Cinnabar is a naturally occurring mercury sulphide which turns red when ground. Its synthetic equivalent is called vermilion.
Cinnabar has been used by Asian artists possibly since the second millennium BC, but it was scarce and therefore very expensive. Its main European source was Spain, where the mines at Almaden had been active since antiquity. By the 14th century, however, the manufacture of vermilion was well established. Forms of mercury sulphide have very often been identified in illuminated manuscripts.
Cinnabar and vermilion cannot be easily distinguished with the analytical methods used for this project; the two terms are therefore used interchangeably throughout this website.