Cinnabar is the primary ore of mercury and is easily recognized by its distinct, vibrant scarlet-red color and high density. It typically forms in hydrothermal veins associated with volcanic activity and is frequently found as massive, earthy, or granular crusts rather than well-formed crystals. Collectors should prioritize safety, as the mineral is toxic and can release hazardous mercury vapors if heated or improperly handled.
Is this cinnabar?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch cinnabar with a known reference. Cinnabar sits at Mohs 2-2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: scarlet.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine, inclining to metallic when dark; dull in friable material.
- 4Match the color rangeCompare against the expected color range: red, brownish-red, scarlet, lead gray, brown, brown pink, vermilion, gray.
- 5Look at form & habitCrystal system: trigonal. Typical habit: disseminated, druse, massive.
Often confused with
Cinnabar vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Cinnabar leaves scarlet, Realgar leaves red-orange to red; luster reads adamantine, inclining to metallic when dark; dull in friable material on Cinnabar and resinous to greasy on Realgar.
How to tell apart: Cuprite is the harder of the two (Mohs 3.5-4 vs. 2-2.5); streak differs, so Cinnabar leaves scarlet, Cuprite leaves brownish red, shining.
How to tell apart: Hematite is the harder of the two (Mohs 5-6 vs. 2-2.5); streak differs, so Cinnabar leaves scarlet, Hematite leaves cherry-red or reddish brown; luster reads adamantine, inclining to metallic when dark; dull in friable material on Cinnabar and metallic or submetallic to dull on Hematite.
Often found alongside cinnabar
Minerals reported to co-occur with cinnabar. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- HgS
- Mohs hardness
- 2-2.5
- Density
- 8.176 g/cm³
- Colors
- Streak
- Scarlet
- Luster
- Adamantine, inclining to metallic when dark; dull in friable material
- Transparency
- Transparent in thin pieces
- Crystal system
- Trigonal
- Crystal habit
- Disseminated, druse, massive
- Cleavage
- {1010}, perfect
- Rarity
- Uncommon
- Uses
- Collector, Pigment, Ore of mercury
- Host rock
- Formed from low-temperature hydrothermal solutions in veins, and in sedimentary, igneous, and metamorphic host rocks
Where rockhounds find cinnabar
16 mapped spotsClassic worldwide localities
- New Almaden, Santa Clara Co. and New Idria, San Benito Co., California, USA
- Terlingua, Brewster Co., Texas, USA
- Cahill mine, Poverty Peak district, Humboldt Co., and near Lovelock, Pershing Co., Nevada, USA
- Charcas, San Luis Potosí, Mexico
- Almadén, Ciudad Real Province, and Mieres, Asturias, Spain
- Hydercahn, in the Fergana basin, Kazakhstan
Field-hunting tip
Where it forms: Formed from low-temperature hydrothermal solutions in veins, and in sedimentary, igneous, and metamorphic host rocks. If you start seeing mercury, realgar, pyrite in float, you are in the right ground. Typical habit: disseminated, druse, massive. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Nevada, Utah, Arkansas. Start trip planning there.
More cinnabar photos
Common questions
How do you identify cinnabar?+
Where is cinnabar found?+
Can I find cinnabar in the United States?+
Is cinnabar safe to handle?+
What rocks look like cinnabar?+
What minerals are found with cinnabar?+
What kind of rock does cinnabar form in?+
What is cinnabar used for?+
Find cinnabar on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
