Coldwellite is a rare palladium silver sulfide that forms grains. It occurs in a heavy-mineral concentrate from a Cu-PGE-Au deposit, disseminated in gabbro. It was first described from Marathon Deposit, Coldwell Complex, Ontario, Canada.
Is this coldwellite?
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 coldwellite with a known reference. Coldwellite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Coldwellite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Coldwellite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: white, pale yellow.
- 5Look at form & habitCrystal system: cubic. Typical habit: grains.
Often confused with
Coldwellite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside coldwellite
Minerals reported to co-occur with coldwellite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pd₃Ag₂S
- Mohs hardness
- 3-4
- Density
- 9.90 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Alkaline Igneous Complex
Where rockhounds find coldwellite
Classic worldwide localities
- Coldwell Complex, Ontario, Canada
Field-hunting tip
Look in alkaline igneous complex country, the host setting where coldwellite typically forms. If you start seeing chalcopyrite, magnetite, ilmenite in float, you are in the right ground. Field specimens usually show a grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify coldwellite?+
Where is coldwellite found?+
What rocks look like coldwellite?+
What minerals are found with coldwellite?+
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Find coldwellite on the map
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