Giessenite is a rare sulfosalt mineral primarily known from the Binnental region of Switzerland. It typically occurs as small, lead-gray acicular crystals or fibrous masses embedded in dolomitic marble, making it a prized specimen for collectors of rare sulfides and sulfosalts.
Is this giessenite?
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 giessenite with a known reference. Giessenite sits at Mohs ~2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: grayish black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: grayish black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular, pseudo orthorhombic.
Often confused with
Giessenite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Giessenite leaves grayish black, Galena leaves lead-gray.
How to tell apart: Streak differs, so Giessenite leaves grayish black, Bismuthinite leaves lead-gray.
Often found alongside giessenite
Minerals reported to co-occur with giessenite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Cu,Fe)₂Pb₂₆.₄(Bi,Sb)₁₉.₆S₅₇
- Mohs hardness
- ~2.5
- Density
- 7.45 g/cm³
- Colors
- Streak
- Grayish black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Acicular, pseudo orthorhombic
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Of hydrothermal origin, with other sulfides
Where rockhounds find giessenite
Classic worldwide localities
- Turtschi, between Giessen and Binn, about 2 km from the Lengenbach quarry, Binntal, Valais (type locality), Switzerland
- Lake Zervreila, Vals, Graubünden, Switzerland
- Bjørkåsen sulfide deposit, Otoften, Norway
- Vena mines, near Askersund, Örebro, Sweden
- Otome mine, Yamanashi Prefecture, Japan
Field-hunting tip
Where it forms: Of hydrothermal origin, with other sulfides. If you start seeing galena, pyrite, pyrrhotite in float, you are in the right ground. Typical habit: acicular, pseudo orthorhombic. Train your eye for that shape before scanning the outcrop.
Common questions
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Find giessenite on the map
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