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, 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
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
