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, so Gustavite leaves black, Galena leaves lead-gray.
How to tell apart: Gustavite is noticeably harder (Mohs 3 vs. 2); streak differs, so 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, 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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