Polydymite is a rare nickel sulfide mineral often found within complex nickel-copper ore bodies. It typically presents as metallic, grayish-white masses or small octahedra, frequently occurring as a replacement for other nickel-bearing sulfides like pentlandite.
Is this polydymite?
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 polydymite with a known reference. Polydymite sits at Mohs 4.5-5.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Polydymite leaves a dark gray streak.
- 3Read the lusterHold the specimen under a strong light. Polydymite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: gray, grayish-white.
- 5Look at form & habitCrystal system: cubic. Typical habit: octahedral crystals, massive, granular.
Often confused with
Polydymite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Polydymite leaves dark gray, Linnaeite leaves black.
How to tell apart: Streak differs, so Polydymite leaves dark gray, Violarite leaves black.
How to tell apart: Streak differs, so Polydymite leaves dark gray, Pentlandite leaves light bronze-brown.
Often found alongside polydymite
Minerals reported to co-occur with polydymite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ni,Pt)₃S₄
- Mohs hardness
- 4.5-5.5
- Density
- 4.8 g/cm³
- Colors
- Streak
- Dark Gray
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Octahedral Crystals, Massive, Granular
- Cleavage
- Indistinct
- Rarity
- Rare
- Uses
- Collector, Ore of Nickel
- Host rock
- Nickel-copper Sulfide Deposits, Hydrothermal Veins
- Typical price
- $20-150 per specimen depending on crystal size
Where rockhounds find polydymite
Classic worldwide localities
- Sudbury, Ontario, Canada
- Kambalda, Western Australia, Australia
- Gladhammar, Sweden
- Siegen, Germany
Field-hunting tip
Look in nickel-copper sulfide deposits, hydrothermal veins country, the host setting where polydymite typically forms. If you start seeing pentlandite, millerite, chalcopyrite in float, you are in the right ground. Field specimens usually show a octahedral crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify polydymite?+
Where is polydymite found?+
How much is polydymite worth?+
Is polydymite safe to handle?+
What rocks look like polydymite?+
What minerals are found with polydymite?+
What kind of rock does polydymite form in?+
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Find polydymite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
