Bernarlottiite is an extremely rare lead-arsenic sulfosalt found almost exclusively in the famous Lengenbach Quarry in Switzerland. It occurs as small, dark, metallic platy crystals embedded within dolomitic marble, often requiring microscopic examination for positive identification.

Hardness

3-3.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Bernarlottiite

Hardness: 3-3.5
Luster: Metallic
Streak: Black
Transparency: Opaque

No image

Is this bernarlottiite?

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 bernarlottiite with a known reference. Bernarlottiite sits at Mohs 3-3.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Bernarlottiite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Bernarlottiite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: black.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy crystals.

Often confused with

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

mineral

Sartorite

Mohs 3

How to tell apart: Streak differs — Bernarlottiite leaves black, Sartorite leaves chocolate-brown.

Often found alongside bernarlottiite

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

All properties

Chemical formula: Pb₁₆As₁₆S₃₅
Mohs hardness: 3-3.5
Density: 5.45 g/cm³
Colors: Black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Monoclinic
Crystal habit: Platy Crystals
Cleavage: Perfect On {001}
Rarity: Rare
Uses: Collector
Host rock: Dolomitic Marble
Typical price: $100-500+ for micro-specimens

Where rockhounds find bernarlottiite

Classic worldwide localities

Lengenbach Quarry, Binn Valley, Switzerland

Field-hunting tip

Look in dolomitic marble country — that is the host setting where bernarlottiite typically forms. If you start seeing sartorite, baumhauerite, realgar in float, you are in the right ground. Field specimens usually show a platy crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify bernarlottiite?+

Mohs hardness is 3-3.5. It typically shows a metallic luster. The streak is black. Common colors include black.

Where is bernarlottiite found?+

Notable localities include Lengenbach Quarry, Binn Valley, Switzerland.

How much is bernarlottiite worth?+

Typical asking prices fall in the range of $100-500+ for micro-specimens. Quality, size, and provenance can move individual specimens well outside that range.

Is bernarlottiite safe to handle?+

It contains toxic constituents. Contains lead and arsenic; wash hands thoroughly after handling and avoid inhaling dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like bernarlottiite?+

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

What minerals are found with bernarlottiite?+

Bernarlottiite commonly co-occurs with Sartorite, Baumhauerite, Realgar, Pyrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does bernarlottiite form in?+

Bernarlottiite typically forms in dolomitic marble. Working float back to the host body is the standard way to chase a fresh occurrence.

What is bernarlottiite used for?+

Bernarlottiite is used in collector.

Find bernarlottiite on the map

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