Valleriite is a rare copper-iron sulfide mineral known for its striking bronze-brown metallic luster and extremely soft, foliated habit. It is often mistaken for molybdenite or graphite due to its greasy feel and flaky nature, though its specific occurrence in copper-rich ore deposits helps distinguish it.
Is this valleriite?
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 valleriite with a known reference. Valleriite 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. Valleriite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Valleriite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: bronze-brown, blackish-brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: massive, foliated, scaly aggregates.
Often confused with
Valleriite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Valleriite leaves black, Molybdenite leaves greenish-gray.
How to tell apart: Pyrrhotite is the harder of the two (Mohs 3.5-4.5 vs. 1); streak differs, so Valleriite leaves black, Pyrrhotite leaves dark grey to black.
Often found alongside valleriite
Minerals reported to co-occur with valleriite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₄Fe₃S₇
- Mohs hardness
- 1
- Density
- 3.16 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Massive, Foliated, Scaly Aggregates
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Copper Deposits in Alkaline Igneous Complexes
- Typical price
- $20-150 thumbnail specimens
Where rockhounds find valleriite
Classic worldwide localities
- Palabora Mine, South Africa
- Kola Peninsula, Russia
- Sudbury, Ontario, Canada
- Boliden, Sweden
Field-hunting tip
Look in hydrothermal copper deposits in alkaline igneous complexes country, the host setting where valleriite typically forms. If you start seeing chalcopyrite, pentlandite, pyrrhotite in float, you are in the right ground. Field specimens usually show a massive, foliated, scaly aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find valleriite on the map
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