Fischesserite is an extremely rare silver-gold selenide typically found in trace amounts in epithermal deposits. It is best identified by its association with other selenide minerals and metallic luster, usually requiring analytical verification due to its microscopic habit.
Is this fischesserite?
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 fischesserite with a known reference. Fischesserite sits at Mohs 2-2.5, 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.
- 4Match the color rangeCompare against the expected color range: silver white.
- 5Look at form & habitCrystal system: cubic. Typical habit: anhedral grains, massive, granular.
Often confused with
Fischesserite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Fischesserite leaves black, Petzite leaves grayish black.
How to tell apart: Streak differs, so Fischesserite leaves black, Eucairite leaves shining.
How to tell apart: Streak differs, so Fischesserite leaves black, Aguilarite leaves grayish black.
Often found alongside fischesserite
Minerals reported to co-occur with fischesserite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ag₃AuSe₂
- Mohs hardness
- 2-2.5
- Density
- 9.05 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Anhedral grains, massive, granular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Research
- Host rock
- In carbonate veins in epithermal precious metal deposits (Předbořice, Czech Republic)
Where rockhounds find fischesserite
Classic worldwide localities
- De Lamar mine, Silver City district, Owyhee Co., Idaho, USA
- Ken Snyder, Bonberger, and Eastern Star mines, Gold Circle district, Elko Co., Nevada, USA
- Předbořice uranium deposit, near Krásna Hora, Czech Republic (type locality)
- Hope’s Nose, Torquay, Devon, England
- Kidd Creek mine, near Timmins, Ontario, Canada
- Flamenco, Atacama, Chile
Field-hunting tip
Where it forms: In carbonate veins in epithermal precious metal deposits (Předbořice, Czech Republic). If you start seeing naumannite, clausthalite, permingeatite in float, you are in the right ground. Typical habit: anhedral grains, massive, granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify fischesserite?+
Where is fischesserite found?+
Is fischesserite safe to handle?+
What rocks look like fischesserite?+
What minerals are found with fischesserite?+
What kind of rock does fischesserite form in?+
What is fischesserite used for?+
Find fischesserite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
