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Image credit: RRUFF


Raman of buttgenbachite
Image credit: RRUFF

A rare secondary mineral composed of a hydrous copper nitrate with chlorine occurring in mattes of blue acicular crystals. Buttgenbachite was named in honor of Belgian Professor Henri jean Francois Buttgenbach, former mineralogist at the University of Liege in Belgium who studied Congo minerals for much of his life. The crystals have been found in some artificial copper patinas (Riederer 1992).

Physical and Chemical Properties

  • Composition = Cu19(NO3)2(OH)32Cl4
  • Description = deep blue
  • Luster=vitreous to glassy
  • Streak = light blue
  • Hardness = 3
  • Density = 3.42

Resources and Citations

  • J. Riederer, "Zur Historischen Entwicklung der Kenntnis von Korrosionsprodukten auf Kulturgeschichtlichen Objekten aus Kupferleigierungen" Berliner Beitrage zur Archaometrie 11:93-111, 1992.