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, 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.
