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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