Cinnabar is a bright red mineral primarily composed of mercury sulfide (HgS). It is the most important ore of mercury and has been used for centuries in various applications, including pigments for art and cosmetics. The mineral often forms in hydrothermal veins and can be found in regions with volcanic activity. In addition to its historical uses, cinnabar is also significant in geology and mining. Due to its mercury content, it is important to handle cinnabar with care, as mercury is toxic. Cinnabar can be processed to extract mercury, which has applications in thermometers, barometers, and electrical switches.