Corrosion of copper

First, copper does not rust, only iron does that-by definition.
The green could be any compound that has reacted with the copper. A common suspect would be a chloride from a maritime climate.
I am away from my reference books, so look up copper oxides and see if you come up with a green one.
Your school or teacher should have a CRC or Lange's Handbook where you can go to copper and look at the color of hundreds of copper compounds.

Riiiiight!

Andrew,
Pure copper cannot rust. Rust is iron oxide and you know there is no iron in pure copper, right? The green patina that forms on copper occurs naturally over time when exposed to Oxygen. The reaction is accelerated when heat is applied and the surface can turn brown.
Copper reacts with the Oxygen and forms Copper Oxide. Because I won't do your homework for you, you can balance the reaction, then the equation. Good Luck!

Andrew,

You are obviously expecting us to do you homework for you. Mmm...isn't going to happen.

Will give you a clue though. Copper doesn't rust, it corrodes. Rusting is a term associated with iron only really.

Otherwise utilise the internet or your local library where you will find the answers are easily come by.