Robinsonite is a rare lead antimony sulfosalt that typically occurs as fibrous to needle-like gray aggregates in hydrothermal environments. It is often visually indistinguishable from other lead-antimony sulfosalts like jamesonite without formal analytical verification like X-ray diffraction. Collectors value it as an elusive species found primarily in complex sulfide deposit zones.
Is this robinsonite?
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 robinsonite with a known reference. Robinsonite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Robinsonite leaves a gray streak.
- 3Read the lusterHold the specimen under a strong light. Robinsonite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: lead-gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular or fibrous aggregates, striated laths.
Often confused with
Robinsonite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside robinsonite
Minerals reported to co-occur with robinsonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₄Sb₆S₁₃
- Mohs hardness
- 2.5
- Density
- 5.36 g/cm³
- Colors
- Streak
- Gray
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Acicular or Fibrous Aggregates, Striated Laths
- Cleavage
- Poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Sulfide Veins
- Typical price
- $50-300 per specimen
Where rockhounds find robinsonite
Classic worldwide localities
- Jas Roux, France
- Wolfsberg, Germany
- Madoc, Ontario, Canada
- Tintic district, Utah, USA
Field-hunting tip
Look in hydrothermal sulfide veins country — that is the host setting where robinsonite typically forms. If you start seeing galena, stibnite, pyrite in float, you are in the right ground. Field specimens usually show a acicular or fibrous aggregates, striated laths habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find robinsonite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
