Meat iridescence colours are a known issue. They occur on raw meat but are perhaps more common on smooth surfaced cooked/cured meats. They depend on the lighting angle. They could depend on the cutting blade and meat moisture content. Unpleasant greens are common, also reds and pinks.
Animal muscle is composed of quasi regularly spaced and oriented bundles of individual fibres. In turn, the fibres contain long oriented myofibrils also regularly positioned. When meat is sliced the fibres and fibrils can partly protrude from the surface to form a two-dimensional stepped array that forms a diffraction grating. Microfibrils at cut fibre ends can also act as quasi-periodic scattering areas.
Light waves scattered by the regularly spaced protrusions and microfibrils constructively interfere and send coloured light in particular directions.
Birefringence could also contribute.
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