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 — Cubanite leaves black, Chalcopyrite leaves greenish-black.

How to tell apart: Streak differs — 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 — that is 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.