Description
The mineral cinnabar is a mercury sulfide with the chemical formula HgS. Gray, brown, or dark red (vermilion) cinnabar has a bright red streak color and complete cleavage along the crystal plane [1010]. The crystal system is trigonal, and the density is high at 8.1. The hardness is 2 to 2.5. Cinnabar is not radioactive. The rare metacinnaberite is still found in California. The chemical composition is similar to that of cinnabar, but the structure is different (namely, cubic). The word cinnabar originally meant vermilion and comes from Persian (shangarf). It has reached our language via Greek, Latin, and French. Cinnabar is found primarily in low-temperature hydrothermal veins. The type locality, and long an important source of mercury ore, is Almadén, Spain, where it was already mined by the Celts. Cinnabar is the most important ore of mercury. Cinnabar was already known in ancient times and has been used as a pigment in China for over 1,000 years. Mercury can be obtained from cinnabar by subliming it at 583°C (856 K). This process releases liquid mercury.
