The white tail on your rooster means he probably has dominant white genetics. Dominant white is a gene that turns feathers that would normally be black to white. It has no effect on a red feather. Since dominant white is dominant, you only need one gene at that gene pair to be dominant white to have its effect. I don't know if that rooster has one or two dominant white genes at that gene pair, but he gave one to that white chick.
I don't know if that chick's mother was pure for the black genetics or split, whether both genes at that gene pair were black or only one. But she gave a black gene to that chick. Black is pretty dominant. The dominant white turned it to white.
The above is the most likely scenario but very few things in chick genetics are that simple. If both the rooster and the hen had one copy of recessive white at that gene pair and the chick wound up with two recessive whites, it would be solid white. The recessive white gene has to have both genes at that gene pair to have an effect so you would never know the rooster or hen had one copy by looking at them.
lets me pet him. fully orange with white tail + black spots in it
