Bernardite is a rare thallium-arsenic sulfosalt primarily found at the Allchar deposit in North Macedonia. It typically occurs as small, flattened, deep-red to black tabular crystals that are highly sought after by systematic mineral collectors.
Is this bernardite?
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 bernardite with a known reference. Bernardite sits at Mohs 3-3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Bernardite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Bernardite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: red, dark red, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals.
Often confused with
Bernardite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Bernardite is noticeably harder (Mohs 3-3.5 vs. 1.5-2); streak differs — Bernardite leaves yellow, Realgar leaves orange-red; luster reads adamantine on Bernardite and resinous on Realgar.
How to tell apart: Bernardite is noticeably harder (Mohs 3-3.5 vs. 1.5-2); streak differs — Bernardite leaves yellow, Smithite leaves orange-red.
Often found alongside bernardite
Minerals reported to co-occur with bernardite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- TlAs₅S₈
- Mohs hardness
- 3-3.5
- Density
- 4.95 g/cm³
- Streak
- Yellow
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals
- Cleavage
- Good On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins in Carbonate Rocks
- Typical price
- $50-500 depending on specimen size and clarity
Where rockhounds find bernardite
Classic worldwide localities
- Allchar, North Macedonia
Field-hunting tip
Look in hydrothermal veins in carbonate rocks country — that is the host setting where bernardite typically forms. If you start seeing realgar, orpiment, pyrite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find bernardite on the map
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