How to identify Chalcopyrite with Malachite

To correctly identify Chalcopyrite with Malachite (CuFeS2 with 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

   Chalcopyrite: Brassy yellow, often with iridescent tarnish (blue, purple, red). Malachite: Bright green to dark green, often banded.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Chalcopyrite: Metallic. Malachite: Silky, dull, or earthy in massive forms; vitreous in crystalline forms.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Chalcopyrite: Crystalline, massive, granular. Malachite: Botryoidal, mammillary, stalactitic, fibrous, massive, earthy.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Chalcopyrite: Tetragonal, often pseudocubic or tetrahedral crystals, massive. Malachite: Monoclinic, typically forms aggregates, crusts, or radiating fibrous masses; rarely distinct crystals.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Chalcopyrite: Poor, indistinct {011}. Malachite: Perfect {001}, good {100} (rarely observed due to habit).

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in the oxidized zones of copper sulfide deposits, where primary chalcopyrite has been altered by circulating groundwater containing dissolved carbon dioxide.

Key Facts

Hardness

Chalcopyrite: 3.5-4 on Mohs scale. Malachite: 3.5-4 on Mohs scale.

Specific Gravity

Chalcopyrite: 4.1-4.3. Malachite: 3.9-4.03.

Crystal System

Chalcopyrite: Tetragonal. Malachite: Monoclinic.

Color

Chalcopyrite: Brassy yellow, often tarnished iridescent. Malachite: Bright green to dark green.

Luster

Chalcopyrite: Metallic. Malachite: Silky, dull, earthy, or vitreous.

Transparency

Chalcopyrite: Opaque. Malachite: Translucent to opaque.

Fracture

Chalcopyrite: Uneven to conchoidal. Malachite: Uneven to subconchoidal.

Cleavage

Chalcopyrite: Poor, indistinct {011}. Malachite: Perfect {001}, good {100}.

Composition

Chalcopyrite: Copper iron sulfide (CuFeS2). Malachite: Copper carbonate hydroxide (Cu2(CO3)(OH)2).

Physical characteristics

• Crystal Habit: Chalcopyrite: Tetrahedral, pseudocubic, massive, granular. Malachite: Botryoidal, mammillary, stalactitic, fibrous, massive, earthy, crusts.
• Cleavage Type: Chalcopyrite: Indistinct. Malachite: Perfect in one direction, good in another (rarely seen).
• Fracture Type: Uneven to conchoidal for both.
• Tenacity: Chalcopyrite: Brittle. Malachite: Brittle.
• Luster Type: Chalcopyrite: Metallic. Malachite: Silky, dull, earthy, or vitreous.

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