Cobalt_Blue

Cobalt Blue: (CoAl2O4), a blue pigment made by sintering Cobalt Oxide (CoO) with Aluminium Oxide (Al3O2) forming cobalt aluminate (CoAl2O4). It has long been used in Chinese porcelain in its impure form for centuries, however, the first mention of cobalt as a colour in English was in 1777 CE.