also: りょくしょう
noun
verdigris; green rust on copper
Refers to the greenish patina that forms on copper, brass, or bronze surfaces due to oxidation. Often seen on old statues, roofs, and coins.
銅像に緑青が浮いている。
Verdigris has formed on the bronze statue.
古い十円玉には緑青がついていることがある。
Old ten-yen coins sometimes have green rust on them.