Gustavite is a rare lead-silver-bismuth sulfosalt that typically occurs as small, metallic lead-gray masses within hydrothermal sulfide deposits. It is often challenging to identify macroscopically and usually requires laboratory confirmation such as X-ray diffraction or chemical analysis to distinguish it from other lead-bismuth sulfosalts like lillianite.
Is this gustavite?
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 gustavite with a known reference. Gustavite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Gustavite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Gustavite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: lead-gray, steel-gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive, granular, or anhedral grains.
Often confused with
Gustavite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Gustavite leaves black, Galena leaves lead-gray.
How to tell apart: Gustavite is noticeably harder (Mohs 3 vs. 2); streak differs — Gustavite leaves black, Bismuthinite leaves lead-gray.
Often found alongside gustavite
Minerals reported to co-occur with gustavite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PbAgBi₃S₆
- Mohs hardness
- 3
- Density
- 7.02 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Massive, Granular, Or Anhedral Grains
- Cleavage
- Poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Sulfide Veins
- Typical price
- $50-300 per specimen
Where rockhounds find gustavite
Classic worldwide localities
- Gustavsbergsgruvan, Dalarna, Sweden
- Boliden, Sweden
- Broken Hill, Australia
- Guanajuato, Mexico
Field-hunting tip
Look in hydrothermal sulfide veins country — that is the host setting where gustavite typically forms. If you start seeing galena, tetrahedrite, pyrite in float, you are in the right ground. Field specimens usually show a massive, granular, or anhedral grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find gustavite on the map
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