Iridescence on deli meat?

[GTS Jeff]

I've noticed that some deli meats are iridescent, especially roast beef. It's fresh and quite common. WTF is this caused by and how? My guess is preservatives, but I don't actually know.

[kiwi]

ha ha, this is what I found on Google...
http://www.madsci.org/posts/archives/sep2001/1001732824.Ch.r.html

[GTS Jeff]

Cool, mini water/meat prisms within the meat. Thanks.