Cinnabar (red)
as an earthy coating on gneiss. The brown is an iron stain.
Hexagonal Cinnabar Crystals
Massive
Cinnabar. Go to Cinnabar Pictures (left margin) to see the tiny drops of
mercury that have accumulated on this specimen.
CHEMISTRY HgS Mercury sulfide
CRYSTALLOGRAPHY Hexagonal
CRYSTAL GROWTH AND HABITS Crystals are typically rhombohedral and often twinned. Cinnabar normally produces granular masses or earthy encrustations throughout the host rock.
COLOR AND OTHER OPTICAL PROPERTIES Cinnabar is red when pure to brownish red with impurities. It is also translucent to opaque.
HARDNESS 2.5
SPECIFIC GRAVITY 8.1 - 8.2
LUSTER Cinnabar has an adamantine luster when pure, grading into dull and earthy.
STREAK Scarlet red
BREAKABILITY 1 very good cleavage direction, subconchoidal fracture
OCCURRENCE Found as a vein filling mineral associated with recent volcanic activity and alkaline hot springs.
ASSOCIATED MINERALS Pyrite, Marcasite, Stibnite, Quartz, Calcite Fluorite
NOTE: May be associated with elemental (liquid) mercury and thus be dangerous to handle. Body temperature is often enough to vaporize the mercury out of the rock and this gas can be absorbed through the skin.