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Image credit: Rob Lavinsky


Raman spectrum of Connellite, Credit: RRUFF

A rare blue green copper corrosion product that forms delicate acicular crystals. Connellite was found as a mineral in Cornwall in 1802 by Philip Rashleigh and was examined chemically by Arthur Connell in 1847. It has also been found on prehistoric bronzes.

Physical and Chemical Properties

  • Composition = Cu19Cl4SO4)(OH)32 3H2O
  • Blue green to light blue fibrous to acicular needles
  • Lust = vitreous to glass
  • Streak = light blue green
  • Hardness = 3
  • Density = 3.4

Resources and Citations

  • H. Otto 'Das Vorkommen von Conellit in Patinaschichten", Die Naturwissenschaften 50(1):16-17, 1963.
  • Walter A. Franke, Magda Mircea, "Plutarch's Report on the Blue Patina of Bronze Statues at Delphi: A Scientific Explanation" JAIC 44(2):103, 2005.