Allochalcoselite is an extremely rare copper-lead-bismuth selenide mineral. It is primarily identified from the Predborice hydrothermal veins in the Czech Republic where it occurs in minute quantities associated with other selenide minerals.

Hardness

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Allochalcoselite

Hardness: 2
Luster: Metallic
Streak: Black
Transparency: Opaque

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Is this allochalcoselite?

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 allochalcoselite with a known reference. Allochalcoselite 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. Allochalcoselite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Allochalcoselite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: dark gray, black.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: tabular crystals.

Often confused with

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

mineral

Clausthalite

Mohs 2.5-3

How to tell apart: Streak differs, so Allochalcoselite leaves black, Clausthalite leaves gray-black.

Often found alongside allochalcoselite

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

All properties

Chemical formula: Cu⁺PbBiSe₃
Mohs hardness: 2
Density: 5.7 g/cm³
Colors: Dark Gray Black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Tabular Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins
Typical price: $100-500 for micro-mounts

Where rockhounds find allochalcoselite

Classic worldwide localities

Predborice, Czech Republic

Field-hunting tip

Look in hydrothermal veins country, the host setting where allochalcoselite typically forms. If you start seeing clausthalite, berzelianite, umangite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify allochalcoselite?+

Mohs hardness is 2. It typically shows a metallic luster. The streak is black. Common colors include dark gray, black.

Where is allochalcoselite found?+

Notable localities include Predborice, Czech Republic.

How much is allochalcoselite worth?+

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

Is allochalcoselite safe to handle?+

It contains toxic constituents. Contains selenium, lead, and copper. Handle with caution, avoid ingestion or inhalation of dust, and wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like allochalcoselite?+

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

What minerals are found with allochalcoselite?+

Allochalcoselite commonly co-occurs with Clausthalite, Berzelianite, Umangite, Klockmannite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does allochalcoselite form in?+

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

What is allochalcoselite used for?+

Allochalcoselite is used in collector.

Find allochalcoselite on the map

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