CINNABAR

Composition:  HgS

Crystal System:  Hexagonal (trigonal)

Color:  Various shades of red

Cinnabar, or mercury sulfide, is the principal ore of mercury.  The name Cinnabar comes from the Persian word zinjifrah, thought to mean 'dragon's blood.'  Crystals generally form rhombohedra; rarely hexagonal prisms. Cinnabar is easily identified by its red color and high density.  It is usually found as veins, seams, and small crystals in low temperature deposits.  Hot springs commonly deposit cinnabar along with opaline sinter or calcite. 

Cinnabar has been mined for thousands of years.  Famous deposits include Almaden, Spain; Idrija, Slovenia; New Almaden, California; and Huancavelica, Peru.  Ancient cultures often used the bright red cinnabar as makeup, and it was used as a paint pigment in the middle ages.  The ancient Chinese even used it as medicine.  As cinnabar is relatively insoluble, it has very few health risks compared to native mercury and other mercury compounds. 

Cinnabar, New Almaden, Santa Clara Co., California.

Cinnabar crystals, Poverty Peak District, Humboldt Co., Nevada. Photo by Ben Schumer