Bornite is a significant copper ore known for its distinctive iridescent tarnish that turns shades of blue and purple upon exposure to air, earning it the nickname 'peacock ore.' While typically found in massive, granular forms, it can occasionally present in poorly defined cubic or dodecahedral crystals associated with other sulfide minerals.
Is this bornite?
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 bornite with a known reference. Bornite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Bornite leaves a greyish black streak.
- 3Read the lusterHold the specimen under a strong light. Bornite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: copper red, bronze, iridescent blue, purple.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: massive, granular, or compact; rare cubic or dodecahedral crystals.
Often confused with
Bornite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Bornite leaves greyish black, Chalcopyrite leaves greenish-black.
How to tell apart: Bornite is noticeably harder (Mohs 3 vs. 1.5-2); streak differs — Bornite leaves greyish black, Covellite leaves lead gray to black.
How to tell apart: Streak differs — Bornite leaves greyish black, Chalcocite leaves lead-gray to black.
Often found alongside bornite
Minerals reported to co-occur with bornite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₅FeS₄
- Mohs hardness
- 3
- Density
- 4.9-5.3 g/cm³
- Streak
- Greyish Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Massive, Granular, Or Compact; Rare Cubic or Dodecahedral Crystals
- Cleavage
- None
- Rarity
- Common
- Uses
- Collector, Ore of Copper
- Host rock
- Hydrothermal Veins, Contact Metamorphic Deposits, And Igneous Rocks
- Typical price
- $5-50 thumbnail, $30-200 cabinet
Where rockhounds find bornite
32 mapped spotsClassic worldwide localities
- Butte, Montana, USA
- Cornwall, England
- Katanga, DR Congo
- Kazakhstan
- Mexico
U.S. states with bornite
Each link opens a state-specific list of mapped rockhounding spots that produce bornite.
Field-hunting tip
Look in hydrothermal veins, contact metamorphic deposits, and igneous rocks country — that is the host setting where bornite typically forms. If you start seeing chalcopyrite, pyrite, chalcocite in float, you are in the right ground. Field specimens usually show a massive, granular, or compact; rare cubic or dodecahedral crystals habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah, New Jersey, Wisconsin — start trip planning there.
Common questions
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Find bornite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
