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Gypsum

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Formula:
CaSO
 
4
· 2H
 
2
O
System:MonoclinicColour:Colourless to white, ...
Hardness:2
Name:First known mention is by Theophrastus about 300-325 BCE from the Greek γυψοζ (gypsos) meaning plaster.
Isostructural with:Ardealite, Brushite, Pharmacolite


The most common sulphate mineral.
Found as both massive material, including the alabaster variety; and clear crystals, the selenite variety; and, parallel fibrous, the satin spar variety. Typically colourless to white, transparent crystals, thick tabular to lenticular, sometimes prismatic.

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Classification of Gypsum

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:6/C.22-20
Nickel-Strunz 10th (pending) edition ID:7.CD.40

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
C : Sulfates (selenates, etc.) without additional anions, with H2O
D : With only large cations
Dana 7th edition ID:29.6.3.1
Dana 8th edition ID:29.6.3.1

29 : HYDRATED ACID AND NORMAL SULFATES
6 : AXO4·xH2O
Hey's CIM Ref.:25.4.3

25 : Sulphates
4 : Sulphates of Ca, Sr and Ba
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Occurrences of Gypsum

Geological Setting:Commonest of the sulphate minerals, gypsum is found in marine evaporites, in caves where the air is dry enough to allow it to be deposited and remain, at fumaroles, and in the oxidized zones of sulfide deposits on occasion.

Physical Properties of Gypsum

Lustre:Vitreous, Sub-Vitreous, Silky, Pearly, Dull
Diaphaneity (Transparency):Transparent, Translucent, Opaque
Comment:Wide range of luster based on varieties, pearly on {010}
Colour:Colourless to white, often tinged other hues due to impurities; colourless in transmitted light..
Streak:White.
Hardness (Mohs):2
Hardness Data:Mohs hardness reference species
Comment:Hardness varies with direction down to 1.5
Tenacity:Flexible
Cleavage:Perfect
Perfect (eminent) and easy on {010}, almost micaceous in some samples; on {100} distinct, yielding a surface with a conchoidal fracture; on {011}, yielding a fibrous fracture {001}.
Fracture:Splintery, Conchoidal
Translation gliding:Readily undergroes translation gliding with T{010}, t{[001], which can also be generated by torsion about [001], or bending {010} about [010].
Comment:Also inelastic. Breakage depends on orientation.
Density (measured):2.312 - 2.322 g/cm3
Density (calculated):2.308 g/cm3

Crystallography of Gypsum

Crystal System:Monoclinic
Class (H-M):2/m - Prismatic
Cell Parameters:a = 5.679(5) Å, b = 15.202(14) Å, c = 6.522(6) Å
β = 118.43°
Ratio:a:b:c = 0.374 : 1 : 0.429
Unit Cell Volume:V 495.15 ų (Calculated from Unit Cell)
Z:4
Morphology:Thin to thick tabular crystals, {010} with {111} and {120}; also prismatic [001], stout to acicular, with the prism zone often striated. Crystals may have warped surfaces, or be bent or twisted. Rosette-like clusters of lenticular crystals are common. Also found as granular masses, massive beds, and fibrous masses ("satin spar").
Twinning:{100} ("swallow-tail"), very common, with a re-entrant angle formed ordinarily by {111}; on {101} as contact twins ("butterfly" or "heart-shaped"), along {111}; on {209}; also as cruciform penetration twins.
Comment:Data for I2/c cell (non-standard setting). There is another setting with space group C2/c and beta ~ 127°, and a further C2/c setting with a ~6.27, b ~15.20, c ~5.67 A, beta ~114°.
Crystal Atlas:
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Gypsum no.4 - Goldschmidt (1913-1926)
Gypsum no.23 - Goldschmidt (1913-1926)
Gypsum no.36 - Goldschmidt (1913-1926)
Gypsum no.52 - Goldschmidt (1913-1926)
Gypsum no.101 - Goldschmidt (1913-1926)

About Crystal Atlas

The mindat.org Crystal Atlas allows you to view a selection of crystal drawings of real and idealised crystal forms for this mineral and, in certain cases, 3d rotating crystal objects. The 3d models and HTML5 code are kindly provided by www.smorf.nl.

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Structure
  Reference
Boeyens J C A Ichharam V V H (2002) Redetermination of the crystal structure of calcium sulphate dihydrate, CaSO4*2H2O Locality: synthetic. Zeitschrift fur Kristallographie 217:9-10.

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More Crystal Structures
Click here to view more crystal structures at the American Mineralogist Crystal Structure Database
X-Ray Powder Diffraction:
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Radiation - Copper Kα
Data Set:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data:
Data courtesy of RRUFF project at University of Arizona, used with permission.
X-Ray Powder Diffraction:
d-spacingIntensity
7.63(100)
4.28(100)
3.80(20)
3.07(80)
2.87(50)
2.69(40)
2.22(20)
2.09(300

Optical Data of Gypsum

Type:Biaxial (+)
RI values: nα = 1.519 - 1.521 nβ = 1.522 - 1.523 nγ = 1.529 - 1.530
2V:Measured: 58° , Calculated: 58° to 68°
Maximum Birefringence:δ = 0.010

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Low
Dispersion:Strong r > v inclined

Chemical Properties of Gypsum

Formula:
CaSO
 
4
· 2H
 
2
O
Simplified for copy/paste:CaSO4·2H2O
Essential elements:Ca, H, O, S
All elements listed in formula:Ca, H, O, S
Analytical Data:Slightly soluble in water. Soluble in HCl.

Relationship of Gypsum to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
7.CD.05Matteuccite
NaHSO
 
4
· H
 
2
O
7.CD.10Mirabilite
Na
 
2
SO
 
4
· 10H
 
2
O
7.CD.15Lecontite
(NH
 
4
,K)NaSO
 
4
· 2H
 
2
O
7.CD.20Hydroglauberite
Na
 
10
Ca
 
3
(SO
 
4
)
 
8
· 6H
 
2
O
7.CD.25Eugsterite
Na
 
4
Ca(SO
 
4
)
 
3
· 2H
 
2
O
7.CD.30Görgeyite
K
 
2
Ca
 
5
(SO
 
4
)
 
6
· H
 
2
O
7.CD.35Koktaite
(NH
 
4
)
 
2
Ca(SO
 
4
)
 
2
· H
 
2
O
7.CD.35Syngenite
K
 
2
Ca(SO
 
4
)
 
2
· H
 
2
O
7.CD.45Bassanite
CaSO
 
4
· 0.5H
 
2
O
7.CD.50Zircosulfate
(Zr,Ti)(SO
 
4
)
 
2
· 4H
 
2
O
7.CD.55Schieffelinite
Pb
 
8
(TeO
 
4
)
 
5
(SO
 
4
)
 
3
· 8H
 
2
O
7.CD.60Montanite
Bi
 
2
(TeO
 
6
) · 2H
 
2
O
7.CD.65Omongwaite
Na
 
2
Ca
 
5
(SO
 
4
)
 
6
· 3H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
25.4.1Anhydrite
CaSO
 
4
25.4.2Bassanite
CaSO
 
4
· 0.5H
 
2
O
25.4.4Glauberite
Na
 
2
Ca(SO
 
4
)
 
2
25.4.5Cesanite
Na
 
3
Ca
 
2
(SO
 
4
)
 
3
(OH)
25.4.6Eugsterite
Na
 
4
Ca(SO
 
4
)
 
3
· 2H
 
2
O
25.4.7Hydroglauberite
Na
 
10
Ca
 
3
(SO
 
4
)
 
8
· 6H
 
2
O
25.4.8Syngenite
K
 
2
Ca(SO
 
4
)
 
2
· H
 
2
O
25.4.9Görgeyite
K
 
2
Ca
 
5
(SO
 
4
)
 
6
· H
 
2
O
25.4.10Polyhalite
K
 
2
Ca
 
2
Mg(SO
 
4
)
 
4
· 2H
 
2
O
25.4.11Koktaite
(NH
 
4
)
 
2
Ca(SO
 
4
)
 
2
· H
 
2
O
25.4.12Ye'elimite
Ca
 
4
Al
 
6
(SO
 
4
)O
 
12
25.4.13Ettringite
Ca
 
6
Al
 
2
(SO
 
4
)
 
3
(OH)
 
12
· 26H
 
2
O
25.4.14Bentorite
Ca
 
6
(Cr
3+
 
,Al)
 
2
(SO
 
4
)
 
3
(OH)
 
12
· 26H
 
2
O
25.4.15Celestine
SrSO
 
4
25.4.16Kalistrontite
K
 
2
Sr(SO
 
4
)
 
2
25.4.17Baryte
BaSO
 
4

Other Names for Gypsum

Synonyms:
AphroselenonGypsiteGypsum RoseLapis SpecularisMarmor fugax
MontmartriteOulopholiteSpectacle-StoneSulphate of Lime
Other Languages:
Arabic:جص
Bulgarian:Гипс
Catalan:Guix
Croatian:Gips
Czech:Sádrovec
Danish:Gips
Dutch:Gips
Esperanto:Gipsoŝtono
Gipso
Estonian:Kips
French:Gypse
Chaux sulfatée
German:Gips
Atlasgips
Gipsrose
Gyps
Gypsit
Oulopholit
Greek:Γύψος
Hebrew:גבס
Hungarian:Gipsz
Italian:Gesso
Acido vitriolo saturata
Geso
Japanese:石膏
Korean:석고
Latin:Gypsum
Latvian:Ģipsis
Lithuanian:Gipsas
Norwegian (Bokmål):Gips
Polish:Gips
Portuguese:Gipsita
Romanian:Gips
Russian:Гипс
Serbian (Cyrillic Script):Гипс
Simplified Chinese:石膏
Slovak:Sadrovec
Slovenian:Sadra
Spanish:Yeso
Gypsita
Oulopholita
Swedish:Gips
Thai:ยิปซัม
Traditional Chinese:石膏
Vietnamese:Thạch cao
Varieties:
AlabasterOrditeSatin Spar GypsumSelenite

Other Information

Fluorescence in UV light:Common and varied. Most common colours of fluorescence are baby-blue and shades of golden yellow to yellow. Selenite crystals often exhibit zoned "hourglass" fluorescence in zones that may, or may not, be evident in ordinary light.
Electrical:Not piezoelectric.
Thermal Behaviour:Dehydrates and turns white.
Other Information:Crystals containing impurities such as sand may exhibit "hourglass" shaped zones with and without the included matter. Cleavage plates may exhibit asterism when held up against a source of light.
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:Plaster, plasterboard.

References for Gypsum

Reference List:

- +
Linnaeus (1736) Systema Naturae of Linnaeus (as Marmor fugax).

Delamétherie, J.C. (1812) Leçons de minéralogie. 8vo, Paris: volume 2: 380 (as Montmartrite).

Reuss (1869) Annalen der Physik, Halle, Leipzig: 136: 135.

Baumhauer (1875) Akademie der Wissenschaften, Munich, Sitzber.: 169.

Beckenkamp (1882) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 6: 450.

Mügge (1883) Neues Jahrbuch für Mineralogie, Geologie und Paleontologie, Heidelberg, Stuttgart: II: 14.

Reuss (1883) Akademie der Wissenschaften, Berlin (Sitzungsberichte der): 259.

Mügge (1884) Neues Jahrbuch für Mineralogie, Geologie und Paleontologie, Heidelberg, Stuttgart: I: 50.

Des Cloizeaux (1886) Bulletin de la Société française de Minéralogie: 9: 175.

Dana, E.S. (1892) System of Mineralogy, 6th. Edition, New York: 933.

Auerbach (1896) Annalen der Physik, Halle, Leipzig: 58: 357.

Viola (1897) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 28: 573.

Mügge (1898) Neues Jahrbuch für Mineralogie, Geologie und Paleontologie, Heidelberg, Stuttgart: I: 90.

Tutton (1909) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 46: 135.

Berek (1912) Jahrbuch Minerl., Beil.-Bd.: 33: 583.

Hutchinson and Tutton (1913) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 52: 223.

Kraus and Young (1914) Centralblatt für Mineralogie, Geologie und Paleontologie, Stuttgart: 356.

Grengg (1915) Mineralogische und petrographische Mitteilungen, Vienna: 33: 210.

Rosický (1916) Ak. Česká, Roz., Cl. 2: 25: No. 13.

Goldschmidt, V. (1918) Atlas der Krystallformen. 9 volumes, atlas, and text: vol. 4: 93.

Gaudefroy (1919) Bulletin de la Société française de Minéralogie: 42: 284.

Richardson (1920) Mineralogical Magazine: 19: 77.

Gross (1922) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 57: 145.

Mellor, J.W. (1923) A Comprehensive Treatise on Inorganic and Theoretical Chemistry. 16 volumes, London: 3: 767.

Carobbi (1925) Ann. R. Osservat. Vesuviano [3]: 2: 125.

Dammer and Tietze (1927) Die nutzbaren mineralien, Stuttgart, 2nd. edition.

Foshag (1927) American Mineralogist: 12: 252.

Himmel (1927) Centralblatt für Mineralogie, Geologie und Paleontologie, Stuttgart: 342.

Matsuura (1927) Japanese Journal of Geology and Geography: 4: 65.

Nagy (1928) Zeitschrift für Physik, Brunswick, Berlin: 51: 410.

Berger, et al (1929) Akademie der Wissenschaften, Leipzig, Ber.: 81: 171.

Hintze, Carl (1929) Handbuch der Mineralogie. Berlin and Leipzig. 6 volumes: 1 [3B], 4274. (localities)

Ramsdell and Partridge (1929) American Mineralogist: 14: 59.

Josten (1932) Centralblatt für Mineralogie, Geologie und Paleontologie, Stuttgart: 432.

Parsons (1932) University of Toronto Studies, Geology Series, No. 32: 25.

Gallitelli (1933) Periodico de Mineralogia-Roma: 4: 132.

Gaubert (1933) Comptes rendus de l’Académie des sciences de Paris: 197: 72.

Beljankin and Feodotiev (1934) Trav. inst. pétrog. ac. sc. U.R.S.S., no. 6: 453.

Caspari (1936) Proceedings of the Royal Society of London: 155A: 41.

Terpstra (1936) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 97: 229.

Weiser, et al (1936) Journal of the American Chemical Society: 58: 1261.

Wooster (1936) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 94: 375.

Büssem and Gallitelli (1937) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 96: 376.

Gossner (1937) Forschritte der Mineralogie, Kristallographie und Petrographie, Jena: 21: 34.

Gossner (1937) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 96: 488.

Hill (1937) Journal of the American Chemical Society: 59: 2242.

de Jong and Bouman (1938) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 100: 275.

Posnjak (1939) American Journal of Science: 35: 247.

Tokody (1939) Ann. Mus. Nat. Hungar., Min. Geol. Pal.: 32: 12.

Tourtsev (1939) Bull. Académie of Sciences of the U.S.S.R., Ser. Geol., no. 4: 180.

Huff (1940) Journal of Geology: 48: 641.

Acta Crystallographica: B38: 1074-1077.

Bromehead (1943) Mineralogical Magazine: 26: 325.

Miropolsky and Borovick (1943) Comptes rendus de l’académie des sciences de U.R.S.S.: 38: 33.

Berg and Sveshnikova (1946) Bull. ac. sc. U.R.S.S.: 51: 535.

Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged, 1124 pp.: 481-486.

Groves, A.W. (1958), Gypsum and Anhydrite, 108 p. Overseas Geological Surveys, London.

Hardie, L.A. (1967), The gypsum-anhydrite equilibrium at one atmosphere pressure: American Mineralogist: 52: 171-200.

Gaines, Richard V., H. Catherine, W. Skinner, Eugene E. Foord, Brian Mason, Abraham Rosenzweig (1997), Dana's New Mineralogy : The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, 8th. edition: 598.

Sarma, L.P., P.S.R. Prasad, and N. Ravikumar (1998), Raman spectroscopy of phase transition in natural gypsum: Journal of Raman Spectroscopy: 29: 851-856.

Freyer, D. & Voigt, W. (2003): Crystallization and phase stability of CaSO4 and CaSO4-based salts. Monatshefte für Chemie, 134, 693-719.

S. Nazzareni, P. Comodi, L. Bindi, L. Dubrovinski (2010) The crystal structure of gypsum-II by single-crystal synchrotron X-ray diffraction data. American Mineralogist, 95, 655-658.

Mindat.org articles about Gypsum

Article entries:
Iowa's GiantJames Gates
Saint David Gypsum CollectingRolf Luetcke

Best Localities for Gypsum

Best of Species:Gypsum

Internet Links for Gypsum

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  • Specimens:The following Gypsum specimens are currently listed for sale on minfind.com.

    Localities for Gypsum

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