Sodium sulfate, anhydrous

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Thenardite (sodium sulfate)


White, hygroscopic crystals or powder. Anhydrous sodium sulfate occurs in nature as the mineral thenardite. Thenardite occurs most often as an evaporation product near salt lakes and playas, and is mined in arid regions of northern Africa, Siberia, Canada, and the western United States. Anhydrous sodium sulfate is used in the manufacture of Kraft paper, Paperboard, Glass, synthetic ultramarine blue, and ceramic Glaze. It is also used as a leveling agent in dyeing textiles to ensure even color acceptance.

Synonyms and Related Terms

anhydrous sodium sulfate; anhydrous sodium sulphate (Br.); thenardite; salt cake

Chemical structure

Sodium sulfate, anhydrous.jpg


  • Noncombustible.
  • ThermoFisher: SDS

Physical and Chemical Properties

  • Soluble in water, glycerol. Insoluble in ethanol.
  • Orthorhombic crystals with perfect cleavage in one direction.
  • Mineral thenardite is vitreous, translucent and produces a white streak.
Composition Na2SO4
CAS 7757-82-6
Mohs Hardness 2.5-3.0
Melting Point 888 C
Density 2.671 g/ml
Molecular Weight mol. wt. = 142.1

Resources and Citations

  • Grossi, "Acoustic emission monitoring to study sodium sulfate crystallization in monumental porous carbonate stone" Studies in Conservation 42 (1997), p. 115-125.
  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p.785
  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • The Dictionary of Paper, American Paper Institute, New York, Fourth Edition, 1980
  • Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
  • Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
  • The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983
  • The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
  • C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
  • John and Margaret Cannon, Dye Plants and Dyeing, Herbert Press, London, 1994
  • Susan E. Schur, Conservation Terminology: A review of Past & Current Nomenclature of Materials, Technology and Conservation, Spring (p.34-39); Summer (p.35-38); Fall (p.25-36), 1985
  • Photographic chemicals at