Twinnite is a rare lead-antimony sulfosalt mineral found primarily in metamorphic carbonate rocks. It is visually indistinguishable from other sulfosalts in the field and typically requires advanced analytical techniques like X-ray diffraction for positive identification.
Is this twinnite?
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 twinnite with a known reference. Twinnite 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. Twinnite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Twinnite 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: acicular crystals, massive, granular.
Often confused with
Twinnite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Twinnite leaves black, Sartorite leaves chocolate-brown.
How to tell apart: Streak differs — Twinnite leaves black, Boulangerite leaves brownish-gray.
How to tell apart: Twinnite is noticeably harder (Mohs 3.5 vs. 2.5); streak differs — Twinnite leaves black, Jamesonite leaves gray-black.
Often found alongside twinnite
Minerals reported to co-occur with twinnite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₁₄Sb₁₄S₃₃
- Mohs hardness
- 3.5
- Density
- 5.6-5.7 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Acicular Crystals, Massive, Granular
- Cleavage
- Poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Dolomite Rocks
- Typical price
- $50-500 thumbnail, $200-2000 cabinet
Where rockhounds find twinnite
Classic worldwide localities
- Binntal, Switzerland
- Radusa, North Macedonia
- Boldut, Romania
Field-hunting tip
Look in dolomite rocks country — that is the host setting where twinnite typically forms. If you start seeing sartorite, baumhauerite, galena in float, you are in the right ground. Field specimens usually show a acicular crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find twinnite on the map
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