Selenopolybasite is a rare selenium-dominant member of the polybasite group, typically found in low-temperature silver-rich hydrothermal veins. It usually appears as dark, metallic, pseudo-hexagonal tabular crystals that are difficult to distinguish visually from other members of the polybasite-pearceite series without laboratory analysis.
Is this selenopolybasite?
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 selenopolybasite with a known reference. Selenopolybasite sits at Mohs 2.5-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Selenopolybasite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Selenopolybasite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: black, iron-black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, massive, pseudo-hexagonal plates.
Often confused with
Selenopolybasite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside selenopolybasite
Minerals reported to co-occur with selenopolybasite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ag,Cu)₁₆(Sb,As)₂Se₉
- Mohs hardness
- 2.5-3
- Density
- 6.5-6.7 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Massive, Pseudo-hexagonal Plates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Epithermal Hydrothermal Veins
- Typical price
- $50-500 thumbnail depending on matrix and size
Where rockhounds find selenopolybasite
Classic worldwide localities
- Kremnitz, Slovakia
- Guanajuato, Mexico
- Freiberg, Germany
Field-hunting tip
Look in epithermal hydrothermal veins country — that is the host setting where selenopolybasite typically forms. If you start seeing acanthite, pyrargyrite, quartz in float, you are in the right ground. Field specimens usually show a tabular crystals, massive, pseudo-hexagonal plates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify selenopolybasite?+
Where is selenopolybasite found?+
How much is selenopolybasite worth?+
Is selenopolybasite safe to handle?+
What rocks look like selenopolybasite?+
What minerals are found with selenopolybasite?+
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Find selenopolybasite on the map
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