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A natural hydrated cobalt arsenate mineral. Erythrite occurs in deposits in Morocco (Bou Azzer), Germany (Saxony), Canada (Ontario), Mexico (Sonora). and the U.S. (Idaho). The pink to violet mineral was used as a pigment in paints, glass, and ceramics.

Synonyms and Related Terms

eritrite (Port.); cobalt bloom; erythrine; peach blossom ore; cobaltous arsenate; light cobalt violet


  • Highly toxic by ingestion and inhalation.

Physical and Chemical Properties

  • Soluble in dilute mineral acids and ammonium hydroxide. Insoluble in water.
  • Monoclinic crystals.
  • Perfect cleavage in one direction.
  • Luster = vitreous to pearly.
  • Streak = pale red to pink
  • Under crossed polars, crystals are highly birefringent
Composition CO3(As4)2.8H2O
Mohs Hardness 1.5 - 2.0
Density 2.91-2.95 g/ml
Refractive Index 1.626-1.701

Resources and Citations

  • Nicholas Eastaugh, Valentine Walsh, Tracey Chaplin, Ruth Siddall, Pigment Compendium, Elsevier Butterworth-Heinemann, Oxford, 2004
  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 206
  • 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 2495
  • C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
  • Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
  • The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998

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