Pyrrhotite is a distinctive iron sulfide characterized by its bronzy, metallic luster and magnetic properties. It is often found in massive, granular forms and is a significant ore for nickel when found alongside pentlandite in magmatic sulfide deposits.
Is this pyrrhotite?
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 pyrrhotite with a known reference. Pyrrhotite sits at Mohs 3.5-4.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Pyrrhotite leaves a dark grey to black streak.
- 3Read the lusterHold the specimen under a strong light. Pyrrhotite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: bronze, brown, red-brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular, prismatic crystals or massive, granular aggregates.
Often confused with
Pyrrhotite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Pyrite is the harder of the two (Mohs 6-6.5 vs. 3.5-4.5); streak differs — Pyrrhotite leaves dark grey to black, Pyrite leaves greenish-black to brownish-black.
How to tell apart: Marcasite is the harder of the two (Mohs 6-6.5 vs. 3.5-4.5); streak differs — Pyrrhotite leaves dark grey to black, Marcasite leaves greyish-black.
How to tell apart: Streak differs — Pyrrhotite leaves dark grey to black, Pentlandite leaves light bronze-brown.
Often found alongside pyrrhotite
Minerals reported to co-occur with pyrrhotite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe₁₋ₓS
- Mohs hardness
- 3.5-4.5
- Density
- 4.58-4.65 g/cm³
- Streak
- Dark Grey to Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Tabular, Prismatic Crystals or Massive, Granular Aggregates
- Cleavage
- None
- Rarity
- Common
- Uses
- Collector, Ore
- Host rock
- Igneous and Metamorphic Rocks
- Typical price
- $5-50 for small specimens, $100+ for large cabinet pieces
Where rockhounds find pyrrhotite
19 mapped spotsClassic worldwide localities
- Sudbury, Ontario, Canada
- Dalnegorsk, Russia
- Santa Eulalia, Mexico
- Treptice, Czech Republic
Field-hunting tip
Look in igneous and metamorphic rocks country — that is the host setting where pyrrhotite typically forms. If you start seeing pentlandite, chalcopyrite, pyrite in float, you are in the right ground. Field specimens usually show a tabular, prismatic crystals or massive, granular aggregates habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Vermont, Idaho, Maine — start trip planning there.
Common questions
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Find pyrrhotite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
