Ciriottiite is a rare sulfosalt mineral primarily found in manganese-rich hydrothermal deposits in Italy. It typically occurs as small, dark brown to black anhedral grains associated with manganese oxides and various sulfides. Due to its extreme rarity and very small grain size, it is almost exclusively sought after by advanced systematic mineral collectors.
Is this ciriottiite?
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 ciriottiite with a known reference. Ciriottiite sits at Mohs 3-3.5, 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: black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: anhedral to subhedral grains.
Often confused with
Ciriottiite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside ciriottiite
Minerals reported to co-occur with ciriottiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₄Pb₁₉(Sb,As,Bi)₂₂(As₂)S₅₆
- Mohs hardness
- 3-3.5
- Density
- 5.918 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Anhedral to subhedral grains
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a vug in a quartz vein in a complex hydrothermal sulfide deposit
Where rockhounds find ciriottiite
Classic worldwide localities
- Espérance superiore tunnel, Tavagnasco Pb-Bi-Zn-As-Fe-Cu district, ~50 km north of Turin, Piedmont, Italy
Field-hunting tip
Where it forms: In a vug in a quartz vein in a complex hydrothermal sulfide deposit. If you start seeing arsenopyrite in float, you are in the right ground. Typical habit: anhedral to subhedral grains. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ciriottiite?+
Where is ciriottiite found?+
Is ciriottiite safe to handle?+
What rocks look like ciriottiite?+
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Find ciriottiite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
