Ferrotochilinite is a rare, complex sulfide-hydroxide mineral belonging to the tochilinite group, typically found as microscopic platy or foliated aggregates. It is characterized by its metallic luster and black color, often occurring as an alteration product within serpentinized rocks associated with magnetite. Due to its scarcity, it is primarily sought after by advanced mineral collectors focusing on rare sulfide species.
Is this ferrotochilinite?
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 ferrotochilinite with a known reference. Ferrotochilinite sits at Mohs <1, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic (fresh), dull, or tarnishes to iridescent purplish or golden-brown.
- 4Match the color rangeCompare against the expected color range: dark bronze fresh, to nearly black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals or massive aggregates.
Often confused with
Ferrotochilinite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside ferrotochilinite
Minerals reported to co-occur with ferrotochilinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- 6FeS·5Fe(OH)₂
- Mohs hardness
- <1
- Density
- 3.467 g/cm³
- Colors
- Dark bronze freshTo nearly black
- Streak
- Black
- Luster
- Metallic (fresh), dull, or tarnishes to iridescent purplish or golden-brown
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Platy crystals or massive aggregates
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Of low-temperature hydrothermal origin coating cavities in pentlandite-mooihoekite-cubanite ore with minor magnetite and chalcopyrite
Where rockhounds find ferrotochilinite
Classic worldwide localities
- Shaft no 1, Oktyabr’skiy mine, Oktyabr’skoye Cu-Ni-PGM deposit, Talnakh, Norilsk district, Krasnoyarskiy Kray, Siberia, Russia
Field-hunting tip
Where it forms: Of low-temperature hydrothermal origin coating cavities in pentlandite-mooihoekite-cubanite ore with minor magnetite and chalcopyrite. If you start seeing ferrovalleriite, magnetite in float, you are in the right ground. Typical habit: platy crystals or massive aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferrotochilinite?+
Where is ferrotochilinite found?+
What rocks look like ferrotochilinite?+
What minerals are found with ferrotochilinite?+
What kind of rock does ferrotochilinite form in?+
What is ferrotochilinite used for?+
Find ferrotochilinite on the map
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