Isocubanite is a rare high-temperature cubic polymorph of cubanite that typically occurs in complex sulfide ore deposits. It is often found intergrown with other copper-iron sulfides, requiring microscopic analysis or X-ray diffraction for definitive identification in the field.
Is this isocubanite?
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 isocubanite with a known reference. Isocubanite sits at Mohs 3.5, 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.
- 4Match the color rangeCompare against the expected color range: bronze.
- 5Look at form & habitCrystal system: cubic. Typical habit: massive, granular.
Often confused with
Isocubanite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Isocubanite leaves black, Chalcopyrite leaves greenish black.
How to tell apart: Streak differs, so Isocubanite leaves black, Pyrrhotite leaves dark grayish black.
Often found alongside isocubanite
Minerals reported to co-occur with isocubanite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CuFe₂S₃
- Mohs hardness
- 3.5
- Density
- 3.925 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Massive, granular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- In mixtures of sulfides formed around modern undersea “black smoker” chimneys; in hydrothermal copper sulfide deposits; in pumice from volcanic eruptions
Where rockhounds find isocubanite
Classic worldwide localities
- Kilauea, Hawaii, USA
- Axial Seamount, Juan de Fuca Ridge, northeast Pacific Ocean
- Talnakh area, Noril’sk region, western Siberia, Russia
- Tunaberg, Sweden
- Mooihoek mine, Lydenburg district, Transvaal, South Africa
- Strathcona mine, Sudbury, Ontario, Canada
Field-hunting tip
Where it forms: In mixtures of sulfides formed around modern undersea “black smoker” chimneys; in hydrothermal copper sulfide deposits; in pumice from volcanic eruptions. If you start seeing chalcopyrite, pyrrhotite, pyrite in float, you are in the right ground. Typical habit: massive, granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify isocubanite?+
Where is isocubanite found?+
Is isocubanite safe to handle?+
What rocks look like isocubanite?+
What minerals are found with isocubanite?+
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Find isocubanite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
