I was just curious of something and was wondering if anyone could shed some light on this. I have a metal screen (like the kind you have on your water taps). I think it is made out of steel or something? Anyways, I was bored one day so I put a lighter up to it till it started glowing red. After the glowing died down, I noticed a rainbow-like pattern perimeter around the previously-glowing-red circle. Almost like the pattern found in oil on the street. Does anyone know what could be causing this? Could it just be something the metal is coded in that is being pushed to the outside or something?