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 — Benjaminite leaves black, Galena leaves lead-gray.
How to tell apart: Benjaminite is noticeably harder (Mohs 3.5 vs. 2-2.5); streak differs — 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 — that is 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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