Barrotite is a rare copper aluminum arsenate, typically intense blue. It is a secondary mineral in sandstone. Associated minerals include chalcophyllite, malachite and cuprite. It was first described from the copper mines of Roua, Alpes-Maritimes, France.

Hardness

Mohs

Luster

Vitreous to Subadamantine

Streak

Pale Blue

Transparency

Transparent

mineralrare

Barrotite

Hardness: 2
Luster: Vitreous to Subadamantine
Streak: Pale Blue
Transparency: Transparent

No image

Is this barrotite?

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 barrotite with a known reference. Barrotite 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. Barrotite leaves a pale blue streak.
3
Read the luster
Hold the specimen under a strong light. Barrotite typically shows a vitreous to subadamantine luster.
4
Match the color range
Compare against the expected color range: intense blue.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: acicular crystals, radiating clusters.

Often confused with

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

mineral

Hemimorphite

Mohs 4.5-5

How to tell apart: Hemimorphite is the harder of the two (Mohs 4.5-5 vs. 2); streak differs, so Barrotite leaves pale blue, Hemimorphite leaves white; luster reads vitreous to subadamantine on Barrotite and vitreous on Hemimorphite.

Compare →

Often found alongside barrotite

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

All properties

Chemical formula: Cu₉Al(HSiO₄)₂[(SO₄)(HAsO₄)₀.₅](OH)₁₂·8H₂O
Mohs hardness: 2
Density: 2.90 g/cm³
Colors: Intense Blue
Streak: Pale Blue
Luster: Vitreous to Subadamantine
Transparency: Transparent
Crystal system: Hexagonal
Crystal habit: Acicular Crystals, Radiating Clusters
Cleavage: Perfect Mica-like On {001}
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins

Where rockhounds find barrotite

Classic worldwide localities

Barrois, France

Field-hunting tip

Look in hydrothermal veins country, the host setting where barrotite typically forms. If you start seeing calcite, smithsonite in float, you are in the right ground. Field specimens usually show a acicular crystals, radiating clusters habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify barrotite?+

Mohs hardness is 2. It typically shows a vitreous to subadamantine luster. The streak is pale blue. Common colors include intense blue.

Where is barrotite found?+

Notable localities include Barrois, France.

Is barrotite safe to handle?+

It contains toxic constituents. Contains arsenic, which is toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid creating dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like barrotite?+

Barrotite is most often confused with Hemimorphite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with barrotite?+

Barrotite commonly co-occurs with Calcite, Smithsonite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does barrotite form in?+

Barrotite typically forms in hydrothermal veins. Working float back to the host body is the standard way to chase a fresh occurrence.

What is barrotite used for?+

Barrotite is used in collector.

Find barrotite on the map

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