How to remove a stain?

How to remove copper stain from aluminum?

• I left a wet, tarnished copper-bottomed pot on a bright, unfinished aluminum cookie sheet. The aluminum now has a medium to dark grey circular mark on it. The dishwasher did not remove the stain. Dish soap did not remove the stain. A micro-abrasive sponge (Magic Eraser) did not remove the stain. A household tarnish remover (acid-based) explicitly states it is not for use on aluminum. An internet search for variations on "(how to remove/removing) copper stain(s) on/from aluminum" did not yield any solutions. I greatly appreciate any solutions, my wife isn't too pleased that I stained her good, heavyweight cookie sheet.

• Answer:

  use metal polish if u dont have any try lemon juice or backing soda tooth paste