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. Corderoite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Corderoite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: bright red, orange-red, yellowish-orange.
- 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 — Corderoite leaves yellow, Cinnabar leaves scarlet.
How to tell apart: Corderoite is noticeably harder (Mohs 3 vs. 1.5-2); streak differs — Corderoite leaves yellow, Calomel leaves white.
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
- 8.27 g/cm³
- Streak
- Yellow
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Cubic
- Crystal habit
- Massive, Crusts, Or Small Octahedral Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Mercury Deposits
- Typical price
- $50-500 depending on specimen size and quality
Where rockhounds find corderoite
Classic worldwide localities
- Cordero Mine, Nevada, USA
- New Almaden, California, USA
- Terlingua, Texas, USA
Field-hunting tip
Look in hydrothermal mercury deposits country — that is the host setting where corderoite typically forms. If you start seeing cinnabar, mercury, calomel in float, you are in the right ground. Field specimens usually show a massive, crusts, or small octahedral crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find corderoite on the map
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