Cubanite is a brass-yellow sulfide mineral that is typically found as a result of exsolution from chalcopyrite-pyrrhotite solid solutions. It is best identified by its distinct bronze-yellow color and its frequent occurrence as characteristic twinned bladed crystals in hydrothermal ore deposits.
Is this cubanite?
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 cubanite with a known reference. Cubanite 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: brass yellow, bronze yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: striated.
Often confused with
Cubanite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside cubanite
Minerals reported to co-occur with cubanite. 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
- 4.03-4.18 g/cm³
- Colors
- Brass yellowBronze yellow
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Striated
- Cleavage
- Parting on {110} and {130}
- Rarity
- Uncommon
- Uses
- Collector, Research
- Host rock
- In hydrothermal deposits formed at relatively high temperature, in pyrrhotite–pentlandite ores in which it commonly occurs as intimate oriented intergrowths with chalcopyrite
Where rockhounds find cubanite
Classic worldwide localities
- Fierro, Grant Co., New Mexico, USA
- Christmas mine, Gila Co., Arizona, USA
- Prince William Sound, Alaska, USA
- Barracanao, Cuba (type locality)
- Strathcona mine, Sudbury, Ontario, Canada
- Chibougamau, Quebec, Canada
Field-hunting tip
Where it forms: In hydrothermal deposits formed at relatively high temperature, in pyrrhotite–pentlandite ores in which it commonly occurs as intimate oriented intergrowths with chalcopyrite. If you start seeing chalcopyrite, pyrite, pyrrhotite in float, you are in the right ground. Typical habit: striated. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify cubanite?+
Where is cubanite found?+
Is cubanite safe to handle?+
What rocks look like cubanite?+
What minerals are found with cubanite?+
What kind of rock does cubanite form in?+
What is cubanite used for?+
Find cubanite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
