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 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: microscopic crystals.
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
- (Cu,Ag)₆PbS₄
- Mohs hardness
- 3
- Density
- 6.74 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Microscopic crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In veinlets of stromeyerite that cut bornite in the Kuroko zone of a stratabound, Kuroko-type, massive sulfide deposit (Furutobe mine, Japan)
Where rockhounds find furutobeite
Classic worldwide localities
- Akita Prefecture, in the Daikokuzawa-Higashi deposit of the Furutobe mine (type locality), and the No. 11 deposit of the Shakanai mine, near Ohdate City, Japan
- Tsumeb, Namibia
- Erasmus mine, Leogang, Salzburg, Austria
Field-hunting tip
Where it forms: In veinlets of stromeyerite that cut bornite in the Kuroko zone of a stratabound, Kuroko-type, massive sulfide deposit (Furutobe mine, Japan). If you start seeing stromeyerite, bornite, galena in float, you are in the right ground. Typical habit: microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify furutobeite?+
Where is furutobeite found?+
Is furutobeite safe to handle?+
What rocks look like furutobeite?+
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Find furutobeite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
