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 2-2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Klyuchevskite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Klyuchevskite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: green, yellow-green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, crusts, 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 — Klyuchevskite leaves white, Alumoklyuchevskite leaves pale green.
How to tell apart: Lammerite is the harder of the two (Mohs 3.5 vs. 2-2.5); streak differs — Klyuchevskite leaves white, Lammerite leaves light green.
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
- 2-2.5
- Density
- 3.32 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Crusts, Aggregates
- Cleavage
- None Observed
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Fumarolic Deposits of Volcanic Vents
- Typical price
- $50-300 per specimen
Where rockhounds find klyuchevskite
Classic worldwide localities
- Tolbachik volcano, Kamchatka Peninsula, Russia
Field-hunting tip
Look in fumarolic deposits of volcanic vents country — that is the host setting where klyuchevskite typically forms. If you start seeing alumoklyuchevskite, lammerite, tenorite in float, you are in the right ground. Field specimens usually show a tabular crystals, crusts, aggregates habit, so 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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