Calcium sulfate, dihydrate

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Description

White lumps or powder that is commonly called by its mineral name of gypsum. Calcium sulfate dihydrate is used in the manufacture of portland cement. Gypsum is also used as a filler and pigment in paints, enamels, glazes and paper.

Synonyms and Related Terms

native calcium sulfate; precipitated calcium sulfate; gypsum; alabaster; selenite; terra alba; satinite; mineral white; satin spar; light spar; Pigment White 25

FTIR

CalciumsulfatedihydrateMFAIR.jpg

XRD

PIGCASO4.jpg


Other Properties

Soluble in water. Slightly soluble in glycerol. Insoluble in most organic solvents. Gypsum fluoresces purple.

Composition CaSO4-2H2O
CAS 13397-24-5
Mohs Hardness 1.5 - 2.0
Melting Point 100-150
Density 2.32-2.36
Molecular Weight mol. wt. = 172.2
Refractive Index 1.520; 1.530; 1.523

Hazards and Safety

Noncombustible.

LINK: International Chemical Safety Card

Comparisons

Characteristics of Common White Pigments


Sources Checked for Data in Record

  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 1753