Cinnabar

Cinnabar’s brilliant hue has made it a symbol of vitality and prestige in ancient Rome, China, and the Americas. Known as "Zhu Sha" in Chinese, it adorned artworks, lacquerware, and was once used in traditional medicine (now discouraged). Its legacy as vermilion pigment is woven into the history of illuminated manuscripts, murals, and ceremonial objects.

• Cinnabar is the world’s principal source of mercury.
• Its pigment, vermilion, was so valued that it adorned imperial palaces and sacred artifacts.
• Exposure to cinnabar can be hazardous due to mercury content.
• Major deposits have shaped mining history in Spain, Slovenia, Peru, and California.
• Cinnabar can alter to metacinnabar, a black form of mercury sulfide.

Cinnabar’s chemical formula is HgS, composed of mercury (Hg) and sulfur (S) in a 1:1 ratio. This simple yet potent combination defines its mineralogical identity and industrial value.

Cinnabar crystallizes in the trigonal system, specifically the hexagonal scalenohedral class. Its crystals are often prismatic, though massive forms are common, and twinned crystals are rare. The ordered atomic arrangement imparts its distinctive cleavage and optical qualities.

Cinnabar is soft, with a Mohs hardness of 2–2.5, and exceptionally dense (specific gravity 8.1). Its color ranges from bright red to reddish-brown, with a scarlet streak and adamantine to dull luster. The mineral is opaque, brittle, and displays perfect cleavage on {1011}.

Cinnabar is typically found in hydrothermal veins and volcanic rocks, often linked to recent volcanic activity. It also occurs in sedimentary deposits and mercury-rich environments. Notable localities include Almaden (Spain), Idrija (Slovenia), Huancavelica (Peru), and California (USA), where it is frequently associated with minerals such as quartz, calcite, pyrite, and dolomite.

Recognized synonyms for cinnabar include vermilion (as pigment), Chinese red, mercury sulfide, and Zhu Sha (Chinese). While there are no widely accepted mineral varieties, pigment grades and regional forms may be distinguished in art and commerce.

Cinnabar’s primary industrial role is as the chief ore for mercury extraction. Historically, it was ground to produce vermilion pigment for paints, lacquers, and inks. Medicinal uses have been abandoned due to toxicity, and modern applications are limited by health concerns surrounding mercury exposure.

• Look for intense red coloration and scarlet streak when scratched.
• Check for perfect cleavage and brittle texture.
• Test density—cinnabar feels noticeably heavy for its size.
• Be cautious: avoid heat or abrasion due to mercury vapor risk.

• Store cinnabar specimens in cool, dry, and well-ventilated areas, away from heat and direct sunlight.
• Handle with gloves to prevent skin contact and avoid inhaling dust.
• Do not clean with abrasive methods; gently brush with a soft, dry cloth.
• Display in sealed cases if possible, especially in public or educational settings.

Legendary cinnabar specimens hail from the Almaden mines in Spain, which supplied much of the world’s mercury for centuries. Idrija (Slovenia) and Huancavelica (Peru) are also renowned for historic finds, with museum-quality crystals displayed in major mineral collections worldwide.