Eleomelanite is a rare potassium lead copper sulfate, typically black. It is a sublimate at an active volcanic fumarole. It was first described from the Arsenatnaya fumarole, Tolbachik Volcano, Kamchatka, Russia.
Is this eleomelanite?
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 eleomelanite with a known reference. Eleomelanite 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: dark green.
- 3Read the lusterHold the specimen under a strong light. Luster: oleaginous on crystal faces, vitreous on cleavage surfaces.
- 4Match the color rangeCompare against the expected color range: black, dark green in thin fragments.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive.
Often confused with
Eleomelanite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Ilmenite is the harder of the two (Mohs 5-6 vs. ~3); streak differs, so Eleomelanite leaves dark green, Ilmenite leaves black to reddish brown; luster reads oleaginous on crystal faces, vitreous on cleavage surfaces on Eleomelanite and metallic to submetallic on Ilmenite.
How to tell apart: Magnetite is the harder of the two (Mohs 5.5-6.5 vs. ~3); streak differs, so Eleomelanite leaves dark green, Magnetite leaves black; luster reads oleaginous on crystal faces, vitreous on cleavage surfaces on Eleomelanite and metallic to submetallic, may be dull on Magnetite.
Often found alongside eleomelanite
Minerals reported to co-occur with eleomelanite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (K₂Pb)Cu₄O₂(SO₄)₄
- Mohs hardness
- ~3
- Density
- 3.790 g/cm³
- Colors
- BlackDark green in thin fragments
- Streak
- Dark green
- Luster
- Oleaginous on crystal faces, vitreous on cleavage surfaces
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Massive
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A sublimate at an active volcanic fumarole
Where rockhounds find eleomelanite
Classic worldwide localities
- Arsenatnaya fumarole, Second scoria cone, Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik Volcano, Kamchatka, Russia
Field-hunting tip
Where it forms: A sublimate at an active volcanic fumarole. If you start seeing euchlorine, fedotovite, wulffite in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify eleomelanite?+
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What rocks look like eleomelanite?+
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Find eleomelanite on the map
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