Lapeyreite is a very rare copper arsenate mineral known primarily from its type locality in Utah. It typically occurs as small, delicate, dark pistachio-green bladed crystals often associated with other rare copper secondary minerals in oxidized hydrothermal zones.

Hardness

Mohs

Luster

Vitreous

Streak

Yellowish Green

Transparency

Transparent

mineralrare

Lapeyreite

Hardness: 3
Luster: Vitreous
Streak: Yellowish Green
Transparency: Transparent

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Is this lapeyreite?

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 lapeyreite with a known reference. Lapeyreite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Lapeyreite leaves a yellowish green streak.
3
Read the luster
Hold the specimen under a strong light. Lapeyreite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: dark pistachio-green.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: bladed crystals, aggregates.

Often confused with

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

mineral

Clinoclase

Mohs 2.5-3

How to tell apart: Streak differs, so Lapeyreite leaves yellowish green, Clinoclase leaves bluish-green.

Compare →

Often found alongside lapeyreite

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

All properties

Chemical formula: Cu₃O(AsO₄)(OH)₃
Mohs hardness: 3
Density: 4.38 g/cm³
Colors: Dark Pistachio-green
Streak: Yellowish Green
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Bladed Crystals, Aggregates
Cleavage: Good in One Direction
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Mineralized Veins

Where rockhounds find lapeyreite

Classic worldwide localities

Roua, Dme de Barrot, Departement Alpes-Maritimes, France

Field-hunting tip

Look in hydrothermal mineralized veins country, the host setting where lapeyreite typically forms. If you start seeing tyrolite, clinoclase, azurite in float, you are in the right ground. Field specimens usually show a bladed crystals, aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify lapeyreite?+

Mohs hardness is 3. It typically shows a vitreous luster. The streak is yellowish green. Common colors include dark pistachio-green.

Where is lapeyreite found?+

Notable localities include Roua, Dme de Barrot, Departement Alpes-Maritimes, France.

Is lapeyreite safe to handle?+

It contains toxic constituents. Contains arsenic and copper; avoid ingestion, inhalation of dust, or skin contact. Wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like lapeyreite?+

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

What minerals are found with lapeyreite?+

Lapeyreite commonly co-occurs with tyrolite, clinoclase, azurite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does lapeyreite form in?+

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

What is lapeyreite used for?+

Lapeyreite is used in collector.

Find lapeyreite on the map

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