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. Isocubanite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Isocubanite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: brass-yellow, bronze-yellow.
- 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 — Isocubanite leaves black, Chalcopyrite leaves greenish-black.
How to tell apart: Streak differs — Isocubanite leaves black, Pyrrhotite leaves dark grey to 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
- 4.15 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Massive, Granular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Hydrothermal Sulfide Deposits, Magmatic Nickel-copper Deposits
- Typical price
- $20-100 per specimen
Where rockhounds find isocubanite
Classic worldwide localities
- Sudbury, Ontario, Canada
- Norilsk, Russia
- Kuroko-type deposits, Japan
- Huelva, Spain
Field-hunting tip
Look in hydrothermal sulfide deposits, magmatic nickel-copper deposits country — that is the host setting where isocubanite typically forms. If you start seeing chalcopyrite, pyrrhotite, pentlandite in float, you are in the right ground. Field specimens usually show a massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find isocubanite on the map
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