A natural phenomenon in cured meat (and some fresh meat) is the occurrence of iridescence or a rainbow appearance on the cut lean surface.So ,some meat may also show an iridescent sheen. This is because meat contains iron, fat, and other compounds. When light shines on a slice of meat, it splits into colors like a rainbow.
There are various pigments in meat compounds that can give it an iridescent or greenish cast when exposed to heat and processing. Wrapping the meat in airtight packages and storing it away from light will help prevent this situation. Iridescence does not signal decreased quality or safety.