VERDIGRIS
Verdigris garments are coloured using turquoise dye extracted from copper. Copper verdigris was used as a dye by the Romans, who laid grape leaves onto copper sheets, to speed up the natural corrosion of the metal. Verdigris was popular as a green paint, suspended in oil, until the 1800s.
Vintage jeans often show green staining around the copper rivets- this is the same verdigris which dyes these clothes.