Cobalt violet, light

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Cobalt violet light

Description

A pale to medium violet pigment originally composed of cobaltous arsenate. Cobaltous arsenate occurs in nature as cobalt bloom or erythrite. Once it was synthetically produced in 1880, it became an important permanent, violet pigment. Cobaltous arsenate is now rarely used because of its toxicity. It has been replaced by the use of cobaltous phosphate (deep cobalt violet) and cobaltous ammonium phosphate. Light cobalt violet was used as a colorant in paints, glass, glazes, and enamels.

Synonyms and Related Terms

cobalt arsenate (arsenite); Pigment Violet 14; CI 77350; erythrite (mineral); violeta de cobalto claro (Esp.); Kobaltviolett (hell) (Deut.); violet de cobalt (clair) (Fr.); iodes toy kobaltioy anoikto (Gr.); violetto di cobalto chiaro (It.); cobalt violet (licht) (Ned.); violeta de cobalto, claro (Port.); red cobalt; cobalt bloom; ; pale cobalt violet

FTIR

MFA- Cobalt violet light.jpg

SEM

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EDS

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Other Properties

Monoclinic crystal system with prismatic or euhedral crystals. Perfect cleavage parallel to long axes. Weakly pleochroic. High birefringence under crossed polars.

Composition Co3(AsO4)2 - 8H2O
Mohs Hardness 1.5-2.5 (erythrite)
Density 3.06
Refractive Index 1.626-1.701

Hazards and Safety

Highly toxic by ingestion, inhalation, and contact.

Additional Information

° Pigments Through the Ages: Cobalt violet

° Corbeil, Marie-Claude, Jean-Pierre Charland, Elizabeth Moffatt. 'The characterization of cobalt violet pigments' Studies in Conservation vol.47 (2002), pp.237-249.

Sources Checked for Data in Record

  • Reed Kay, The Painter's Guide To Studio Methods and Materials, Prentice-Hall, Inc., Englewood Cliffs, NJ, 1983
  • Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
  • Thomas B. Brill, Light Its Interaction with Art and Antiquities, Plenum Press, New York City, 1980

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