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. Streak: black, with a slightly brownish tint.
- 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: triclinic. Typical habit: microscopic crystals, twinning common.
Often confused with
Twinnite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Twinnite leaves black, with a slightly brownish tint, Sartorite leaves chocolate-brown.
How to tell apart: Streak differs, so Twinnite leaves black, with a slightly brownish tint, Boulangerite leaves brownish.
How to tell apart: Twinnite is noticeably harder (Mohs 3.5 vs. 2.5); streak differs, so Twinnite leaves black, with a slightly brownish tint, Jamesonite leaves black. grayish.
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
- PbSbAsS₄
- Mohs hardness
- 3.5
- Density
- 5.26 g/cm³
- Colors
- Streak
- Black, with a slightly brownish tint
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Triclinic
- Crystal habit
- Microscopic crystals, twinning common
- Cleavage
- Perfect on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In marble with other lead sulfantimonides (Madoc, Canada)
Where rockhounds find twinnite
Classic worldwide localities
- Madoc (type locality), and in the Hemlo gold deposit, Thunder Bay district, Ontario, Canada
- Jas Roux deposit, 10 km east of Chapelle-en-Valgaudemar, Hautes-Alpes, France
- Rujevac Sb–Zn–Pb deposit, western Serbia
- Novoye, Khaydarkan, Fergana Valley, Alai Range, Kyrgyzstan
Field-hunting tip
Where it forms: In marble with other lead sulfantimonides (Madoc, Canada). If you start seeing chabournéite, pierrotite, parapierrotite in float, you are in the right ground. Typical habit: microscopic crystals, twinning common. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify twinnite?+
Where is twinnite found?+
Is twinnite safe to handle?+
What rocks look like twinnite?+
What minerals are found with twinnite?+
What kind of rock does twinnite form in?+
What is twinnite used for?+
Find twinnite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
