Yvonite is an extremely rare secondary copper arsenate mineral found primarily in the oxidation zone of polymetallic deposits. It typically forms delicate, needle-like acicular crystals or small, turquoise-blue radial sprays that are highly sought after by micromount collectors.

Hardness

3.5-4

Mohs

Luster

Vitreous

Streak

Blue

Transparency

Transparent

mineralrare

Yvonite

Hardness: 3.5-4
Luster: Vitreous
Streak: Blue
Transparency: Transparent

Is this yvonite?

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 yvonite with a known reference. Yvonite sits at Mohs 3.5-4, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: blue.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: turquoise blue.
5
Look at form & habit
Crystal system: triclinic. Typical habit: radial, spherical.

Often confused with

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

mineral

Conichalcite

Mohs 4.5

How to tell apart: Streak differs, so Yvonite leaves blue, Conichalcite leaves green.

How to tell apart: Streak differs, so Yvonite leaves blue, Mixite leaves pale bluish green.

Compare →

Often found alongside yvonite

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

All properties

Chemical formula: Cu(AsO₃OH)·2H₂O
Mohs hardness: 3.5-4
Density: 3.20 g/cm³
Colors: Turquoise blue
Streak: Blue
Luster: Vitreous
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Radial, spherical
Cleavage: On {100}, perfect; on {010}, poor
Rarity: Rare
Uses: Collector
Host rock: A secondary mineral formed on specimens from mine dumps at a gold-bearing arsenic sulfide deposit

Where rockhounds find yvonite

Classic worldwide localities

Salsigne mine, 15 km north of Carcassone, Aude, France

Field-hunting tip

Where it forms: A secondary mineral formed on specimens from mine dumps at a gold-bearing arsenic sulfide deposit. If you start seeing geminite, lindackerite, arsenopyrite in float, you are in the right ground. Typical habit: radial, spherical. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify yvonite?+

Mohs hardness is 3.5-4. Luster: vitreous. The streak is blue. Common colors include turquoise blue.

Where is yvonite found?+

Notable localities include Salsigne mine, 15 km north of Carcassone, Aude, France.

Is yvonite safe to handle?+

Yvonite contains arsenic and copper and calls for real care. Contains arsenic and copper; wash hands thoroughly after handling and avoid inhaling dust.

What rocks look like yvonite?+

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

What minerals are found with yvonite?+

Yvonite commonly co-occurs with Geminite, Lindackerite, Arsenopyrite, Bismuth, Chalcopyrite, Pushcharovskite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does yvonite form in?+

Where it forms: A secondary mineral formed on specimens from mine dumps at a gold-bearing arsenic sulfide deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is yvonite used for?+

Yvonite is used in collector.

Find yvonite on the map

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