Plancheite

Cu₈(Si₄O₁₁)₂(OH)₄.H₂O

This sample of plancheite is displayed in the Smithsonian Museum of Natural History. Plancheite is a silicate mineral of copper with the composition Cu₈(Si₄O₁₁)₂(OH)₄.H₂O. The sample at left is about 20 cm across and is from D. R. Congo. It is described as plancheite with dioptase.

Mindat describes plancheite as a rare secondary copper silicate. The bluegreen is its typical color.