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.

Hardness

3-4

Mohs

Luster

Metallic

Transparency

Opaque

mineralrare

Coldwellite

Hardness: 3-4
Luster: Metallic
Transparency: Opaque

No image

Is this coldwellite?

3-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch coldwellite with a known reference. Coldwellite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
2
Read the luster
Hold the specimen under a strong light. Luster: metallic.
3
Look at form & habit
Crystal 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
Luster: Metallic
Transparency: Opaque
Crystal system: Cubic
Crystal habit: Grains
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: In a heavy-mineral concentrate from a Cu-PGE-Au deposit,disseminated in gabbro

Where rockhounds find coldwellite

Classic worldwide localities

Marathon Deposit, Coldwell Complex, Ontario, Canada

Field-hunting tip

Where it forms: In a heavy-mineral concentrate from a Cu-PGE-Au deposit,disseminated in gabbro. If you start seeing au-ag alloy, hollingworthite, isoferroplatinum in float, you are in the right ground. Typical habit: grains. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify coldwellite?+

Mohs hardness is 3-4. Luster: metallic.

Where is coldwellite found?+

Notable localities include Marathon Deposit, Coldwell Complex, Ontario, Canada.

What rocks look like coldwellite?+

Coldwellite is most often confused with Stibiopalladinite, Geversite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with coldwellite?+

Coldwellite commonly co-occurs with Au-Ag alloy, Hollingworthite, Isoferroplatinum, Keithconnite, Kotulskite, Mertieite-II. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does coldwellite form in?+

Where it forms: In a heavy-mineral concentrate from a Cu-PGE-Au deposit,disseminated in gabbro. Working float back to the host body is the standard way to chase a fresh occurrence.

What is coldwellite used for?+

Coldwellite is used in collector.

Find coldwellite on the map

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