(noun) – a green or bluish patina formed on copper, brass, or bronze surfaces exposed to the atmosphere for long periods of time, consisting principally of basic copper sulfate.
Hurriedly hurtling down the bike path, he almost missed the necklace completely. Only because Cathy had called out his name from behind him did he grip his brakes and slow down. She was walking, still about 80 paces away. He impatiently glanced at his watch. A glimmer caught his eye, just above the 11 on the clock face. There, nestled in the decomposing, autumn leaves at his feet, was a piece of jewelry — tarnished save for a tiny, bronze glint shining through a chip in the verdigris enveloping it.