Julienite is a very rare cobalt thiocyanate mineral characterized by its distinct blue-green color and platy, micaceous habit. It is primarily found as crusts or small aggregates in oxidized copper-cobalt mines and is highly prized by advanced mineral collectors due to its unique chemical composition and scarcity.
Is this julienite?
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 julienite with a known reference. Julienite 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: blue.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly.
- 4Match the color rangeCompare against the expected color range: blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: encrustations.
Often confused with
Julienite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Julienite leaves blue, Chalcanthite leaves white; luster reads pearly on Julienite and vitreous to resinous on Chalcanthite.
How to tell apart: Streak differs, so Julienite leaves blue, Linarite leaves pale blue; luster reads pearly on Julienite and vitreous to subadamantine on Linarite.
All properties
- Chemical formula
- Na₂Co(NCS)₄·8H₂O
- Mohs hardness
- 2
- Density
- 1.648 g/cm³
- Colors
- Streak
- Blue
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Encrustations
- Cleavage
- K elongation
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A very rare incrustation on talc schist
Where rockhounds find julienite
Classic worldwide localities
- Chamibumba, near Kambove, Katanga Province, Congo (Shaba Province, Zaire)
Field-hunting tip
Where it forms: A very rare incrustation on talc schist. If you start seeing cobaltian wad in float, you are in the right ground. Typical habit: encrustations. Train your eye for that shape before scanning the outcrop.
Common questions
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Find julienite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
