Cinnabar

Cinnabar, the principal ore of mercury, is a mercury sulfide (HgS) and one of the densest non-metallic minerals, with a specific gravity between 8.10 and 8.20. It crystallizes in the trigonal system, forming rhombohedral, massive, or encrusting habits, and typically develops near volcanic hot springs and fumaroles. The mineral has an adamantine luster, a scarlet streak, perfect prismatic cleavage, and a low Mohs hardness of 2 to 2.5. Its striking scarlet color made cinnabar a prized pigment, known as vermilion, from antiquity onward, though its mercury content renders the raw material toxic to handle. Its high density and perfect prismatic cleavage aid identification where the scarlet color alone would be ambiguous.

Cinnabar is the principal ore of mercury and one of the densest non-metallic minerals. Its striking scarlet color has made it a prized pigment (vermilion) since antiquity. It typically forms near volcanic hot springs and fumaroles.