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Gypsum

A valid IMA mineral species - grandfathered
This page kindly sponsored by Dragon Minerals
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About GypsumHide

Formula:
CaSO4 · 2H2O
Colour:
Colourless to white, often tinged other hues due to impurities; colourless in transmitted light.
Lustre:
Vitreous, Sub-Vitreous, Silky, Pearly, Dull
Hardness:
2
Specific Gravity:
2.312 - 2.322
Crystal System:
Monoclinic
Name:
First known mention is by Theophrastus about 300-325 BCE from the Greek γυψοζ (gypsos) meaning plaster.
Isostructural with:
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.

May dehydrate to bassanite at elevated temperatures.




Unique IdentifiersHide

Mindat ID:
1784
Long-form identifier:
mindat:1:1:1784:4
GUID
(UUID V4):
73d301d2-d38c-46b4-be8b-988120461591

IMA Classification of GypsumHide

Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Ca(SO4) · 2H2O

Classification of GypsumHide

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 ed.:
29.6.3.1
29.6.3.1

29 : HYDRATED ACID AND NORMAL SULFATES
6 : AXO4·xH2O
25.4.3

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

Mineral SymbolsHide

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.

SymbolSourceReference
GpIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43
GpKretz (1983)Kretz, R. (1983) Symbols of rock-forming minerals. American Mineralogist, 68, 277–279.
GpSiivolam & Schmid (2007)Siivolam, J. and Schmid, R. (2007) Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks: List of mineral abbreviations. Web-version 01.02.07. IUGS Commission on the Systematics in Petrology. download
GpWhitney & Evans (2010)Whitney, D.L. and Evans, B.W. (2010) Abbreviations for names of rock-forming minerals. American Mineralogist, 95, 185–187 doi:10.2138/am.2010.3371
GpThe Canadian Mineralogist (2019)The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download
GpWarr (2020)Warr, L.N. (2020) Recommended abbreviations for the names of clay minerals and associated phases. Clay Minerals, 55, 261–264 doi:10.1180/clm.2020.30

Pronunciation of GypsumHide

Pronunciation:
PlayRecorded byCountry
Jolyon RalphUnited Kingdom

Physical Properties of GypsumHide

Vitreous, Sub-Vitreous, Silky, Pearly, Dull
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:
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 undergoes 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:
2.312 - 2.322 g/cm3 (Measured)    2.308 g/cm3 (Calculated)

Optical Data of GypsumHide

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°
Birefringence:
0.010
Max Birefringence:
δ = 0.010
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Low
Dispersion:
Strong r > v inclined
Optical Extinction:
Y = b; Z ∧ c = 52°.

Chemistry of GypsumHide

Mindat Formula:
CaSO4 · 2H2O

Crystallography of GypsumHide

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 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 may 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°.

Crystallographic forms of GypsumHide

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)
3d models and HTML5 code kindly provided by www.smorf.nl.

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Crystal StructureHide

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IDSpeciesReferenceLinkYearLocalityPressure (GPa)Temp (K)
0001807GypsumSchofield P F, Knight K S, Stretton I C (1996) Thermal expansion of gypsum investigated by neutron powder diffraction American Mineralogist 81 847-851199604.2
0001808GypsumSchofield P F, Knight K S, Stretton I C (1996) Thermal expansion of gypsum investigated by neutron powder diffraction American Mineralogist 81 847-85119960150
0001809GypsumSchofield P F, Knight K S, Stretton I C (1996) Thermal expansion of gypsum investigated by neutron powder diffraction American Mineralogist 81 847-85119960320
0004651GypsumComodi P, Nazzareni S, Zanazzi P F, Speziale S (2008) High-pressure behavior of gypsum: A single-crystal X-ray study American Mineralogist 93 1530-15372008Valle di Caramanico, Abruzzo, Italy0.0001293
0004652GypsumComodi P, Nazzareni S, Zanazzi P F, Speziale S (2008) High-pressure behavior of gypsum: A single-crystal X-ray study American Mineralogist 93 1530-15372008Valle di Caramanico, Abruzzo, Italy0.25293
0004653GypsumComodi P, Nazzareni S, Zanazzi P F, Speziale S (2008) High-pressure behavior of gypsum: A single-crystal X-ray study American Mineralogist 93 1530-15372008Valle di Caramanico, Abruzzo, Italy0.33293
0004654GypsumComodi P, Nazzareni S, Zanazzi P F, Speziale S (2008) High-pressure behavior of gypsum: A single-crystal X-ray study American Mineralogist 93 1530-15372008Valle di Caramanico, Abruzzo, Italy0.56293
0004655GypsumComodi P, Nazzareni S, Zanazzi P F, Speziale S (2008) High-pressure behavior of gypsum: A single-crystal X-ray study American Mineralogist 93 1530-15372008Valle di Caramanico, Abruzzo, Italy1.01293
0004656GypsumComodi P, Nazzareni S, Zanazzi P F, Speziale S (2008) High-pressure behavior of gypsum: A single-crystal X-ray study American Mineralogist 93 1530-15372008Valle di Caramanico, Abruzzo, Italy2.03293
0004657GypsumComodi P, Nazzareni S, Zanazzi P F, Speziale S (2008) High-pressure behavior of gypsum: A single-crystal X-ray study American Mineralogist 93 1530-15372008Valle di Caramanico, Abruzzo, Italy3.15293
0004658GypsumComodi P, Nazzareni S, Zanazzi P F, Speziale S (2008) High-pressure behavior of gypsum: A single-crystal X-ray study American Mineralogist 93 1530-15372008Valle di Caramanico, Abruzzo, Italy3.94293
0008228GypsumKnight K S, Stretton I C, Schofield P F (1999) Temperature evolution between 50 K and 320 K of the thermal expansion tensor of gypsum derived from neutron powder diffraction data Physics and Chemistry of Minerals 26 477-48319990293
0017897GypsumWooster W (1936) On the crystal structure of gypsum Ca S O4 (H2 O)2 _cod_database_code 1010981 Zeitschrift fur Kristallographie 94 375-39619360293
0011093GypsumBoeyens J C A, Ichharam V V H (2002) Redetermination of the crystal structure of calcium sulphate dihydrate, CaSO4*2H2O Zeitschrift fur Kristallographie 217 9-102002synthetic0293
CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

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Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
d-spacingIntensity
7.63 Å(100)
4.283 Å(100)
3.799 Å(17)
3.172 Å(4)
3.065 Å(75)
2.873 Å(45)
2.789 Å(10)
2.732 Å(2)
2.685 Å(35)
2.597 Å(6)
2.534 Å(2)
2.495 Å(11)
2.476 Å(1)
2.452 Å(6)
2.406 Å(4)
2.291 Å(1)
2.219 Å(15)
2.142 Å(2)
2.086 Å(25)
2.074 Å(15)
2.048 Å(6)
2.032 Å(1)
1.992 Å(4)
1.963 Å(3)
1.8998 Å(16)
1.8795 Å(12)
1.8650 Å(3)
1.8118 Å(13)
1.7995 Å(6)
1.7844 Å(9)
1.7785 Å(12)
1.7093 Å(1)
1.6846 Å(3)
1.6640 Å(6)
1.6456 Å(4)
1.6209 Å(9)
1.6005 Å(1)
1.5846 Å(4)
1.5327 Å(2)
1.5209 Å(1)
1.5119 Å(1)
1.4982 Å(1)
1.4947 Å(1)
1.4591 Å(3)
1.4392 Å(5)
1.4354 Å(3)
1.4278 Å(2)
1.4178 Å(3)
1.4015 Å(2)
1.3657 Å(5)
Comments:
ICDD 33-311

Geological EnvironmentHide

Paragenetic Mode(s):
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.

Synonyms of GypsumHide

Other Language Names for GypsumHide

Arabic:جص
Bulgarian:Гипс
Catalan:Guix
Croatian:Gips
Czech:Sádrovec
Danish:Gips
Dutch:Gips
Estonian:Kips
Hebrew:גבס
Hungarian:Gipsz
Irish Gaelic:Gipseam
Japanese:石膏
Korean:석고
Latin:Gypsum
Latvian:Ģipsis
Lithuanian:Gipsas
Norwegian:Gips
Polish:Gips
Portuguese:Gesso
Romanian:Gips
Russian:Гипс
Serbian:Гипс
Simplified Chinese:石膏
Slovak:Sadrovec
Slovenian:Sadra
Spanish:Yeso
Swedish:Gips
Traditional Chinese:石膏
Vietnamese:Thạch cao

Varieties of GypsumHide

AlabasterA fine-grained massive form of gypsum.

Note that archaeologists and the stone processing industry use the word differently from geoscientists. The former use it in a wider sense that includes varieties of two different minerals: the fine-grained massive ...
OrditePseudomorphs of gypsum after an unidentified mineral [Clark, 1993 - "Hey's Mineral Index"].

Originally described from Orda, Permskaya Oblast', Middle Urals, Urals Region, Russia.
Satin Spar GypsumA fibrous variety of Gypsum. See also the main page on Satin Spar.
SeleniteThe name 'selenite' is mostly synonymous with gypsum but has been used historically to describe the transparent variety, as opposed to satin spar gypsum for the fibrous variety and alabaster for the fine-grained massive form.

The original name was given...

Relationship of Gypsum to other SpeciesHide

Other Members of this group:
BrushiteCa(PO3OH) · 2H2OMon. m : Bb
Churchite-(Y)Y(PO4) · 2H2OMon. 2/m : B2/b
PharmacoliteCa(HAsO4) · 2H2OMon. m

Common AssociatesHide

Associated Minerals Based on Photo Data:
490 photos of Gypsum associated with CalciteCaCO3
288 photos of Gypsum associated with QuartzSiO2
146 photos of Gypsum associated with PyriteFeS2
142 photos of Gypsum associated with MalachiteCu2(CO3)(OH)2
141 photos of Gypsum associated with CopperCu
140 photos of Gypsum associated with HaliteNaCl
139 photos of Gypsum associated with SideriteFeCO3
134 photos of Gypsum associated with DolomiteCaMg(CO3)2
132 photos of Gypsum associated with SulphurS8
117 photos of Gypsum associated with AzuriteCu3(CO3)2(OH)2

Related Minerals - Strunz-mindat GroupingHide

7.CD.Argesite(NH4)7Bi3Cl16 Trig. 3m (3 2/m) : R3c
7.CD.Campostriniite(Bi3+,Na)3(NH4,K)2Na2(SO4)6 · H2OMon. 2/m : B2/b
7.CD.05MatteucciteNaHSO4 · H2OMon. m
7.CD.10MirabiliteNa2SO4 · 10H2OMon. 2/m : P21/b
7.CD.15Lecontite(NH4,K)NaSO4 · 2H2OOrth. 2 2 2 : P21 21 21
7.CD.20HydroglauberiteNa10Ca3(SO4)8 · 6H2OMon.
7.CD.25EugsteriteNa4Ca(SO4)3 · 2H2OMon.
7.CD.30GörgeyiteK2Ca5(SO4)6 · H2OMon. 2/m : B2/b
7.CD.35Koktaite(NH4)2Ca(SO4)2 · H2OMon. 2/m : P21/b
7.CD.35SyngeniteK2Ca(SO4)2 · H2OMon. 2/m : P21/m
7.CD.35AntofagastaiteNa2Ca(SO4)2 · 1.5H2OMon. 2/m : P21/m
7.CD.45BassaniteCa(SO4) · 0.5H2OMon. 2 : B2
7.CD.45Chinleite-(Y)NaY(SO4)2 · H2OTrig. 3 2
7.CD.45Chinleite-(Nd)NaNd(SO4)2 · H2OTrig. 3 2 : P32 2 1
7.CD.50Zircosulfate(Zr,Ti)(SO4)2 · 4H2OOrth. mmm (2/m 2/m 2/m) : Fddd
7.CD.55SchieffelinitePb10Te6+6O20(OH)14(SO4)(H2O)5Orth. mmm (2/m 2/m 2/m) : Cmcm
7.CD.60MontaniteBi2(TeO6) · nH2OHex. 6 : P6
7.CD.65OmongwaiteNa2Ca5(SO4)6 · 3H2OMon. 2 : B2

Fluorescence of GypsumHide

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.

Other InformationHide

Electrical:
Not piezoelectric.
Thermal Behaviour:
Dehydrates and turns white. Heated in a closed tube, it gives off water and becomes opaque. Fuses at 2.5-3, coloring the flame reddish yellow.
Notes:
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.

Soluble in HCl. Soluble in ~500 parts water.
Health Risks:
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.

Gypsum in petrologyHide

An essential component of rock names highlighted in red, an accessory component in rock names highlighted in green.

Internet Links for GypsumHide

References for GypsumHide

Reference List:

Localities for GypsumHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListShow

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