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 — Polydymite leaves dark gray, Linnaeite leaves black.
How to tell apart: Streak differs — Polydymite leaves dark gray, Violarite leaves black.
How to tell apart: Streak differs — 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 — that is 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
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