Karchevskyite is a rare layered double hydroxide mineral typically found in the hydrothermal cavities of alkaline rocks. It forms delicate, thin, platy crystals that resemble other hydrotalcite-group members, often appearing in white to colorless aggregates.
Is this karchevskyite?
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 karchevskyite with a known reference. Karchevskyite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, pearly on cleavage surfaces.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: platy, spherical.
Often confused with
Karchevskyite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous, pearly on cleavage surfaces on Karchevskyite and satiny to greasy or waxy on Hydrotalcite.
How to tell apart: Luster reads vitreous, pearly on cleavage surfaces on Karchevskyite and pearly on Meixnerite.
Often found alongside karchevskyite
Minerals reported to co-occur with karchevskyite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₁₈Al₉(OH)₅₄Sr₂(CO₃)₉(H₂O)₆(H₃O)₅
- Mohs hardness
- 2
- Density
- 2.21 g/cm³
- Streak
- White
- Luster
- Vitreous, pearly on cleavage surfaces
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Platy, spherical
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A late-stage hydrothermal mineral, finely intergrown with quintinite-3T, in cavities in dolomite in a carbonatite complex
Where rockhounds find karchevskyite
Classic worldwide localities
- Zhelezny open-pit mine, Kovdor carbonatite massif, Kola Peninsula, Russia
Field-hunting tip
Where it forms: A late-stage hydrothermal mineral, finely intergrown with quintinite-3T, in cavities in dolomite in a carbonatite complex. If you start seeing dolomite, magnetite, strontium carbonate-fluorapatite in float, you are in the right ground. Typical habit: platy, spherical. Train your eye for that shape before scanning the outcrop.
Common questions
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Find karchevskyite on the map
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