How to identify Peacock Ore

To correctly identify Peacock Ore (Bornite (iridescently tarnished)), 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, resembling a peacock's feathers.

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. Less commonly found as distinct crystals.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Crystals are rare, usually pseudocubic or dodecahedral, but most commonly found as massive, granular, or compact aggregates.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Poor to 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 sedimentary copper deposits. It is often found in association with other copper sulfides like chalcopyrite, chalcocite, and covellite.

Key Facts

Hardness

3 on the Mohs scale.

Specific Gravity

4.9-5.3.

Crystal System

Orthorhombic (pseudocubic).

Color

Reddish-brown to copper-red (fresh); iridescent blue, purple, red, green (tarnished).

Luster

Metallic.

Transparency

Opaque.

Fracture

Conchoidal to uneven.

Cleavage

Poor to indistinct on {111}.

Composition

Copper iron sulfide (Cu5FeS4).

Physical characteristics

• Crystal Habit: Typically massive, granular, or compact. Less commonly as pseudocubic or dodecahedral crystals.
• Cleavage Type: Poor to indistinct.
• Fracture Type: Conchoidal to uneven.
• Tenacity: Brittle.
• Luster Type: Metallic.

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