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.

Hardness

Mohs

Luster

Pearly

Streak

Pale Blue

Transparency

Translucent

mineralrare

Julienite

Hardness: 2
Luster: Pearly
Streak: Pale Blue
Transparency: Translucent

Is this julienite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch julienite with a known reference. Julienite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Julienite leaves a pale blue streak.
3
Read the luster
Hold the specimen under a strong light. Julienite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: blue, blue-green.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: platy crystals, crusts, radial aggregates.

Often confused with

Julienite vs. its common look-alikes — and how to tell them apart in the field.

mineral

Chalcanthite

Mohs 2.5

How to tell apart: Streak differs — Julienite leaves pale blue, Chalcanthite leaves white; luster reads pearly on Julienite and vitreous on Chalcanthite.

How to tell apart: Luster reads pearly on Julienite and vitreous on Linarite.

Compare →

Often found alongside julienite

Minerals reported to co-occur with julienite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: Na₂Co(NCS)₄·8H₂O
Mohs hardness: 2
Density: 2.4 g/cm³
Colors: Blue Blue-green
Streak: Pale Blue
Luster: Pearly
Transparency: Translucent
Crystal system: Orthorhombic
Crystal habit: Platy Crystals, Crusts, Radial Aggregates
Cleavage: Perfect in One Direction
Rarity: Rare
Uses: Collector
Host rock: Oxidized Zones of Copper-cobalt Deposits
Typical price: $50-300 per specimen

Where rockhounds find julienite

Classic worldwide localities

Kamoto mine, Democratic Republic of the Congo

Field-hunting tip

Look in oxidized zones of copper-cobalt deposits country — that is the host setting where julienite typically forms. If you start seeing heterogenite, malachite, sphaerocobaltite in float, you are in the right ground. Field specimens usually show a platy crystals, crusts, radial aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify julienite?+

Mohs hardness is 2. It typically shows a pearly luster. The streak is pale blue. Common colors include blue, blue-green.

Where is julienite found?+

Notable localities include Kamoto mine, Democratic Republic of the Congo.

How much is julienite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is julienite safe to handle?+

It contains toxic constituents. Contains cobalt and thiocyanate; avoid inhalation of dust and wash hands thoroughly after handling. Should be stored in a sealed container as it is sensitive to humidity and light. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like julienite?+

Julienite is most often confused with Chalcanthite, Linarite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with julienite?+

Julienite commonly co-occurs with heterogenite, malachite, sphaerocobaltite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does julienite form in?+

Julienite typically forms in oxidized zones of copper-cobalt deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is julienite used for?+

Julienite is used in collector.

Find julienite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.