Thank you for your replies. Yes, I had wondered about washing it, but I am scared I will ruin the shawl, I had never made anything like it before, it was quite a challenge. My husband has done a bit of research and thinks the wool has 'nickel silver' in it and the green is the oxidation of the copper.
My mother recently gave me some quite scary looking black and silver ribbon-type yarn, I think I shall follow my own advice before deciding how to use it. My first thought was to knit my own robot, when I saw it.
I have been using a glitter yarn to crochet a shawl. The first ball was fine, the second one has turned my fingers green!! It is almost finished; I have only the neck to do and now I am worried that if I wear it I will have some reaction.