Yakhontovite is a rare copper-bearing phyllosilicate mineral that typically forms as soft, earthy, or powdery coatings in oxidized copper deposits. It is best identified by its distinct sky-blue to greenish-blue color and association with other copper secondary minerals. Collectors often find it in the oxidation zones of hydrothermal veins where it has replaced other minerals.
Is this yakhontovite?
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 yakhontovite with a known reference. Yakhontovite 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: dull.
- 4Match the color rangeCompare against the expected color range: pistachio green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: aggregates.
Often confused with
Yakhontovite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Yakhontovite leaves light green, Chrysocolla leaves white when pure; luster reads dull on Yakhontovite and vitreous, porcelaneous, earthy on Chrysocolla.
How to tell apart: Streak differs, so Yakhontovite leaves light green, Allophane leaves white; luster reads dull on Yakhontovite and vitreous to earthy, waxy on Allophane.
Often found alongside yakhontovite
Minerals reported to co-occur with yakhontovite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,Na,K)₀.₂(Cu,Fe,Mg)₂Si₄O₁₀(OH)₂·3H₂O
- Mohs hardness
- 2-3
- Density
- 2.5 g/cm³
- Colors
- Pistachio green
- Streak
- Light green
- Luster
- Dull
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As veins and coatings in deeply oxidized sulfide-cassiterite ores
Where rockhounds find yakhontovite
Classic worldwide localities
- Pridorozhnoye [Roadside] tin deposit, right bank of the Silinka River, nine km from its confluence with the Amur River, near Komsomol'sk-on-Amur, Russia
Field-hunting tip
Where it forms: As veins and coatings in deeply oxidized sulfide-cassiterite ores. If you start seeing pyrrhotite, chalcopyrite, pyrite in float, you are in the right ground. Typical habit: aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify yakhontovite?+
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Is yakhontovite safe to handle?+
What rocks look like yakhontovite?+
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Find yakhontovite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
