Klyuchevskite is an extremely rare sulfate mineral formed as a product of fumarolic activity at the Tolbachik volcano in Russia. It typically appears as bright green, thin tabular crystals or delicate encrustations inside volcanic vents. Collectors prize it for its unique chemical composition and highly specific type locality.
Is this klyuchevskite?
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 klyuchevskite with a known reference. Klyuchevskite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale green.
- 3Read the lusterHold the specimen under a strong light. Luster: submetallic.
- 4Match the color rangeCompare against the expected color range: dark green, olive green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular, aggregates.
Often confused with
Klyuchevskite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Klyuchevskite leaves pale green, Alumoklyuchevskite leaves light green; luster reads submetallic on Klyuchevskite and vitreous on Alumoklyuchevskite.
How to tell apart: Luster reads submetallic on Klyuchevskite and vitreous on Lammerite.
Often found alongside klyuchevskite
Minerals reported to co-occur with klyuchevskite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₃Cu₃Fe³⁺O₂(SO₄)₄
- Mohs hardness
- 2.5
- Density
- 3.00-3.15 g/cm³
- Colors
- Streak
- Pale green
- Luster
- Submetallic
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Acicular, aggregates
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In cavities in volcanic fumaroles
Where rockhounds find klyuchevskite
Classic worldwide localities
- Tolbachik fissure volcano, Kamchatka Peninsula, Russia
Field-hunting tip
Where it forms: In cavities in volcanic fumaroles. If you start seeing alarsite, fedotovite, lammerite in float, you are in the right ground. Typical habit: acicular, aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
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Find klyuchevskite on the map
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