Coccinite is a rare mercury iodide mineral that typically occurs as thin crusts or powdery coatings in mercury-rich deposits. It is known for its distinct deep red color which can change depending on temperature, reflecting its unstable nature in various environmental conditions.
Is this coccinite?
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 coccinite with a known reference. Coccinite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Coccinite leaves a yellowish-orange streak.
- 3Read the lusterHold the specimen under a strong light. Coccinite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: red, reddish-brown.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: crusts, coatings.
Often confused with
Coccinite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Coccinite leaves yellowish-orange, Cinnabar leaves scarlet.
How to tell apart: Streak differs, so Coccinite leaves yellowish-orange, Realgar leaves orange-red; luster reads adamantine on Coccinite and resinous on Realgar.
Often found alongside coccinite
Minerals reported to co-occur with coccinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- HgI₂
- Mohs hardness
- 2
- Density
- 6.2 g/cm³
- Colors
- Streak
- Yellowish-orange
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Crusts, Coatings
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Epithermal Mercury Deposits
- Typical price
- $50-500 depending on specimen size and quality
Where rockhounds find coccinite
Classic worldwide localities
- Mexico
- Italy
- Japan
Field-hunting tip
Look in epithermal mercury deposits country, the host setting where coccinite typically forms. If you start seeing cinnabar, mercury, sulfur in float, you are in the right ground. Field specimens usually show a crusts, coatings habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find coccinite on the map
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