Valleyite (often spelled Valleriite) is an extremely soft, malleable sulfide mineral that typically occurs as small platy aggregates or coatings within copper-nickel sulfide ores. Due to its very low hardness and perfect cleavage, it is often mistaken for graphite or molybdenite, though its distinct bronze-brown metallic luster helps distinguish it. It is primarily found as an alteration product in ultramafic or hydrothermal sulfide deposits.
Is this valleyite?
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 valleyite with a known reference. Valleyite 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. Valleyite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Valleyite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: bronze-brown, black.
- 5Look at form & habitCrystal system: trigonal. Typical habit: platy crystals, foliated masses, or coatings.
Often confused with
Valleyite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside valleyite
Minerals reported to co-occur with valleyite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CuFeS₂·1.5Mg(OH)₂
- Mohs hardness
- 1
- Density
- 3.1-3.2 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Platy Crystals, Foliated Masses, Or Coatings
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Ore Deposits in Basic Igneous Rocks
- Typical price
- $20-100 per specimen
Where rockhounds find valleyite
Classic worldwide localities
- Boliden, Sweden
- Sudbury, Canada
- Bushveld Complex, South Africa
- Kola Peninsula, Russia
Field-hunting tip
Look in hydrothermal ore deposits in basic igneous rocks country — that is the host setting where valleyite typically forms. If you start seeing chalcopyrite, pentlandite, magnetite in float, you are in the right ground. Field specimens usually show a platy crystals, foliated masses, or coatings habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find valleyite on the map
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