Troilite is a rare terrestrial sulfide, though it is the most common sulfide mineral found in iron meteorites. It typically occurs as bronze-colored, non-magnetic massive grains embedded within meteoritic iron-nickel alloys. Collectors primarily find this mineral as distinct inclusions within curated meteorite specimens rather than as individual terrestrial crystal specimens.
Is this troilite?
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 troilite with a known reference. Troilite 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. Streak: dark grayish brown.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: bronze brown, gray brown.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: massive, platy, tabular.
Often confused with
Troilite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Troilite leaves dark grayish brown, Pentlandite leaves pale bronze-brown.
How to tell apart: Pyrite is the harder of the two (Mohs 6-6.5 vs. 3.5-4.5); streak differs, so Troilite leaves dark grayish brown, Pyrite leaves greenish black to brownish black.
Often found alongside troilite
Minerals reported to co-occur with troilite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- FeS
- Mohs hardness
- 3.5-4.5
- Density
- 4.67-4.79 g/cm³
- Colors
- Streak
- Dark grayish brown
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Hexagonal
- Crystal habit
- Massive, platy, tabular
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Collector, Meteorite study
- Host rock
- In serpentine (Del Norte Co., California, USA); with Fe–Cu–Ni sulfides in a layered ultramafic intrusive (Sally Malay deposit, Australia); and as nodules in meteorites
Where rockhounds find troilite
Classic worldwide localities
- Alta mine, Del Norte Co., California, USA
- Wannaway Fe–Ni–Cu deposit, and at the Sally Malay Cu–Ni deposit, 120 km north of Halls Creek, Western Australia
- Panzhihua-Xichang district, Sichuan Province, China
- Disco Island and the Ilímaussaq intrusion, southern Greenland
- Nordfjellmark, Norway
Field-hunting tip
Where it forms: In serpentine (Del Norte Co., California, USA); with Fe–Cu–Ni sulfides in a layered ultramafic intrusive (Sally Malay deposit, Australia); and as nodules in meteorites. If you start seeing pyrrhotite, pentlandite, mackinawite in float, you are in the right ground. Typical habit: massive, platy, tabular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify troilite?+
Where is troilite found?+
What rocks look like troilite?+
What minerals are found with troilite?+
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Find troilite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
