Furutobeite is a rare copper-lead sulfide mineral primarily discovered in Japanese Kuroko-type volcanic-hosted massive sulfide deposits. It typically appears as lead-gray to black metallic masses embedded within complex sulfide ore assemblages. Collectors prioritize specimens from the type locality, often identifying it by its association with galena and chalcopyrite in polished sections.
Is this furutobeite?
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 furutobeite with a known reference. Furutobeite sits at Mohs 2.5-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Furutobeite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Furutobeite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: lead-gray, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive, granular, or fine-grained aggregates.
Often confused with
Furutobeite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside furutobeite
Minerals reported to co-occur with furutobeite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₆PbS₄
- Mohs hardness
- 2.5-3
- Density
- 6.25 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Massive, Granular, Or Fine-grained Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Kuroko-type Hydrothermal Massive Sulfide Deposits
- Typical price
- $50-300 per specimen depending on size and purity
Where rockhounds find furutobeite
Classic worldwide localities
- Furutobe mine, Akita Prefecture, Japan
Field-hunting tip
Look in kuroko-type hydrothermal massive sulfide deposits country — that is the host setting where furutobeite typically forms. If you start seeing galena, chalcopyrite, sphalerite in float, you are in the right ground. Field specimens usually show a massive, granular, or fine-grained aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find furutobeite on the map
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