Benjaminite is a rare silver-lead-bismuth sulfosalt that is typically found as small, lead-gray metallic grains within hydrothermal vein deposits. It is often challenging to identify in the field and usually requires microscopic analysis or X-ray diffraction to distinguish from other complex sulfide minerals. Collectors prize it as a rare example of silver-bismuth mineralization often found in association with other sulfosalts.
Is this benjaminite?
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 benjaminite with a known reference. Benjaminite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Benjaminite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Benjaminite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: lead-gray, white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive, granular, or fine-grained lamellar aggregates.
Often confused with
Benjaminite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Benjaminite is noticeably harder (Mohs 3.5 vs. 2.5); streak differs, so Benjaminite leaves black, Galena leaves lead-gray.
How to tell apart: Benjaminite is noticeably harder (Mohs 3.5 vs. 2-2.5); streak differs, so Benjaminite leaves black, Aikinite leaves lead-gray.
Often found alongside benjaminite
Minerals reported to co-occur with benjaminite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ag,Cu)₃(Bi,Pb)₇S₁₂
- Mohs hardness
- 3.5
- Density
- 6.57 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Massive, Granular, Or Fine-grained Lamellar Aggregates
- Cleavage
- Good On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $50-500 thumbnail
Where rockhounds find benjaminite
Classic worldwide localities
- Round Mountain, Nevada, USA
- Moctezuma, Sonora, Mexico
- Wolfsberg, Germany
- Hokkaido, Japan
Field-hunting tip
Look in hydrothermal veins country, the host setting where benjaminite typically forms. If you start seeing quartz, fluorite, galena in float, you are in the right ground. Field specimens usually show a massive, granular, or fine-grained lamellar aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find benjaminite on the map
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