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.

Hardness

3.5-4

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineraluncommon

Cubanite

Also: chalmersite

Hardness: 3.5-4
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this cubanite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch cubanite with a known reference. Cubanite sits at Mohs 3.5-4, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Cubanite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Cubanite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: brass-yellow, bronze-yellow.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: tabular crystals, massive, twinned blades.

Often confused with

Cubanite vs. its common look-alikes, and how to tell them apart in the field.

mineral

Chalcopyrite

Mohs 3.5-4

How to tell apart: Streak differs, so Cubanite leaves black, Chalcopyrite leaves greenish-black.

How to tell apart: Streak differs, so Cubanite leaves black, Pyrrhotite leaves dark grey to black.

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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: 3.5-4
Density: 4.07-4.18 g/cm³
Colors: Brass-yellow Bronze-yellow
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Tabular Crystals, Massive, Twinned Blades
Cleavage: Poor
Rarity: Uncommon
Uses: Collector, Research
Host rock: Hydrothermal Sulfide Deposits, Igneous Mafic Rocks
Typical price: $15-100 per specimen

Where rockhounds find cubanite

Classic worldwide localities

Mayarí, Cuba
Sudbury, Ontario, Canada
Morro Velho, Brazil
Voisey's Bay, Canada

Field-hunting tip

Look in hydrothermal sulfide deposits, igneous mafic rocks country, the host setting where cubanite typically forms. If you start seeing chalcopyrite, pyrrhotite, pentlandite in float, you are in the right ground. Field specimens usually show a tabular crystals, massive, twinned blades habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify cubanite?+

Mohs hardness is 3.5-4. It typically shows a metallic luster. The streak is black. Common colors include brass-yellow, bronze-yellow.

Where is cubanite found?+

Notable localities include Mayarí, Cuba; Sudbury, Ontario, Canada; Morro Velho, Brazil; Voisey's Bay, Canada.

How much is cubanite worth?+

Typical asking prices fall in the range of $15-100 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like cubanite?+

Cubanite is most often confused with Chalcopyrite, Pyrrhotite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with cubanite?+

Cubanite commonly co-occurs with Chalcopyrite, Pyrrhotite, Pentlandite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does cubanite form in?+

Cubanite typically forms in hydrothermal sulfide deposits, igneous mafic rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is cubanite used for?+

Cubanite is used in collector, research.

Find cubanite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.