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 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Avdoninite leaves a light blue streak.
- 3Read the lusterHold the specimen under a strong light. Avdoninite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: blue, green-blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular to prismatic crystals, crusts.
Often confused with
Avdoninite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Avdoninite leaves light blue, Eriochalcite leaves white.
How to tell apart: Atacamite is the harder of the two (Mohs 3-3.5 vs. 2); streak differs — Avdoninite leaves light blue, 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
- 2
- Density
- 3.31 g/cm³
- Colors
- Streak
- Light Blue
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular to Prismatic Crystals, Crusts
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Fumarole Sublimates in Volcanic Environments
- Typical price
- $50-300 per micro-specimen
Where rockhounds find avdoninite
Classic worldwide localities
- Tolbachik volcano, Kamchatka, Russia
Field-hunting tip
Look in fumarole sublimates in volcanic environments country — that is the host setting where avdoninite typically forms. If you start seeing tolbachite, eriochalcite, tenorite in float, you are in the right ground. Field specimens usually show a tabular to prismatic crystals, crusts habit, so 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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