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 — 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 — 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 — that is 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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