Eldragónite is a rare copper bismuth selenide mineral identified in the Tuminico mine. It is typically found as small, metallic-brownish to light maroon anhedral grains intergrown with other rare selenide minerals in hydrothermal vein systems.
Is this eldragónite?
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 eldragónite with a known reference. Eldragónite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brownish black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: brownish.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: anhedral grains.
Often confused with
Eldragónite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Eldragónite is noticeably harder (Mohs 3.5 vs. 2.7); streak differs, so Eldragónite leaves brownish black, Berzelianite leaves shining.
How to tell apart: Streak differs, so Eldragónite leaves brownish black, Umangite leaves black.
How to tell apart: Streak differs, so Eldragónite leaves brownish black, Klockmannite leaves black.
Often found alongside eldragónite
Minerals reported to co-occur with eldragónite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₆BiSe₄(Se₂)
- Mohs hardness
- 3.5
- Density
- 6.76 g/cm³
- Colors
- Streak
- Brownish black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Anhedral grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Forms inclusions in compositionally zoned krut’aite masses, in a low-temperature hydrothermal vein-type deposit
Where rockhounds find eldragónite
Classic worldwide localities
- El Dragón mine, Quijarro Province, Department of Potosí, Bolivia
Field-hunting tip
Where it forms: Forms inclusions in compositionally zoned krut’aite masses, in a low-temperature hydrothermal vein-type deposit. If you start seeing krut’aite, clausthalite, klockmannite in float, you are in the right ground. Typical habit: anhedral grains. Train your eye for that shape before scanning the outcrop.
Common questions
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Find eldragónite on the map
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