Alumoklyuchevskite is a rare copper-potassium sulfate mineral found exclusively in the volcanic fumarole deposits of the Tolbachik volcano in Russia. It typically occurs as small, elongated prismatic crystals in association with other rare fumarolic minerals.
Is this alumoklyuchevskite?
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 alumoklyuchevskite with a known reference. Alumoklyuchevskite sits at Mohs 2.3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: dark green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular, prismatic.
Often confused with
Alumoklyuchevskite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Langbeinite is the harder of the two (Mohs 3.5-4 vs. 2.3); streak differs, so Alumoklyuchevskite leaves light green, Langbeinite leaves white.
How to tell apart: Euchlorine is the harder of the two (Mohs 3 vs. 2.3); streak differs, so Alumoklyuchevskite leaves light green, Euchlorine leaves pistachio green.
Often found alongside alumoklyuchevskite
Minerals reported to co-occur with alumoklyuchevskite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₃Cu₃AlO₂(SO₄)₄
- Mohs hardness
- 2.3
- Density
- 3.1 g/cm³
- Colors
- Streak
- Light green
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Acicular, prismatic
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Deposited by fumarolic gases
Where rockhounds find alumoklyuchevskite
Classic worldwide localities
- Tolbachik fissure volcano, Kamchatka Peninsula, Russia
Field-hunting tip
Where it forms: Deposited by fumarolic gases. If you start seeing fedotovite, tenorite, lammerite in float, you are in the right ground. Typical habit: acicular, prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify alumoklyuchevskite?+
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Find alumoklyuchevskite on the map
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