If he's carrying blue, & he's bred to blue partridge you can get some splash partridges/calico, or you may get splashes with some leakage. Not all the chicks will be splash though. Some maybe black, or blue.
It's also possible it could be your black hen is carrying blue. But yet your rooster maybe.
It'll only be proven if you can breed your rooster to a different black hen.
Blue partridge is able to be created in the calculator. I use it alot.