Mercury sulfide and the primary ore of mercury. Has the highest refractive index of any mineral. Historically ground as vermillion pigment. Color: Bright red, brownish-red. Luster: Adamantine to dull. Streak: Scarlet red. Cleavage: Perfect in three directions. Hardness: 2-2.5. Transparency: Transparent to opaque. Crystal system: Hexagonal Trigonal. Chemical formula: HgS. Specific gravity: 8.0-8.2. Formation: Forms from low-temperature hydrothermal fluids near volcanic hot springs and in fractures. Common geological settings: Spain Almadén , China, Italy, USA California ; found near volcanic activity and hot springs. Common look-alikes and related entries: Realgar, Cuprite, Hematite. Specimen safety: Keep this mercury-bearing specimen intact and enclosed. Do not cut, grind, polish, streak, lick, heat, or use acid on it. Avoid creating or breathing dust or vapour, wash your hands with soap and water after handling, and keep it away from food, children, and pets.
Red minerals — Place this specimen in a broader field-identification workflow.
Sources, scope & corrections
These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.
Editorial owner
GeoMiner
Last updated
2026-03-30T14:36:58.771405+00:00
Review status
Published; not independently peer-reviewed
IMA–CNMNC List of Mineral Names — International Mineralogical Association. Official mineral-name, nomenclature, and classification records.
Mineral ID Key — Mineralogical Society of America. Physical-property identification methods, repeat-testing guidance, and limitations.
Mercury compounds — CDC/NIOSH. Official occupational-hazard, exposure-route, symptom, and protective-equipment information for mercury compounds.
Mercury sulfide and the primary ore of mercury. Has the highest refractive index of any mineral. Historically ground as vermillion pigment.
How can you identify Cinnabar?
Compare several properties rather than relying on colour alone. This entry records colour: Bright red, brownish-red; lustre: Adamantine to dull; streak: Scarlet red; Mohs hardness: 2-2.5; cleavage: Perfect in three directions; crystal system: Hexagonal Trigonal; transparency: Transparent to opaque. Confirm an important identification with additional field tests or qualified laboratory work.
How does Cinnabar form?
Forms from low-temperature hydrothermal fluids near volcanic hot springs and in fractures.
Where is Cinnabar commonly found?
Spain Almadén , China, Italy, USA California ; found near volcanic activity and hot springs.
Is Cinnabar safe to handle?
Keep this mercury-bearing specimen intact and enclosed. Do not cut, grind, polish, streak, lick, heat, or use acid on it. Avoid creating or breathing dust or vapour, wash your hands with soap and water after handling, and keep it away from food, children, and pets. Avoid creating dust or using destructive tests on an unknown specimen, and follow site-specific safety procedures.
What is Cinnabar commonly confused with?
Cinnabar may be confused with Realgar, Cuprite, Hematite. Compare multiple diagnostic properties because colour and surface appearance can overlap.
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