Wallisite is an extremely rare lead-thallium sulfosalt mineral found almost exclusively in the famous Lengenbach Quarry in Switzerland. It typically occurs as small, dark metallic crystals associated with other complex sulfosalts in dolomite. Due to its toxicity and extreme rarity, it is highly sought after by advanced systematic mineral collectors.
Is this wallisite?
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 wallisite with a known reference. Wallisite 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.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: lead gray, black.
- 5Look at form & habitCrystal system: triclinic. Typical habit: massive.
Often confused with
Wallisite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Wallisite leaves black, Sartorite leaves chocolate-brown.
How to tell apart: Streak differs, so Wallisite leaves black, Liveingite leaves chocolate-brown.
How to tell apart: Streak differs, so Wallisite leaves black, Dufrénoysite leaves reddish brown to chocolate-brown; luster reads metallic on Wallisite and submetallic on Dufrénoysite.
Often found alongside wallisite
Minerals reported to co-occur with wallisite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PbTlCuAs₂S₅
- Mohs hardness
- 3.5
- Density
- 5.71 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Triclinic
- Crystal habit
- Massive
- Cleavage
- Pronounced on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Overgrowing other lead sulfosalts
Where rockhounds find wallisite
Classic worldwide localities
- Lengenbach quarry, Binntal, Valais, Switzerland
Field-hunting tip
Where it forms: Overgrowing other lead sulfosalts. If you start seeing dufrénoysite, rathite, pyrite in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify wallisite?+
Where is wallisite found?+
Is wallisite safe to handle?+
What rocks look like wallisite?+
What minerals are found with wallisite?+
What kind of rock does wallisite form in?+
What is wallisite used for?+
Find wallisite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
