Cumengeite

IMA formula: Pb₂₁Cu₂₀Cl₄₂(OH)₄₀(H₂O)₆

Crystallography: Tetragonal. I4/mmm. a = 15.065(2) Å, c = 24.436(5) Å. Z = 2.

Specimen #56. Cumengeite and botallackite. Herzog Julius smelter slag locality, Astfeld, Langelsheim, Goslar District, Lower Saxony, Germany. FOV 5.2 mm.