Polybasite is a complex silver sulfosalt that often forms distinct pseudo-hexagonal tabular crystals. It is primarily found in silver-rich epithermal veins and is a key indicator mineral for high-grade silver deposits.
Is this polybasite?
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 polybasite with a known reference. Polybasite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: black, dark ruby red.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: granular, massive, pseudo hexagonal.
Often confused with
Polybasite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside polybasite
Minerals reported to co-occur with polybasite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- [Ag₉CuS₄][(Ag,Cu)₆(Sb,As)₂S₇]
- Mohs hardness
- 2-3
- Density
- 6.1 g/cm³
- Colors
- BlackDark ruby red
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Granular, massive, pseudo hexagonal
- Cleavage
- Imperfect on {001}
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- In silver veins of low to medium temperature of formation
Where rockhounds find polybasite
1 mapped spotsClassic worldwide localities
- Ouray district, Ouray Co., Colorado, USA
- Gilman district, Eagle Co., Colorado, USA
- Red Mountain district, San Juan Co., Colorado, USA
- Tonopah, Nye Co., Goldfield, Esmeralda Co., and in the Comstock Lode, Virginia City, Storey Co., Nevada, USA
- Neuer Morgenstern (type locality) and other mines, Freiberg, Saxony, and at St. Andreasberg, Harz Mountains, Germany
- Banská Hodruša, near Banská Štiavnica (Schemnitz), Slovakia
Field-hunting tip
Where it forms: In silver veins of low to medium temperature of formation. If you start seeing pyrargyrite, tetrahedrite, stephanite in float, you are in the right ground. Typical habit: granular, massive, pseudo hexagonal. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Montana. Start trip planning there.
Common questions
How do you identify polybasite?+
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Can I find polybasite in the United States?+
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Find polybasite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
