Valve Cover questions

My valve cover is green with blue patches and rust patches, so i took it
off to give it a once over with some Simple Green to see if this blue
stuff came off.  It didn't but i didn't really expect it to.  Is green the
original color of this valve cover?  I've seen alot if engine pics and
have seen few green valve covers.  The car's a 61 Midget.  Also, what
material should the valve cover gasket be made of?  

-Ryan Irwin
'61 Midget