Mercuric sulfide, red

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A dense red powder that occurs in nature as the mineral Cinnabar. Red mercuric sulfide is one of two crystalline forms of mercuric sulfide, the other being black. It is made synthetically by precipitation from a solution of mercuric acetate, ammonium thiocyanate, glacial Acetic acid, and Hydrogen sulfide. Red mercuric sulfide, also called Vermilion, is used as a pigment for paints, plastics, sealing wax, and colored paper. It slowly turns black with exposure to ultraviolet light.

Synonyms and Related Terms

vermilion; Pigment Red 106; CI 77766; cinnabar (mineral); sulfuro de mercurio rojo (Esp.); cianbrio (Esp.); bermellón (Esp.); cinabre (Fr.); sulfure de mercure rouge (Fr.); sulfureto de mercúrio, vermelho (Port.); Chinese red; Chinese vermilion; artificial cinnabar; red mercury sulfuret


  • Highly toxic by ingestion, inhalation and skin absorption.
  • Turns black with exposure to ultraviolet light.
  • Sensitive to moisture.
  • ThermoFisher: SDS

Physical and Chemical Properties

  • Insoluble in water and most cold acids. Soluble in aqua regia.
  • Hexagonal crystal system.
  • Perfect cleavage in three directions (60 and 120 degree angles)
  • Streak = scarlet.
  • Fracture = subconchoidal to uneven.
  • Luster = adamantine to dull.
Composition HgS
CAS 1344-48-5
Mohs Hardness 2.0-2.5
Density 8.10 g/ml
Molecular Weight mol. wt. = 232.65
Refractive Index 2.819 - 3.146

Resources and Citations

  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 200
  • 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 5945
  • 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
  • Dictionary of Building Preservation, Ward Bucher, ed., John Wiley & Sons, Inc., New York City, 1996

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