Borodaevite is a rare silver-iron-antimony sulfosalt that typically occurs as microscopic grains or inclusions within larger metallic sulfides. It is primarily identified through electron microprobe analysis rather than macroscopic features due to its scarcity and typical mode of occurrence in ore assemblages.
Is this borodaevite?
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 borodaevite with a known reference. Borodaevite sits at Mohs 3.5, 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: gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: anhedral grains, inclusions.
Often confused with
Borodaevite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Borodaevite is noticeably harder (Mohs 3.5 vs. 2-2.5); streak differs, so Borodaevite leaves black, Stephanite leaves iron-black.
How to tell apart: Borodaevite is noticeably harder (Mohs 3.5 vs. 2.5); streak differs, so Borodaevite leaves black, Pyrargyrite leaves purplish red; luster reads metallic on Borodaevite and adamantine on Pyrargyrite.
Often found alongside borodaevite
Minerals reported to co-occur with borodaevite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ag₄.₈₃Fe₀.₂₁Pb₀.₄₅(Bi,Sb)₈.₈₄S₁₆
- Mohs hardness
- 3.5
- Density
- 7.9 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Anhedral grains, inclusions
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a hydrothermal Sn–W deposit
Where rockhounds find borodaevite
Classic worldwide localities
- Alaskitovoye Sn–W deposit, near Ust-Nera, Sakha, Russia (type locality)
Field-hunting tip
Where it forms: In a hydrothermal Sn–W deposit. If you start seeing matildite, gustavite–andorite, aramayoite in float, you are in the right ground. Typical habit: anhedral grains, inclusions. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify borodaevite?+
Where is borodaevite found?+
Is borodaevite safe to handle?+
What rocks look like borodaevite?+
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Find borodaevite on the map
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