.519–1.521
nβ = 1.522–1.523
nγ = 1.529–1.530
Birefringence δ = 0.010
Pleochroism None
2V angle 58°
Fusibility 5
Solubility Hot, dilute HCl
References [2] [3] [4]
Major varieties
Satin sparPearly, fibrous masses
Selenite Transparent and bladed crystals
Alabaster Fine-grained, slightly colored

Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. [4] It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywall. A massive fine-grained white or lightly tinted variety of gypsum, called alabaster, has been used for sculpture by many cultures including Ancient Egypt, Mesopotamia, Ancient Rome, the Byzantine Empire, and the Nottingham alabasters of Medieval England. Gypsum also crystallizes as translucent crystals of selenite. It forms as an evaporite mineral and as a hydration product of anhydrite.


The Mohs scale of mineral hardness defines gypsum as hardness value 2 based on scratch hardness comparison.

Etymology and history

The word gypsum is derived from the Greek word γύψος (gypsos), "plaster". [5] Because the quarries of the Montmartre district of Paris have long furnished burnt gypsum (calcined gypsum) used for various purposes, this dehydrated gypsum became known as plaster of Paris. Upon adding water, after a few dozen minutes, plaster of Paris becomes regular gypsum (dihydrate) again, causing the material to harden or "set" in ways that are useful for casting and construction. [6]

Gypsum was known in Old English as spærstān, "spear stone", referring to its crystalline projections. (Thus, the word spar in mineralogy is by way of comparison to gypsum, referring to any non-ore mineral or crystal that forms in spearlike projections). In the mid-18th century, the German clergyman and agriculturalist Johann Friderich Mayer investigated and publicized gypsum's use as a fertilizer. [7] Gypsum may act as a source of sulfur for plant growth, and in the early 19th century, it was regarded as an almost miraculous fertilizer. American farmers were so anxious to acquire it that a lively smuggling trade with Nova Scotia evolved, resulting in the so-called "Plaster War" of 1820. [8]

Physical properties

Gypsum crystals are soft enough to bend under pressure of the hand. Sample on display at Musee cantonal de geologie de Lausanne. Gypsum deformed cristal-MCG 7747-P4150901-black.jpg
Gypsum crystals are soft enough to bend under pressure of the hand. Sample on display at Musée cantonal de géologie de Lausanne.

Gypsum is moderately water-soluble (~2.0–2.5 g/l at 25 °C) [9] and, in contrast to most other salts, it exhibits retrograde solubility, becoming less soluble at higher temperatures. When gypsum is heated in air it loses water and converts first to calcium sulfate hemihydrate, (bassanite, often simply called "plaster") and, if heated further, to anhydrous calcium sulfate (anhydrite). As with anhydrite, the solubility of gypsum in saline solutions and in brines is also strongly dependent on NaCl (common table salt) concentration. [9]

The structure of gypsum consists of layers of calcium (Ca2+) and sulfate (SO2−4) ions tightly bound together. These layers are bonded by sheets of anion water molecules via weaker hydrogen bonding, which gives the crystal perfect cleavage along the sheets (in the {010} plane). [4] [10]

Crystal varieties

Gypsum occurs in nature as flattened and often twinned crystals, and transparent, cleavable masses called selenite. Selenite contains no significant selenium; rather, both substances were named for the ancient Greek word for the Moon.

Selenite may also occur in a silky, fibrous form, in which case it is commonly called "satin spar". Finally, it may also be granular or quite compact. In hand-sized samples, it can be anywhere from transparent to opaque. A very fine-grained white or lightly tinted variety of gypsum, called alabaster, is prized for ornamental work of various 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]


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 halite and sulfur. Gypsum is the most common sulfate mineral. [13] Pure gypsum is white, but other substances found as impurities may give a wide range of colors to local deposits.

Because gypsum dissolves over time in water, gypsum is rarely found in the form of sand. However, the unique conditions of the White Sands National Park in the US state of New Mexico have created a 710 km2 (270 sq mi) expanse of white gypsum sand, enough to supply the US construction industry with drywall for 1,000 years. [14] Commercial exploitation of the area, strongly opposed by area residents, was permanently prevented in 1933 when President Herbert Hoover declared the gypsum dunes a protected national monument.

Gypsum is also formed as a by-product of sulfide oxidation, amongst others by pyrite oxidation, when the sulfuric acid generated reacts with calcium carbonate. Its presence indicates oxidizing conditions. Under reducing conditions, the sulfates it contains can be reduced back to sulfide by sulfate-reducing bacteria. This can lead to accumulation of elemental sulfur in oil-bearing formations, [15] such as salt domes, [16] where it can be mined using the Frasch process [17] Electric power stations burning coal with flue gas desulfurization produce large quantities of gypsum as a byproduct from the scrubbers.

Orbital pictures from the Mars Reconnaissance Orbiter (MRO) have indicated the existence of gypsum dunes in the northern polar region of Mars, [18] which were later confirmed at ground level by the Mars Exploration Rover (MER) Opportunity . [19]


Estimated production of Gypsum in 2015
(thousand metric tons) [20]
China 132,000
Iran 22,0001,600
Thailand 12,500
United States 11,500700,000
Turkey 10,000
Spain 6,400
Mexico 5,300
Japan 5,000
Russia 4,500
Italy 4,100
India 3,50039,000
Australia 3,500
Oman 3,500
Brazil 3,300290,000
France 3,300
Canada 2,700450,000
Saudi Arabia 2,400
Algeria 2,200
Germany 1,800450,000
Argentina 1,400
Pakistan 1,300
United Kingdom 1,20055,000
Other countries15,000
World total258,000

Commercial quantities of gypsum are found in the cities of Araripina and Grajaú in Brazil; in Pakistan, Jamaica, Iran (world's second largest producer), Thailand, Spain (the main producer in Europe), Germany, Italy, England, Ireland, Canada [21] and the United States. Large open pit quarries are located in many places including Fort Dodge, Iowa, which sits on one of the largest deposits of gypsum in the world, [22] and Plaster City, California, United States, and East Kutai, Kalimantan, Indonesia. Several small mines also exist in places such as Kalannie in Western Australia, where gypsum is sold to private buyers for additions of calcium and sulfur as well as reduction of aluminum toxicities on soil for agricultural purposes.

Crystals of gypsum up to 11 m (36 ft) long have been found in the caves of the Naica Mine of Chihuahua, Mexico. The crystals thrived in the cave's extremely rare and stable natural environment. Temperatures stayed at 58 °C (136 °F), and the cave was filled with mineral-rich water that drove the crystals' growth. The largest of those crystals weighs 55 tonnes (61 short tons) and is around 500,000 years old. [23]


Synthetic gypsum is produced as a waste product or by-product in a range of industrial processes.


Flue gas desulfurization gypsum (FGDG) is recovered at some coal-fired power plants. The main contaminants are Mg, K, Cl, F, B, Al, Fe, Si, and Se. They come both from the limestone used in desulfurization and from the coal burned. This product is pure enough to replace natural gypsum in a wide variety of fields including drywalls, water treatment, and cement set retarder. Improvements in flue gas desulfurization have greatly reduced the amount of toxic elements present. [24]


Gypsum precipitates onto brackish water membranes, a phenomenon known as mineral salt scaling, such as during brackish water desalination of water with high concentrations of calcium and sulfate. Scaling decreases membrane life and productivity. [25] This is one of the main obstacles in brackish water membrane desalination processes, such as reverse osmosis or nanofiltration. Other forms of scaling, such as calcite scaling, depending on the water source, can also be important considerations in distillation, as well as in heat exchangers, where either the salt solubility or concentration can change rapidly.

A new study has suggested that the formation of gypsum starts as tiny crystals of a mineral called bassanite (CaSO4·0.5H2O). [26] This process occurs via a three-stage pathway:

  1. homogeneous nucleation of nanocrystalline bassanite;
  2. self-assembly of bassanite into aggregates, and
  3. transformation of bassanite into gypsum.

Refinery waste

The production of phosphate fertilizers requires breaking down calcium-containing phosphate rock with acid, producing calcium sulfate waste known as phosphogypsum (PG). This form of gypsum is contaminated by impurities found in the rock, namely fluoride, silica, radioactive elements such as radium, and heavy metal elements such as cadmium. [27] Similarly, production of titanium dioxide produces titanium gypsum (TG) due to neutralization of excess acid with lime. The product is contaminated with silica, fluorides, organic matters, and alkalis. [28]

Impurities in refinery gypsum waste have, in many cases, prevented them from being used as normal gypsum in fields such as construction. As a result, waste gypsum is stored in stacks indefinitely, with significant risk of leaching their contaminants into water and soil. [27] To reduce the accumulation and ultimately clear out these stacks, research is underway to find more applications for such waste products. [28]

Occupational safety

NFPA 704
fire diamond

People can be exposed to gypsum in the workplace by breathing it in, skin contact, and eye contact. Calcium sulfate per se is nontoxic and is even approved as a food additive, [30] but as powdered gypsum, it can irritate skin and mucous membranes. [31]

United States

The Occupational Safety and Health Administration (OSHA) has set the legal limit (permissible exposure limit) for gypsum exposure in the workplace as TWA 15 mg/m3 for total exposure and TWA 5 mg/m3 for respiratory exposure over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of TWA 10 mg/m3 for total exposure and TWA 5 mg/m3 for respiratory exposure over an 8-hour workday. [31]


Gypsum works, Valencian Museum of Ethnology 2.-Calera. Cal i guix (26561676342).jpg
Gypsum works, Valencian Museum of Ethnology
Map of gypsum deposits in northern Ohio, black squares indicate the location of deposits, from "Geography of Ohio", 1923 Geography of Ohio - DPLA - aaba7b3295ff6973b6fd1e23e33cde14 (page 96) (cropped2).jpg
Map of gypsum deposits in northern Ohio, black squares indicate the location of deposits, from "Geography of Ohio", 1923

Gypsum is used in a wide variety of applications:

Construction industry


Modeling, sculpture and art

Food and drink

Medicine and cosmetics


See also

Related Research Articles

Calcite Calcium carbonate mineral

Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scratch hardness comparison. Large calcite crystals are used in optical equipment, and limestone composed mostly of calcite has numerous uses.

<span class="mw-page-title-main">Celestine (mineral)</span> Sulfate mineral

Celestine (the IMA-accepted name) or celestite is a mineral consisting of strontium sulfate (SrSO4). The mineral is named for its occasional delicate blue color. Celestine and the carbonate mineral strontianite are the principal sources of the element strontium, commonly used in fireworks and in various metal alloys.

Evaporite Water-soluble mineral deposit formed by evaporation from an aqueous solution

An evaporite is a water-soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporite deposits: marine, which can also be described as ocean deposits, and non-marine, which are found in standing bodies of water such as lakes. Evaporites are considered sedimentary rocks and are formed by chemical sediments.

<span class="mw-page-title-main">Bentonite</span> Rock type or smectite-rich clay material consisting mostly of montmorillonite

Bentonite is an absorbent swelling clay consisting mostly of montmorillonite which can either be Na-montmorillonite or Ca-montmorillonite. Na-montmorillonite has a considerably greater swelling capacity than Ca-montmorillonite.

Plaster Broad range of building and sculpture materials

Plaster is a building material used for the protective or decorative coating of walls and ceilings and for moulding and casting decorative elements. In English, "plaster" usually means a material used for the interiors of buildings, while "render" commonly refers to external applications. Another imprecise term used for the material is stucco, which is also often used for plasterwork that is worked in some way to produce relief decoration, rather than flat surfaces.

Calcium hydroxide Inorganic compound of formula Ca(OH)2

Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca(OH)2. It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed or slaked with water. It has many names including hydrated lime, caustic lime, builders' lime, slaked lime, cal, and pickling lime. Calcium hydroxide is used in many applications, including food preparation, where it has been identified as E number E526. Limewater, also called milk of lime, is the common name for a saturated solution of calcium hydroxide.

Selenite (mineral) Mineral variety of gypsum

Selenite, satin spar, desert rose, gypsum flower are crystal habit varieties of the mineral gypsum.

Calcium sulfate Laboratory and industrial chemical

Calcium sulfate (or calcium sulphate) is the inorganic compound with the formula CaSO4 and related hydrates. In the form of γ-anhydrite (the anhydrous form), it is used as a desiccant. One particular hydrate is better known as plaster of Paris, and another occurs naturally as the mineral gypsum. It has many uses in industry. All forms are white solids that are poorly soluble in water. Calcium sulfate causes permanent hardness in water.

Anhydrite Mineral, anhydrous calcium sulfate

Anhydrite, or anhydrous calcium sulfate, is a mineral with the chemical formula CaSO4. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with the orthorhombic barium (baryte) and strontium (celestine) sulfates, as might be expected from the chemical formulas. Distinctly developed crystals are somewhat rare, the mineral usually presenting the form of cleavage masses. The Mohs hardness is 3.5, and the specific gravity is 2.9. The color is white, sometimes greyish, bluish, or purple. On the best developed of the three cleavages, the lustre is pearly; on other surfaces it is glassy. When exposed to water, anhydrite readily transforms to the more commonly occurring gypsum, (CaSO4·2H2O) by the absorption of water. This transformation is reversible, with gypsum or calcium sulfate hemihydrate forming anhydrite by heating to around 200 °C (400 °F) under normal atmospheric conditions. Anhydrite is commonly associated with calcite, halite, and sulfides such as galena, chalcopyrite, molybdenite, and pyrite in vein deposits.

Potassium sulfate Chemical compound

Potassium sulfate (US) or potassium sulphate (UK), also called sulphate of potash (SOP), arcanite, or archaically potash of sulfur, is the inorganic compound with formula K2SO4, a white water-soluble solid. It is commonly used in fertilizers, providing both potassium and sulfur.

Ammonium sulfate Chemical compound

Ammonium sulfate (American English and international scientific usage; ammonium sulphate in British English); (NH4)2SO4, is an inorganic salt with a number of commercial uses. The most common use is as a soil fertilizer. It contains 21% nitrogen and 24% sulfur.

Lime (material) Calcium mineral

Lime is a calcium-containing inorganic material composed primarily of oxides, and hydroxide, usually calcium oxide and/or calcium hydroxide. It is also the name for calcium oxide which occurs as a product of coal-seam fires and in altered limestone xenoliths in volcanic ejecta. The International Mineralogical Association recognizes lime as a mineral with the chemical formula of CaO. The word lime originates with its earliest use as building mortar and has the sense of sticking or adhering.

Sulfur cycle Biogeochemical cycle of sulfur

The sulfur cycle is a biogeochemical cycle in which the sulfur moves between rocks, waterways and living systems. It is important in geology as it affects many minerals and in life because sulfur is an essential element (CHNOPS), being a constituent of many proteins and cofactors, and sulfur compounds can be used as oxidants or reductants in microbial respiration. The global sulfur cycle involves the transformations of sulfur species through different oxidation states, which play an important role in both geological and biological processes. Steps of the sulfur cycle are:

Soil acidification is the buildup of hydrogen cations, which reduces the soil pH. Chemically, this happens when a proton donor gets added to the soil. The donor can be an acid, such as nitric acid, sulfuric acid, or carbonic acid. It can also be a compound such as aluminium sulfate, which reacts in the soil to release protons. Acidification also occurs when base cations such as calcium, magnesium, potassium and sodium are leached from the soil.

Lithium sulfate Chemical compound

Lithium sulfate is a white inorganic salt with the formula Li2SO4. It is the lithium salt of sulfuric acid.

Sulfur water

Sulfur water is a condition where water is exposed to hydrogen sulfide gas, giving a distinct "rotten egg" smell. This condition has different purposes in culture varying to health and implications to plumbing.

Calcium sulfite Chemical compound

Calcium sulfite, or calcium sulphite, is a chemical compound, the calcium salt of sulfite with the formula CaSO3·x(H2O). Two crystalline forms are known, the hemihydrate and the tetrahydrate, respectively CaSO3·½(H2O) and CaSO3·4(H2O). All forms are white solids. It is most notable as the product of flue-gas desulfurization.

<span class="mw-page-title-main">Composition of Mars</span> Branch of the geology of Mars

The composition of Mars covers the branch of the geology of Mars that describes the make-up of the planet Mars.


Bassanite is a calcium sulfate mineral with formula CaSO4·1/2H2O or 2CaSO4·H2O. In other words it has half a water molecule per CaSO4 unit, hence its synonym calcium sulfate hemihydrate.

A sulfite sulfate is a chemical compound that contains both sulfite and sulfate anions [SO3]2− [SO4]2−. These compounds were discovered in the 1980s as calcium and rare earth element salts. Minerals in this class were later discovered. Minerals may have sulfite as an essential component, or have it substituted for another anion as in alloriite. The related ions [O3SOSO2]2− and [(O2SO)2SO2]2− may be produced in a reaction between sulfur dioxide and sulfate and exist in the solid form as tetramethyl ammonium salts. They have a significant partial pressure of sulfur dioxide.


  1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID   235729616.
  2. Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C., eds. (2003). "Gypsum" (PDF). Handbook of Mineralogy. Vol. V (Borates, Carbonates, Sulfates). Chantilly, VA, US: Mineralogical Society of America. ISBN   978-0962209703.
  3. Gypsum. Mindat
  4. 1 2 3 Klein, Cornelis; Hurlbut, Cornelius S., Jr. (1985), Manual of Mineralogy (20th ed.), John Wiley, pp.  352–353, ISBN   978-0-471-80580-9
  5. "Compact Oxford English Dictionary: gypsum". Archived from the original on 19 July 2012.
  6. Szostakowski, B.; Smitham, P.; Khan, W.S. (17 April 2017). "Plaster of Paris–Short History of Casting and Injured Limb Immobilzation". The Open Orthopaedics Journal. 11: 291–296. doi:10.2174/1874325001711010291. ISSN   1874-3250. PMC   5420179 . PMID   28567158.
  7. See:
    • Thaer, Albrecht Daniel; Shaw, William, trans.; Johnson, Cuthbert W., trans. (1844). The Principles of Agriculture. Vol. 1. London, England: Ridgway. pp. 519–520.
    • Klaus Herrmann (1990), "Mayer, Johann Friedrich", Neue Deutsche Biographie (in German), vol. 16, Berlin: Duncker & Humblot, pp. 544–545; ( full text online ) From p. 544: " … er bewirtschaftete nebenbei ein Pfarrgüttchen, … für die Düngung der Felder mit dem in den nahen Waldenburger Bergen gefundenen Gips einsetzte." ( … he also managed a small parson's estate, on which he repeatedly conducted agricultural experiments. In 1768, he first published the fruits of his experiences during this time as "Instruction about Gypsum", in which he espoused the fertilizing of fields with the gypsum that was found in the nearby Waldenburg mountains.)
    • Beckmann, Johann (1775). Grundsätze der deutschen Landwirthschaft [Fundamentals of German Agriculture] (in German) (2nd ed.). Göttingen, (Germany): Johann Christian Dieterich. p. 60. From p. 60: "Schon seit undenklichen Zeiten … ein Gewinn zu erhalten seyn wird." (Since times immemorial, in our vicinity, in the ministry of Niedeck [a village southeast of Göttingen], one has already made this use of gypsum; but Mr. Mayer has the merit to have made it generally known. In the History of Farming in Kupferzell, he had depicted a crushing mill (p. 74), in order to pulverize gypsum, from which a profit has been obtained, albeit with difficulty.)
    • Mayer, Johann Friderich (1768). Lehre vom Gyps als vorzueglich guten Dung zu allen Erd-Gewaechsen auf Aeckern und Wiesen, Hopfen- und Weinbergen [Instruction in gypsum as an ideal good manure for all things grown in soil on fields and pastures, hops yards and vineyards] (in German). Anspach, (Germany): Jacob Christoph Posch.
  8. Smith, Joshua (2007). Borderland smuggling: Patriots, loyalists, and illicit trade in the Northeast, 1780–1820. Gainesville, FL: UPF. pp. passim. ISBN   978-0-8130-2986-3.
  9. 1 2 Bock, E. (1961). "On the solubility of anhydrous calcium sulphate and of gypsum in concentrated solutions of sodium chloride at 25 °C, 30 °C, 40 °C, and 50 °C". Canadian Journal of Chemistry. 39 (9): 1746–1751. doi:10.1139/v61-228.
  10. Mandal, Pradip K; Mandal, Tanuj K (2002). "Anion water in gypsum (CaSO4·2H2O) and hemihydrate (CaSO4·1/2H2O)". Cement and Concrete Research. 32 (2): 313. doi:10.1016/S0008-8846(01)00675-5.
  11. García-Ruiz, Juan Manuel; Villasuso, Roberto; Ayora, Carlos; Canals, Angels; Otálora, Fermín (2007). "Formation of natural gypsum megacrystals in Naica, Mexico" (PDF). Geology. 35 (4): 327–330. Bibcode:2007Geo....35..327G. doi:10.1130/G23393A.1. hdl: 10261/3439 .
  12. Cockell, C. S.; Raven, J. A. (2007). "Ozone and life on the Archaean Earth". Philosophical Transactions of the Royal Society A. 365 (1856): 1889–1901. Bibcode:2007RSPTA.365.1889C. doi:10.1098/rsta.2007.2049. PMID   17513273. S2CID   4716.
  13. Deer, W.A.; Howie, R.A.; Zussman, J. (1966). An Introduction to the Rock Forming Minerals. London: Longman. p. 469. ISBN   978-0-582-44210-8.
  14. Abarr, James (7 February 1999). "Sea of sand". The Albuquerque Journal. Archived from the original on 30 June 2006. Retrieved 27 January 2007.
  15. Machel, H.G (April 2001). "Bacterial and thermochemical sulfate reduction in diagenetic settings — old and new insights". Sedimentary Geology. 140 (1–2): 143–175. Bibcode:2001SedG..140..143M. doi:10.1016/S0037-0738(00)00176-7.
  16. Sassen, Roger; Chinn, E.W.; McCabe, C. (December 1988). "Recent hydrocarbon alteration, sulfate reduction and formation of elemental sulfur and metal sulfides in salt dome cap rock". Chemical Geology. 74 (1–2): 57–66. Bibcode:1988ChGeo..74...57S. doi:10.1016/0009-2541(88)90146-5.
  17. Wolfgang Nehb, Karel Vydra. "Sulfur". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a25_507.pub2.
  18. High-resolution Mars image gallery. University of Arizona
  19. NASA Mars Rover Finds Mineral Vein Deposited by Water, NASA, 7 December 2011.
  20. "GYPSUM" (PDF). U.S. Geological Survey.
  21. "Mines, mills and concentrators in Canada". Natural Resources Canada. 24 October 2005. Archived from the original on 13 March 2005. Retrieved 27 January 2007.
  22. The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide. Helion. 2018 via Credo Reference.
  23. Alleyne, Richard (27 October 2008). "World's largest crystal discovered in Mexican cave". The Telegraph. London. Retrieved 6 June 2009.
  24. Koralegedara, NH; Pinto, PX; Dionysiou, DD; Al-Abed, SR (1 December 2019). "Recent advances in flue gas desulfurization gypsum processes and applications - A review". Journal of Environmental Management. 251: 109572. doi:10.1016/j.jenvman.2019.109572. PMC   7396127 . PMID   31561139.
  25. Uchymiak, Michal; Lyster, Eric; Glater, Julius; Cohen, Yoram (April 2008). "Kinetics of gypsum crystal growth on a reverse osmosis membrane". Journal of Membrane Science. 314 (1–2): 163–172. doi:10.1016/j.memsci.2008.01.041.
  26. Van Driessche, A.E.S.; Benning, L. G.; Rodriguez-Blanco, J. D.; Ossorio, M.; Bots, P.; García-Ruiz, J. M. (2012). "The role and implications of bassanite as a stable precursor phase to gypsum precipitation". Science . 336 (6077): 69–72. Bibcode:2012Sci...336...69V. doi:10.1126/science.1215648. PMID   22491851. S2CID   9355745.
  27. 1 2 Tayibi, Hanan; Choura, Mohamed; López, Félix A.; Alguacil, Francisco J.; López-Delgado, Aurora (2009). "Environmental Impact and Management of Phosphogypsum". Journal of Environmental Management. 90 (8): 2377–2386. doi:10.1016/j.jenvman.2009.03.007. hdl: 10261/45241 . PMID   19406560.
  28. 1 2 Zhang, Y; Wang, F; Huang, H; Guo, Y; Li, B; Liu, Y; Chu, PK (2016). "Gypsum blocks produced from TiO2 production by-products" (PDF). Environmental Technology. 37 (9): 1094–100. doi:10.1080/09593330.2015.1102329. PMID   26495867. S2CID   28458281.
  29. Michigan Gypsum. "MATERIAL SAFETY DATA SHEET Gypsum (Calcium Sulfate Dihydrate)" (PDF). Consumer Information. NorthCentral Missouri College. Retrieved 21 November 2021.
  30. "Compound Summary for CID 24497 - Calcium Sulfate". PubChem.
  31. 1 2 "CDC – NIOSH Pocket Guide to Chemical Hazards – Gypsum". Retrieved 3 November 2015.
  32. Bonewitz, Ronald (2008). Rock and Gem: The Definitive Guide to Rocks, Minerals, Gems, and Fossils. United States: DK. p. 47.
  33. Graham, Gerald S. (1938). "The Gypsum Trade of the Maritime Provinces: Its Relation to American Diplomacy and Agriculture in the Early Nineteenth Century". Agricultural History. 12 (3): 209–223. JSTOR   3739630.
  34. 1 2 "Gypsum as an agricultural product | Soil Science Society of America".
  35. Genesis and Management of Sodic (Alkali) Soils. (2017). (n.p.): Scientific Publishers.
  36. Oster, J. D.; Frenkel, H. (1980). "The chemistry of the reclamation of sodic soils with gypsum and lime". Soil Science Society of America Journal . 44 (1): 41–45. Bibcode:1980SSASJ..44...41O. doi:10.2136/sssaj1980.03615995004400010010x.
  37. Ley, Willy (October 1961). "The Home-Made Land". For Your Information. Galaxy Science Fiction. pp. 92–106.
  38. Hogan, C. Michael (2007). "Knossos fieldnotes". Modern Antiquarian.
  39. Durner, W.; Or, D. (2006). "Soil water potential measurement" (PDF). In Anderson, M.G. (ed.). Encyclopedia of hydrological sciences. John Wiley & Sons Ltd. ISBN   978-0471491033 . Retrieved 23 May 2022.
  40. Rapp, George (2009). "Soft Stones and Other Carvable Materials". Archaeomineralogy. Natural Science in Archaeology: 121–142. doi:10.1007/978-3-540-78594-1_6. ISBN   978-3-540-78593-4.
  41. Kloppmann, W.; Leroux, L.; Bromblet, P.; Le Pogam, P.-Y.; Cooper, A. H.; Worley, N.; Guerrot, C.; Montech, A. T.; Gallas, A. M.; Aillaud, R. (7 November 2017). "Competing English, Spanish, and French alabaster trade in Europe over five centuries as evidenced by isotope fingerprinting". Proceedings of the National Academy of Sciences. 114 (45): 11856–11860. Bibcode:2017PNAS..11411856K. doi: 10.1073/pnas.1707450114 . PMC   5692548 . PMID   29078309.
  42. Brown, Michelle (1995). Understanding illuminated manuscripts : a guide to technical terms. Los Angeles, California. p. 58. ISBN   9780892362172.
  43. Shurtleff, William (2000). Tofu & soymilk production : a craft and technical manual. Lafayette, CA: Soyfoods Center. ISBN   9781928914044.
  44. Palmer, John. "Water Chemistry Adjustment for Extract Brewing". Retrieved 15 December 2008.
  45. "Calcium sulphate for the baking industry" (PDF). United States Gypsum Company. Archived from the original (PDF) on 4 July 2013. Retrieved 1 March 2013.
  46. "Tech sheet for yeast food" (PDF). Lesaffre Yeast Corporation. Archived from the original (PDF) on November 2014. Retrieved 1 March 2013.
  47. Austin, R.T. (March 1983). "Treatment of broken legs before and after the introduction of gypsum". Injury. 14 (5): 389–394. doi:10.1016/0020-1383(83)90089-X. PMID   6347885.
  48. Drennon, David G.; Johnson, Glen H. (February 1990). "The effect of immersion disinfection of elastomeric impressions on the surface detail reproduction of improved gypsum casts". The Journal of Prosthetic Dentistry. 63 (2): 233–241. doi:10.1016/0022-3913(90)90111-O. PMID   2106026.
  49. Govender, Desania R.; Focke, Walter W.; Tichapondwa, Shepherd M.; Cloete, William E. (20 June 2018). "Burn Rate of Calcium Sulfate Dihydrate–Aluminum Thermites". ACS Applied Materials & Interfaces. 10 (24): 20679–20687. doi:10.1021/acsami.8b04205. hdl:2263/66006. PMID   29842778. S2CID   206483977.
  50. Astilleros, J.M.; Godelitsas, A.; Rodríguez-Blanco, J.D.; Fernández-Díaz, L.; Prieto, M.; Lagoyannis, A.; Harissopulos, S. (2010). "Interaction of gypsum with lead in aqueous solutions" (PDF). Applied Geochemistry. 25 (7): 1008. Bibcode:2010ApGC...25.1008A. doi:10.1016/j.apgeochem.2010.04.007.
  51. Rodriguez, J. D.; Jimenez, A.; Prieto, M.; Torre, L.; Garcia-Granda, S. (2008). "Interaction of gypsum with As(V)-bearing aqueous solutions: Surface precipitation of guerinite, sainfeldite, and Ca2NaH(AsO4)2⋅6H2O, a synthetic arsenate". American Mineralogist. 93 (5–6): 928. Bibcode:2008AmMin..93..928R. doi:10.2138/am.2008.2750. S2CID   98249784.
  52. Rodríguez-Blanco, Juan Diego; Jiménez, Amalia; Prieto, Manuel (2007). "Oriented Overgrowth of Pharmacolite (CaHAsO4⋅2H2O) on Gypsum (CaSO4⋅2H2O)". Cryst. Growth Des. 7 (12): 2756–2763. doi:10.1021/cg070222+.