Avdoninite is a rare copper chloride mineral found primarily in volcanic fumaroles. It typically forms as delicate, transparent blue tabular crystals and is highly sensitive to moisture, requiring dry storage conditions.
Is this avdoninite?
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 avdoninite with a known reference. Avdoninite sits at Mohs 3, 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: vitreous.
- 4Match the color rangeCompare against the expected color range: green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: druse, prismatic, tabular.
Often confused with
Avdoninite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Avdoninite leaves pale green, Eriochalcite leaves white.
How to tell apart: Streak differs, so Avdoninite leaves pale green, Atacamite leaves apple-green; luster reads vitreous on Avdoninite and adamantine to vitreous on Atacamite.
Often found alongside avdoninite
Minerals reported to co-occur with avdoninite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₂Cu₅Cl₈(OH)₄·2H₂O
- Mohs hardness
- 3
- Density
- 3.03 g/cm³
- Colors
- Streak
- Pale green
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Druse, prismatic, tabular
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A product of precipitation from fumarolic gases (Tolbachik Volcano, Russiaa); also reported as an alteration on massive sulfide ore exposed at the Earth’s surface
Where rockhounds find avdoninite
Classic worldwide localities
- Yadovitaya fumarole in the Second Cinder Cone at the Northern Breach of the Great Fissure Tolbachik Eruption, Tolbachik volcano, Kamchatka Peninsula, Russia (type locality)
Field-hunting tip
Where it forms: A product of precipitation from fumarolic gases (Tolbachik Volcano, Russiaa); also reported as an alteration on massive sulfide ore exposed at the Earth’s surface. If you start seeing euchlorite, paratacamite, belloite in float, you are in the right ground. Typical habit: druse, prismatic, tabular. Train your eye for that shape before scanning the outcrop.
Common questions
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Find avdoninite on the map
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