Cinnabar

Cinnabar, also known as cinnabarite, is the bright scarlet to brick-red form of mercury(II) sulfide (HgS). It is the most common source ore for refining elemental mercury and has been mined for this purpose for thousands of years.

Properties:

• Chemical Formula: HgS
• Crystal System: Trigonal
• Color: Scarlet red to brownish red, sometimes almost black. May streak scarlet red.
• Luster: Adamantine to metallic
• Hardness: 2-2.5 on the Mohs scale
• Specific Gravity: 8.0 – 8.2
• Transparency: Translucent to opaque
• Fracture: Uneven
• Streak: Scarlet red

Occurrence:

Cinnabar typically forms as a vein-filling mineral associated with recent volcanic activity and alkaline hot springs. It is found worldwide in areas of active volcanism or where hot springs have been active. Notable occurrences include Almadén, Spain; Idrija, Slovenia; Monte Amiata, Italy; Guizhou province, China; California, USA; and Peru.

Uses:

The primary use of cinnabar is as an ore of mercury. Mercury is extracted from cinnabar by heating the ore in a furnace in the presence of oxygen. This process releases mercury vapor, which is then condensed and collected.

Historically, cinnabar has also been used as a pigment. Its vibrant red color made it a popular pigment in ancient times, particularly in China (where it was called vermilion) and the Americas. However, due to its toxicity, its use as a pigment has largely been discontinued in modern times, although it can still be found in some traditional art forms.

Toxicity:

Cinnabar is highly toxic due to its mercury content. Ingestion or inhalation of cinnabar dust can lead to mercury poisoning, which can cause severe neurological damage, kidney problems, and other health issues. Handling cinnabar requires caution and appropriate safety measures to prevent exposure. Even though cinnabar is relatively insoluble in water, mercury can be released from cinnabar through microbial activity, making its presence in the environment a potential health concern.

Etymology:

The name "cinnabar" is believed to derive from the Persian word "zinjifrah," meaning "dragon's blood." This likely refers to its deep red color.

Related Minerals:

• Metacinnabar: A black, isometric form of HgS that is stable at higher temperatures than cinnabar.
• Hypercinnabar: Another polymorph of HgS, less common than cinnabar and metacinnabar.