Aluminum ammonium sulfate

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A white crystalline powder that is also called ammonium alum. Aluminum ammonium sulfate occurs naturally as the mineral tschermigite. It is used in baking powders, dyeing textiles, tanning leathers, and as a substrate for lake pigments. Ammonia alum is also used in developing baths for black and white photographs.

Synonyms and Related Terms

ammonia alum; ammonium aluminum sulfate; alum NF; aluminum ammonium sulphate (Br.); tschermigite


  • Skin contact may cause allergies.
  • ThermoFisher: SDS

Physical and Chemical Properties

  • Soluble in water, glycerol. Insoluble in ethanol.
  • Crystals are fibrous and deliquescent
Composition AlNH4(SO4)2-12H2O
Mohs Hardness 1.5-2.0
Melting Point 94.5 C
Density 1.645 g/ml

Resources and Citations

  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 33
  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
  • John and Margaret Cannon, Dye Plants and Dyeing, Herbert Press, London, 1994
  • The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 335