Gypsum

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Gypsum[1][2]
SA101 1.jpeg
Mineralogical name Gypsum, Selenite
Chemical name Calcium sulfate dihydrate
Trivial name Gypsite, Sulfate of Lime
Chemical formula Ca[SO4]•2H2O
Other forms Anhydrite (CaSO4)
Hemihydrate (CaSO4•0.5H2O)
Crystal system monoclinic
Crystal structure
Deliquescence humidity 20°C
Solubility (g/l) at 20°C 2.14 g/l
Density (g/cm³) 2.2-2.4 g/cm³
Molar volume 74.69 cm3/mol
Molar weight 172.17g /mol
Transparency transparent to opaque
Cleavage perfect
Crystal habit
Twinning
Phase transition
Chemical behavior
Comments hardly soluble in water
Crystal Optics
Refractive Indices α = 1.519-1.521
β = 1.522-1.523
γ = 1.529-1.530
Birefringence Δ = 0.010
Optical Orientation biaxial positive
Pleochroism
Dispersion 58°
Used Literature
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Authors: Hans-Jürgen Schwarz , Nils Mainusch, Tim Müller back to Sulfate

Calciumsulfate and Gipsum[edit]

Solubility properties[edit]

Figure1: Solubility of CaSO4 in water (diagram: Michael Steiger)
Figure 2:Solubility of gipsum compared with other salte (after [Stark.etal:1996]Title: Bauschädliche Salze
Author: Stark, Jochen; Stürmer, Sylvia
Link to Google Scholar
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Photos of gypsum crystals and deterioration pattern caused by gypsum[edit]

On a object[edit]


Under the polarising microscope[edit]


Under the Scanning Electron Microscope (SEM)[edit]


Weblinks[edit]

Literatur[edit]

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Weblinks[edit]