Jankovićite is an extremely rare thallium-antimony sulfosalt known primarily from the unique Allchar deposit in North Macedonia. It typically forms small, black tabular crystals that can be difficult to distinguish from associated arsenic sulfides without analytical testing.
Is this jankovićite?
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 jankovićite with a known reference. Jankovićite sits at Mohs ~2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brown-violet.
- 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: tabular.
Often confused with
Jankovićite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Jankovićite leaves brown-violet, Realgar leaves red-orange to red; luster reads metallic on Jankovićite and resinous to greasy on Realgar.
How to tell apart: Streak differs, so Jankovićite leaves brown-violet, Orpiment leaves pale lemon-yellow; luster reads metallic on Jankovićite and resinous, pearly on cleavage surface on Orpiment.
Often found alongside jankovićite
Minerals reported to co-occur with jankovićite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Tl₅Sb₉(As,Sb)₄S₂₂
- Mohs hardness
- ~2
- Density
- 5.08 g/cm³
- Colors
- Streak
- Brown-violet
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Triclinic
- Crystal habit
- Tabular
- Cleavage
- Perfect on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a hydrothermal Tl–Sb–As deposit, formed at low temperatures
Where rockhounds find jankovićite
Classic worldwide localities
- Crven Dol mine, Alšar (Allchar), near Rošden, Macedonia (type locality)
Field-hunting tip
Where it forms: In a hydrothermal Tl–Sb–As deposit, formed at low temperatures. If you start seeing realgar, stibnite, pyrite in float, you are in the right ground. Typical habit: tabular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify jankovićite?+
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Find jankovićite on the map
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