THE MINERAL CINNABAR

Chemistry: HgS, Mercury Sulfide
Class: Sulfides and Sulfosalts
Uses: primary ore of mercury, a pigment and as a minerals specimen.
Specimens

Cinnabar is a colorful mineral that adds a unique color to the mineral color palette. Its cinnamon to scarlet red color can be very attractive. Well shaped crystals are uncommon and the twinned crystals are considered classics among collectors. The twinning in cinnabar is distinctive and forms a penetration twin that is ridged with six ridges surrounding the point of a pryamid. It could be thought of as two scalahedral crystals grown together with one crystal going the opposite way of the other crystal. Cinnabar was mined by the Roman Empire for its mercury content and it has been the main ore of mercury throughout the centuries. Some mines used by the Romans are still being mined today. Cinnabar shares the same symmetry class with quartz but the two form different crystal habits.

PHYSICAL CHARACTERISTICS:

Color is a bright scarlet or cinnamon red to a brick red.
Luster is adamantine to submetallic in darker specimens.
Transparency crystals are translucent to transparent.
Crystal System is trigonal; 32
Crystal Habits: individual, well formed, large crystals are scarce; crusts and crystal complexes are more common; may be massive, or in capilary needles. Crystals that are found tend to be the six sided trigonal scalahedrons that appear to have opposing three sided pyramids. It also forms modified rhombohedrons, prismatic and twinned crystals as discribed above.
Cleavage is perfect in three directions, forming prisms.
Fracture is uneven to splintery.
Hardness is 2 - 2.5.
Specific Gravity is approximately 8.1+ (very heavy for a non-metallic mineral)
Streak is red
Associated Minerals are realgar, pyrite, dolomite, quartz, stibnite and mercury.
Other Characteristics: silghtly sectile and crystals can be striated.
Notable Occurances include Almaden, Spain; Idria, Serbia; Hunan Prov., China and California, Oregon, Texas, and Arkansas, USA.
Best Field Indicators are crystal habit, density, cleavage, softness and color.