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Pentlandite
Pentlandite is sulfide (nickel iron), (Fe,Ni)₉S₈. In the hand, it rates 3.5 to 4 on the Mohs scale, and it runs bronze yellow and brassy brown. Bronze granular ore almost always married to magnetic pyrrhotite, the world's chief nickel mineral, itself stubbornly non-magnetic. Magmatic sulfide deposits: Sudbury (Ontario, Canada, meteor-impact nickel capital), Norilsk (Russia), Kambalda (Australia).
The geology.
Pentlandite carries the formula (Fe,Ni)₉S₈. It belongs to the isometric system. Catalogues list it as sulfide (nickel iron).
It sits at 3.5 to 4 on the Mohs scale. The surface reads metallic. Light behaviour is opaque. Specific gravity runs 4.6 to 5.0. The streak is light bronze-brown. It breaks with no cleavage; octahedral parting; uneven fracture.
Bronze granular ore almost always married to magnetic pyrrhotite, the world's chief nickel mineral, itself stubbornly non-magnetic.
It reaches buyers as granular masses with pyrrhotite, massive ore or polished ore slabs.
The origins.
Magmatic sulfide deposits: Sudbury (Ontario, Canada, meteor-impact nickel capital), Norilsk (Russia), Kambalda (Australia).
On value, the database notes: inexpensive ore specimen; Sudbury suites interest collectors.
Traditional associations.
In energy work traditions, pentlandite has little established lore; it is an ore-suite collector specimen.
We keep this section because people ask. It sits below the geology on purpose, and none of it describes something the stone does.
Spotting the real thing.
Bronze granular ore almost always married to magnetic pyrrhotite, the world's chief nickel mineral, itself stubbornly non-magnetic.
| Looks like | How to tell them apart |
|---|---|
| Pyrrhotite | The constant companion IS magnetic; pentlandite isn't, a magnet maps which bronze is which |
| Pyrite | Pyrite is paler brass and much harder |
| Chalcopyrite | Chalcopyrite is yellower with greenish-black streak |
At-home tests.
Before anyone talks you into a lab report, these are the checks worth doing yourself on pentlandite.
| Test | What you should see |
|---|---|
| Magnet check | Non-magnetic bronze patches within magnetic ore |
| By eye | Light bronze-brown streak |
| Scratch check | Knife scratches it |
Destructive tests belong to a gemologist, not a kitchen table. If a piece matters to you, pay for an appraisal before you take a file to it.
Care & handling.
At 3.5 to 4 on the Mohs scale this is a soft material. Keep it as a display piece, store it apart from harder stones, and skip daily-wear settings.
It breaks with no cleavage; octahedral parting; uneven fracture, which is worth knowing before you set it or drop it.
Clean it by hand, dry it properly, and keep it away from ultrasonic cleaners and hot steam.
A deeper look.
Extended detail on composition, sourcing, authentication and market value.
The physical record
The formula on record is (Fe,Ni)₉S₈. Crystal system: Isometric. Specific gravity: 4.6 to 5.0. Streak: Light bronze-brown. Cleavage and fracture: No cleavage; octahedral parting; uneven fracture.
How it reaches the market
Magmatic sulfide deposits: Sudbury (Ontario, Canada, meteor-impact nickel capital), Norilsk (Russia), Kambalda (Australia).
What it gets confused with
Pyrrhotite: The constant companion IS magnetic; pentlandite isn't, a magnet maps which bronze is which. Pyrite: Pyrite is paler brass and much harder. Chalcopyrite: Chalcopyrite is yellower with greenish-black streak.
What it is worth
Inexpensive ore specimen; Sudbury suites interest collectors.
One more thing
Sudbury's pentlandite riches sit in a 1.85-billion-year-old asteroid crater, stainless steel by way of cosmic catastrophe.
An education-first guide.
We do not stock pentlandite. Writing it up regardless is the point of a reference library.
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