Berndtite is a rare tin sulfide mineral that typically occurs as soft, platy, metallic crystals. It is most commonly found in hydrothermal tin-bearing veins and is often identified by its perfect cleavage and association with cassiterite.
Is this berndtite?
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 berndtite with a known reference. Berndtite sits at Mohs 1-2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Berndtite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Berndtite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: black, brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: platy crystals, massive.
Often confused with
Berndtite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Berndtite leaves black, Molybdenite leaves greenish-gray.
How to tell apart: Iron Ore is the harder of the two (Mohs 5-6.5 vs. 1-2); streak differs — Berndtite leaves black, Iron Ore leaves reddish-brown to black; luster reads metallic on Berndtite and metallic to submetallic on Iron Ore.
Often found alongside berndtite
Minerals reported to co-occur with berndtite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SnS₂
- Mohs hardness
- 1-2
- Density
- 4.5-5.0 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Platy Crystals, Massive
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Tin Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find berndtite
Classic worldwide localities
- Chocaya mine, Bolivia
- Mount Bischoff, Tasmania
- Tanzania
Field-hunting tip
Look in hydrothermal tin deposits country — that is the host setting where berndtite typically forms. If you start seeing cassiterite, stannite, pyrite in float, you are in the right ground. Field specimens usually show a platy crystals, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find berndtite on the map
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