Nuffieldite is a rare lead-copper-bismuth sulfosalt that typically occurs as fine acicular or fibrous crystals in hydrothermal ore deposits. It is best identified by its metallic lead-gray color and its specific mineral associations with other bismuth-rich species in localized mining districts.
Is this nuffieldite?
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 nuffieldite with a known reference. Nuffieldite 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. Nuffieldite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Nuffieldite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: lead-gray, tin-white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular to prismatic crystals, often as fibrous aggregates.
Often confused with
Nuffieldite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Nuffieldite is noticeably harder (Mohs 3.5 vs. 2-2.5); streak differs — Nuffieldite leaves black, Aikinite leaves lead-gray.
How to tell apart: Nuffieldite is noticeably harder (Mohs 3.5 vs. 2.5); streak differs — Nuffieldite leaves black, Galena leaves lead-gray.
How to tell apart: Streak differs — Nuffieldite leaves black, Bournonite leaves steel-gray.
Often found alongside nuffieldite
Minerals reported to co-occur with nuffieldite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₂CuPb₂(Pb,Bi)₂Bi₂S₇
- Mohs hardness
- 3.5
- Density
- 6.8 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular to Prismatic Crystals, Often as Fibrous Aggregates
- Cleavage
- Good On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Quartz-gold Veins
- Typical price
- $50-300 per specimen depending on size and crystal quality
Where rockhounds find nuffieldite
Classic worldwide localities
- Juno Mine, Tennant Creek, Northern Territory, Australia
- Wolfsberg, Harz Mountains, Germany
Field-hunting tip
Look in hydrothermal quartz-gold veins country — that is the host setting where nuffieldite typically forms. If you start seeing galena, bismuthinite, aikinite in float, you are in the right ground. Field specimens usually show a acicular to prismatic crystals, often as fibrous aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find nuffieldite on the map
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