How to identify Bornite with Malachite

To correctly identify Bornite with Malachite (Bornite (Cu5FeS4) with Malachite (Cu2(CO3)(OH)2)), 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

   Bornite: Fresh surfaces are reddish-brown, quickly tarnishing to iridescent blue, purple, red, and green. Malachite: Bright green to dark green, often banded.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Bornite: Metallic. Malachite: Silky, vitreous, or dull (earthy).

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Bornite: Granular, massive, or rarely in cubic or dodecahedral crystals. Malachite: Botryoidal, mammillary, stalactitic, fibrous, or massive.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Bornite: Isometric system, typically massive, granular, or disseminated. Rarely as distorted cubes or dodecahedra. Malachite: Monoclinic system, typically forms botryoidal, mammillary, or stalactitic masses; also fibrous, radiating, or earthy. Rarely as small acicular crystals.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Bornite: Poor to indistinct on {111}. Malachite: Perfect on {001}, good on {100}.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Oxidized zones of copper sulfide deposits, hydrothermal veins, and contact metamorphic deposits where primary copper sulfides have been altered by weathering processes.

Key Facts

Hardness

Bornite: 3.0-3.25 (Mohs). Malachite: 3.5-4.0 (Mohs).

Specific Gravity

Bornite: 4.9-5.3. Malachite: 3.6-4.0.

Crystal System

Bornite: Isometric. Malachite: Monoclinic.

Color

Bornite: Reddish-brown, tarnishing to iridescent blue, purple, red, green. Malachite: Bright green to dark green.

Luster

Bornite: Metallic. Malachite: Silky, vitreous, dull.

Transparency

Bornite: Opaque. Malachite: Translucent to opaque.

Fracture

Bornite: Uneven to conchoidal. Malachite: Uneven to subconchoidal.

Cleavage

Bornite: Poor to indistinct. Malachite: Perfect on {001}, good on {100}.

Composition

Bornite: Copper iron sulfide (Cu5FeS4). Malachite: Copper carbonate hydroxide (Cu2(CO3)(OH)2).

Physical characteristics

• Crystal Habit: Bornite: Massive, granular, disseminated, rarely cubic or dodecahedral crystals. Malachite: Botryoidal, mammillary, stalactitic, fibrous, radiating, massive, rarely acicular crystals.
• Cleavage Type: Bornite: Poor/indistinct. Malachite: Perfect in one direction, good in another.
• Fracture Type: Bornite: Uneven to conchoidal. Malachite: Uneven to subconchoidal.
• Tenacity: Bornite: Brittle. Malachite: Brittle.
• Luster Type: Bornite: Metallic. Malachite: Silky, vitreous, dull.

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