Corderoite is a rare mercury halide mineral that forms in the oxidized zones of mercury deposits. It is best identified by its distinct bright red to orange color and high density, often found coating other mercury minerals.
Is this corderoite?
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 corderoite with a known reference. Corderoite sits at Mohs ~3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: light gray, light yellow, light orange pink, black.
- 5Look at form & habitCrystal system: cubic. Typical habit: massive, crusts, or small octahedral crystals.
Often confused with
Corderoite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Corderoite leaves yellow, Cinnabar leaves scarlet.
How to tell apart: Corderoite is noticeably harder (Mohs ~3 vs. 1.5); streak differs, so Corderoite leaves yellow, Calomel leaves pale yellowish white.
How to tell apart: Streak differs, so Corderoite leaves yellow, Terlinguaite leaves lemon-yellow, turning olive-green; luster reads adamantine on Corderoite and brilliant adamantine on Terlinguaite.
Often found alongside corderoite
Minerals reported to co-occur with corderoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Hg₃S₂Cl₂
- Mohs hardness
- ~3
- Density
- 6.74 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Adamantine
- Transparency
- Transparent
- Crystal system
- Cubic
- Crystal habit
- Massive, crusts, or small octahedral crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In lake-bed sediments and underlying silicified rhyolite tuffs, possibly of low-temperature secondary origin (McDermitt mine, Nevada, USA); in an oxidized hydrothermal deposit (Arzak deposit, Russia)
Where rockhounds find corderoite
Classic worldwide localities
- McDermitt mercury mine, Opalite district, Humboldt Co. (type locality), Nevada, USA
- Paradise Peak mine, Fairplay district, Nye Co., Nevada, USA
- Gold Quarry mine, near Carlin, Maggie Creek district, Eureka Co., Nevada, USA
- Arzak and Kadyrel mercury deposits, Tuva, Siberia, Russia
- Khaydarkan mercury deposit, Fergana Valley, Alai Range, Kyrgyzstan
- Landsberg, near Obermoschel, and from Königsberg, near Wolfstein, Rhineland-Palatinate, Germany
Field-hunting tip
Where it forms: In lake-bed sediments and underlying silicified rhyolite tuffs, possibly of low-temperature secondary origin (McDermitt mine, Nevada, USA); in an oxidized hydrothermal deposit (Arzak deposit, Russia). If you start seeing cinnabar, kleinite, kenhsuite in float, you are in the right ground. Typical habit: massive, crusts, or small octahedral crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify corderoite?+
Where is corderoite found?+
Is corderoite safe to handle?+
What rocks look like corderoite?+
What minerals are found with corderoite?+
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Find corderoite on the map
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