There has been and still is much controversy on this variety. A slate type bird with a reddish tint to the body and slate-colored, somewhat barred wing feathers with a few random black spots and reddish tan tail with a blue band, finished off with a creme colored tip.
The genotype for most of what I have seen called Red Slate seems to be(b+b+Dd) bronze based with a single slate gene. The red gene is not involved here, the reddish coloration coming through the blue is actually only the bronze color expressing. Bronze Slate or Blue Bronze would be much more accurate names.
They do not breed true: Three results should occur - Red Slate, Lilac and Bronze. The latter two will breed true.