Volkonskoite is a rare chromium-bearing clay mineral known for its striking, intense green color. It typically occurs as massive coatings or crusts within sedimentary sequences and is historically prized as a pigment for oil painting.
Is this volkonskoite?
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 volkonskoite with a known reference. Volkonskoite sits at Mohs 1-2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: blue green.
- 3Read the lusterHold the specimen under a strong light. Luster: dull.
- 4Match the color rangeCompare against the expected color range: bright green, yellow, olive green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: scaly.
Often confused with
Volkonskoite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Volkonskoite leaves blue green, Celadonite leaves greenish white.
How to tell apart: Streak differs, so Volkonskoite leaves blue green, Glauconite leaves light green.
How to tell apart: Streak differs, so Volkonskoite leaves blue green, Chrysocolla leaves white when pure; luster reads dull on Volkonskoite and vitreous, porcelaneous, earthy on Chrysocolla.
Often found alongside volkonskoite
Minerals reported to co-occur with volkonskoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₀.₃(Cr,Mg)₂(Si,Al)₄O₁₀(OH)₂·4H₂O
- Mohs hardness
- 1-2
- Density
- 2.11-2.36 g/cm³
- Streak
- Blue green
- Luster
- Dull
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Scaly
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector, Pigment
- Host rock
- An epigenetic mineral in sandstones, conglomerates, and red beds, commonly filling voids from the decomposition of organic matter (Okhansk region, Russia); a weathering product of serpentinite (Gotse Delchev, Bulgaria)
Where rockhounds find volkonskoite
Classic worldwide localities
- Mt. Efimyatskaya, in the Okhansk region, middle Kama River area, Perm basin, Ural Mountains, Russia
- Belgorod-Dnestrovskii (Akkerman) area, Ukraine
- Gotse Delchev (Nevrokop), Pirin Mountains, Bulgaria
Field-hunting tip
Where it forms: An epigenetic mineral in sandstones, conglomerates, and red beds, commonly filling voids from the decomposition of organic matter (Okhansk region, Russia); a weathering product of serpentinite (Gotse Delchev, Bulgaria). If you start seeing chlorite, tridymite in float, you are in the right ground. Typical habit: scaly. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify volkonskoite?+
Where is volkonskoite found?+
What rocks look like volkonskoite?+
What minerals are found with volkonskoite?+
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Find volkonskoite on the map
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