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, so 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, so 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, 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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