Thanks everyone I have not explained myself very well and hope you are not all losng patience with me.
My chicken does have black spots on the skin of its body. I know the Rooster is pure Silkie and bought the leg horns as pure but perhaps they were not after all.
Could that expain the black skin spots?
Thanks again.
Last question about that chicken I promise.
In some cases you'll get pigment spotting when you cross a fibromelanistic bird with a non-fibro bird. Particularly when you cross with a fibro-restricting gene.
Here's a photo of the leg muscles of a Cuckoo Silkie cockerel I processed this year; Barring (Cuckoo) is a gene that messes with fibro birds and makes their skin (and upper layer of muscle) very spotty. (Warning: Photo was taken during the bird's processing, it's not super graphic, but it does show the muscle beneath the skin).