Ferrovalleriite is an extremely rare iron-rich member of the valleriite group, often appearing as soft, metallic flakes or thin coatings on other sulfide minerals. Due to its unstable nature and high sensitivity to air, it is primarily found in complex magmatic copper-nickel deposits and is highly sought after by advanced mineral collectors.
Is this ferrovalleriite?
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 ferrovalleriite with a known reference. Ferrovalleriite sits at Mohs 1, 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 (fresh), dull, or tarnishes to iridescent golden-brown.
- 4Match the color rangeCompare against the expected color range: dark bronze fresh, to nearly black.
- 5Look at form & habitCrystal system: trigonal. Typical habit: platy, foliated, massive.
Often confused with
Ferrovalleriite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Cubanite is the harder of the two (Mohs 3.5 vs. 1).
How to tell apart: Pyrrhotite is the harder of the two (Mohs 3.5-4.5 vs. 1); streak differs, so Ferrovalleriite leaves black, Pyrrhotite leaves dark grayish black.
Often found alongside ferrovalleriite
Minerals reported to co-occur with ferrovalleriite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- 2(Fe,Cu)S·1.53[(Fe,Al,Mg)(OH)₂]
- Mohs hardness
- 1
- Density
- 3.72 g/cm³
- Colors
- Dark bronze freshTo nearly black
- Streak
- Black
- Luster
- Metallic (fresh), dull, or tarnishes to iridescent golden-brown
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Platy, foliated, massive
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Of low-temperature hydrothermal origin coating cavities in pentlandite-mooihoekite-cubanite ore with minor magnetite and chalcopyrite
Where rockhounds find ferrovalleriite
Classic worldwide localities
- Talnakh, Russia
- Sudbury, Canada
- Bushveld, South Africa
Field-hunting tip
Where it forms: Of low-temperature hydrothermal origin coating cavities in pentlandite-mooihoekite-cubanite ore with minor magnetite and chalcopyrite. If you start seeing ferrotochilinite, magnetite, hibbingite in float, you are in the right ground. Typical habit: platy, foliated, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferrovalleriite?+
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Is ferrovalleriite safe to handle?+
What rocks look like ferrovalleriite?+
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Find ferrovalleriite on the map
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