title: Verdigris
context: Verdigris is the common name for a green pigment obtained through the application of acetic acid to copper plates[2] or the natural patina formed when copper, brass or bronze is weathered and exposed to air or seawater over a period of time. It is usually a basic copper carbonate, but near the sea will be a basic copper chloride.[3] If acetic acid is present at the time of weathering, it may consist of copper(II) acetate.
question: What causes the green color of the Statue of Liberty?
answers: Verdigris