Sternbergite is a rare silver-iron sulfide characterized by its distinct pinchbeck-brown color and metallic luster. It typically forms thin tabular crystals that exhibit deep striations and is most famous for its occurrences in the classic silver mining districts of Central Europe.
Is this sternbergite?
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 sternbergite with a known reference. Sternbergite sits at Mohs 1-1.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic, brilliant on {001}.
- 4Match the color rangeCompare against the expected color range: blue violet, golden brown.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: radial, twinning common.
Often confused with
Sternbergite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Pyrrhotite is the harder of the two (Mohs 3.5-4.5 vs. 1-1.5); streak differs, so Sternbergite leaves black, Pyrrhotite leaves dark grayish black.
How to tell apart: Cubanite is the harder of the two (Mohs 3.5 vs. 1-1.5).
How to tell apart: Chalcopyrite is the harder of the two (Mohs 3.5-4 vs. 1-1.5); streak differs, so Sternbergite leaves black, Chalcopyrite leaves greenish black.
Often found alongside sternbergite
Minerals reported to co-occur with sternbergite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AgFe₂S₃
- Mohs hardness
- 1-1.5
- Density
- 4.101-4.215 g/cm³
- Colors
- Blue violetGolden brown
- Streak
- Black
- Luster
- Metallic, brilliant on {001}
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Radial, twinning common
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In hydrothermal veins with other silver sulfosalt minerals and in Co–Ni–Ag sulfide assemblages
Where rockhounds find sternbergite
Classic worldwide localities
- Leroy mine, Dos Cabezas Mountains, Cochise Co., Arizona, USA
- Jáchymov (Joachimsthal) (type locality), at Příbram, and in the Krušné hory Mountains, at Měděnec, Czech Republic
- Johanngeorgenstadt, Freiberg, Marienberg, and Schneeberg, Saxony, and at St. Andreasberg, Harz Mountains, Germany
- Ruen Pb–Zn deposit, Osogovo region, Bulgaria
- Hiendelaencina, Guadalajara Province, Spain
- Akersberg mine, Oslo, Norway
Field-hunting tip
Where it forms: In hydrothermal veins with other silver sulfosalt minerals and in Co–Ni–Ag sulfide assemblages. If you start seeing stephanite, acanthite, proustite in float, you are in the right ground. Typical habit: radial, twinning common. Train your eye for that shape before scanning the outcrop.
Common questions
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Find sternbergite on the map
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