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. Streak: golden yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous.
- 4Match the color rangeCompare against the expected color range: grayish yellow, yellow brown.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: pseudo hexagonal, tabular.
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 golden yellow, Molybdenite leaves bluish gray; luster reads resinous on Berndtite and metallic on Molybdenite.
How to tell apart: Hematite is the harder of the two (Mohs 5-6 vs. 1-2); streak differs, so Berndtite leaves golden yellow, Hematite leaves cherry-red or reddish brown; luster reads resinous on Berndtite and metallic or submetallic to dull on Hematite.
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 g/cm³
- Streak
- Golden yellow
- Luster
- Resinous
- Transparency
- Translucent to transparent
- Crystal system
- Hexagonal
- Crystal habit
- Pseudo hexagonal, tabular
- Cleavage
- {0001}, marked
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral in tin sulfide ores (Cerro de Potosí, Bolivia); a secondary mineral in a tin-bearing pegmatite (Lagares-do-Estanho tin pegmatite)
Where rockhounds find berndtite
Classic worldwide localities
- Forestville, Northumberland Co., Pennsylvania, USA
- Stiepelmann mine, Arandis, Namibia
Field-hunting tip
Where it forms: A secondary mineral in tin sulfide ores (Cerro de Potosí, Bolivia); a secondary mineral in a tin-bearing pegmatite (Lagares-do-Estanho tin pegmatite). If you start seeing stannite, pyrite, cassiterite in float, you are in the right ground. Typical habit: pseudo hexagonal, tabular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify berndtite?+
Where is berndtite found?+
What rocks look like berndtite?+
What minerals are found with berndtite?+
What kind of rock does berndtite form in?+
What is berndtite used for?+
Find berndtite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
