How to identify Peacock Ore

To correctly identify Peacock Ore (Bornite (often treated to enhance iridescence)), check each of these features in order. Many rocks and minerals look alike, so cross-reference multiple properties before deciding.

Step-by-step identification

1. 1

   Color

   Overall color and any zoning or banding

   Freshly broken surfaces are reddish-brown to copper-red. Upon exposure to air, it rapidly tarnishes to iridescent shades of blue, purple, red, and green.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Metallic.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Typically massive, granular, or disseminated. Crystals are rare but can be cubic, dodecahedral, or octahedral.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Cubic system. Crystals are typically pseudocubic, dodecahedral, or octahedral, but often found as massive aggregates or disseminated grains.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Poor or indistinct on {111}.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Hydrothermal veins, contact metamorphic deposits, disseminated in mafic igneous rocks, and in the supergene enrichment zones of copper sulfide deposits.

Key Facts

Hardness

3 on the Mohs scale.

Specific Gravity

4.9-5.3 g/cm³.

Crystal System

Isometric (Cubic).

Color

Reddish-brown to copper-red, tarnishing to iridescent blue, purple, red, green.

Luster

Metallic.

Transparency

Opaque.

Fracture

Conchoidal to uneven.

Cleavage

Poor/indistinct on {111}.

Composition

Copper iron sulfide (Cu5FeS4).

Physical characteristics

• Crystal Habit: Typically massive, granular, or disseminated. Rarely as pseudocubic, dodecahedral, or octahedral crystals.
• Cleavage Type: Poor to indistinct, typically not observed in hand samples.
• Fracture Type: Conchoidal to uneven.
• Tenacity: Brittle.
• Luster Type: Metallic.

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