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, so 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, so 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, 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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