How to identify Chalcopyrite

To correctly identify Chalcopyrite (CuFeS2), 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

   Brassy yellow, often tarnishing to iridescent shades of blue, purple, red, and green. The fresh surface is distinctly brassy yellow.

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, when present, are usually small and tetrahedral or pseudotetrahedral.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Tetragonal, often forming pseudotetrahedral crystals, but more commonly found as massive, disseminated grains or irregular aggregates. Striations are rare.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Poor to indistinct on {011} and {112}. It typically fractures rather than cleaves cleanly.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Hydrothermal veins, porphyry copper deposits, skarns, volcanogenic massive sulfide (VMS) deposits, magmatic sulfide deposits, and sedimentary exhalative (SEDEX) deposits. It is a common accessory mineral in many igneous and metamorphic rocks.

Key Facts

Hardness

3.5-4 on the Mohs scale

Specific Gravity

4.1-4.3 g/cm³

Crystal System

Tetragonal

Color

Brassy yellow, often with iridescent tarnish

Luster

Metallic

Transparency

Opaque

Fracture

Uneven to conchoidal

Cleavage

Poor to indistinct

Composition

Copper iron sulfide (CuFeS2)

Physical characteristics

• Crystal Habit: Typically massive, disseminated, or granular. Crystals are rare, usually small pseudotetrahedra or sphenoids.
• Cleavage Type: Poor to indistinct on {011} and {112}. It tends to fracture rather than cleave.
• Fracture Type: Uneven to conchoidal.
• Tenacity: Brittle.
• Luster Type: Metallic.

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