Boulangerite is a lead antimony sulfosalt typically found as feathery or hair-like aggregates that give rise to its alternative name, plumosite. Collectors should look for its distinct metallic luster and brittle, fibrous habit when inspecting specimens from hydrothermal ore deposits.
Is this boulangerite?
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 boulangerite with a known reference. Boulangerite 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. Streak: brownish.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic, may be silky.
- 4Match the color rangeCompare against the expected color range: lead gray, blue gray, gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular, massive, plumose.
Often confused with
Boulangerite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Boulangerite leaves brownish, Jamesonite leaves black. grayish.
How to tell apart: Streak differs, so Boulangerite leaves brownish, Stibnite leaves lead-gray.
How to tell apart: Streak differs, so Boulangerite leaves brownish, Bournonite leaves steel-gray to iron-black; luster reads metallic, may be silky on Boulangerite and brilliant to dull on Bournonite.
Often found alongside boulangerite
Minerals reported to co-occur with boulangerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₅Sb₄S₁₁
- Mohs hardness
- 2.5-3
- Density
- 5.7-6.3 g/cm³
- Streak
- Brownish
- Luster
- Metallic, may be silky
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Acicular, massive, plumose
- Cleavage
- Distinct on {100}
- Rarity
- Uncommon
- Uses
- Collector, Ore of lead
- Host rock
- In hydrothermal veins formed at low to medium temperatures
Where rockhounds find boulangerite
Classic worldwide localities
- Iron Mountain mine, Superior, Mineral Co., Montana, USA
- Augusta Mountain, Gunnison Co., Colorado, USA
- Molières, Gard (type locality), and from Saint-Pons, Alpes-de-Haute-Provence, France
- Rings from Bottino, Tuscany, Italy
- Sala, Västmanland, Sweden
- Nasafjell, Lappland, Sweden
Field-hunting tip
Where it forms: In hydrothermal veins formed at low to medium temperatures. If you start seeing lead sulfosalts, galena, stibnite in float, you are in the right ground. Typical habit: acicular, massive, plumose. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify boulangerite?+
Where is boulangerite found?+
Is boulangerite safe to handle?+
What rocks look like boulangerite?+
What minerals are found with boulangerite?+
What kind of rock does boulangerite form in?+
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Find boulangerite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
