Gypsumis a softsulfate mineralcomposed ofcalcium sulfatedihydrate,with thechemical formulaCaSO4·2H2O.[4]It is widely mined and is used as afertilizerand as the main constituent in many forms ofplaster,drywallandblackboardorsidewalk chalk.[5][6][7][8]Gypsum alsocrystallizesas translucent crystals ofselenite.It forms as anevaporitemineral and as ahydrationproduct ofanhydrite.TheMohs scale of mineral hardnessdefines gypsum as hardness value 2 based onscratchhardness comparison.
Gypsum | |
---|---|
![]() | |
General | |
Category | Sulfate minerals |
Formula (repeating unit) | CaSO4·2H2O |
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 |
Identification | |
Color | Colorless (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 scalehardness | 1.5–2 (defining mineral for 2) |
Luster | Vitreous to silky, pearly, or waxy |
Streak | White |
Diaphaneity | Transparent to translucent |
Specific gravity | 2.31–2.33 |
Optical properties | Biaxial (+) |
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 spar | Pearly, fibrous masses |
Selenite | Transparent and bladed crystals |
Alabaster | Fine-grained, slightly colored |
Fine-grained white or lightly tinted forms of gypsum known asalabasterhave been used forsculptureby many cultures includingAncient Egypt,Mesopotamia,Ancient Rome,theByzantine Empire,and theNottingham alabastersofMedieval England.
Etymology and history
editThe wordgypsumis derived from theGreekwordγύψος(gypsos), "plaster".[9]Because thequarriesof theMontmartredistrict ofParishave long furnished burnt gypsum (calcinedgypsum) used for various purposes, this dehydrated gypsum became known asplaster 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.[10]
Gypsum was known in Old English asspærstān,"spear stone", referring to its crystalline projections. Thus, the wordsparin mineralogy, by comparison to gypsum, refers to any non-oremineral or crystal that forms in spearlike projections. In the mid-18th century, the German clergyman and agriculturalistJohann Friderich Mayerinvestigated and publicized gypsum's use as a fertilizer.[11]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.[12]
Physical properties
editGypsum is moderately water-soluble (~2.0–2.5 g/L at 25 °C)[13]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 tocalcium sulfate hemihydrate(bassanite,often simply called "plaster" ) and, if heated further, to anhydrouscalcium sulfate(anhydrite). As withanhydrite,the solubility of gypsum in saline solutions and inbrinesis also strongly dependent onsodium chloride(common table salt) concentration.[13]
The structure of gypsum consists of layers of calcium (Ca2+) and sulfate (SO2−4) ions tightly bound together. These layers are bonded by sheets ofanion watermolecules via weakerhydrogen bonding,which gives the crystal perfect cleavage along the sheets (in the {010} plane).[4][14]
Crystal varieties
editGypsum occurs in nature as flattened and oftentwinnedcrystals,and transparent, cleavable masses calledselenite.Selenite contains no significantselenium;rather, both substances were named for the ancient Greek word for theMoon.
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, calledalabaster,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 calleddesert rose.It also forms some of the largest crystals found in nature, up to 12 m (39 ft) long, in the form of selenite.[15]
Occurrence
editGypsum is a common mineral, with thick and extensiveevaporitebeds in association withsedimentary rocks.Deposits are known to occur instratafrom as far back as theArchaeaneon.[16]Gypsum is deposited from lake and sea water, as well as inhot springs,fromvolcanicvapors, and sulfate solutions inveins.Hydrothermalanhydritein veins is commonly hydrated to gypsum by groundwater in near-surface exposures. It is often associated with the mineralshaliteandsulfur.Gypsum is the most common sulfate mineral.[17]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 theWhite Sands National Parkin the US state ofNew Mexicohave created a 710 km2(270 sq mi) expanse of white gypsum sand, enough to supply the US construction industry withdrywallfor 1,000 years.[18] Commercial exploitation of the area, strongly opposed by area residents, was permanently prevented in 1933 when PresidentHerbert Hooverdeclared the gypsumdunesa protectednational monument.
Gypsum is also formed as a by-product ofsulfideoxidation,amongst others bypyriteoxidation,when thesulfuric acidgenerated reacts withcalcium carbonate.Its presence indicates oxidizing conditions. Under reducing conditions, the sulfates it contains can be reduced back to sulfide bysulfate-reducing bacteria.This can lead to accumulation of elemental sulfur in oil-bearing formations,[19]such as salt domes,[20]where it can be mined using theFrasch process[21]Electric power stations burning coal withflue gas desulfurizationproduce large quantities of gypsum as a byproduct from the scrubbers.
Orbital pictures from theMars Reconnaissance Orbiter(MRO) have indicated the existence of gypsum dunes in the northern polar region of Mars,[22]which were later confirmed at ground level by theMars Exploration Rover(MER)Opportunity.[23]
-
Large gypsum crystals inLechuguilla Cave's "chandelier ballroom"
-
Gypsum crystals in theCave of the Crystalsin Mexico (person at lower right for scale)
-
Gypsum crystals formed as the water evaporated inLake Lucero,White Sands National Park
-
Gypsum veins in the silts/marls of the Tea Green and Grey Marls,Blue Anchor,Somerset,United Kingdom
-
Gypsum veins inCaprock Canyons State Park and Trailway,Texas
-
Dunes made of small crystals of gypsum, White Sands National Park
Mining
editCountry | Production | Reserves |
---|---|---|
China | 132,000 | — |
Iran | 22,000 | 1,600 |
Thailand | 12,500 | — |
United States | 11,500 | 700,000 |
Turkey | 10,000 | — |
Spain | 6,400 | — |
Mexico | 5,300 | — |
Japan | 5,000 | — |
Russia | 4,500 | — |
Italy | 4,100 | — |
India | 3,500 | 39,000 |
Australia | 3,500 | — |
Oman | 3,500 | — |
Brazil | 3,300 | 290,000 |
France | 3,300 | — |
Canada | 2,700 | 450,000 |
Saudi Arabia | 2,400 | — |
Algeria | 2,200 | — |
Germany | 1,800 | 450,000 |
Argentina | 1,400 | — |
Pakistan | 1,300 | — |
United Kingdom | 1,200 | 55,000 |
Other countries | 15,000 | — |
World total | 258,000 | — |
Commercial quantities of gypsum are found in the cities ofAraripinaandGrajaúin Brazil; in Pakistan, Jamaica, Iran (world's second largest producer), Thailand, Spain (the main producer in Europe), Germany, Italy, England, Ireland, Canada[25]and the United States. Large open pit quarries are located in many places includingFort Dodge, Iowa,which sits on one of the largest deposits of gypsum in the world,[26]andPlaster City, California,United States, and EastKutai,Kalimantan,Indonesia. Several small mines also exist in places such asKalannieinWestern Australia,where gypsum is sold to private buyers for additions of calcium and sulfur as well as reduction of aluminum toxicities onsoilfor agricultural purposes.
Crystals of gypsum up to 11 m (36 ft) long have been found in the caves of theNaica MineofChihuahua,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.[27]
-
Golden gypsum crystals fromWinnipeg
Synthesis
editSyntheticgypsum is produced as a waste product or by-product in a range of industrial processes.
Desulfurization
editFlue gas desulfurizationgypsum (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.[28]
Desalination
editGypsum precipitates onto brackish watermembranes,a phenomenon known as mineral saltscaling,such as duringbrackishwaterdesalinationof water with high concentrations ofcalciumandsulfate.Scaling decreases membrane life and productivity.[29]This is one of the main obstacles in brackish water membrane desalination processes, such asreverse osmosisornanofiltration.Other forms of scaling, such ascalcitescaling, depending on the water source, can also be important considerations indistillation,as well as inheat exchangers,where either the saltsolubilityorconcentrationcan change rapidly.
A new study has suggested that the formation of gypsum starts as tiny crystals of a mineral calledbassanite(2CaSO4·H2O).[30]This process occurs via a three-stage pathway:
- homogeneous nucleation of nanocrystalline bassanite;
- self-assembly of bassanite into aggregates, and
- transformation of bassanite into gypsum.
Refinery waste
editThe production ofphosphatefertilizers requires breaking down calcium-containingphosphate rockwith acid, producing calcium sulfate waste known asphosphogypsum(PG). This form of gypsum is contaminated by impurities found in the rock, namelyfluoride,silica,radioactive elements such asradium,and heavy metal elements such ascadmium.[31]Similarly, production oftitanium dioxideproduces titanium gypsum (TG) due to neutralization of excess acid withlime.The product is contaminated with silica, fluorides, organic matters, and alkalis.[32]
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.[31]To reduce the accumulation and ultimately clear out these stacks, research is underway to find more applications for such waste products.[32]
Occupational safety
editNFPA 704 safety square | |
---|---|
Gypsum |
People can be exposed to gypsum in the workplace by breathing it in, skin contact, and eye contact. Calcium sulfateper seis nontoxic and is even approved as a food additive,[34]but as powdered gypsum, it can irritate skin and mucous membranes.[35]
United States
editTheOccupational Safety and Health Administration(OSHA) has set the legal limit (permissible exposure limit) for gypsum exposure in the workplace as TWA 15 mg/m3for total exposure and TWA 5 mg/m3for respiratory exposure over an eight-hour workday. TheNational Institute for Occupational Safety and Health(NIOSH) has set arecommended exposure limit(REL) of TWA 10 mg/m3for total exposure and TWA 5 mg/m3for respiratory exposure over an eight-hour workday.[35]
Uses
editGypsum is used in a wide variety of applications:
Construction industry
edit- Gypsum board[36]is primarily used as a finish for walls and ceilings, and is known in construction as plasterboard, "sheetrock", or drywall. Gypsum provides a degree of fire-resistance to these materials and glass fibers are added to their composition to accentuate this effect. Gypsum has little heat conductivity, giving its plaster some insulative properties.[37]
- Gypsum blocksare used like concrete blocks in building construction.
- Gypsum mortaris an ancient mortar used in building construction.
- A component ofPortland cementused to prevent flash setting (too rapid hardening) ofconcrete.
- A wood substitute in the ancient world: For example, when wood became scarce due to deforestation onBronze AgeCrete,gypsum was employed in building construction at locations where wood was previously used.[38]
Agriculture
edit- Fertilizer:In the late 18th and early 19th centuries, Nova Scotia gypsum, often referred to as plaster, was a highly sought fertilizer for wheat fields in the United States.[39]Gypsum provides two of thesecondary plant macronutrients,calcium and sulfur. Unlike limestone, it generally does not affect soil pH.[40]
- Reclamationofsaline soils,regardless of pH. When gypsum is added to sodic (saline) andacidic soil,the highlysolubleform ofboron(sodium metaborate) is converted to the less solublecalcium metaborate.Exchangeable sodium percentageis also reduced by gypsum application.[41][42]TheZuiderzee Worksuses gypsum for the recovered land.[43]
- Othersoil conditioneruses: Gypsum reduces aluminium and boron toxicity in acidic soils. It also improves soil structure, improving water absorption and aeration.[40]
- Soilwater potentialmonitoring: a gypsum block can be inserted into soil, its electrical resistance measured to derive soil moisture.[44]
Modeling, sculpture and art
edit- Plasterfor casting moulds and modeling.
- Asalabaster,a material for sculpture, it was used especially in the ancient world before steel was developed, when its relative softness made it much easier to carve.[45]During theMiddle AgesandRenaissance,it was preferred even tomarble.[46]
- In the medieval period,scribesandilluminatorsused it as an ingredient ingesso,which was applied to illuminated letters and gilded with gold in illuminated manuscripts.[47]
Food and drink
edit- Atofu(soy bean curd) coagulant, making it ultimately a significant source of dietarycalcium.[48]
- Addinghardnessto water used forbrewing.[49]
- Used in baking as a dough conditioner, reducing stickiness, and as a baked-goods source of dietary calcium.[50]The primary component of mineral yeast food.[51]
- Used in mushroom cultivation to stop grains from clumping together.
Medicine and cosmetics
editOther
editGallery
edit- Unusual gypsum specimens from around the world
-
Green gypsum crystals from Pernatty Lagoon, Mt Gunson,South Australia- its green color is due to presence ofcopperions.
-
Unusual selenite gypsum from theRed River,Winnipeg, Manitoba, Canada
-
Classic "ram's horn" gypsum fromSanta Eulalia, Chihuahua,Mexico, 7.5×4.3×3.8 cm
-
Desert rose,47 cm long
-
Gypsum from Pernatty Lagoon, Mt Gunson, Stuart Shelf area, Andamooka Ranges - Lake Torrens area, South Australia, Australia
-
Gypsum with crystallinenative copperinside
-
Gypsum from Swan Hill, Victoria, Australia. The coloring is due to the copper oxide
-
Waterclear twined crystal of the form known as "Roman sword". Fuentes de Ebro, Zaragoza (Spain)
-
Bright, cherry-red gypsum crystals 2.5 cm in height colored by rich inclusions of the rare mineralbotryogen
-
Gypsum from Naica, Mun. de Saucillo, Chihuahua, Mexico
-
Golden color gem, "fishtail" -twinned crystals of gypsum sitting atop a "ball" of gypsum which is composed of several single bladed crystals
See also
editReferences
edit- ^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.S2CID235729616.
- ^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.ISBN978-0962209703.Archived(PDF)from the original on 6 February 2006.
- ^Gypsum.Mindat
- ^abcKlein, Cornelis; Hurlbut, Cornelius S. Jr. (1985),Manual of Mineralogy(20th ed.), John Wiley, pp.352–353,ISBN978-0-471-80580-9
- ^Institute, Canadian Conservation (14 September 2017)."Care of Objects Made of Plaster of Paris – Canadian Conservation Institute (CCI) Notes 12/2".www.canada.ca.Retrieved20 January2023.
- ^Make your own sidewalk chalk. (1998, July 21). Christian Science Monitor. 13.
- ^"Plaster | Definition, Uses, Types, & Facts".Britannica.Retrieved20 January2023.
- ^"drywall — definition".Merriam-Webster.Retrieved20 January2023.
- ^"Compact Oxford English Dictionary: gypsum".Oxford Dictionaries.Archived fromthe originalon 19 July 2012.
- ^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.ISSN1874-3250.PMC5420179.PMID28567158.
- ^See:
- Thaer, Albrecht Daniel (1844).The Principles of Agriculture.Vol. 1. Translated by Shaw, William; Johnson, Cuthbert W. 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 theHistory 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.
- ^Smith, Joshua (2007).Borderland smuggling: Patriots, loyalists, and illicit trade in the Northeast, 1780–1820.Gainesville, FL: UPF. pp. passim.ISBN978-0-8130-2986-3.
- ^abBock, 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.
- ^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.
- ^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.Archived(PDF)from the original on 16 August 2017.
- ^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.PMID17513273.S2CID4716.
- ^Deer, W.A.; Howie, R.A.; Zussman, J. (1966).An Introduction to the Rock Forming Minerals.London: Longman. p. 469.ISBN978-0-582-44210-8.
- ^Abarr, James (7 February 1999)."Sea of sand".The Albuquerque Journal.Archived fromthe originalon 30 June 2006.Retrieved27 January2007.
- ^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.S2CID4606551.
- ^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.
- ^Wolfgang Nehb, Karel Vydra. "Sulfur".Ullmann's Encyclopedia of Industrial Chemistry.Weinheim: Wiley-VCH.doi:10.1002/14356007.a25_507.pub2.ISBN978-3527306732.
- ^High-resolution Mars image gallery.University of Arizona
- ^NASA Mars Rover Finds Mineral Vein Deposited by WaterArchived15 June 2017 at theWayback Machine,NASA, 7 December 2011.
- ^"GYPSUM"(PDF).U.S. Geological Survey.Archived(PDF)from the original on 12 December 2016.
- ^"Mines, mills and concentrators in Canada".Natural Resources Canada. 24 October 2005. Archived fromthe originalon 13 March 2005.Retrieved27 January2007.
- ^The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide.Helion. 2018 – via Credo Reference.
- ^Alleyne, Richard (27 October 2008)."World's largest crystal discovered in Mexican cave".The Telegraph.London.Retrieved6 June2009.
- ^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.PMC7396127.PMID31561139.
- ^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.
- ^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.PMID22491851.S2CID9355745.
- ^abTayibi, 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.Bibcode:2009JEnvM..90.2377T.doi:10.1016/j.jenvman.2009.03.007.hdl:10261/45241.PMID19406560.
- ^abZhang, 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.Bibcode:2016EnvTe..37.1094Z.doi:10.1080/09593330.2015.1102329.PMID26495867.S2CID28458281.Archived(PDF)from the original on 25 March 2022.
- ^Michigan Gypsum."MATERIAL SAFETY DATA SHEET Gypsum (Calcium Sulfate Dihydrate)"(PDF).Consumer Information.NorthCentral Missouri College.Archived(PDF)from the original on 21 November 2021.Retrieved21 November2021.
- ^"Compound Summary for CID 24497 – Calcium Sulfate".PubChem.
- ^ab"CDC – NIOSH Pocket Guide to Chemical Hazards – Gypsum".www.cdc.gov.Retrieved3 November2015.
- ^*Complimentary list of MasterFormat 2004 Edition numbers and titles(large PDF document)
- ^Bonewitz, Ronald (2008).Rock and Gem: The Definitive Guide to Rocks, Minerals, Gems, and Fossils.United States: DK. p. 47.
- ^Hogan, C. Michael (2007)."Knossos fieldnotes".Modern Antiquarian.
- ^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.JSTOR3739630.
- ^ab"Gypsum as an agricultural product | Soil Science Society of America".www.soils.org.
- ^Genesis and Management of Sodic (Alkali) Soils.(2017). (n.p.): Scientific Publishers.
- ^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.
- ^Ley, Willy (October 1961)."The Home-Made Land".For Your Information.Galaxy Science Fiction.pp. 92–106.
- ^Durner, W.; Or, D. (2006)."Soil water potential measurement"(PDF).In Anderson, M.G. (ed.).Encyclopedia of hydrological sciences.John Wiley & Sons Ltd.ISBN978-0471491033.Archived(PDF)from the original on 16 June 2022.Retrieved23 May2022.
- ^Rapp, George (2009). "Soft Stones and Other Carvable Materials".Archaeomineralogy.Natural Science in Archaeology. pp. 121–142.doi:10.1007/978-3-540-78594-1_6.ISBN978-3-540-78593-4.
- ^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.PMC5692548.PMID29078309.
- ^Brown, Michelle (1995).Understanding illuminated manuscripts: a guide to technical terms.Los Angeles, California: Yale University Press. p. 58.ISBN9780892362172.
- ^Shurtleff, William (2000).Tofu & soymilk production: a craft and technical manual.Lafayette, CA: Soyfoods Center. p. 99.ISBN9781928914044.
- ^Palmer, John."Water Chemistry Adjustment for Extract Brewing".HowToBrew.com.Retrieved15 December2008.
- ^"Calcium sulphate for the baking industry"(PDF).United States Gypsum Company.Archived fromthe original(PDF)on 4 July 2013.Retrieved1 March2013.
- ^"Tech sheet for yeast food"(PDF).Lesaffre Yeast Corporation.Archived fromthe original(PDF)on 29 October 2013.Retrieved1 March2013.
- ^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.PMID6347885.
- ^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.PMID2106026.
- ^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.PMID29842778.S2CID206483977.
- ^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.Archived(PDF)from the original on 9 August 2017.
- ^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.S2CID98249784.
- ^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+.