Cylindrite is a fascinating sulfosalt mineral notable for its unique cylindrical or tubular crystal habit, often looking like tiny rolled-up scrolls or pipes. It is primarily found in the tin-silver deposits of the Oruro and Potosí departments of Bolivia. Collectors prize well-defined cylindrical specimens for their unusual morphology.
Is this cylindrite?
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 cylindrite with a known reference. Cylindrite sits at Mohs 2.5, 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: lead gray, grayish black.
- 5Look at form & habitCrystal system: triclinic. Typical habit: cylindrical, radial.
Often confused with
Cylindrite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Cylindrite leaves black, Franckeite leaves grayish black.
How to tell apart: Streak differs, so Cylindrite leaves black, Jamesonite leaves black. grayish.
How to tell apart: Cylindrite is noticeably harder (Mohs 2.5 vs. 1.5).
Often found alongside cylindrite
Minerals reported to co-occur with cylindrite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₃Sn₄FeSb₂S₁₄
- Mohs hardness
- 2.5
- Density
- 5.42-5.49 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Triclinic
- Crystal habit
- Cylindrical, radial
- Cleavage
- {100}, excellent
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- In tin-bearing hydrothermal veins
Where rockhounds find cylindrite
Classic worldwide localities
- Poopó, in the Santa Cruz (type locality) and Trinacria mines, Bolivia
- Porvenir and Maria Francisca mines, Huanuni, Bolivia
- Nueva Virginia vein, Colquechaca, Bolivia
- Purisima vein, all in Oruro, Bolivia
- Llallagua, Potosí, Bolivia
- Smirnovsk deposit, Transbaikalia, Russia
Field-hunting tip
Where it forms: In tin-bearing hydrothermal veins. If you start seeing franckeite, stannite, incaite in float, you are in the right ground. Typical habit: cylindrical, radial. Train your eye for that shape before scanning the outcrop.
Common questions
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Find cylindrite on the map
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