If some of the aluminum oxide in a cobalt aluminate is replaced with chromiu — m(III) oxide green, the resulting compound is a cobalt chromium aluminate blue — green spinel (C. I. Pigment Blue 36), with basic formula Co(Alx, Cr1-x)2O4, where x ranges from 0 to 1. These pigments can be further modified with zinc, magnesium, and titanium oxides to produce greener blues and teal shades.
Like the cobalt aluminates, cobalt chromium aluminates have excellent heat stability and weatherfastness. In many cases they have significantly better UV opacity than the Pigment Blue 28 grades.