I just took the NPIP breeders' words for the Dark Partridge which is not one of the accepted APA Silkie colors but then there are a lot of Silkie colors not SOP registered yet.Oh, thank you so much! That explains it perfectly.
The hen and the Roo of this particular chick were both black and threw a partridge chick. I get that part but I wasn’t sure what he meant by how it could feather out.
I like taking the opportunity to learn what I can about the geneticsthis makes it clear especially with the photos you posted.