Plancheite is a hydrated copper silicate mineral with the formula Cu8Si8O22(OH)4•(H2O).

It is closely related to shattuckite in structure and appearance, and the two minerals are often confused.

[6] It occurs as sprays of acicular or fibrous radial clusters, with fibers extended parallel to the chains, i.e. along the c crystal axis;[5] it can also form tiny tabular or platy crystals.

[2][3][4][5] Plancheite is a secondary mineral formed in the oxidized zone of copper deposits, associated with other copper minerals chrysocolla, dioptase, malachite, conichalcite and tenorite.

[7] The type locality is the Sanda Mine, Mindouli, Pool Region, Republic of Congo.