verdigris

1) A bluish-green pigment obtained by applying acetic acid to copper plates. Pronunciation here.

2) The natural patina formed when copper, brass or bronze is exposed to air and/or water over time.

verdigrisVerdigris pigment

Bartholdi libertyFrédéric Bartholdi. Liberty Enlightening the World. Copper with iron armature. Liberty Island, New York. 1886.