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 — Coccinite leaves yellowish-orange, Cinnabar leaves scarlet.
How to tell apart: Streak differs — 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 — that is 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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