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.
Is this allochalcoselite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch allochalcoselite with a known reference. Allochalcoselite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Allochalcoselite leaves a brown streak.
- 3Read the lusterHold the specimen under a strong light. Allochalcoselite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: dark gray, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals.
Often confused with
Allochalcoselite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Allochalcoselite leaves brown, Clausthalite leaves gray-black; luster reads adamantine on Allochalcoselite and metallic on Clausthalite.
How to tell apart: Streak differs, so Allochalcoselite leaves brown, Berzelianite leaves black; luster reads adamantine on Allochalcoselite and metallic on Berzelianite.
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
- 3-4
- Density
- 4.61 g/cm³
- Streak
- Brown
- Luster
- Adamantine
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals
- Cleavage
- Perfect On {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
Where rockhounds find allochalcoselite
Classic worldwide localities
- Second cinder cone of the northern breach of the Great Tolbachik Fissure Eruption, Kamchatka Region, Russia
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?+
Where is allochalcoselite found?+
Is allochalcoselite safe to handle?+
What rocks look like allochalcoselite?+
What minerals are found with allochalcoselite?+
What kind of rock does allochalcoselite form in?+
What is allochalcoselite used for?+
Find allochalcoselite on the map
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